#!/bin/sh
# Tcl ignores the next line -*- tcl -*- \
exec wish "$0" -- "$@"

# Copyright (C) 2005 Paul Mackerras.  All rights reserved.
# This program is free software; it may be used, copied, modified
# and distributed under the terms of the GNU General Public Licence,
# either version 2, or (at your option) any later version.

proc gitdir {} {
    global env
    if {[info exists env(GIT_DIR)]} {
        return $env(GIT_DIR)
    } else {
        return ".git"
    }
}

proc parse_args {rargs} {
    global parsed_args

    if {[catch {
        set parse_args [concat --default HEAD $rargs]
        set parsed_args [split [eval exec git-rev-parse $parse_args] "\n"]
    }]} {
        # if git-rev-parse failed for some reason...
        if {$rargs == {}} {
            set rargs HEAD
        }
        set parsed_args $rargs
    }
    return $parsed_args
}

proc start_rev_list {rlargs} {
    global startmsecs nextupdate ncmupdate
    global commfd leftover tclencoding datemode

    set startmsecs [clock clicks -milliseconds]
    set nextupdate [expr {$startmsecs + 100}]
    set ncmupdate 1
    set order "--topo-order"
    if {$datemode} {
        set order "--date-order"
    }
    if {[catch {
        set commfd [open [concat | git-rev-list --header $order \
                              --parents $rlargs] r]
    } err]} {
        puts stderr "Error executing git-rev-list: $err"
        exit 1
    }
    set leftover {}
    fconfigure $commfd -blocking 0 -translation lf
    if {$tclencoding != {}} {
        fconfigure $commfd -encoding $tclencoding
    }
    fileevent $commfd readable [list getcommitlines $commfd]
    . config -cursor watch
    settextcursor watch
}

proc getcommits {rargs} {
    global phase canv mainfont

    set phase getcommits
    start_rev_list [parse_args $rargs]
    $canv delete all
    $canv create text 3 3 -anchor nw -text "Reading commits..." \
        -font $mainfont -tags textitems
}

proc getcommitlines {commfd}  {
    global parents cdate children nchildren
    global commitlisted nextupdate
    global stopped leftover
    global canv

    set stuff [read $commfd]
    if {$stuff == {}} {
        if {![eof $commfd]} return
        # set it blocking so we wait for the process to terminate
        fconfigure $commfd -blocking 1
        if {![catch {close $commfd} err]} {
            after idle finishcommits
            return
        }
        if {[string range $err 0 4] == "usage"} {
            set err \
                "Gitk: error reading commits: bad arguments to git-rev-list.\
                (Note: arguments to gitk are passed to git-rev-list\
                to allow selection of commits to be displayed.)"
        } else {
            set err "Error reading commits: $err"
        }
        error_popup $err
        exit 1
    }
    set start 0
    while 1 {
        set i [string first "\0" $stuff $start]
        if {$i < 0} {
            append leftover [string range $stuff $start end]
            break
        }
        set cmit [string range $stuff $start [expr {$i - 1}]]
        if {$start == 0} {
            set cmit "$leftover$cmit"
            set leftover {}
        }
        set start [expr {$i + 1}]
        set j [string first "\n" $cmit]
        set ok 0
        if {$j >= 0} {
            set ids [string range $cmit 0 [expr {$j - 1}]]
            set ok 1
            foreach id $ids {
                if {![regexp {^[0-9a-f]{40}$} $id]} {
                    set ok 0
                    break
                }
            }
        }
        if {!$ok} {
            set shortcmit $cmit
            if {[string length $shortcmit] > 80} {
                set shortcmit "[string range $shortcmit 0 80]..."
            }
            error_popup "Can't parse git-rev-list output: {$shortcmit}"
            exit 1
        }
        set id [lindex $ids 0]
        set olds [lrange $ids 1 end]
        set cmit [string range $cmit [expr {$j + 1}] end]
        set commitlisted($id) 1
        parsecommit $id $cmit 1 [lrange $ids 1 end]
        drawcommit $id 1
    }
    layoutmore
    if {[clock clicks -milliseconds] >= $nextupdate} {
        doupdate 1
    }
}

proc doupdate {reading} {
    global commfd nextupdate numcommits ncmupdate

    if {$reading} {
        fileevent $commfd readable {}
    }
    update
    set nextupdate [expr {[clock clicks -milliseconds] + 100}]
    if {$numcommits < 100} {
        set ncmupdate [expr {$numcommits + 1}]
    } elseif {$numcommits < 10000} {
        set ncmupdate [expr {$numcommits + 10}]
    } else {
        set ncmupdate [expr {$numcommits + 100}]
    }
    if {$reading} {
        fileevent $commfd readable [list getcommitlines $commfd]
    }
}

proc readcommit {id} {
    if {[catch {set contents [exec git-cat-file commit $id]}]} return
    parsecommit $id $contents 0 {}
}

proc updatecommits {rargs} {
    stopfindproc
    foreach v {children nchildren parents nparents commitlisted
        commitinfo colormap selectedline matchinglines treediffs
        mergefilelist currentid rowtextx commitrow lineid
        rowidlist rowoffsets idrowranges idrangedrawn iddrawn
        linesegends crossings cornercrossings} {
        global $v
        catch {unset $v}
    }
    allcanvs delete all
    readrefs
    getcommits $rargs
}

proc updatechildren {id olds} {
    global children nchildren parents nparents

    if {![info exists nchildren($id)]} {
        set children($id) {}
        set nchildren($id) 0
    }
    set parents($id) $olds
    set nparents($id) [llength $olds]
    foreach p $olds {
        if {![info exists nchildren($p)]} {
            set children($p) [list $id]
            set nchildren($p) 1
        } elseif {[lsearch -exact $children($p) $id] < 0} {
            lappend children($p) $id
            incr nchildren($p)
        }
    }
}

proc parsecommit {id contents listed olds} {
    global commitinfo cdate

    set inhdr 1
    set comment {}
    set headline {}
    set auname {}
    set audate {}
    set comname {}
    set comdate {}
    updatechildren $id $olds
    set hdrend [string first "\n\n" $contents]
    if {$hdrend < 0} {
        # should never happen...
        set hdrend [string length $contents]
    }
    set header [string range $contents 0 [expr {$hdrend - 1}]]
    set comment [string range $contents [expr {$hdrend + 2}] end]
    foreach line [split $header "\n"] {
        set tag [lindex $line 0]
        if {$tag == "author"} {
            set audate [lindex $line end-1]
            set auname [lrange $line 1 end-2]
        } elseif {$tag == "committer"} {
            set comdate [lindex $line end-1]
            set comname [lrange $line 1 end-2]
        }
    }
    set headline {}
    # take the first line of the comment as the headline
    set i [string first "\n" $comment]
    if {$i >= 0} {
        set headline [string trim [string range $comment 0 $i]]
    } else {
        set headline $comment
    }
    if {!$listed} {
        # git-rev-list indents the comment by 4 spaces;
        # if we got this via git-cat-file, add the indentation
        set newcomment {}
        foreach line [split $comment "\n"] {
            append newcomment "    "
            append newcomment $line
            append newcomment "\n"
        }
        set comment $newcomment
    }
    if {$comdate != {}} {
        set cdate($id) $comdate
    }
    set commitinfo($id) [list $headline $auname $audate \
                             $comname $comdate $comment]
}

proc readrefs {} {
    global tagids idtags headids idheads tagcontents
    global otherrefids idotherrefs

    foreach v {tagids idtags headids idheads otherrefids idotherrefs} {
        catch {unset $v}
    }
    set refd [open [list | git-ls-remote [gitdir]] r]
    while {0 <= [set n [gets $refd line]]} {
        if {![regexp {^([0-9a-f]{40})   refs/([^^]*)$} $line \
            match id path]} {
            continue
        }
        if {![regexp {^(tags|heads)/(.*)$} $path match type name]} {
            set type others
            set name $path
        }
        if {$type == "tags"} {
            set tagids($name) $id
            lappend idtags($id) $name
            set obj {}
            set type {}
            set tag {}
            catch {
                set commit [exec git-rev-parse "$id^0"]
                if {"$commit" != "$id"} {
                    set tagids($name) $commit
                    lappend idtags($commit) $name
                }
            }           
            catch {
                set tagcontents($name) [exec git-cat-file tag "$id"]
            }
        } elseif { $type == "heads" } {
            set headids($name) $id
            lappend idheads($id) $name
        } else {
            set otherrefids($name) $id
            lappend idotherrefs($id) $name
        }
    }
    close $refd
}

proc error_popup msg {
    set w .error
    toplevel $w
    wm transient $w .
    message $w.m -text $msg -justify center -aspect 400
    pack $w.m -side top -fill x -padx 20 -pady 20
    button $w.ok -text OK -command "destroy $w"
    pack $w.ok -side bottom -fill x
    bind $w <Visibility> "grab $w; focus $w"
    tkwait window $w
}

proc makewindow {rargs} {
    global canv canv2 canv3 linespc charspc ctext cflist textfont
    global findtype findtypemenu findloc findstring fstring geometry
    global entries sha1entry sha1string sha1but
    global maincursor textcursor curtextcursor
    global rowctxmenu mergemax

    menu .bar
    .bar add cascade -label "File" -menu .bar.file
    menu .bar.file
    .bar.file add command -label "Update" -command [list updatecommits $rargs]
    .bar.file add command -label "Reread references" -command rereadrefs
    .bar.file add command -label "Quit" -command doquit
    menu .bar.edit
    .bar add cascade -label "Edit" -menu .bar.edit
    .bar.edit add command -label "Preferences" -command doprefs
    menu .bar.help
    .bar add cascade -label "Help" -menu .bar.help
    .bar.help add command -label "About gitk" -command about
    . configure -menu .bar

    if {![info exists geometry(canv1)]} {
        set geometry(canv1) [expr {45 * $charspc}]
        set geometry(canv2) [expr {30 * $charspc}]
        set geometry(canv3) [expr {15 * $charspc}]
        set geometry(canvh) [expr {25 * $linespc + 4}]
        set geometry(ctextw) 80
        set geometry(ctexth) 30
        set geometry(cflistw) 30
    }
    panedwindow .ctop -orient vertical
    if {[info exists geometry(width)]} {
        .ctop conf -width $geometry(width) -height $geometry(height)
        set texth [expr {$geometry(height) - $geometry(canvh) - 56}]
        set geometry(ctexth) [expr {($texth - 8) /
                                    [font metrics $textfont -linespace]}]
    }
    frame .ctop.top
    frame .ctop.top.bar
    pack .ctop.top.bar -side bottom -fill x
    set cscroll .ctop.top.csb
    scrollbar $cscroll -command {allcanvs yview} -highlightthickness 0
    pack $cscroll -side right -fill y
    panedwindow .ctop.top.clist -orient horizontal -sashpad 0 -handlesize 4
    pack .ctop.top.clist -side top -fill both -expand 1
    .ctop add .ctop.top
    set canv .ctop.top.clist.canv
    canvas $canv -height $geometry(canvh) -width $geometry(canv1) \
        -bg white -bd 0 \
        -yscrollincr $linespc -yscrollcommand "scrollcanv $cscroll"
    .ctop.top.clist add $canv
    set canv2 .ctop.top.clist.canv2
    canvas $canv2 -height $geometry(canvh) -width $geometry(canv2) \
        -bg white -bd 0 -yscrollincr $linespc
    .ctop.top.clist add $canv2
    set canv3 .ctop.top.clist.canv3
    canvas $canv3 -height $geometry(canvh) -width $geometry(canv3) \
        -bg white -bd 0 -yscrollincr $linespc
    .ctop.top.clist add $canv3
    bind .ctop.top.clist <Configure> {resizeclistpanes %W %w}

    set sha1entry .ctop.top.bar.sha1
    set entries $sha1entry
    set sha1but .ctop.top.bar.sha1label
    button $sha1but -text "SHA1 ID: " -state disabled -relief flat \
        -command gotocommit -width 8
    $sha1but conf -disabledforeground [$sha1but cget -foreground]
    pack .ctop.top.bar.sha1label -side left
    entry $sha1entry -width 40 -font $textfont -textvariable sha1string
    trace add variable sha1string write sha1change
    pack $sha1entry -side left -pady 2

    image create bitmap bm-left -data {
        #define left_width 16
        #define left_height 16
        static unsigned char left_bits[] = {
        0x00, 0x00, 0xc0, 0x01, 0xe0, 0x00, 0x70, 0x00, 0x38, 0x00, 0x1c, 0x00,
        0x0e, 0x00, 0xff, 0x7f, 0xff, 0x7f, 0xff, 0x7f, 0x0e, 0x00, 0x1c, 0x00,
        0x38, 0x00, 0x70, 0x00, 0xe0, 0x00, 0xc0, 0x01};
    }
    image create bitmap bm-right -data {
        #define right_width 16
        #define right_height 16
        static unsigned char right_bits[] = {
        0x00, 0x00, 0xc0, 0x01, 0x80, 0x03, 0x00, 0x07, 0x00, 0x0e, 0x00, 0x1c,
        0x00, 0x38, 0xff, 0x7f, 0xff, 0x7f, 0xff, 0x7f, 0x00, 0x38, 0x00, 0x1c,
        0x00, 0x0e, 0x00, 0x07, 0x80, 0x03, 0xc0, 0x01};
    }
    button .ctop.top.bar.leftbut -image bm-left -command goback \
        -state disabled -width 26
    pack .ctop.top.bar.leftbut -side left -fill y
    button .ctop.top.bar.rightbut -image bm-right -command goforw \
        -state disabled -width 26
    pack .ctop.top.bar.rightbut -side left -fill y

    button .ctop.top.bar.findbut -text "Find" -command dofind
    pack .ctop.top.bar.findbut -side left
    set findstring {}
    set fstring .ctop.top.bar.findstring
    lappend entries $fstring
    entry $fstring -width 30 -font $textfont -textvariable findstring
    pack $fstring -side left -expand 1 -fill x
    set findtype Exact
    set findtypemenu [tk_optionMenu .ctop.top.bar.findtype \
                          findtype Exact IgnCase Regexp]
    set findloc "All fields"
    tk_optionMenu .ctop.top.bar.findloc findloc "All fields" Headline \
        Comments Author Committer Files Pickaxe
    pack .ctop.top.bar.findloc -side right
    pack .ctop.top.bar.findtype -side right
    # for making sure type==Exact whenever loc==Pickaxe
    trace add variable findloc write findlocchange

    panedwindow .ctop.cdet -orient horizontal
    .ctop add .ctop.cdet
    frame .ctop.cdet.left
    set ctext .ctop.cdet.left.ctext
    text $ctext -bg white -state disabled -font $textfont \
        -width $geometry(ctextw) -height $geometry(ctexth) \
        -yscrollcommand ".ctop.cdet.left.sb set" -wrap none
    scrollbar .ctop.cdet.left.sb -command "$ctext yview"
    pack .ctop.cdet.left.sb -side right -fill y
    pack $ctext -side left -fill both -expand 1
    .ctop.cdet add .ctop.cdet.left

    $ctext tag conf filesep -font [concat $textfont bold] -back "#aaaaaa"
    $ctext tag conf hunksep -fore blue
    $ctext tag conf d0 -fore red
    $ctext tag conf d1 -fore "#00a000"
    $ctext tag conf m0 -fore red
    $ctext tag conf m1 -fore blue
    $ctext tag conf m2 -fore green
    $ctext tag conf m3 -fore purple
    $ctext tag conf m4 -fore brown
    $ctext tag conf m5 -fore "#009090"
    $ctext tag conf m6 -fore magenta
    $ctext tag conf m7 -fore "#808000"
    $ctext tag conf m8 -fore "#009000"
    $ctext tag conf m9 -fore "#ff0080"
    $ctext tag conf m10 -fore cyan
    $ctext tag conf m11 -fore "#b07070"
    $ctext tag conf m12 -fore "#70b0f0"
    $ctext tag conf m13 -fore "#70f0b0"
    $ctext tag conf m14 -fore "#f0b070"
    $ctext tag conf m15 -fore "#ff70b0"
    $ctext tag conf mmax -fore darkgrey
    set mergemax 16
    $ctext tag conf mresult -font [concat $textfont bold]
    $ctext tag conf msep -font [concat $textfont bold]
    $ctext tag conf found -back yellow

    frame .ctop.cdet.right
    set cflist .ctop.cdet.right.cfiles
    listbox $cflist -bg white -selectmode extended -width $geometry(cflistw) \
        -yscrollcommand ".ctop.cdet.right.sb set"
    scrollbar .ctop.cdet.right.sb -command "$cflist yview"
    pack .ctop.cdet.right.sb -side right -fill y
    pack $cflist -side left -fill both -expand 1
    .ctop.cdet add .ctop.cdet.right
    bind .ctop.cdet <Configure> {resizecdetpanes %W %w}

    pack .ctop -side top -fill both -expand 1

    bindall <1> {selcanvline %W %x %y}
    #bindall <B1-Motion> {selcanvline %W %x %y}
    bindall <ButtonRelease-4> "allcanvs yview scroll -5 units"
    bindall <ButtonRelease-5> "allcanvs yview scroll 5 units"
    bindall <2> "allcanvs scan mark 0 %y"
    bindall <B2-Motion> "allcanvs scan dragto 0 %y"
    bind . <Key-Up> "selnextline -1"
    bind . <Key-Down> "selnextline 1"
    bind . <Key-Right> "goforw"
    bind . <Key-Left> "goback"
    bind . <Key-Prior> "allcanvs yview scroll -1 pages"
    bind . <Key-Next> "allcanvs yview scroll 1 pages"
    bindkey <Key-Delete> "$ctext yview scroll -1 pages"
    bindkey <Key-BackSpace> "$ctext yview scroll -1 pages"
    bindkey <Key-space> "$ctext yview scroll 1 pages"
    bindkey p "selnextline -1"
    bindkey n "selnextline 1"
    bindkey z "goback"
    bindkey x "goforw"
    bindkey i "selnextline -1"
    bindkey k "selnextline 1"
    bindkey j "goback"
    bindkey l "goforw"
    bindkey b "$ctext yview scroll -1 pages"
    bindkey d "$ctext yview scroll 18 units"
    bindkey u "$ctext yview scroll -18 units"
    bindkey / {findnext 1}
    bindkey <Key-Return> {findnext 0}
    bindkey ? findprev
    bindkey f nextfile
    bind . <Control-q> doquit
    bind . <Control-f> dofind
    bind . <Control-g> {findnext 0}
    bind . <Control-r> findprev
    bind . <Control-equal> {incrfont 1}
    bind . <Control-KP_Add> {incrfont 1}
    bind . <Control-minus> {incrfont -1}
    bind . <Control-KP_Subtract> {incrfont -1}
    bind $cflist <<ListboxSelect>> listboxsel
    bind . <Destroy> {savestuff %W}
    bind . <Button-1> "click %W"
    bind $fstring <Key-Return> dofind
    bind $sha1entry <Key-Return> gotocommit
    bind $sha1entry <<PasteSelection>> clearsha1

    set maincursor [. cget -cursor]
    set textcursor [$ctext cget -cursor]
    set curtextcursor $textcursor

    set rowctxmenu .rowctxmenu
    menu $rowctxmenu -tearoff 0
    $rowctxmenu add command -label "Diff this -> selected" \
        -command {diffvssel 0}
    $rowctxmenu add command -label "Diff selected -> this" \
        -command {diffvssel 1}
    $rowctxmenu add command -label "Make patch" -command mkpatch
    $rowctxmenu add command -label "Create tag" -command mktag
    $rowctxmenu add command -label "Write commit to file" -command writecommit
}

proc scrollcanv {cscroll f0 f1} {
    $cscroll set $f0 $f1
    drawfrac $f0 $f1
}

# when we make a key binding for the toplevel, make sure
# it doesn't get triggered when that key is pressed in the
# find string entry widget.
proc bindkey {ev script} {
    global entries
    bind . $ev $script
    set escript [bind Entry $ev]
    if {$escript == {}} {
        set escript [bind Entry <Key>]
    }
    foreach e $entries {
        bind $e $ev "$escript; break"
    }
}

# set the focus back to the toplevel for any click outside
# the entry widgets
proc click {w} {
    global entries
    foreach e $entries {
        if {$w == $e} return
    }
    focus .
}

proc savestuff {w} {
    global canv canv2 canv3 ctext cflist mainfont textfont
    global stuffsaved findmergefiles maxgraphpct
    global maxwidth

    if {$stuffsaved} return
    if {![winfo viewable .]} return
    catch {
        set f [open "~/.gitk-new" w]
        puts $f [list set mainfont $mainfont]
        puts $f [list set textfont $textfont]
        puts $f [list set findmergefiles $findmergefiles]
        puts $f [list set maxgraphpct $maxgraphpct]
        puts $f [list set maxwidth $maxwidth]
        puts $f "set geometry(width) [winfo width .ctop]"
        puts $f "set geometry(height) [winfo height .ctop]"
        puts $f "set geometry(canv1) [expr {[winfo width $canv]-2}]"
        puts $f "set geometry(canv2) [expr {[winfo width $canv2]-2}]"
        puts $f "set geometry(canv3) [expr {[winfo width $canv3]-2}]"
        puts $f "set geometry(canvh) [expr {[winfo height $canv]-2}]"
        set wid [expr {([winfo width $ctext] - 8) \
                           / [font measure $textfont "0"]}]
        puts $f "set geometry(ctextw) $wid"
        set wid [expr {([winfo width $cflist] - 11) \
                           / [font measure [$cflist cget -font] "0"]}]
        puts $f "set geometry(cflistw) $wid"
        close $f
        file rename -force "~/.gitk-new" "~/.gitk"
    }
    set stuffsaved 1
}

proc resizeclistpanes {win w} {
    global oldwidth
    if {[info exists oldwidth($win)]} {
        set s0 [$win sash coord 0]
        set s1 [$win sash coord 1]
        if {$w < 60} {
            set sash0 [expr {int($w/2 - 2)}]
            set sash1 [expr {int($w*5/6 - 2)}]
        } else {
            set factor [expr {1.0 * $w / $oldwidth($win)}]
            set sash0 [expr {int($factor * [lindex $s0 0])}]
            set sash1 [expr {int($factor * [lindex $s1 0])}]
            if {$sash0 < 30} {
                set sash0 30
            }
            if {$sash1 < $sash0 + 20} {
                set sash1 [expr {$sash0 + 20}]
            }
            if {$sash1 > $w - 10} {
                set sash1 [expr {$w - 10}]
                if {$sash0 > $sash1 - 20} {
                    set sash0 [expr {$sash1 - 20}]
                }
            }
        }
        $win sash place 0 $sash0 [lindex $s0 1]
        $win sash place 1 $sash1 [lindex $s1 1]
    }
    set oldwidth($win) $w
}

proc resizecdetpanes {win w} {
    global oldwidth
    if {[info exists oldwidth($win)]} {
        set s0 [$win sash coord 0]
        if {$w < 60} {
            set sash0 [expr {int($w*3/4 - 2)}]
        } else {
            set factor [expr {1.0 * $w / $oldwidth($win)}]
            set sash0 [expr {int($factor * [lindex $s0 0])}]
            if {$sash0 < 45} {
                set sash0 45
            }
            if {$sash0 > $w - 15} {
                set sash0 [expr {$w - 15}]
            }
        }
        $win sash place 0 $sash0 [lindex $s0 1]
    }
    set oldwidth($win) $w
}

proc allcanvs args {
    global canv canv2 canv3
    eval $canv $args
    eval $canv2 $args
    eval $canv3 $args
}

proc bindall {event action} {
    global canv canv2 canv3
    bind $canv $event $action
    bind $canv2 $event $action
    bind $canv3 $event $action
}

proc about {} {
    set w .about
    if {[winfo exists $w]} {
        raise $w
        return
    }
    toplevel $w
    wm title $w "About gitk"
    message $w.m -text {
Gitk - a commit viewer for git

Copyright © 2005-2006 Paul Mackerras

Use and redistribute under the terms of the GNU General Public License} \
            -justify center -aspect 400
    pack $w.m -side top -fill x -padx 20 -pady 20
    button $w.ok -text Close -command "destroy $w"
    pack $w.ok -side bottom
}

proc shortids {ids} {
    set res {}
    foreach id $ids {
        if {[llength $id] > 1} {
            lappend res [shortids $id]
        } elseif {[regexp {^[0-9a-f]{40}$} $id]} {
            lappend res [string range $id 0 7]
        } else {
            lappend res $id
        }
    }
    return $res
}

proc incrange {l x o} {
    set n [llength $l]
    while {$x < $n} {
        set e [lindex $l $x]
        if {$e ne {}} {
            lset l $x [expr {$e + $o}]
        }
        incr x
    }
    return $l
}

proc ntimes {n o} {
    set ret {}
    for {} {$n > 0} {incr n -1} {
        lappend ret $o
    }
    return $ret
}

proc usedinrange {id l1 l2} {
    global children commitrow

    if {[info exists commitrow($id)]} {
        set r $commitrow($id)
        if {$l1 <= $r && $r <= $l2} {
            return [expr {$r - $l1 + 1}]
        }
    }
    foreach c $children($id) {
        if {[info exists commitrow($c)]} {
            set r $commitrow($c)
            if {$l1 <= $r && $r <= $l2} {
                return [expr {$r - $l1 + 1}]
            }
        }
    }
    return 0
}

proc sanity {row {full 0}} {
    global rowidlist rowoffsets

    set col -1
    set ids $rowidlist($row)
    foreach id $ids {
        incr col
        if {$id eq {}} continue
        if {$col < [llength $ids] - 1 &&
            [lsearch -exact -start [expr {$col+1}] $ids $id] >= 0} {
            puts "oops: [shortids $id] repeated in row $row col $col: {[shortids $rowidlist($row)]}"
        }
        set o [lindex $rowoffsets($row) $col]
        set y $row
        set x $col
        while {$o ne {}} {
            incr y -1
            incr x $o
            if {[lindex $rowidlist($y) $x] != $id} {
                puts "oops: rowoffsets wrong at row [expr {$y+1}] col [expr {$x-$o}]"
                puts "  id=[shortids $id] check started at row $row"
                for {set i $row} {$i >= $y} {incr i -1} {
                    puts "  row $i ids={[shortids $rowidlist($i)]} offs={$rowoffsets($i)}"
                }
                break
            }
            if {!$full} break
            set o [lindex $rowoffsets($y) $x]
        }
    }
}

proc makeuparrow {oid x y z} {
    global rowidlist rowoffsets uparrowlen idrowranges

    for {set i 1} {$i < $uparrowlen && $y > 1} {incr i} {
        incr y -1
        incr x $z
        set off0 $rowoffsets($y)
        for {set x0 $x} {1} {incr x0} {
            if {$x0 >= [llength $off0]} {
                set x0 [llength $rowoffsets([expr {$y-1}])]
                break
            }
            set z [lindex $off0 $x0]
            if {$z ne {}} {
                incr x0 $z
                break
            }
        }
        set z [expr {$x0 - $x}]
        set rowidlist($y) [linsert $rowidlist($y) $x $oid]
        set rowoffsets($y) [linsert $rowoffsets($y) $x $z]
    }
    set tmp [lreplace $rowoffsets($y) $x $x {}]
    set rowoffsets($y) [incrange $tmp [expr {$x+1}] -1]
    lappend idrowranges($oid) $y
}

proc initlayout {} {
    global rowidlist rowoffsets displayorder
    global rowlaidout rowoptim
    global idinlist rowchk

    set rowidlist(0) {}
    set rowoffsets(0) {}
    catch {unset idinlist}
    catch {unset rowchk}
    set rowlaidout 0
    set rowoptim 0
}

proc visiblerows {} {
    global canv numcommits linespc

    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax == 0} return
    set f [$canv yview]
    set y0 [expr {int([lindex $f 0] * $ymax)}]
    set r0 [expr {int(($y0 - 3) / $linespc) - 1}]
    if {$r0 < 0} {
        set r0 0
    }
    set y1 [expr {int([lindex $f 1] * $ymax)}]
    set r1 [expr {int(($y1 - 3) / $linespc) + 1}]
    if {$r1 >= $numcommits} {
        set r1 [expr {$numcommits - 1}]
    }
    return [list $r0 $r1]
}

proc layoutmore {} {
    global rowlaidout rowoptim commitidx numcommits optim_delay
    global uparrowlen

    set row $rowlaidout
    set rowlaidout [layoutrows $row $commitidx 0]
    set orow [expr {$rowlaidout - $uparrowlen - 1}]
    if {$orow > $rowoptim} {
        checkcrossings $rowoptim $orow
        optimize_rows $rowoptim 0 $orow
        set rowoptim $orow
    }
    set canshow [expr {$rowoptim - $optim_delay}]
    if {$canshow > $numcommits} {
        showstuff $canshow
    }
}

proc showstuff {canshow} {
    global numcommits
    global canvy0 linespc
    global linesegends idrowranges idrangedrawn

    set row $numcommits
    set numcommits $canshow
    allcanvs conf -scrollregion \
        [list 0 0 0 [expr {$canvy0 + ($numcommits - 0.5) * $linespc + 2}]]
    set rows [visiblerows]
    set r0 [lindex $rows 0]
    set r1 [lindex $rows 1]
    for {set r $row} {$r < $canshow} {incr r} {
        if {[info exists linesegends($r)]} {
            foreach id $linesegends($r) {
                set i -1
                foreach {s e} $idrowranges($id) {
                    incr i
                    if {$e ne {} && $e < $numcommits && $s <= $r1 && $e >= $r0
                        && ![info exists idrangedrawn($id,$i)]} {
                        drawlineseg $id $i 1
                        set idrangedrawn($id,$i) 1
                    }
                }
            }
        }
    }
    if {$canshow > $r1} {
        set canshow $r1
    }
    while {$row < $canshow} {
        drawcmitrow $row
        incr row
    }
}

proc layoutrows {row endrow last} {
    global rowidlist rowoffsets displayorder
    global uparrowlen downarrowlen maxwidth mingaplen
    global nchildren parents nparents
    global idrowranges linesegends
    global commitidx
    global idinlist rowchk

    set idlist $rowidlist($row)
    set offs $rowoffsets($row)
    while {$row < $endrow} {
        set id [lindex $displayorder $row]
        set oldolds {}
        set newolds {}
        foreach p $parents($id) {
            if {![info exists idinlist($p)]} {
                lappend newolds $p
            } elseif {!$idinlist($p)} {
                lappend oldolds $p
            }
        }
        set nev [expr {[llength $idlist] + [llength $newolds]
                       + [llength $oldolds] - $maxwidth + 1}]
        if {$nev > 0} {
            if {!$last && $row + $uparrowlen + $mingaplen >= $commitidx} break
            for {set x [llength $idlist]} {[incr x -1] >= 0} {} {
                set i [lindex $idlist $x]
                if {![info exists rowchk($i)] || $row >= $rowchk($i)} {
                    set r [usedinrange $i [expr {$row - $downarrowlen}] \
                               [expr {$row + $uparrowlen + $mingaplen}]]
                    if {$r == 0} {
                        set idlist [lreplace $idlist $x $x]
                        set offs [lreplace $offs $x $x]
                        set offs [incrange $offs $x 1]
                        set idinlist($i) 0
                        lappend linesegends($row) $i
                        lappend idrowranges($i) [expr {$row-1}]
                        if {[incr nev -1] <= 0} break
                        continue
                    }
                    set rowchk($id) [expr {$row + $r}]
                }
            }
            set rowidlist($row) $idlist
            set rowoffsets($row) $offs
        }
        set col [lsearch -exact $idlist $id]
        if {$col < 0} {
            set col [llength $idlist]
            lappend idlist $id
            set rowidlist($row) $idlist
            set z {}
            if {$nchildren($id) > 0} {
                set z [expr {[llength $rowidlist([expr {$row-1}])] - $col}]
                unset idinlist($id)
            }
            lappend offs $z
            set rowoffsets($row) $offs
            if {$z ne {}} {
                makeuparrow $id $col $row $z
            }
        } else {
            unset idinlist($id)
        }
        if {[info exists idrowranges($id)]} {
            lappend linesegends($row) $id
            lappend idrowranges($id) $row
        }
        incr row
        set offs [ntimes [llength $idlist] 0]
        set l [llength $newolds]
        set idlist [eval lreplace \$idlist $col $col $newolds]
        set o 0
        if {$l != 1} {
            set offs [lrange $offs 0 [expr {$col - 1}]]
            foreach x $newolds {
                lappend offs {}
                incr o -1
            }
            incr o
            set tmp [expr {[llength $idlist] - [llength $offs]}]
            if {$tmp > 0} {
                set offs [concat $offs [ntimes $tmp $o]]
            }
        } else {
            lset offs $col {}
        }
        foreach i $newolds {
            set idinlist($i) 1
            set idrowranges($i) $row
        }
        incr col $l
        foreach oid $oldolds {
            set idinlist($oid) 1
            set idlist [linsert $idlist $col $oid]
            set offs [linsert $offs $col $o]
            makeuparrow $oid $col $row $o
            incr col
        }
        set rowidlist($row) $idlist
        set rowoffsets($row) $offs
    }
    return $row
}

proc addextraid {id row} {
    global displayorder commitrow lineid commitinfo nparents
    global commitidx

    incr commitidx
    lappend displayorder $id
    set commitrow($id) $row
    set lineid($row) $id
    readcommit $id
    if {![info exists commitinfo($id)]} {
        set commitinfo($id) {"No commit information available"}
        set nparents($id) 0
    }
}

proc layouttail {} {
    global rowidlist rowoffsets idinlist commitidx
    global idrowranges linesegends

    set row $commitidx
    set idlist $rowidlist($row)
    while {$idlist ne {}} {
        set col [expr {[llength $idlist] - 1}]
        set id [lindex $idlist $col]
        addextraid $id $row
        unset idinlist($id)
        lappend linesegends($row) $id
        lappend idrowranges($id) $row
        incr row
        set offs [ntimes $col 0]
        set idlist [lreplace $idlist $col $col]
        set rowidlist($row) $idlist
        set rowoffsets($row) $offs
    }

    foreach id [array names idinlist] {
        addextraid $id $row
        set rowidlist($row) [list $id]
        set rowoffsets($row) 0
        makeuparrow $id 0 $row 0
        lappend linesegends($row) $id
        lappend idrowranges($id) $row
        incr row
    }
}

proc insert_pad {row col npad} {
    global rowidlist rowoffsets

    set pad [ntimes $npad {}]
    set rowidlist($row) [eval linsert \$rowidlist($row) $col $pad]
    set tmp [eval linsert \$rowoffsets($row) $col $pad]
    set rowoffsets($row) [incrange $tmp [expr {$col + $npad}] [expr {-$npad}]]
}

proc optimize_rows {row col endrow} {
    global rowidlist rowoffsets idrowranges

    for {} {$row < $endrow} {incr row} {
        set idlist $rowidlist($row)
        set offs $rowoffsets($row)
        set haspad 0
        for {} {$col < [llength $offs]} {incr col} {
            if {[lindex $idlist $col] eq {}} {
                set haspad 1
                continue
            }
            set z [lindex $offs $col]
            if {$z eq {}} continue
            set isarrow 0
            set x0 [expr {$col + $z}]
            set y0 [expr {$row - 1}]
            set z0 [lindex $rowoffsets($y0) $x0]
            if {$z0 eq {}} {
                set id [lindex $idlist $col]
                if {[info exists idrowranges($id)] &&
                    $y0 > [lindex $idrowranges($id) 0]} {
                    set isarrow 1
                }
            }
            if {$z < -1 || ($z < 0 && $isarrow)} {
                set npad [expr {-1 - $z + $isarrow}]
                set offs [incrange $offs $col $npad]
                insert_pad $y0 $x0 $npad
                if {$y0 > 0} {
                    optimize_rows $y0 $x0 $row
                }
                set z [lindex $offs $col]
                set x0 [expr {$col + $z}]
                set z0 [lindex $rowoffsets($y0) $x0]
            } elseif {$z > 1 || ($z > 0 && $isarrow)} {
                set npad [expr {$z - 1 + $isarrow}]
                set y1 [expr {$row + 1}]
                set offs2 $rowoffsets($y1)
                set x1 -1
                foreach z $offs2 {
                    incr x1
                    if {$z eq {} || $x1 + $z < $col} continue
                    if {$x1 + $z > $col} {
                        incr npad
                    }
                    set rowoffsets($y1) [incrange $offs2 $x1 $npad]
                    break
                }
                set pad [ntimes $npad {}]
                set idlist [eval linsert \$idlist $col $pad]
                set tmp [eval linsert \$offs $col $pad]
                incr col $npad
                set offs [incrange $tmp $col [expr {-$npad}]]
                set z [lindex $offs $col]
                set haspad 1
            }
            if {$z0 ne {} && $z < 0 && $z0 > 0} {
                insert_pad $y0 $x0 1
                set offs [incrange $offs $col 1]
                optimize_rows $y0 [expr {$x0 + 1}] $row
            }
        }
        if {!$haspad} {
            for {set col [llength $idlist]} {[incr col -1] >= 0} {} {
                set o [lindex $offs $col]
                if {$o eq {} || $o <= 0} break
            }
            if {[incr col] < [llength $idlist]} {
                set y1 [expr {$row + 1}]
                set offs2 $rowoffsets($y1)
                set x1 -1
                foreach z $offs2 {
                    incr x1
                    if {$z eq {} || $x1 + $z < $col} continue
                    set rowoffsets($y1) [incrange $offs2 $x1 1]
                    break
                }
                set idlist [linsert $idlist $col {}]
                set tmp [linsert $offs $col {}]
                incr col
                set offs [incrange $tmp $col -1]
            }
        }
        set rowidlist($row) $idlist
        set rowoffsets($row) $offs
        set col 0
    }
}

proc xc {row col} {
    global canvx0 linespc
    return [expr {$canvx0 + $col * $linespc}]
}

proc yc {row} {
    global canvy0 linespc
    return [expr {$canvy0 + $row * $linespc}]
}

proc drawlineseg {id i wid} {
    global rowoffsets rowidlist idrowranges
    global canv colormap lthickness

    set startrow [lindex $idrowranges($id) [expr {2 * $i}]]
    set row [lindex $idrowranges($id) [expr {2 * $i + 1}]]
    if {$startrow == $row} return
    assigncolor $id
    set coords {}
    set col [lsearch -exact $rowidlist($row) $id]
    if {$col < 0} {
        puts "oops: drawline: id $id not on row $row"
        return
    }
    set lasto {}
    set ns 0
    while {1} {
        set o [lindex $rowoffsets($row) $col]
        if {$o eq {}} break
        if {$o ne $lasto} {
            # changing direction
            set x [xc $row $col]
            set y [yc $row]
            lappend coords $x $y
            set lasto $o
        }
        incr col $o
        incr row -1
    }
    if {$coords eq {}} return
    set last [expr {[llength $idrowranges($id)] / 2 - 1}]
    set arrow [expr {2 * ($i > 0) + ($i < $last)}]
    set arrow [lindex {none first last both} $arrow]
    set wid [expr {$wid * $lthickness}]
    set x [xc $row $col]
    set y [yc $row]
    lappend coords $x $y
    set t [$canv create line $coords -width $wid \
               -fill $colormap($id) -tags lines.$id -arrow $arrow]
    $canv lower $t
    bindline $t $id
}

proc drawparentlinks {id row col olds wid} {
    global rowoffsets rowidlist canv colormap lthickness

    set row2 [expr {$row + 1}]
    set x [xc $row $col]
    set y [yc $row]
    set y2 [yc $row2]
    set ids $rowidlist($row2)
    set offs $rowidlist($row2)
    # rmx = right-most X coord used
    set rmx 0
    set wid [expr {$wid * $lthickness}]
    foreach p $olds {
        set i [lsearch -exact $ids $p]
        if {$i < 0} {
            puts "oops, parent $p of $id not in list"
            continue
        }
        assigncolor $p
        # should handle duplicated parents here...
        set coords [list $x $y]
        if {$i < $col - 1} {
            lappend coords [xc $row [expr {$i + 1}]] $y
        } elseif {$i > $col + 1} {
            lappend coords [xc $row [expr {$i - 1}]] $y
        }
        set x2 [xc $row2 $i]
        if {$x2 > $rmx} {
            set rmx $x2
        }
        lappend coords $x2 $y2
        set t [$canv create line $coords -width $wid \
                   -fill $colormap($p) -tags lines.$p]
        $canv lower $t
        bindline $t $p
    }
    return $rmx
}

proc drawlines {id xtra} {
    global colormap canv
    global idrowranges idrangedrawn
    global children iddrawn commitrow rowidlist

    $canv delete lines.$id
    set wid [expr {$xtra + 1}]
    set nr [expr {[llength $idrowranges($id)] / 2}]
    for {set i 0} {$i < $nr} {incr i} {
        if {[info exists idrangedrawn($id,$i)]} {
            drawlineseg $id $i $wid
        }
    }
    if {[info exists children($id)]} {
        foreach child $children($id) {
            if {[info exists iddrawn($child)]} {
                set row $commitrow($child)
                set col [lsearch -exact $rowidlist($row) $child]
                if {$col >= 0} {
                    drawparentlinks $child $row $col [list $id] $wid
                }
            }
        }
    }
}

proc drawcmittext {id row col rmx} {
    global linespc canv canv2 canv3 canvy0
    global commitlisted commitinfo rowidlist
    global rowtextx idpos idtags idheads idotherrefs
    global linehtag linentag linedtag
    global mainfont namefont

    set ofill [expr {[info exists commitlisted($id)]? "blue": "white"}]
    set x [xc $row $col]
    set y [yc $row]
    set orad [expr {$linespc / 3}]
    set t [$canv create oval [expr {$x - $orad}] [expr {$y - $orad}] \
               [expr {$x + $orad - 1}] [expr {$y + $orad - 1}] \
               -fill $ofill -outline black -width 1]
    $canv raise $t
    $canv bind $t <1> {selcanvline {} %x %y}
    set xt [xc $row [llength $rowidlist($row)]]
    if {$xt < $rmx} {
        set xt $rmx
    }
    set rowtextx($row) $xt
    set idpos($id) [list $x $xt $y]
    if {[info exists idtags($id)] || [info exists idheads($id)]
        || [info exists idotherrefs($id)]} {
        set xt [drawtags $id $x $xt $y]
    }
    set headline [lindex $commitinfo($id) 0]
    set name [lindex $commitinfo($id) 1]
    set date [lindex $commitinfo($id) 2]
    set date [formatdate $date]
    set linehtag($row) [$canv create text $xt $y -anchor w \
                            -text $headline -font $mainfont ]
    $canv bind $linehtag($row) <Button-3> "rowmenu %X %Y $id"
    set linentag($row) [$canv2 create text 3 $y -anchor w \
                            -text $name -font $namefont]
    set linedtag($row) [$canv3 create text 3 $y -anchor w \
                            -text $date -font $mainfont]
}

proc drawcmitrow {row} {
    global displayorder rowidlist rowoffsets
    global idrowranges idrangedrawn iddrawn
    global commitinfo commitlisted parents numcommits

    if {![info exists rowidlist($row)]} return
    foreach id $rowidlist($row) {
        if {![info exists idrowranges($id)]} continue
        set i -1
        foreach {s e} $idrowranges($id) {
            incr i
            if {$row < $s} continue
            if {$e eq {}} break
            if {$row <= $e} {
                if {$e < $numcommits && ![info exists idrangedrawn($id,$i)]} {
                    drawlineseg $id $i 1
                    set idrangedrawn($id,$i) 1
                }
                break
            }
        }
    }

    set id [lindex $displayorder $row]
    if {[info exists iddrawn($id)]} return
    set col [lsearch -exact $rowidlist($row) $id]
    if {$col < 0} {
        puts "oops, row $row id $id not in list"
        return
    }
    if {![info exists commitinfo($id)]} {
        readcommit $id
        if {![info exists commitinfo($id)]} {
            set commitinfo($id) {"No commit information available"}
            set nparents($id) 0
        }
    }
    assigncolor $id
    if {[info exists commitlisted($id)] && [info exists parents($id)]
        && $parents($id) ne {}} {
        set rmx [drawparentlinks $id $row $col $parents($id) 1]
    } else {
        set rmx 0
    }
    drawcmittext $id $row $col $rmx
    set iddrawn($id) 1
}

proc drawfrac {f0 f1} {
    global numcommits canv
    global linespc

    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax == 0} return
    set y0 [expr {int($f0 * $ymax)}]
    set row [expr {int(($y0 - 3) / $linespc) - 1}]
    if {$row < 0} {
        set row 0
    }
    set y1 [expr {int($f1 * $ymax)}]
    set endrow [expr {int(($y1 - 3) / $linespc) + 1}]
    if {$endrow >= $numcommits} {
        set endrow [expr {$numcommits - 1}]
    }
    for {} {$row <= $endrow} {incr row} {
        drawcmitrow $row
    }
}

proc drawvisible {} {
    global canv
    eval drawfrac [$canv yview]
}

proc clear_display {} {
    global iddrawn idrangedrawn

    allcanvs delete all
    catch {unset iddrawn}
    catch {unset idrangedrawn}
}

proc assigncolor {id} {
    global colormap colors nextcolor
    global parents nparents children nchildren
    global cornercrossings crossings

    if {[info exists colormap($id)]} return
    set ncolors [llength $colors]
    if {$nchildren($id) == 1} {
        set child [lindex $children($id) 0]
        if {[info exists colormap($child)]
            && $nparents($child) == 1} {
            set colormap($id) $colormap($child)
            return
        }
    }
    set badcolors {}
    if {[info exists cornercrossings($id)]} {
        foreach x $cornercrossings($id) {
            if {[info exists colormap($x)]
                && [lsearch -exact $badcolors $colormap($x)] < 0} {
                lappend badcolors $colormap($x)
            }
        }
        if {[llength $badcolors] >= $ncolors} {
            set badcolors {}
        }
    }
    set origbad $badcolors
    if {[llength $badcolors] < $ncolors - 1} {
        if {[info exists crossings($id)]} {
            foreach x $crossings($id) {
                if {[info exists colormap($x)]
                    && [lsearch -exact $badcolors $colormap($x)] < 0} {
                    lappend badcolors $colormap($x)
                }
            }
            if {[llength $badcolors] >= $ncolors} {
                set badcolors $origbad
            }
        }
        set origbad $badcolors
    }
    if {[llength $badcolors] < $ncolors - 1} {
        foreach child $children($id) {
            if {[info exists colormap($child)]
                && [lsearch -exact $badcolors $colormap($child)] < 0} {
                lappend badcolors $colormap($child)
            }
            if {[info exists parents($child)]} {
                foreach p $parents($child) {
                    if {[info exists colormap($p)]
                        && [lsearch -exact $badcolors $colormap($p)] < 0} {
                        lappend badcolors $colormap($p)
                    }
                }
            }
        }
        if {[llength $badcolors] >= $ncolors} {
            set badcolors $origbad
        }
    }
    for {set i 0} {$i <= $ncolors} {incr i} {
        set c [lindex $colors $nextcolor]
        if {[incr nextcolor] >= $ncolors} {
            set nextcolor 0
        }
        if {[lsearch -exact $badcolors $c]} break
    }
    set colormap($id) $c
}

proc initgraph {} {
    global numcommits nextcolor linespc
    global nchildren

    allcanvs delete all
    set nextcolor 0
    set numcommits 0
}

proc bindline {t id} {
    global canv

    $canv bind $t <Enter> "lineenter %x %y $id"
    $canv bind $t <Motion> "linemotion %x %y $id"
    $canv bind $t <Leave> "lineleave $id"
    $canv bind $t <Button-1> "lineclick %x %y $id 1"
}

proc drawtags {id x xt y1} {
    global idtags idheads idotherrefs
    global linespc lthickness
    global canv mainfont commitrow rowtextx

    set marks {}
    set ntags 0
    set nheads 0
    if {[info exists idtags($id)]} {
        set marks $idtags($id)
        set ntags [llength $marks]
    }
    if {[info exists idheads($id)]} {
        set marks [concat $marks $idheads($id)]
        set nheads [llength $idheads($id)]
    }
    if {[info exists idotherrefs($id)]} {
        set marks [concat $marks $idotherrefs($id)]
    }
    if {$marks eq {}} {
        return $xt
    }

    set delta [expr {int(0.5 * ($linespc - $lthickness))}]
    set yt [expr {$y1 - 0.5 * $linespc}]
    set yb [expr {$yt + $linespc - 1}]
    set xvals {}
    set wvals {}
    foreach tag $marks {
        set wid [font measure $mainfont $tag]
        lappend xvals $xt
        lappend wvals $wid
        set xt [expr {$xt + $delta + $wid + $lthickness + $linespc}]
    }
    set t [$canv create line $x $y1 [lindex $xvals end] $y1 \
               -width $lthickness -fill black -tags tag.$id]
    $canv lower $t
    foreach tag $marks x $xvals wid $wvals {
        set xl [expr {$x + $delta}]
        set xr [expr {$x + $delta + $wid + $lthickness}]
        if {[incr ntags -1] >= 0} {
            # draw a tag
            set t [$canv create polygon $x [expr {$yt + $delta}] $xl $yt \
                       $xr $yt $xr $yb $xl $yb $x [expr {$yb - $delta}] \
                       -width 1 -outline black -fill yellow -tags tag.$id]
            $canv bind $t <1> [list showtag $tag 1]
            set rowtextx($commitrow($id)) [expr {$xr + $linespc}]
        } else {
            # draw a head or other ref
            if {[incr nheads -1] >= 0} {
                set col green
            } else {
                set col "#ddddff"
            }
            set xl [expr {$xl - $delta/2}]
            $canv create polygon $x $yt $xr $yt $xr $yb $x $yb \
                -width 1 -outline black -fill $col -tags tag.$id
        }
        set t [$canv create text $xl $y1 -anchor w -text $tag \
                   -font $mainfont -tags tag.$id]
        if {$ntags >= 0} {
            $canv bind $t <1> [list showtag $tag 1]
        }
    }
    return $xt
}

proc checkcrossings {row endrow} {
    global displayorder parents rowidlist

    for {} {$row < $endrow} {incr row} {
        set id [lindex $displayorder $row]
        set i [lsearch -exact $rowidlist($row) $id]
        if {$i < 0} continue
        set idlist $rowidlist([expr {$row+1}])
        foreach p $parents($id) {
            set j [lsearch -exact $idlist $p]
            if {$j > 0} {
                if {$j < $i - 1} {
                    notecrossings $row $p $j $i [expr {$j+1}]
                } elseif {$j > $i + 1} {
                    notecrossings $row $p $i $j [expr {$j-1}]
                }
            }
        }
    }
}

proc notecrossings {row id lo hi corner} {
    global rowidlist crossings cornercrossings

    for {set i $lo} {[incr i] < $hi} {} {
        set p [lindex $rowidlist($row) $i]
        if {$p == {}} continue
        if {$i == $corner} {
            if {![info exists cornercrossings($id)]
                || [lsearch -exact $cornercrossings($id) $p] < 0} {
                lappend cornercrossings($id) $p
            }
            if {![info exists cornercrossings($p)]
                || [lsearch -exact $cornercrossings($p) $id] < 0} {
                lappend cornercrossings($p) $id
            }
        } else {
            if {![info exists crossings($id)]
                || [lsearch -exact $crossings($id) $p] < 0} {
                lappend crossings($id) $p
            }
            if {![info exists crossings($p)]
                || [lsearch -exact $crossings($p) $id] < 0} {
                lappend crossings($p) $id
            }
        }
    }
}

proc xcoord {i level ln} {
    global canvx0 xspc1 xspc2

    set x [expr {$canvx0 + $i * $xspc1($ln)}]
    if {$i > 0 && $i == $level} {
        set x [expr {$x + 0.5 * ($xspc2 - $xspc1($ln))}]
    } elseif {$i > $level} {
        set x [expr {$x + $xspc2 - $xspc1($ln)}]
    }
    return $x
}

proc drawcommit {id reading} {
    global phase todo nchildren nextupdate
    global displayorder parents
    global commitrow commitidx lineid

    if {$phase != "incrdraw"} {
        set phase incrdraw
        set displayorder {}
        set todo {}
        set commitidx 0
        initlayout
        initgraph
    }
    set commitrow($id) $commitidx
    set lineid($commitidx) $id
    incr commitidx
    lappend displayorder $id
}

proc finishcommits {} {
    global phase
    global canv mainfont ctext maincursor textcursor

    if {$phase == "incrdraw"} {
        drawrest
    } else {
        $canv delete all
        $canv create text 3 3 -anchor nw -text "No commits selected" \
            -font $mainfont -tags textitems
        set phase {}
    }
    . config -cursor $maincursor
    settextcursor $textcursor
}

# Don't change the text pane cursor if it is currently the hand cursor,
# showing that we are over a sha1 ID link.
proc settextcursor {c} {
    global ctext curtextcursor

    if {[$ctext cget -cursor] == $curtextcursor} {
        $ctext config -cursor $c
    }
    set curtextcursor $c
}

proc drawrest {} {
    global phase
    global numcommits
    global startmsecs
    global canvy0 numcommits linespc
    global rowlaidout commitidx

    set row $rowlaidout
    layoutrows $rowlaidout $commitidx 1
    layouttail
    optimize_rows $row 0 $commitidx
    showstuff $commitidx

    set phase {}
    set drawmsecs [expr {[clock clicks -milliseconds] - $startmsecs}]
    #puts "overall $drawmsecs ms for $numcommits commits"
}

proc findmatches {f} {
    global findtype foundstring foundstrlen
    if {$findtype == "Regexp"} {
        set matches [regexp -indices -all -inline $foundstring $f]
    } else {
        if {$findtype == "IgnCase"} {
            set str [string tolower $f]
        } else {
            set str $f
        }
        set matches {}
        set i 0
        while {[set j [string first $foundstring $str $i]] >= 0} {
            lappend matches [list $j [expr {$j+$foundstrlen-1}]]
            set i [expr {$j + $foundstrlen}]
        }
    }
    return $matches
}

proc dofind {} {
    global findtype findloc findstring markedmatches commitinfo
    global numcommits lineid linehtag linentag linedtag
    global mainfont namefont canv canv2 canv3 selectedline
    global matchinglines foundstring foundstrlen

    stopfindproc
    unmarkmatches
    focus .
    set matchinglines {}
    if {$findloc == "Pickaxe"} {
        findpatches
        return
    }
    if {$findtype == "IgnCase"} {
        set foundstring [string tolower $findstring]
    } else {
        set foundstring $findstring
    }
    set foundstrlen [string length $findstring]
    if {$foundstrlen == 0} return
    if {$findloc == "Files"} {
        findfiles
        return
    }
    if {![info exists selectedline]} {
        set oldsel -1
    } else {
        set oldsel $selectedline
    }
    set didsel 0
    set fldtypes {Headline Author Date Committer CDate Comment}
    for {set l 0} {$l < $numcommits} {incr l} {
        set id $lineid($l)
        set info $commitinfo($id)
        set doesmatch 0
        foreach f $info ty $fldtypes {
            if {$findloc != "All fields" && $findloc != $ty} {
                continue
            }
            set matches [findmatches $f]
            if {$matches == {}} continue
            set doesmatch 1
            if {$ty == "Headline"} {
                drawcmitrow $l
                markmatches $canv $l $f $linehtag($l) $matches $mainfont
            } elseif {$ty == "Author"} {
                drawcmitrow $l
                markmatches $canv2 $l $f $linentag($l) $matches $namefont
            } elseif {$ty == "Date"} {
                drawcmitrow $l
                markmatches $canv3 $l $f $linedtag($l) $matches $mainfont
            }
        }
        if {$doesmatch} {
            lappend matchinglines $l
            if {!$didsel && $l > $oldsel} {
                findselectline $l
                set didsel 1
            }
        }
    }
    if {$matchinglines == {}} {
        bell
    } elseif {!$didsel} {
        findselectline [lindex $matchinglines 0]
    }
}

proc findselectline {l} {
    global findloc commentend ctext
    selectline $l 1
    if {$findloc == "All fields" || $findloc == "Comments"} {
        # highlight the matches in the comments
        set f [$ctext get 1.0 $commentend]
        set matches [findmatches $f]
        foreach match $matches {
            set start [lindex $match 0]
            set end [expr {[lindex $match 1] + 1}]
            $ctext tag add found "1.0 + $start c" "1.0 + $end c"
        }
    }
}

proc findnext {restart} {
    global matchinglines selectedline
    if {![info exists matchinglines]} {
        if {$restart} {
            dofind
        }
        return
    }
    if {![info exists selectedline]} return
    foreach l $matchinglines {
        if {$l > $selectedline} {
            findselectline $l
            return
        }
    }
    bell
}

proc findprev {} {
    global matchinglines selectedline
    if {![info exists matchinglines]} {
        dofind
        return
    }
    if {![info exists selectedline]} return
    set prev {}
    foreach l $matchinglines {
        if {$l >= $selectedline} break
        set prev $l
    }
    if {$prev != {}} {
        findselectline $prev
    } else {
        bell
    }
}

proc findlocchange {name ix op} {
    global findloc findtype findtypemenu
    if {$findloc == "Pickaxe"} {
        set findtype Exact
        set state disabled
    } else {
        set state normal
    }
    $findtypemenu entryconf 1 -state $state
    $findtypemenu entryconf 2 -state $state
}

proc stopfindproc {{done 0}} {
    global findprocpid findprocfile findids
    global ctext findoldcursor phase maincursor textcursor
    global findinprogress

    catch {unset findids}
    if {[info exists findprocpid]} {
        if {!$done} {
            catch {exec kill $findprocpid}
        }
        catch {close $findprocfile}
        unset findprocpid
    }
    if {[info exists findinprogress]} {
        unset findinprogress
        if {$phase != "incrdraw"} {
            . config -cursor $maincursor
            settextcursor $textcursor
        }
    }
}

proc findpatches {} {
    global findstring selectedline numcommits
    global findprocpid findprocfile
    global finddidsel ctext lineid findinprogress
    global findinsertpos

    if {$numcommits == 0} return

    # make a list of all the ids to search, starting at the one
    # after the selected line (if any)
    if {[info exists selectedline]} {
        set l $selectedline
    } else {
        set l -1
    }
    set inputids {}
    for {set i 0} {$i < $numcommits} {incr i} {
        if {[incr l] >= $numcommits} {
            set l 0
        }
        append inputids $lineid($l) "\n"
    }

    if {[catch {
        set f [open [list | git-diff-tree --stdin -s -r -S$findstring \
                         << $inputids] r]
    } err]} {
        error_popup "Error starting search process: $err"
        return
    }

    set findinsertpos end
    set findprocfile $f
    set findprocpid [pid $f]
    fconfigure $f -blocking 0
    fileevent $f readable readfindproc
    set finddidsel 0
    . config -cursor watch
    settextcursor watch
    set findinprogress 1
}

proc readfindproc {} {
    global findprocfile finddidsel
    global commitrow matchinglines findinsertpos

    set n [gets $findprocfile line]
    if {$n < 0} {
        if {[eof $findprocfile]} {
            stopfindproc 1
            if {!$finddidsel} {
                bell
            }
        }
        return
    }
    if {![regexp {^[0-9a-f]{40}} $line id]} {
        error_popup "Can't parse git-diff-tree output: $line"
        stopfindproc
        return
    }
    if {![info exists commitrow($id)]} {
        puts stderr "spurious id: $id"
        return
    }
    set l $commitrow($id)
    insertmatch $l $id
}

proc insertmatch {l id} {
    global matchinglines findinsertpos finddidsel

    if {$findinsertpos == "end"} {
        if {$matchinglines != {} && $l < [lindex $matchinglines 0]} {
            set matchinglines [linsert $matchinglines 0 $l]
            set findinsertpos 1
        } else {
            lappend matchinglines $l
        }
    } else {
        set matchinglines [linsert $matchinglines $findinsertpos $l]
        incr findinsertpos
    }
    markheadline $l $id
    if {!$finddidsel} {
        findselectline $l
        set finddidsel 1
    }
}

proc findfiles {} {
    global selectedline numcommits lineid ctext
    global ffileline finddidsel parents nparents
    global findinprogress findstartline findinsertpos
    global treediffs fdiffid fdiffsneeded fdiffpos
    global findmergefiles

    if {$numcommits == 0} return

    if {[info exists selectedline]} {
        set l [expr {$selectedline + 1}]
    } else {
        set l 0
    }
    set ffileline $l
    set findstartline $l
    set diffsneeded {}
    set fdiffsneeded {}
    while 1 {
        set id $lineid($l)
        if {$findmergefiles || $nparents($id) == 1} {
            if {![info exists treediffs($id)]} {
                append diffsneeded "$id\n"
                lappend fdiffsneeded $id
            }
        }
        if {[incr l] >= $numcommits} {
            set l 0
        }
        if {$l == $findstartline} break
    }

    # start off a git-diff-tree process if needed
    if {$diffsneeded ne {}} {
        if {[catch {
            set df [open [list | git-diff-tree -r --stdin << $diffsneeded] r]
        } err ]} {
            error_popup "Error starting search process: $err"
            return
        }
        catch {unset fdiffid}
        set fdiffpos 0
        fconfigure $df -blocking 0
        fileevent $df readable [list readfilediffs $df]
    }

    set finddidsel 0
    set findinsertpos end
    set id $lineid($l)
    . config -cursor watch
    settextcursor watch
    set findinprogress 1
    findcont $id
    update
}

proc readfilediffs {df} {
    global findid fdiffid fdiffs

    set n [gets $df line]
    if {$n < 0} {
        if {[eof $df]} {
            donefilediff
            if {[catch {close $df} err]} {
                stopfindproc
                bell
                error_popup "Error in git-diff-tree: $err"
            } elseif {[info exists findid]} {
                set id $findid
                stopfindproc
                bell
                error_popup "Couldn't find diffs for $id"
            }
        }
        return
    }
    if {[regexp {^([0-9a-f]{40})$} $line match id]} {
        # start of a new string of diffs
        donefilediff
        set fdiffid $id
        set fdiffs {}
    } elseif {[string match ":*" $line]} {
        lappend fdiffs [lindex $line 5]
    }
}

proc donefilediff {} {
    global fdiffid fdiffs treediffs findid
    global fdiffsneeded fdiffpos

    if {[info exists fdiffid]} {
        while {[lindex $fdiffsneeded $fdiffpos] ne $fdiffid
               && $fdiffpos < [llength $fdiffsneeded]} {
            # git-diff-tree doesn't output anything for a commit
            # which doesn't change anything
            set nullid [lindex $fdiffsneeded $fdiffpos]
            set treediffs($nullid) {}
            if {[info exists findid] && $nullid eq $findid} {
                unset findid
                findcont $nullid
            }
            incr fdiffpos
        }
        incr fdiffpos

        if {![info exists treediffs($fdiffid)]} {
            set treediffs($fdiffid) $fdiffs
        }
        if {[info exists findid] && $fdiffid eq $findid} {
            unset findid
            findcont $fdiffid
        }
    }
}

proc findcont {id} {
    global findid treediffs parents nparents
    global ffileline findstartline finddidsel
    global lineid numcommits matchinglines findinprogress
    global findmergefiles

    set l $ffileline
    while 1 {
        if {$findmergefiles || $nparents($id) == 1} {
            if {![info exists treediffs($id)]} {
                set findid $id
                set ffileline $l
                return
            }
            set doesmatch 0
            foreach f $treediffs($id) {
                set x [findmatches $f]
                if {$x != {}} {
                    set doesmatch 1
                    break
                }
            }
            if {$doesmatch} {
                insertmatch $l $id
            }
        }
        if {[incr l] >= $numcommits} {
            set l 0
        }
        if {$l == $findstartline} break
        set id $lineid($l)
    }
    stopfindproc
    if {!$finddidsel} {
        bell
    }
}

# mark a commit as matching by putting a yellow background
# behind the headline
proc markheadline {l id} {
    global canv mainfont linehtag commitinfo

    drawcmitrow $l
    set bbox [$canv bbox $linehtag($l)]
    set t [$canv create rect $bbox -outline {} -tags matches -fill yellow]
    $canv lower $t
}

# mark the bits of a headline, author or date that match a find string
proc markmatches {canv l str tag matches font} {
    set bbox [$canv bbox $tag]
    set x0 [lindex $bbox 0]
    set y0 [lindex $bbox 1]
    set y1 [lindex $bbox 3]
    foreach match $matches {
        set start [lindex $match 0]
        set end [lindex $match 1]
        if {$start > $end} continue
        set xoff [font measure $font [string range $str 0 [expr {$start-1}]]]
        set xlen [font measure $font [string range $str 0 [expr {$end}]]]
        set t [$canv create rect [expr {$x0+$xoff}] $y0 \
                   [expr {$x0+$xlen+2}] $y1 \
                   -outline {} -tags matches -fill yellow]
        $canv lower $t
    }
}

proc unmarkmatches {} {
    global matchinglines findids
    allcanvs delete matches
    catch {unset matchinglines}
    catch {unset findids}
}

proc selcanvline {w x y} {
    global canv canvy0 ctext linespc
    global rowtextx
    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax == {}} return
    set yfrac [lindex [$canv yview] 0]
    set y [expr {$y + $yfrac * $ymax}]
    set l [expr {int(($y - $canvy0) / $linespc + 0.5)}]
    if {$l < 0} {
        set l 0
    }
    if {$w eq $canv} {
        if {![info exists rowtextx($l)] || $x < $rowtextx($l)} return
    }
    unmarkmatches
    selectline $l 1
}

proc commit_descriptor {p} {
    global commitinfo
    set l "..."
    if {[info exists commitinfo($p)]} {
        set l [lindex $commitinfo($p) 0]
    }
    return "$p ($l)"
}

# append some text to the ctext widget, and make any SHA1 ID
# that we know about be a clickable link.
proc appendwithlinks {text} {
    global ctext commitrow linknum

    set start [$ctext index "end - 1c"]
    $ctext insert end $text
    $ctext insert end "\n"
    set links [regexp -indices -all -inline {[0-9a-f]{40}} $text]
    foreach l $links {
        set s [lindex $l 0]
        set e [lindex $l 1]
        set linkid [string range $text $s $e]
        if {![info exists commitrow($linkid)]} continue
        incr e
        $ctext tag add link "$start + $s c" "$start + $e c"
        $ctext tag add link$linknum "$start + $s c" "$start + $e c"
        $ctext tag bind link$linknum <1> [list selectline $commitrow($linkid) 1]
        incr linknum
    }
    $ctext tag conf link -foreground blue -underline 1
    $ctext tag bind link <Enter> { %W configure -cursor hand2 }
    $ctext tag bind link <Leave> { %W configure -cursor $curtextcursor }
}

proc selectline {l isnew} {
    global canv canv2 canv3 ctext commitinfo selectedline
    global lineid linehtag linentag linedtag
    global canvy0 linespc parents nparents children
    global cflist currentid sha1entry
    global commentend idtags linknum
    global mergemax

    $canv delete hover
    normalline
    if {![info exists lineid($l)]} return
    set y [expr {$canvy0 + $l * $linespc}]
    set ymax [lindex [$canv cget -scrollregion] 3]
    set ytop [expr {$y - $linespc - 1}]
    set ybot [expr {$y + $linespc + 1}]
    set wnow [$canv yview]
    set wtop [expr {[lindex $wnow 0] * $ymax}]
    set wbot [expr {[lindex $wnow 1] * $ymax}]
    set wh [expr {$wbot - $wtop}]
    set newtop $wtop
    if {$ytop < $wtop} {
        if {$ybot < $wtop} {
            set newtop [expr {$y - $wh / 2.0}]
        } else {
            set newtop $ytop
            if {$newtop > $wtop - $linespc} {
                set newtop [expr {$wtop - $linespc}]
            }
        }
    } elseif {$ybot > $wbot} {
        if {$ytop > $wbot} {
            set newtop [expr {$y - $wh / 2.0}]
        } else {
            set newtop [expr {$ybot - $wh}]
            if {$newtop < $wtop + $linespc} {
                set newtop [expr {$wtop + $linespc}]
            }
        }
    }
    if {$newtop != $wtop} {
        if {$newtop < 0} {
            set newtop 0
        }
        allcanvs yview moveto [expr {$newtop * 1.0 / $ymax}]
        drawvisible
    }

    if {![info exists linehtag($l)]} return
    $canv delete secsel
    set t [eval $canv create rect [$canv bbox $linehtag($l)] -outline {{}} \
               -tags secsel -fill [$canv cget -selectbackground]]
    $canv lower $t
    $canv2 delete secsel
    set t [eval $canv2 create rect [$canv2 bbox $linentag($l)] -outline {{}} \
               -tags secsel -fill [$canv2 cget -selectbackground]]
    $canv2 lower $t
    $canv3 delete secsel
    set t [eval $canv3 create rect [$canv3 bbox $linedtag($l)] -outline {{}} \
               -tags secsel -fill [$canv3 cget -selectbackground]]
    $canv3 lower $t

    if {$isnew} {
        addtohistory [list selectline $l 0]
    }

    set selectedline $l

    set id $lineid($l)
    set currentid $id
    $sha1entry delete 0 end
    $sha1entry insert 0 $id
    $sha1entry selection from 0
    $sha1entry selection to end

    $ctext conf -state normal
    $ctext delete 0.0 end
    set linknum 0
    $ctext mark set fmark.0 0.0
    $ctext mark gravity fmark.0 left
    set info $commitinfo($id)
    set date [formatdate [lindex $info 2]]
    $ctext insert end "Author: [lindex $info 1]  $date\n"
    set date [formatdate [lindex $info 4]]
    $ctext insert end "Committer: [lindex $info 3]  $date\n"
    if {[info exists idtags($id)]} {
        $ctext insert end "Tags:"
        foreach tag $idtags($id) {
            $ctext insert end " $tag"
        }
        $ctext insert end "\n"
    }
 
    set comment {}
    if {$nparents($id) > 1} {
        set np 0
        foreach p $parents($id) {
            if {$np >= $mergemax} {
                set tag mmax
            } else {
                set tag m$np
            }
            $ctext insert end "Parent: " $tag
            appendwithlinks [commit_descriptor $p]
            incr np
        }
    } else {
        if {[info exists parents($id)]} {
            foreach p $parents($id) {
                append comment "Parent: [commit_descriptor $p]\n"
            }
        }
    }

    if {[info exists children($id)]} {
        foreach c $children($id) {
            append comment "Child:  [commit_descriptor $c]\n"
        }
    }
    append comment "\n"
    append comment [lindex $info 5]

    # make anything that looks like a SHA1 ID be a clickable link
    appendwithlinks $comment

    $ctext tag delete Comments
    $ctext tag remove found 1.0 end
    $ctext conf -state disabled
    set commentend [$ctext index "end - 1c"]

    $cflist delete 0 end
    $cflist insert end "Comments"
    if {$nparents($id) == 1} {
        startdiff $id
    } elseif {$nparents($id) > 1} {
        mergediff $id
    }
}

proc selnextline {dir} {
    global selectedline
    if {![info exists selectedline]} return
    set l [expr {$selectedline + $dir}]
    unmarkmatches
    selectline $l 1
}

proc unselectline {} {
    global selectedline

    catch {unset selectedline}
    allcanvs delete secsel
}

proc addtohistory {cmd} {
    global history historyindex

    if {$historyindex > 0
        && [lindex $history [expr {$historyindex - 1}]] == $cmd} {
        return
    }

    if {$historyindex < [llength $history]} {
        set history [lreplace $history $historyindex end $cmd]
    } else {
        lappend history $cmd
    }
    incr historyindex
    if {$historyindex > 1} {
        .ctop.top.bar.leftbut conf -state normal
    } else {
        .ctop.top.bar.leftbut conf -state disabled
    }
    .ctop.top.bar.rightbut conf -state disabled
}

proc goback {} {
    global history historyindex

    if {$historyindex > 1} {
        incr historyindex -1
        set cmd [lindex $history [expr {$historyindex - 1}]]
        eval $cmd
        .ctop.top.bar.rightbut conf -state normal
    }
    if {$historyindex <= 1} {
        .ctop.top.bar.leftbut conf -state disabled
    }
}

proc goforw {} {
    global history historyindex

    if {$historyindex < [llength $history]} {
        set cmd [lindex $history $historyindex]
        incr historyindex
        eval $cmd
        .ctop.top.bar.leftbut conf -state normal
    }
    if {$historyindex >= [llength $history]} {
        .ctop.top.bar.rightbut conf -state disabled
    }
}

proc mergediff {id} {
    global parents diffmergeid diffopts mdifffd
    global difffilestart

    set diffmergeid $id
    catch {unset difffilestart}
    # this doesn't seem to actually affect anything...
    set env(GIT_DIFF_OPTS) $diffopts
    set cmd [concat | git-diff-tree --no-commit-id --cc $id]
    if {[catch {set mdf [open $cmd r]} err]} {
        error_popup "Error getting merge diffs: $err"
        return
    }
    fconfigure $mdf -blocking 0
    set mdifffd($id) $mdf
    fileevent $mdf readable [list getmergediffline $mdf $id]
    set nextupdate [expr {[clock clicks -milliseconds] + 100}]
}

proc getmergediffline {mdf id} {
    global diffmergeid ctext cflist nextupdate nparents mergemax
    global difffilestart

    set n [gets $mdf line]
    if {$n < 0} {
        if {[eof $mdf]} {
            close $mdf
        }
        return
    }
    if {![info exists diffmergeid] || $id != $diffmergeid} {
        return
    }
    $ctext conf -state normal
    if {[regexp {^diff --cc (.*)} $line match fname]} {
        # start of a new file
        $ctext insert end "\n"
        set here [$ctext index "end - 1c"]
        set i [$cflist index end]
        $ctext mark set fmark.$i $here
        $ctext mark gravity fmark.$i left
        set difffilestart([expr {$i-1}]) $here
        $cflist insert end $fname
        set l [expr {(78 - [string length $fname]) / 2}]
        set pad [string range "----------------------------------------" 1 $l]
        $ctext insert end "$pad $fname $pad\n" filesep
    } elseif {[regexp {^@@} $line]} {
        $ctext insert end "$line\n" hunksep
    } elseif {[regexp {^[0-9a-f]{40}$} $line] || [regexp {^index} $line]} {
        # do nothing
    } else {
        # parse the prefix - one ' ', '-' or '+' for each parent
        set np $nparents($id)
        set spaces {}
        set minuses {}
        set pluses {}
        set isbad 0
        for {set j 0} {$j < $np} {incr j} {
            set c [string range $line $j $j]
            if {$c == " "} {
                lappend spaces $j
            } elseif {$c == "-"} {
                lappend minuses $j
            } elseif {$c == "+"} {
                lappend pluses $j
            } else {
                set isbad 1
                break
            }
        }
        set tags {}
        set num {}
        if {!$isbad && $minuses ne {} && $pluses eq {}} {
            # line doesn't appear in result, parents in $minuses have the line
            set num [lindex $minuses 0]
        } elseif {!$isbad && $pluses ne {} && $minuses eq {}} {
            # line appears in result, parents in $pluses don't have the line
            lappend tags mresult
            set num [lindex $spaces 0]
        }
        if {$num ne {}} {
            if {$num >= $mergemax} {
                set num "max"
            }
            lappend tags m$num
        }
        $ctext insert end "$line\n" $tags
    }
    $ctext conf -state disabled
    if {[clock clicks -milliseconds] >= $nextupdate} {
        incr nextupdate 100
        fileevent $mdf readable {}
        update
        fileevent $mdf readable [list getmergediffline $mdf $id]
    }
}

proc startdiff {ids} {
    global treediffs diffids treepending diffmergeid

    set diffids $ids
    catch {unset diffmergeid}
    if {![info exists treediffs($ids)]} {
        if {![info exists treepending]} {
            gettreediffs $ids
        }
    } else {
        addtocflist $ids
    }
}

proc addtocflist {ids} {
    global treediffs cflist
    foreach f $treediffs($ids) {
        $cflist insert end $f
    }
    getblobdiffs $ids
}

proc gettreediffs {ids} {
    global treediff parents treepending
    set treepending $ids
    set treediff {}
    if {[catch \
         {set gdtf [open [concat | git-diff-tree --no-commit-id -r $ids] r]} \
        ]} return
    fconfigure $gdtf -blocking 0
    fileevent $gdtf readable [list gettreediffline $gdtf $ids]
}

proc gettreediffline {gdtf ids} {
    global treediff treediffs treepending diffids diffmergeid

    set n [gets $gdtf line]
    if {$n < 0} {
        if {![eof $gdtf]} return
        close $gdtf
        set treediffs($ids) $treediff
        unset treepending
        if {$ids != $diffids} {
            gettreediffs $diffids
        } else {
            if {[info exists diffmergeid]} {
                contmergediff $ids
            } else {
                addtocflist $ids
            }
        }
        return
    }
    set file [lindex $line 5]
    lappend treediff $file
}

proc getblobdiffs {ids} {
    global diffopts blobdifffd diffids env curdifftag curtagstart
    global difffilestart nextupdate diffinhdr treediffs

    set env(GIT_DIFF_OPTS) $diffopts
    set cmd [concat | git-diff-tree --no-commit-id -r -p -C $ids]
    if {[catch {set bdf [open $cmd r]} err]} {
        puts "error getting diffs: $err"
        return
    }
    set diffinhdr 0
    fconfigure $bdf -blocking 0
    set blobdifffd($ids) $bdf
    set curdifftag Comments
    set curtagstart 0.0
    catch {unset difffilestart}
    fileevent $bdf readable [list getblobdiffline $bdf $diffids]
    set nextupdate [expr {[clock clicks -milliseconds] + 100}]
}

proc getblobdiffline {bdf ids} {
    global diffids blobdifffd ctext curdifftag curtagstart
    global diffnexthead diffnextnote difffilestart
    global nextupdate diffinhdr treediffs

    set n [gets $bdf line]
    if {$n < 0} {
        if {[eof $bdf]} {
            close $bdf
            if {$ids == $diffids && $bdf == $blobdifffd($ids)} {
                $ctext tag add $curdifftag $curtagstart end
            }
        }
        return
    }
    if {$ids != $diffids || $bdf != $blobdifffd($ids)} {
        return
    }
    $ctext conf -state normal
    if {[regexp {^diff --git a/(.*) b/(.*)} $line match fname newname]} {
        # start of a new file
        $ctext insert end "\n"
        $ctext tag add $curdifftag $curtagstart end
        set curtagstart [$ctext index "end - 1c"]
        set header $newname
        set here [$ctext index "end - 1c"]
        set i [lsearch -exact $treediffs($diffids) $fname]
        if {$i >= 0} {
            set difffilestart($i) $here
            incr i
            $ctext mark set fmark.$i $here
            $ctext mark gravity fmark.$i left
        }
        if {$newname != $fname} {
            set i [lsearch -exact $treediffs($diffids) $newname]
            if {$i >= 0} {
                set difffilestart($i) $here
                incr i
                $ctext mark set fmark.$i $here
                $ctext mark gravity fmark.$i left
            }
        }
        set curdifftag "f:$fname"
        $ctext tag delete $curdifftag
        set l [expr {(78 - [string length $header]) / 2}]
        set pad [string range "----------------------------------------" 1 $l]
        $ctext insert end "$pad $header $pad\n" filesep
        set diffinhdr 1
    } elseif {[regexp {^(---|\+\+\+)} $line]} {
        set diffinhdr 0
    } elseif {[regexp {^@@ -([0-9]+),([0-9]+) \+([0-9]+),([0-9]+) @@(.*)} \
                   $line match f1l f1c f2l f2c rest]} {
        $ctext insert end "$line\n" hunksep
        set diffinhdr 0
    } else {
        set x [string range $line 0 0]
        if {$x == "-" || $x == "+"} {
            set tag [expr {$x == "+"}]
            $ctext insert end "$line\n" d$tag
        } elseif {$x == " "} {
            $ctext insert end "$line\n"
        } elseif {$diffinhdr || $x == "\\"} {
            # e.g. "\ No newline at end of file"
            $ctext insert end "$line\n" filesep
        } else {
            # Something else we don't recognize
            if {$curdifftag != "Comments"} {
                $ctext insert end "\n"
                $ctext tag add $curdifftag $curtagstart end
                set curtagstart [$ctext index "end - 1c"]
                set curdifftag Comments
            }
            $ctext insert end "$line\n" filesep
        }
    }
    $ctext conf -state disabled
    if {[clock clicks -milliseconds] >= $nextupdate} {
        incr nextupdate 100
        fileevent $bdf readable {}
        update
        fileevent $bdf readable "getblobdiffline $bdf {$ids}"
    }
}

proc nextfile {} {
    global difffilestart ctext
    set here [$ctext index @0,0]
    for {set i 0} {[info exists difffilestart($i)]} {incr i} {
        if {[$ctext compare $difffilestart($i) > $here]} {
            if {![info exists pos]
                || [$ctext compare $difffilestart($i) < $pos]} {
                set pos $difffilestart($i)
            }
        }
    }
    if {[info exists pos]} {
        $ctext yview $pos
    }
}

proc listboxsel {} {
    global ctext cflist currentid
    if {![info exists currentid]} return
    set sel [lsort [$cflist curselection]]
    if {$sel eq {}} return
    set first [lindex $sel 0]
    catch {$ctext yview fmark.$first}
}

proc setcoords {} {
    global linespc charspc canvx0 canvy0 mainfont
    global xspc1 xspc2 lthickness

    set linespc [font metrics $mainfont -linespace]
    set charspc [font measure $mainfont "m"]
    set canvy0 [expr {int(3 + 0.5 * $linespc)}]
    set canvx0 [expr {int(3 + 0.5 * $linespc)}]
    set lthickness [expr {int($linespc / 9) + 1}]
    set xspc1(0) $linespc
    set xspc2 $linespc
}

proc redisplay {} {
    global canv canvy0 linespc numcommits
    global selectedline

    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax == 0} return
    set span [$canv yview]
    clear_display
    allcanvs conf -scrollregion \
        [list 0 0 0 [expr {$canvy0 + ($numcommits - 0.5) * $linespc + 2}]]
    allcanvs yview moveto [lindex $span 0]
    drawvisible
    if {[info exists selectedline]} {
        selectline $selectedline 0
    }
}

proc incrfont {inc} {
    global mainfont namefont textfont ctext canv phase
    global stopped entries
    unmarkmatches
    set mainfont [lreplace $mainfont 1 1 [expr {[lindex $mainfont 1] + $inc}]]
    set namefont [lreplace $namefont 1 1 [expr {[lindex $namefont 1] + $inc}]]
    set textfont [lreplace $textfont 1 1 [expr {[lindex $textfont 1] + $inc}]]
    setcoords
    $ctext conf -font $textfont
    $ctext tag conf filesep -font [concat $textfont bold]
    foreach e $entries {
        $e conf -font $mainfont
    }
    if {$phase == "getcommits"} {
        $canv itemconf textitems -font $mainfont
    }
    redisplay
}

proc clearsha1 {} {
    global sha1entry sha1string
    if {[string length $sha1string] == 40} {
        $sha1entry delete 0 end
    }
}

proc sha1change {n1 n2 op} {
    global sha1string currentid sha1but
    if {$sha1string == {}
        || ([info exists currentid] && $sha1string == $currentid)} {
        set state disabled
    } else {
        set state normal
    }
    if {[$sha1but cget -state] == $state} return
    if {$state == "normal"} {
        $sha1but conf -state normal -relief raised -text "Goto: "
    } else {
        $sha1but conf -state disabled -relief flat -text "SHA1 ID: "
    }
}

proc gotocommit {} {
    global sha1string currentid commitrow tagids
    global lineid numcommits

    if {$sha1string == {}
        || ([info exists currentid] && $sha1string == $currentid)} return
    if {[info exists tagids($sha1string)]} {
        set id $tagids($sha1string)
    } else {
        set id [string tolower $sha1string]
        if {[regexp {^[0-9a-f]{4,39}$} $id]} {
            set matches {}
            for {set l 0} {$l < $numcommits} {incr l} {
                if {[string match $id* $lineid($l)]} {
                    lappend matches $lineid($l)
                }
            }
            if {$matches ne {}} {
                if {[llength $matches] > 1} {
                    error_popup "Short SHA1 id $id is ambiguous"
                    return
                }
                set id [lindex $matches 0]
            }
        }
    }
    if {[info exists commitrow($id)]} {
        selectline $commitrow($id) 1
        return
    }
    if {[regexp {^[0-9a-fA-F]{4,}$} $sha1string]} {
        set type "SHA1 id"
    } else {
        set type "Tag"
    }
    error_popup "$type $sha1string is not known"
}

proc lineenter {x y id} {
    global hoverx hovery hoverid hovertimer
    global commitinfo canv

    if {![info exists commitinfo($id)]} return
    set hoverx $x
    set hovery $y
    set hoverid $id
    if {[info exists hovertimer]} {
        after cancel $hovertimer
    }
    set hovertimer [after 500 linehover]
    $canv delete hover
}

proc linemotion {x y id} {
    global hoverx hovery hoverid hovertimer

    if {[info exists hoverid] && $id == $hoverid} {
        set hoverx $x
        set hovery $y
        if {[info exists hovertimer]} {
            after cancel $hovertimer
        }
        set hovertimer [after 500 linehover]
    }
}

proc lineleave {id} {
    global hoverid hovertimer canv

    if {[info exists hoverid] && $id == $hoverid} {
        $canv delete hover
        if {[info exists hovertimer]} {
            after cancel $hovertimer
            unset hovertimer
        }
        unset hoverid
    }
}

proc linehover {} {
    global hoverx hovery hoverid hovertimer
    global canv linespc lthickness
    global commitinfo mainfont

    set text [lindex $commitinfo($hoverid) 0]
    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax == {}} return
    set yfrac [lindex [$canv yview] 0]
    set x [expr {$hoverx + 2 * $linespc}]
    set y [expr {$hovery + $yfrac * $ymax - $linespc / 2}]
    set x0 [expr {$x - 2 * $lthickness}]
    set y0 [expr {$y - 2 * $lthickness}]
    set x1 [expr {$x + [font measure $mainfont $text] + 2 * $lthickness}]
    set y1 [expr {$y + $linespc + 2 * $lthickness}]
    set t [$canv create rectangle $x0 $y0 $x1 $y1 \
               -fill \#ffff80 -outline black -width 1 -tags hover]
    $canv raise $t
    set t [$canv create text $x $y -anchor nw -text $text -tags hover -font $mainfont]
    $canv raise $t
}

proc clickisonarrow {id y} {
    global lthickness idrowranges

    set thresh [expr {2 * $lthickness + 6}]
    set n [expr {[llength $idrowranges($id)] - 1}]
    for {set i 1} {$i < $n} {incr i} {
        set row [lindex $idrowranges($id) $i]
        if {abs([yc $row] - $y) < $thresh} {
            return $i
        }
    }
    return {}
}

proc arrowjump {id n y} {
    global idrowranges canv

    # 1 <-> 2, 3 <-> 4, etc...
    set n [expr {(($n - 1) ^ 1) + 1}]
    set row [lindex $idrowranges($id) $n]
    set yt [yc $row]
    set ymax [lindex [$canv cget -scrollregion] 3]
    if {$ymax eq {} || $ymax <= 0} return
    set view [$canv yview]
    set yspan [expr {[lindex $view 1] - [lindex $view 0]}]
    set yfrac [expr {$yt / $ymax - $yspan / 2}]
    if {$yfrac < 0} {
        set yfrac 0
    }
    allcanvs yview moveto $yfrac
}

proc lineclick {x y id isnew} {
    global ctext commitinfo children cflist canv thickerline

    unmarkmatches
    unselectline
    normalline
    $canv delete hover
    # draw this line thicker than normal
    drawlines $id 1
    set thickerline $id
    if {$isnew} {
        set ymax [lindex [$canv cget -scrollregion] 3]
        if {$ymax eq {}} return
        set yfrac [lindex [$canv yview] 0]
        set y [expr {$y + $yfrac * $ymax}]
    }
    set dirn [clickisonarrow $id $y]
    if {$dirn ne {}} {
        arrowjump $id $dirn $y
        return
    }

    if {$isnew} {
        addtohistory [list lineclick $x $y $id 0]
    }
    # fill the details pane with info about this line
    $ctext conf -state normal
    $ctext delete 0.0 end
    $ctext tag conf link -foreground blue -underline 1
    $ctext tag bind link <Enter> { %W configure -cursor hand2 }
    $ctext tag bind link <Leave> { %W configure -cursor $curtextcursor }
    $ctext insert end "Parent:\t"
    $ctext insert end $id [list link link0]
    $ctext tag bind link0 <1> [list selbyid $id]
    set info $commitinfo($id)
    $ctext insert end "\n\t[lindex $info 0]\n"
    $ctext insert end "\tAuthor:\t[lindex $info 1]\n"
    set date [formatdate [lindex $info 2]]
    $ctext insert end "\tDate:\t$date\n"
    if {[info exists children($id)]} {
        $ctext insert end "\nChildren:"
        set i 0
        foreach child $children($id) {
            incr i
            set info $commitinfo($child)
            $ctext insert end "\n\t"
            $ctext insert end $child [list link link$i]
            $ctext tag bind link$i <1> [list selbyid $child]
            $ctext insert end "\n\t[lindex $info 0]"
            $ctext insert end "\n\tAuthor:\t[lindex $info 1]"
            set date [formatdate [lindex $info 2]]
            $ctext insert end "\n\tDate:\t$date\n"
        }
    }
    $ctext conf -state disabled

    $cflist delete 0 end
}

proc normalline {} {
    global thickerline
    if {[info exists thickerline]} {
        drawlines $thickerline 0
        unset thickerline
    }
}

proc selbyid {id} {
    global commitrow
    if {[info exists commitrow($id)]} {
        selectline $commitrow($id) 1
    }
}

proc mstime {} {
    global startmstime
    if {![info exists startmstime]} {
        set startmstime [clock clicks -milliseconds]
    }
    return [format "%.3f" [expr {([clock click -milliseconds] - $startmstime) / 1000.0}]]
}

proc rowmenu {x y id} {
    global rowctxmenu commitrow selectedline rowmenuid

    if {![info exists selectedline] || $commitrow($id) eq $selectedline} {
        set state disabled
    } else {
        set state normal
    }
    $rowctxmenu entryconfigure 0 -state $state
    $rowctxmenu entryconfigure 1 -state $state
    $rowctxmenu entryconfigure 2 -state $state
    set rowmenuid $id
    tk_popup $rowctxmenu $x $y
}

proc diffvssel {dirn} {
    global rowmenuid selectedline lineid

    if {![info exists selectedline]} return
    if {$dirn} {
        set oldid $lineid($selectedline)
        set newid $rowmenuid
    } else {
        set oldid $rowmenuid
        set newid $lineid($selectedline)
    }
    addtohistory [list doseldiff $oldid $newid]
    doseldiff $oldid $newid
}

proc doseldiff {oldid newid} {
    global ctext cflist
    global commitinfo

    $ctext conf -state normal
    $ctext delete 0.0 end
    $ctext mark set fmark.0 0.0
    $ctext mark gravity fmark.0 left
    $cflist delete 0 end
    $cflist insert end "Top"
    $ctext insert end "From "
    $ctext tag conf link -foreground blue -underline 1
    $ctext tag bind link <Enter> { %W configure -cursor hand2 }
    $ctext tag bind link <Leave> { %W configure -cursor $curtextcursor }
    $ctext tag bind link0 <1> [list selbyid $oldid]
    $ctext insert end $oldid [list link link0]
    $ctext insert end "\n     "
    $ctext insert end [lindex $commitinfo($oldid) 0]
    $ctext insert end "\n\nTo   "
    $ctext tag bind link1 <1> [list selbyid $newid]
    $ctext insert end $newid [list link link1]
    $ctext insert end "\n     "
    $ctext insert end [lindex $commitinfo($newid) 0]
    $ctext insert end "\n"
    $ctext conf -state disabled
    $ctext tag delete Comments
    $ctext tag remove found 1.0 end
    startdiff [list $oldid $newid]
}

proc mkpatch {} {
    global rowmenuid currentid commitinfo patchtop patchnum

    if {![info exists currentid]} return
    set oldid $currentid
    set oldhead [lindex $commitinfo($oldid) 0]
    set newid $rowmenuid
    set newhead [lindex $commitinfo($newid) 0]
    set top .patch
    set patchtop $top
    catch {destroy $top}
    toplevel $top
    label $top.title -text "Generate patch"
    grid $top.title - -pady 10
    label $top.from -text "From:"
    entry $top.fromsha1 -width 40 -relief flat
    $top.fromsha1 insert 0 $oldid
    $top.fromsha1 conf -state readonly
    grid $top.from $top.fromsha1 -sticky w
    entry $top.fromhead -width 60 -relief flat
    $top.fromhead insert 0 $oldhead
    $top.fromhead conf -state readonly
    grid x $top.fromhead -sticky w
    label $top.to -text "To:"
    entry $top.tosha1 -width 40 -relief flat
    $top.tosha1 insert 0 $newid
    $top.tosha1 conf -state readonly
    grid $top.to $top.tosha1 -sticky w
    entry $top.tohead -width 60 -relief flat
    $top.tohead insert 0 $newhead
    $top.tohead conf -state readonly
    grid x $top.tohead -sticky w
    button $top.rev -text "Reverse" -command mkpatchrev -padx 5
    grid $top.rev x -pady 10
    label $top.flab -text "Output file:"
    entry $top.fname -width 60
    $top.fname insert 0 [file normalize "patch$patchnum.patch"]
    incr patchnum
    grid $top.flab $top.fname -sticky w
    frame $top.buts
    button $top.buts.gen -text "Generate" -command mkpatchgo
    button $top.buts.can -text "Cancel" -command mkpatchcan
    grid $top.buts.gen $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - -pady 10 -sticky ew
    focus $top.fname
}

proc mkpatchrev {} {
    global patchtop

    set oldid [$patchtop.fromsha1 get]
    set oldhead [$patchtop.fromhead get]
    set newid [$patchtop.tosha1 get]
    set newhead [$patchtop.tohead get]
    foreach e [list fromsha1 fromhead tosha1 tohead] \
            v [list $newid $newhead $oldid $oldhead] {
        $patchtop.$e conf -state normal
        $patchtop.$e delete 0 end
        $patchtop.$e insert 0 $v
        $patchtop.$e conf -state readonly
    }
}

proc mkpatchgo {} {
    global patchtop

    set oldid [$patchtop.fromsha1 get]
    set newid [$patchtop.tosha1 get]
    set fname [$patchtop.fname get]
    if {[catch {exec git-diff-tree -p $oldid $newid >$fname &} err]} {
        error_popup "Error creating patch: $err"
    }
    catch {destroy $patchtop}
    unset patchtop
}

proc mkpatchcan {} {
    global patchtop

    catch {destroy $patchtop}
    unset patchtop
}

proc mktag {} {
    global rowmenuid mktagtop commitinfo

    set top .maketag
    set mktagtop $top
    catch {destroy $top}
    toplevel $top
    label $top.title -text "Create tag"
    grid $top.title - -pady 10
    label $top.id -text "ID:"
    entry $top.sha1 -width 40 -relief flat
    $top.sha1 insert 0 $rowmenuid
    $top.sha1 conf -state readonly
    grid $top.id $top.sha1 -sticky w
    entry $top.head -width 60 -relief flat
    $top.head insert 0 [lindex $commitinfo($rowmenuid) 0]
    $top.head conf -state readonly
    grid x $top.head -sticky w
    label $top.tlab -text "Tag name:"
    entry $top.tag -width 60
    grid $top.tlab $top.tag -sticky w
    frame $top.buts
    button $top.buts.gen -text "Create" -command mktaggo
    button $top.buts.can -text "Cancel" -command mktagcan
    grid $top.buts.gen $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - -pady 10 -sticky ew
    focus $top.tag
}

proc domktag {} {
    global mktagtop env tagids idtags

    set id [$mktagtop.sha1 get]
    set tag [$mktagtop.tag get]
    if {$tag == {}} {
        error_popup "No tag name specified"
        return
    }
    if {[info exists tagids($tag)]} {
        error_popup "Tag \"$tag\" already exists"
        return
    }
    if {[catch {
        set dir [gitdir]
        set fname [file join $dir "refs/tags" $tag]
        set f [open $fname w]
        puts $f $id
        close $f
    } err]} {
        error_popup "Error creating tag: $err"
        return
    }

    set tagids($tag) $id
    lappend idtags($id) $tag
    redrawtags $id
}

proc redrawtags {id} {
    global canv linehtag commitrow idpos selectedline

    if {![info exists commitrow($id)]} return
    drawcmitrow $commitrow($id)
    $canv delete tag.$id
    set xt [eval drawtags $id $idpos($id)]
    $canv coords $linehtag($commitrow($id)) $xt [lindex $idpos($id) 2]
    if {[info exists selectedline] && $selectedline == $commitrow($id)} {
        selectline $selectedline 0
    }
}

proc mktagcan {} {
    global mktagtop

    catch {destroy $mktagtop}
    unset mktagtop
}

proc mktaggo {} {
    domktag
    mktagcan
}

proc writecommit {} {
    global rowmenuid wrcomtop commitinfo wrcomcmd

    set top .writecommit
    set wrcomtop $top
    catch {destroy $top}
    toplevel $top
    label $top.title -text "Write commit to file"
    grid $top.title - -pady 10
    label $top.id -text "ID:"
    entry $top.sha1 -width 40 -relief flat
    $top.sha1 insert 0 $rowmenuid
    $top.sha1 conf -state readonly
    grid $top.id $top.sha1 -sticky w
    entry $top.head -width 60 -relief flat
    $top.head insert 0 [lindex $commitinfo($rowmenuid) 0]
    $top.head conf -state readonly
    grid x $top.head -sticky w
    label $top.clab -text "Command:"
    entry $top.cmd -width 60 -textvariable wrcomcmd
    grid $top.clab $top.cmd -sticky w -pady 10
    label $top.flab -text "Output file:"
    entry $top.fname -width 60
    $top.fname insert 0 [file normalize "commit-[string range $rowmenuid 0 6]"]
    grid $top.flab $top.fname -sticky w
    frame $top.buts
    button $top.buts.gen -text "Write" -command wrcomgo
    button $top.buts.can -text "Cancel" -command wrcomcan
    grid $top.buts.gen $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - -pady 10 -sticky ew
    focus $top.fname
}

proc wrcomgo {} {
    global wrcomtop

    set id [$wrcomtop.sha1 get]
    set cmd "echo $id | [$wrcomtop.cmd get]"
    set fname [$wrcomtop.fname get]
    if {[catch {exec sh -c $cmd >$fname &} err]} {
        error_popup "Error writing commit: $err"
    }
    catch {destroy $wrcomtop}
    unset wrcomtop
}

proc wrcomcan {} {
    global wrcomtop

    catch {destroy $wrcomtop}
    unset wrcomtop
}

proc listrefs {id} {
    global idtags idheads idotherrefs

    set x {}
    if {[info exists idtags($id)]} {
        set x $idtags($id)
    }
    set y {}
    if {[info exists idheads($id)]} {
        set y $idheads($id)
    }
    set z {}
    if {[info exists idotherrefs($id)]} {
        set z $idotherrefs($id)
    }
    return [list $x $y $z]
}

proc rereadrefs {} {
    global idtags idheads idotherrefs
    global tagids headids otherrefids

    set refids [concat [array names idtags] \
                    [array names idheads] [array names idotherrefs]]
    foreach id $refids {
        if {![info exists ref($id)]} {
            set ref($id) [listrefs $id]
        }
    }
    readrefs
    set refids [lsort -unique [concat $refids [array names idtags] \
                        [array names idheads] [array names idotherrefs]]]
    foreach id $refids {
        set v [listrefs $id]
        if {![info exists ref($id)] || $ref($id) != $v} {
            redrawtags $id
        }
    }
}

proc showtag {tag isnew} {
    global ctext cflist tagcontents tagids linknum

    if {$isnew} {
        addtohistory [list showtag $tag 0]
    }
    $ctext conf -state normal
    $ctext delete 0.0 end
    set linknum 0
    if {[info exists tagcontents($tag)]} {
        set text $tagcontents($tag)
    } else {
        set text "Tag: $tag\nId:  $tagids($tag)"
    }
    appendwithlinks $text
    $ctext conf -state disabled
    $cflist delete 0 end
}

proc doquit {} {
    global stopped
    set stopped 100
    destroy .
}

proc doprefs {} {
    global maxwidth maxgraphpct diffopts findmergefiles
    global oldprefs prefstop

    set top .gitkprefs
    set prefstop $top
    if {[winfo exists $top]} {
        raise $top
        return
    }
    foreach v {maxwidth maxgraphpct diffopts findmergefiles} {
        set oldprefs($v) [set $v]
    }
    toplevel $top
    wm title $top "Gitk preferences"
    label $top.ldisp -text "Commit list display options"
    grid $top.ldisp - -sticky w -pady 10
    label $top.spacer -text " "
    label $top.maxwidthl -text "Maximum graph width (lines)" \
        -font optionfont
    spinbox $top.maxwidth -from 0 -to 100 -width 4 -textvariable maxwidth
    grid $top.spacer $top.maxwidthl $top.maxwidth -sticky w
    label $top.maxpctl -text "Maximum graph width (% of pane)" \
        -font optionfont
    spinbox $top.maxpct -from 1 -to 100 -width 4 -textvariable maxgraphpct
    grid x $top.maxpctl $top.maxpct -sticky w
    checkbutton $top.findm -variable findmergefiles
    label $top.findml -text "Include merges for \"Find\" in \"Files\"" \
        -font optionfont
    grid $top.findm $top.findml - -sticky w
    label $top.ddisp -text "Diff display options"
    grid $top.ddisp - -sticky w -pady 10
    label $top.diffoptl -text "Options for diff program" \
        -font optionfont
    entry $top.diffopt -width 20 -textvariable diffopts
    grid x $top.diffoptl $top.diffopt -sticky w
    frame $top.buts
    button $top.buts.ok -text "OK" -command prefsok
    button $top.buts.can -text "Cancel" -command prefscan
    grid $top.buts.ok $top.buts.can
    grid columnconfigure $top.buts 0 -weight 1 -uniform a
    grid columnconfigure $top.buts 1 -weight 1 -uniform a
    grid $top.buts - - -pady 10 -sticky ew
}

proc prefscan {} {
    global maxwidth maxgraphpct diffopts findmergefiles
    global oldprefs prefstop

    foreach v {maxwidth maxgraphpct diffopts findmergefiles} {
        set $v $oldprefs($v)
    }
    catch {destroy $prefstop}
    unset prefstop
}

proc prefsok {} {
    global maxwidth maxgraphpct
    global oldprefs prefstop

    catch {destroy $prefstop}
    unset prefstop
    if {$maxwidth != $oldprefs(maxwidth)
        || $maxgraphpct != $oldprefs(maxgraphpct)} {
        redisplay
    }
}

proc formatdate {d} {
    return [clock format $d -format "%Y-%m-%d %H:%M:%S"]
}

# This list of encoding names and aliases is distilled from
# http://www.iana.org/assignments/character-sets.
# Not all of them are supported by Tcl.
set encoding_aliases {
    { ANSI_X3.4-1968 iso-ir-6 ANSI_X3.4-1986 ISO_646.irv:1991 ASCII
      ISO646-US US-ASCII us IBM367 cp367 csASCII }
    { ISO-10646-UTF-1 csISO10646UTF1 }
    { ISO_646.basic:1983 ref csISO646basic1983 }
    { INVARIANT csINVARIANT }
    { ISO_646.irv:1983 iso-ir-2 irv csISO2IntlRefVersion }
    { BS_4730 iso-ir-4 ISO646-GB gb uk csISO4UnitedKingdom }
    { NATS-SEFI iso-ir-8-1 csNATSSEFI }
    { NATS-SEFI-ADD iso-ir-8-2 csNATSSEFIADD }
    { NATS-DANO iso-ir-9-1 csNATSDANO }
    { NATS-DANO-ADD iso-ir-9-2 csNATSDANOADD }
    { SEN_850200_B iso-ir-10 FI ISO646-FI ISO646-SE se csISO10Swedish }
    { SEN_850200_C iso-ir-11 ISO646-SE2 se2 csISO11SwedishForNames }
    { KS_C_5601-1987 iso-ir-149 KS_C_5601-1989 KSC_5601 korean csKSC56011987 }
    { ISO-2022-KR csISO2022KR }
    { EUC-KR csEUCKR }
    { ISO-2022-JP csISO2022JP }
    { ISO-2022-JP-2 csISO2022JP2 }
    { JIS_C6220-1969-jp JIS_C6220-1969 iso-ir-13 katakana x0201-7
      csISO13JISC6220jp }
    { JIS_C6220-1969-ro iso-ir-14 jp ISO646-JP csISO14JISC6220ro }
    { IT iso-ir-15 ISO646-IT csISO15Italian }
    { PT iso-ir-16 ISO646-PT csISO16Portuguese }
    { ES iso-ir-17 ISO646-ES csISO17Spanish }
    { greek7-old iso-ir-18 csISO18Greek7Old }
    { latin-greek iso-ir-19 csISO19LatinGreek }
    { DIN_66003 iso-ir-21 de ISO646-DE csISO21German }
    { NF_Z_62-010_(1973) iso-ir-25 ISO646-FR1 csISO25French }
    { Latin-greek-1 iso-ir-27 csISO27LatinGreek1 }
    { ISO_5427 iso-ir-37 csISO5427Cyrillic }
    { JIS_C6226-1978 iso-ir-42 csISO42JISC62261978 }
    { BS_viewdata iso-ir-47 csISO47BSViewdata }
    { INIS iso-ir-49 csISO49INIS }
    { INIS-8 iso-ir-50 csISO50INIS8 }
    { INIS-cyrillic iso-ir-51 csISO51INISCyrillic }
    { ISO_5427:1981 iso-ir-54 ISO5427Cyrillic1981 }
    { ISO_5428:1980 iso-ir-55 csISO5428Greek }
    { GB_1988-80 iso-ir-57 cn ISO646-CN csISO57GB1988 }
    { GB_2312-80 iso-ir-58 chinese csISO58GB231280 }
    { NS_4551-1 iso-ir-60 ISO646-NO no csISO60DanishNorwegian
      csISO60Norwegian1 }
    { NS_4551-2 ISO646-NO2 iso-ir-61 no2 csISO61Norwegian2 }
    { NF_Z_62-010 iso-ir-69 ISO646-FR fr csISO69French }
    { videotex-suppl iso-ir-70 csISO70VideotexSupp1 }
    { PT2 iso-ir-84 ISO646-PT2 csISO84Portuguese2 }
    { ES2 iso-ir-85 ISO646-ES2 csISO85Spanish2 }
    { MSZ_7795.3 iso-ir-86 ISO646-HU hu csISO86Hungarian }
    { JIS_C6226-1983 iso-ir-87 x0208 JIS_X0208-1983 csISO87JISX0208 }
    { greek7 iso-ir-88 csISO88Greek7 }
    { ASMO_449 ISO_9036 arabic7 iso-ir-89 csISO89ASMO449 }
    { iso-ir-90 csISO90 }
    { JIS_C6229-1984-a iso-ir-91 jp-ocr-a csISO91JISC62291984a }
    { JIS_C6229-1984-b iso-ir-92 ISO646-JP-OCR-B jp-ocr-b
      csISO92JISC62991984b }
    { JIS_C6229-1984-b-add iso-ir-93 jp-ocr-b-add csISO93JIS62291984badd }
    { JIS_C6229-1984-hand iso-ir-94 jp-ocr-hand csISO94JIS62291984hand }
    { JIS_C6229-1984-hand-add iso-ir-95 jp-ocr-hand-add
      csISO95JIS62291984handadd }
    { JIS_C6229-1984-kana iso-ir-96 csISO96JISC62291984kana }
    { ISO_2033-1983 iso-ir-98 e13b csISO2033 }
    { ANSI_X3.110-1983 iso-ir-99 CSA_T500-1983 NAPLPS csISO99NAPLPS }
    { ISO_8859-1:1987 iso-ir-100 ISO_8859-1 ISO-8859-1 latin1 l1 IBM819
      CP819 csISOLatin1 }
    { ISO_8859-2:1987 iso-ir-101 ISO_8859-2 ISO-8859-2 latin2 l2 csISOLatin2 }
    { T.61-7bit iso-ir-102 csISO102T617bit }
    { T.61-8bit T.61 iso-ir-103 csISO103T618bit }
    { ISO_8859-3:1988 iso-ir-109 ISO_8859-3 ISO-8859-3 latin3 l3 csISOLatin3 }
    { ISO_8859-4:1988 iso-ir-110 ISO_8859-4 ISO-8859-4 latin4 l4 csISOLatin4 }
    { ECMA-cyrillic iso-ir-111 KOI8-E csISO111ECMACyrillic }
    { CSA_Z243.4-1985-1 iso-ir-121 ISO646-CA csa7-1 ca csISO121Canadian1 }
    { CSA_Z243.4-1985-2 iso-ir-122 ISO646-CA2 csa7-2 csISO122Canadian2 }
    { CSA_Z243.4-1985-gr iso-ir-123 csISO123CSAZ24341985gr }
    { ISO_8859-6:1987 iso-ir-127 ISO_8859-6 ISO-8859-6 ECMA-114 ASMO-708
      arabic csISOLatinArabic }
    { ISO_8859-6-E csISO88596E ISO-8859-6-E }
    { ISO_8859-6-I csISO88596I ISO-8859-6-I }
    { ISO_8859-7:1987 iso-ir-126 ISO_8859-7 ISO-8859-7 ELOT_928 ECMA-118
      greek greek8 csISOLatinGreek }
    { T.101-G2 iso-ir-128 csISO128T101G2 }
    { ISO_8859-8:1988 iso-ir-138 ISO_8859-8 ISO-8859-8 hebrew
      csISOLatinHebrew }
    { ISO_8859-8-E csISO88598E ISO-8859-8-E }
    { ISO_8859-8-I csISO88598I ISO-8859-8-I }
    { CSN_369103 iso-ir-139 csISO139CSN369103 }
    { JUS_I.B1.002 iso-ir-141 ISO646-YU js yu csISO141JUSIB1002 }
    { ISO_6937-2-add iso-ir-142 csISOTextComm }
    { IEC_P27-1 iso-ir-143 csISO143IECP271 }
    { ISO_8859-5:1988 iso-ir-144 ISO_8859-5 ISO-8859-5 cyrillic
      csISOLatinCyrillic }
    { JUS_I.B1.003-serb iso-ir-146 serbian csISO146Serbian }
    { JUS_I.B1.003-mac macedonian iso-ir-147 csISO147Macedonian }
    { ISO_8859-9:1989 iso-ir-148 ISO_8859-9 ISO-8859-9 latin5 l5 csISOLatin5 }
    { greek-ccitt iso-ir-150 csISO150 csISO150GreekCCITT }
    { NC_NC00-10:81 cuba iso-ir-151 ISO646-CU csISO151Cuba }
    { ISO_6937-2-25 iso-ir-152 csISO6937Add }
    { GOST_19768-74 ST_SEV_358-88 iso-ir-153 csISO153GOST1976874 }
    { ISO_8859-supp iso-ir-154 latin1-2-5 csISO8859Supp }
    { ISO_10367-box iso-ir-155 csISO10367Box }
    { ISO-8859-10 iso-ir-157 l6 ISO_8859-10:1992 csISOLatin6 latin6 }
    { latin-lap lap iso-ir-158 csISO158Lap }
    { JIS_X0212-1990 x0212 iso-ir-159 csISO159JISX02121990 }
    { DS_2089 DS2089 ISO646-DK dk csISO646Danish }
    { us-dk csUSDK }
    { dk-us csDKUS }
    { JIS_X0201 X0201 csHalfWidthKatakana }
    { KSC5636 ISO646-KR csKSC5636 }
    { ISO-10646-UCS-2 csUnicode }
    { ISO-10646-UCS-4 csUCS4 }
    { DEC-MCS dec csDECMCS }
    { hp-roman8 roman8 r8 csHPRoman8 }
    { macintosh mac csMacintosh }
    { IBM037 cp037 ebcdic-cp-us ebcdic-cp-ca ebcdic-cp-wt ebcdic-cp-nl
      csIBM037 }
    { IBM038 EBCDIC-INT cp038 csIBM038 }
    { IBM273 CP273 csIBM273 }
    { IBM274 EBCDIC-BE CP274 csIBM274 }
    { IBM275 EBCDIC-BR cp275 csIBM275 }
    { IBM277 EBCDIC-CP-DK EBCDIC-CP-NO csIBM277 }
    { IBM278 CP278 ebcdic-cp-fi ebcdic-cp-se csIBM278 }
    { IBM280 CP280 ebcdic-cp-it csIBM280 }
    { IBM281 EBCDIC-JP-E cp281 csIBM281 }
    { IBM284 CP284 ebcdic-cp-es csIBM284 }
    { IBM285 CP285 ebcdic-cp-gb csIBM285 }
    { IBM290 cp290 EBCDIC-JP-kana csIBM290 }
    { IBM297 cp297 ebcdic-cp-fr csIBM297 }
    { IBM420 cp420 ebcdic-cp-ar1 csIBM420 }
    { IBM423 cp423 ebcdic-cp-gr csIBM423 }
    { IBM424 cp424 ebcdic-cp-he csIBM424 }
    { IBM437 cp437 437 csPC8CodePage437 }
    { IBM500 CP500 ebcdic-cp-be ebcdic-cp-ch csIBM500 }
    { IBM775 cp775 csPC775Baltic }
    { IBM850 cp850 850 csPC850Multilingual }
    { IBM851 cp851 851 csIBM851 }
    { IBM852 cp852 852 csPCp852 }
    { IBM855 cp855 855 csIBM855 }
    { IBM857 cp857 857 csIBM857 }
    { IBM860 cp860 860 csIBM860 }
    { IBM861 cp861 861 cp-is csIBM861 }
    { IBM862 cp862 862 csPC862LatinHebrew }
    { IBM863 cp863 863 csIBM863 }
    { IBM864 cp864 csIBM864 }
    { IBM865 cp865 865 csIBM865 }
    { IBM866 cp866 866 csIBM866 }
    { IBM868 CP868 cp-ar csIBM868 }
    { IBM869 cp869 869 cp-gr csIBM869 }
    { IBM870 CP870 ebcdic-cp-roece ebcdic-cp-yu csIBM870 }
    { IBM871 CP871 ebcdic-cp-is csIBM871 }
    { IBM880 cp880 EBCDIC-Cyrillic csIBM880 }
    { IBM891 cp891 csIBM891 }
    { IBM903 cp903 csIBM903 }
    { IBM904 cp904 904 csIBBM904 }
    { IBM905 CP905 ebcdic-cp-tr csIBM905 }
    { IBM918 CP918 ebcdic-cp-ar2 csIBM918 }
    { IBM1026 CP1026 csIBM1026 }
    { EBCDIC-AT-DE csIBMEBCDICATDE }
    { EBCDIC-AT-DE-A csEBCDICATDEA }
    { EBCDIC-CA-FR csEBCDICCAFR }
    { EBCDIC-DK-NO csEBCDICDKNO }
    { EBCDIC-DK-NO-A csEBCDICDKNOA }
    { EBCDIC-FI-SE csEBCDICFISE }
    { EBCDIC-FI-SE-A csEBCDICFISEA }
    { EBCDIC-FR csEBCDICFR }
    { EBCDIC-IT csEBCDICIT }
    { EBCDIC-PT csEBCDICPT }
    { EBCDIC-ES csEBCDICES }
    { EBCDIC-ES-A csEBCDICESA }
    { EBCDIC-ES-S csEBCDICESS }
    { EBCDIC-UK csEBCDICUK }
    { EBCDIC-US csEBCDICUS }
    { UNKNOWN-8BIT csUnknown8BiT }
    { MNEMONIC csMnemonic }
    { MNEM csMnem }
    { VISCII csVISCII }
    { VIQR csVIQR }
    { KOI8-R csKOI8R }
    { IBM00858 CCSID00858 CP00858 PC-Multilingual-850+euro }
    { IBM00924 CCSID00924 CP00924 ebcdic-Latin9--euro }
    { IBM01140 CCSID01140 CP01140 ebcdic-us-37+euro }
    { IBM01141 CCSID01141 CP01141 ebcdic-de-273+euro }
    { IBM01142 CCSID01142 CP01142 ebcdic-dk-277+euro ebcdic-no-277+euro }
    { IBM01143 CCSID01143 CP01143 ebcdic-fi-278+euro ebcdic-se-278+euro }
    { IBM01144 CCSID01144 CP01144 ebcdic-it-280+euro }
    { IBM01145 CCSID01145 CP01145 ebcdic-es-284+euro }
    { IBM01146 CCSID01146 CP01146 ebcdic-gb-285+euro }
    { IBM01147 CCSID01147 CP01147 ebcdic-fr-297+euro }
    { IBM01148 CCSID01148 CP01148 ebcdic-international-500+euro }
    { IBM01149 CCSID01149 CP01149 ebcdic-is-871+euro }
    { IBM1047 IBM-1047 }
    { PTCP154 csPTCP154 PT154 CP154 Cyrillic-Asian }
    { Amiga-1251 Ami1251 Amiga1251 Ami-1251 }
    { UNICODE-1-1 csUnicode11 }
    { CESU-8 csCESU-8 }
    { BOCU-1 csBOCU-1 }
    { UNICODE-1-1-UTF-7 csUnicode11UTF7 }
    { ISO-8859-14 iso-ir-199 ISO_8859-14:1998 ISO_8859-14 latin8 iso-celtic
      l8 }
    { ISO-8859-15 ISO_8859-15 Latin-9 }
    { ISO-8859-16 iso-ir-226 ISO_8859-16:2001 ISO_8859-16 latin10 l10 }
    { GBK CP936 MS936 windows-936 }
    { JIS_Encoding csJISEncoding }
    { Shift_JIS MS_Kanji csShiftJIS }
    { Extended_UNIX_Code_Packed_Format_for_Japanese csEUCPkdFmtJapanese
      EUC-JP }
    { Extended_UNIX_Code_Fixed_Width_for_Japanese csEUCFixWidJapanese }
    { ISO-10646-UCS-Basic csUnicodeASCII }
    { ISO-10646-Unicode-Latin1 csUnicodeLatin1 ISO-10646 }
    { ISO-Unicode-IBM-1261 csUnicodeIBM1261 }
    { ISO-Unicode-IBM-1268 csUnicodeIBM1268 }
    { ISO-Unicode-IBM-1276 csUnicodeIBM1276 }
    { ISO-Unicode-IBM-1264 csUnicodeIBM1264 }
    { ISO-Unicode-IBM-1265 csUnicodeIBM1265 }
    { ISO-8859-1-Windows-3.0-Latin-1 csWindows30Latin1 }
    { ISO-8859-1-Windows-3.1-Latin-1 csWindows31Latin1 }
    { ISO-8859-2-Windows-Latin-2 csWindows31Latin2 }
    { ISO-8859-9-Windows-Latin-5 csWindows31Latin5 }
    { Adobe-Standard-Encoding csAdobeStandardEncoding }
    { Ventura-US csVenturaUS }
    { Ventura-International csVenturaInternational }
    { PC8-Danish-Norwegian csPC8DanishNorwegian }
    { PC8-Turkish csPC8Turkish }
    { IBM-Symbols csIBMSymbols }
    { IBM-Thai csIBMThai }
    { HP-Legal csHPLegal }
    { HP-Pi-font csHPPiFont }
    { HP-Math8 csHPMath8 }
    { Adobe-Symbol-Encoding csHPPSMath }
    { HP-DeskTop csHPDesktop }
    { Ventura-Math csVenturaMath }
    { Microsoft-Publishing csMicrosoftPublishing }
    { Windows-31J csWindows31J }
    { GB2312 csGB2312 }
    { Big5 csBig5 }
}

proc tcl_encoding {enc} {
    global encoding_aliases
    set names [encoding names]
    set lcnames [string tolower $names]
    set enc [string tolower $enc]
    set i [lsearch -exact $lcnames $enc]
    if {$i < 0} {
        # look for "isonnn" instead of "iso-nnn" or "iso_nnn"
        if {[regsub {^iso[-_]} $enc iso encx]} {
            set i [lsearch -exact $lcnames $encx]
        }
    }
    if {$i < 0} {
        foreach l $encoding_aliases {
            set ll [string tolower $l]
            if {[lsearch -exact $ll $enc] < 0} continue
            # look through the aliases for one that tcl knows about
            foreach e $ll {
                set i [lsearch -exact $lcnames $e]
                if {$i < 0} {
                    if {[regsub {^iso[-_]} $e iso ex]} {
                        set i [lsearch -exact $lcnames $ex]
                    }
                }
                if {$i >= 0} break
            }
            break
        }
    }
    if {$i >= 0} {
        return [lindex $names $i]
    }
    return {}
}

# defaults...
set datemode 0
set diffopts "-U 5 -p"
set wrcomcmd "git-diff-tree --stdin -p --pretty"

set gitencoding {}
catch {
    set gitencoding [exec git-repo-config --get i18n.commitencoding]
}
if {$gitencoding == ""} {
    set gitencoding "utf-8"
}
set tclencoding [tcl_encoding $gitencoding]
if {$tclencoding == {}} {
    puts stderr "Warning: encoding $gitencoding is not supported by Tcl/Tk"
}

set mainfont {Helvetica 9}
set textfont {Courier 9}
set findmergefiles 0
set maxgraphpct 50
set maxwidth 16
set revlistorder 0
set fastdate 0
set uparrowlen 7
set downarrowlen 7
set mingaplen 30

set colors {green red blue magenta darkgrey brown orange}

catch {source ~/.gitk}

set namefont $mainfont

font create optionfont -family sans-serif -size -12

set revtreeargs {}
foreach arg $argv {
    switch -regexp -- $arg {
        "^$" { }
        "^-d" { set datemode 1 }
        default {
            lappend revtreeargs $arg
        }
    }
}

# check that we can find a .git directory somewhere...
set gitdir [gitdir]
if {![file isdirectory $gitdir]} {
    error_popup "Cannot find the git directory \"$gitdir\"."
    exit 1
}

set history {}
set historyindex 0

set optim_delay 16

set stopped 0
set stuffsaved 0
set patchnum 0
setcoords
makewindow $revtreeargs
readrefs
getcommits $revtreeargs