# git-gui diff viewer
# Copyright (C) 2006, 2007 Shawn Pearce

proc clear_diff {} {
        global ui_diff current_diff_path current_diff_header
        global ui_index ui_workdir

        $ui_diff conf -state normal
        $ui_diff delete 0.0 end
        $ui_diff conf -state disabled

        set current_diff_path {}
        set current_diff_header {}

        $ui_index tag remove in_diff 0.0 end
        $ui_workdir tag remove in_diff 0.0 end
}

proc reshow_diff {} {
        global ui_status_value file_states file_lists
        global current_diff_path current_diff_side

        set p $current_diff_path
        if {$p eq {}} {
                # No diff is being shown.
        } elseif {$current_diff_side eq {}
                || [catch {set s $file_states($p)}]
                || [lsearch -sorted -exact $file_lists($current_diff_side) $p] == -1} {
                clear_diff
        } else {
                show_diff $p $current_diff_side
        }
}

proc handle_empty_diff {} {
        global current_diff_path file_states file_lists

        set path $current_diff_path
        set s $file_states($path)
        if {[lindex $s 0] ne {_M}} return

        info_popup "No differences detected.

[short_path $path] has no changes.

The modification date of this file was updated by another application, but the content within the file was not changed.

A rescan will be automatically started to find other files which may have the same state."

        clear_diff
        display_file $path __
        rescan {set ui_status_value {Ready.}} 0
}

proc show_diff {path w {lno {}}} {
        global file_states file_lists
        global is_3way_diff diff_active repo_config
        global ui_diff ui_status_value ui_index ui_workdir
        global current_diff_path current_diff_side current_diff_header

        if {$diff_active || ![lock_index read]} return

        clear_diff
        if {$lno == {}} {
                set lno [lsearch -sorted -exact $file_lists($w) $path]
                if {$lno >= 0} {
                        incr lno
                }
        }
        if {$lno >= 1} {
                $w tag add in_diff $lno.0 [expr {$lno + 1}].0
        }

        set s $file_states($path)
        set m [lindex $s 0]
        set is_3way_diff 0
        set diff_active 1
        set current_diff_path $path
        set current_diff_side $w
        set current_diff_header {}
        set ui_status_value "Loading diff of [escape_path $path]..."

        # - Git won't give us the diff, there's nothing to compare to!
        #
        if {$m eq {_O}} {
                set max_sz [expr {128 * 1024}]
                if {[catch {
                                set fd [open $path r]
                                set content [read $fd $max_sz]
                                close $fd
                                set sz [file size $path]
                        } err ]} {
                        set diff_active 0
                        unlock_index
                        set ui_status_value "Unable to display [escape_path $path]"
                        error_popup "Error loading file:\n\n$err"
                        return
                }
                $ui_diff conf -state normal
                if {![catch {set type [exec file $path]}]} {
                        set n [string length $path]
                        if {[string equal -length $n $path $type]} {
                                set type [string range $type $n end]
                                regsub {^:?\s*} $type {} type
                        }
                        $ui_diff insert end "* $type\n" d_@
                }
                if {[string first "\0" $content] != -1} {
                        $ui_diff insert end \
                                "* Binary file (not showing content)." \
                                d_@
                } else {
                        if {$sz > $max_sz} {
                                $ui_diff insert end \
"* Untracked file is $sz bytes.
* Showing only first $max_sz bytes.
" d_@
                        }
                        $ui_diff insert end $content
                        if {$sz > $max_sz} {
                                $ui_diff insert end "
* Untracked file clipped here by [appname].
* To see the entire file, use an external editor.
" d_@
                        }
                }
                $ui_diff conf -state disabled
                set diff_active 0
                unlock_index
                set ui_status_value {Ready.}
                return
        }

        set cmd [list | git]
        if {$w eq $ui_index} {
                lappend cmd diff-index
                lappend cmd --cached
        } elseif {$w eq $ui_workdir} {
                if {[string index $m 0] eq {U}} {
                        lappend cmd diff
                } else {
                        lappend cmd diff-files
                }
        }

        lappend cmd -p
        lappend cmd --no-color
        if {$repo_config(gui.diffcontext) >= 0} {
                lappend cmd "-U$repo_config(gui.diffcontext)"
        }
        if {$w eq $ui_index} {
                lappend cmd [PARENT]
        }
        lappend cmd --
        lappend cmd $path

        if {[catch {set fd [open $cmd r]} err]} {
                set diff_active 0
                unlock_index
                set ui_status_value "Unable to display [escape_path $path]"
                error_popup "Error loading diff:\n\n$err"
                return
        }

        fconfigure $fd \
                -blocking 0 \
                -encoding binary \
                -translation binary
        fileevent $fd readable [list read_diff $fd]
}

proc read_diff {fd} {
        global ui_diff ui_status_value diff_active
        global is_3way_diff current_diff_header

        $ui_diff conf -state normal
        while {[gets $fd line] >= 0} {
                # -- Cleanup uninteresting diff header lines.
                #
                if {   [string match {diff --git *}      $line]
                        || [string match {diff --cc *}       $line]
                        || [string match {diff --combined *} $line]
                        || [string match {--- *}             $line]
                        || [string match {+++ *}             $line]} {
                        append current_diff_header $line "\n"
                        continue
                }
                if {[string match {index *} $line]} continue
                if {$line eq {deleted file mode 120000}} {
                        set line "deleted symlink"
                }

                # -- Automatically detect if this is a 3 way diff.
                #
                if {[string match {@@@ *} $line]} {set is_3way_diff 1}

                if {[string match {mode *} $line]
                        || [string match {new file *} $line]
                        || [string match {deleted file *} $line]
                        || [string match {Binary files * and * differ} $line]
                        || $line eq {\ No newline at end of file}
                        || [regexp {^\* Unmerged path } $line]} {
                        set tags {}
                } elseif {$is_3way_diff} {
                        set op [string range $line 0 1]
                        switch -- $op {
                        {  } {set tags {}}
                        {@@} {set tags d_@}
                        { +} {set tags d_s+}
                        { -} {set tags d_s-}
                        {+ } {set tags d_+s}
                        {- } {set tags d_-s}
                        {--} {set tags d_--}
                        {++} {
                                if {[regexp {^\+\+([<>]{7} |={7})} $line _g op]} {
                                        set line [string replace $line 0 1 {  }]
                                        set tags d$op
                                } else {
                                        set tags d_++
                                }
                        }
                        default {
                                puts "error: Unhandled 3 way diff marker: {$op}"
                                set tags {}
                        }
                        }
                } else {
                        set op [string index $line 0]
                        switch -- $op {
                        { } {set tags {}}
                        {@} {set tags d_@}
                        {-} {set tags d_-}
                        {+} {
                                if {[regexp {^\+([<>]{7} |={7})} $line _g op]} {
                                        set line [string replace $line 0 0 { }]
                                        set tags d$op
                                } else {
                                        set tags d_+
                                }
                        }
                        default {
                                puts "error: Unhandled 2 way diff marker: {$op}"
                                set tags {}
                        }
                        }
                }
                $ui_diff insert end $line $tags
                if {[string index $line end] eq "\r"} {
                        $ui_diff tag add d_cr {end - 2c}
                }
                $ui_diff insert end "\n" $tags
        }
        $ui_diff conf -state disabled

        if {[eof $fd]} {
                close $fd
                set diff_active 0
                unlock_index
                set ui_status_value {Ready.}

                if {[$ui_diff index end] eq {2.0}} {
                        handle_empty_diff
                }
        }
}

proc apply_hunk {x y} {
        global current_diff_path current_diff_header current_diff_side
        global ui_diff ui_index file_states

        if {$current_diff_path eq {} || $current_diff_header eq {}} return
        if {![lock_index apply_hunk]} return

        set apply_cmd {git apply --cached --whitespace=nowarn}
        set mi [lindex $file_states($current_diff_path) 0]
        if {$current_diff_side eq $ui_index} {
                set mode unstage
                lappend apply_cmd --reverse
                if {[string index $mi 0] ne {M}} {
                        unlock_index
                        return
                }
        } else {
                set mode stage
                if {[string index $mi 1] ne {M}} {
                        unlock_index
                        return
                }
        }

        set s_lno [lindex [split [$ui_diff index @$x,$y] .] 0]
        set s_lno [$ui_diff search -backwards -regexp ^@@ $s_lno.0 0.0]
        if {$s_lno eq {}} {
                unlock_index
                return
        }

        set e_lno [$ui_diff search -forwards -regexp ^@@ "$s_lno + 1 lines" end]
        if {$e_lno eq {}} {
                set e_lno end
        }

        if {[catch {
                set p [open "| $apply_cmd" w]
                fconfigure $p -translation binary -encoding binary
                puts -nonewline $p $current_diff_header
                puts -nonewline $p [$ui_diff get $s_lno $e_lno]
                close $p} err]} {
                error_popup "Failed to $mode selected hunk.\n\n$err"
                unlock_index
                return
        }

        $ui_diff conf -state normal
        $ui_diff delete $s_lno $e_lno
        $ui_diff conf -state disabled

        if {[$ui_diff get 1.0 end] eq "\n"} {
                set o _
        } else {
                set o ?
        }

        if {$current_diff_side eq $ui_index} {
                set mi ${o}M
        } elseif {[string index $mi 0] eq {_}} {
                set mi M$o
        } else {
                set mi ?$o
        }
        unlock_index
        display_file $current_diff_path $mi
        if {$o eq {_}} {
                clear_diff
        }
}