#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano.
#

USAGE='[--interactive | -i] [-v] [--force-rebase | -f] [--no-ff] [--onto <newbase>] [<upstream>|--root] [<branch>] [--quiet | -q]'
LONG_USAGE='git-rebase replaces <branch> with a new branch of the
same name.  When the --onto option is provided the new branch starts
out with a HEAD equal to <newbase>, otherwise it is equal to <upstream>
It then attempts to create a new commit for each commit from the original
<branch> that does not exist in the <upstream> branch.

It is possible that a merge failure will prevent this process from being
completely automatic.  You will have to resolve any such merge failure
and run git rebase --continue.  Another option is to bypass the commit
that caused the merge failure with git rebase --skip.  To check out the
original <branch> and remove the .git/rebase-apply working files, use the
command git rebase --abort instead.

Note that if <branch> is not specified on the command line, the
currently checked out branch is used.

Example:       git-rebase master~1 topic

        A---B---C topic                   A'\''--B'\''--C'\'' topic
       /                   -->           /
  D---E---F---G master          D---E---F---G master
'

SUBDIRECTORY_OK=Yes
OPTIONS_KEEPDASHDASH=
OPTIONS_SPEC="\
git rebase [-i] [options] [--onto <newbase>] [<upstream>] [<branch>]
git rebase [-i] [options] --onto <newbase> --root [<branch>]
git-rebase [-i] --continue | --abort | --skip
--
 Available options are
v,verbose!         display a diffstat of what changed upstream
q,quiet!           be quiet. implies --no-stat
onto=!             rebase onto given branch instead of upstream
p,preserve-merges! try to recreate merges instead of ignoring them
s,strategy=!       use the given merge strategy
no-ff!             cherry-pick all commits, even if unchanged
m,merge!           use merging strategies to rebase
i,interactive!     let the user edit the list of commits to rebase
k,keep-empty       preserve empty commits during rebase
f,force-rebase!    force rebase even if branch is up to date
X,strategy-option=! pass the argument through to the merge strategy
stat!              display a diffstat of what changed upstream
n,no-stat!         do not show diffstat of what changed upstream
verify             allow pre-rebase hook to run
rerere-autoupdate  allow rerere to update index with resolved conflicts
root!              rebase all reachable commits up to the root(s)
autosquash         move commits that begin with squash!/fixup! under -i
committer-date-is-author-date! passed to 'git am'
ignore-date!       passed to 'git am'
whitespace=!       passed to 'git apply'
ignore-whitespace! passed to 'git apply'
C=!                passed to 'git apply'
 Actions:
continue!          continue
abort!             abort and check out the original branch
skip!              skip current patch and continue
"
. git-sh-setup
set_reflog_action rebase
require_work_tree_exists
cd_to_toplevel

LF='
'
ok_to_skip_pre_rebase=
resolvemsg="
When you have resolved this problem run \"git rebase --continue\".
If you would prefer to skip this patch, instead run \"git rebase --skip\".
To check out the original branch and stop rebasing run \"git rebase --abort\".
"
unset onto
strategy=
strategy_opts=
do_merge=
merge_dir="$GIT_DIR"/rebase-merge
apply_dir="$GIT_DIR"/rebase-apply
verbose=
diffstat=
test "$(git config --bool rebase.stat)" = true && diffstat=t
git_am_opt=
rebase_root=
force_rebase=
allow_rerere_autoupdate=
# Non-empty if a rebase was in progress when 'git rebase' was invoked
in_progress=
# One of {am, merge, interactive}
type=
# One of {"$GIT_DIR"/rebase-apply, "$GIT_DIR"/rebase-merge}
state_dir=
# One of {'', continue, skip, abort}, as parsed from command line
action=
preserve_merges=
autosquash=
keep_empty=
test "$(git config --bool rebase.autosquash)" = "true" && autosquash=t

read_basic_state () {
        head_name=$(cat "$state_dir"/head-name) &&
        onto=$(cat "$state_dir"/onto) &&
        # We always write to orig-head, but interactive rebase used to write to
        # head. Fall back to reading from head to cover for the case that the
        # user upgraded git with an ongoing interactive rebase.
        if test -f "$state_dir"/orig-head
        then
                orig_head=$(cat "$state_dir"/orig-head)
        else
                orig_head=$(cat "$state_dir"/head)
        fi &&
        GIT_QUIET=$(cat "$state_dir"/quiet) &&
        test -f "$state_dir"/verbose && verbose=t
        test -f "$state_dir"/strategy && strategy="$(cat "$state_dir"/strategy)"
        test -f "$state_dir"/strategy_opts &&
                strategy_opts="$(cat "$state_dir"/strategy_opts)"
        test -f "$state_dir"/allow_rerere_autoupdate &&
                allow_rerere_autoupdate="$(cat "$state_dir"/allow_rerere_autoupdate)"
}

write_basic_state () {
        echo "$head_name" > "$state_dir"/head-name &&
        echo "$onto" > "$state_dir"/onto &&
        echo "$orig_head" > "$state_dir"/orig-head &&
        echo "$GIT_QUIET" > "$state_dir"/quiet &&
        test t = "$verbose" && : > "$state_dir"/verbose
        test -n "$strategy" && echo "$strategy" > "$state_dir"/strategy
        test -n "$strategy_opts" && echo "$strategy_opts" > \
                "$state_dir"/strategy_opts
        test -n "$allow_rerere_autoupdate" && echo "$allow_rerere_autoupdate" > \
                "$state_dir"/allow_rerere_autoupdate
}

output () {
        case "$verbose" in
        '')
                output=$("$@" 2>&1 )
                status=$?
                test $status != 0 && printf "%s\n" "$output"
                return $status
                ;;
        *)
                "$@"
                ;;
        esac
}

move_to_original_branch () {
        case "$head_name" in
        refs/*)
                message="rebase finished: $head_name onto $onto"
                git update-ref -m "$message" \
                        $head_name $(git rev-parse HEAD) $orig_head &&
                git symbolic-ref \
                        -m "rebase finished: returning to $head_name" \
                        HEAD $head_name ||
                die "Could not move back to $head_name"
                ;;
        esac
}

run_specific_rebase () {
        if [ "$interactive_rebase" = implied ]; then
                GIT_EDITOR=:
                export GIT_EDITOR
                autosquash=
        fi
        . git-rebase--$type
}

run_pre_rebase_hook () {
        if test -z "$ok_to_skip_pre_rebase" &&
           test -x "$GIT_DIR/hooks/pre-rebase"
        then
                "$GIT_DIR/hooks/pre-rebase" ${1+"$@"} ||
                die "The pre-rebase hook refused to rebase."
        fi
}

test -f "$apply_dir"/applying &&
        die 'It looks like git-am is in progress. Cannot rebase.'

if test -d "$apply_dir"
then
        type=am
        state_dir="$apply_dir"
elif test -d "$merge_dir"
then
        if test -f "$merge_dir"/interactive
        then
                type=interactive
                interactive_rebase=explicit
        else
                type=merge
        fi
        state_dir="$merge_dir"
fi
test -n "$type" && in_progress=t

total_argc=$#
while test $# != 0
do
        case "$1" in
        --no-verify)
                ok_to_skip_pre_rebase=yes
                ;;
        --verify)
                ok_to_skip_pre_rebase=
                ;;
        --continue|--skip|--abort)
                test $total_argc -eq 2 || usage
                action=${1##--}
                ;;
        --onto)
                test 2 -le "$#" || usage
                onto="$2"
                shift
                ;;
        -i)
                interactive_rebase=explicit
                ;;
        -k)
                keep_empty=yes
                ;;
        -p)
                preserve_merges=t
                test -z "$interactive_rebase" && interactive_rebase=implied
                ;;
        --autosquash)
                autosquash=t
                ;;
        --no-autosquash)
                autosquash=
                ;;
        -M|-m)
                do_merge=t
                ;;
        -X)
                shift
                strategy_opts="$strategy_opts $(git rev-parse --sq-quote "--$1")"
                do_merge=t
                test -z "$strategy" && strategy=recursive
                ;;
        -s)
                shift
                strategy="$1"
                do_merge=t
                ;;
        -n)
                diffstat=
                ;;
        --stat)
                diffstat=t
                ;;
        -v)
                verbose=t
                diffstat=t
                GIT_QUIET=
                ;;
        -q)
                GIT_QUIET=t
                git_am_opt="$git_am_opt -q"
                verbose=
                diffstat=
                ;;
        --whitespace)
                shift
                git_am_opt="$git_am_opt --whitespace=$1"
                case "$1" in
                fix|strip)
                        force_rebase=t
                        ;;
                esac
                ;;
        --ignore-whitespace)
                git_am_opt="$git_am_opt $1"
                ;;
        --committer-date-is-author-date|--ignore-date)
                git_am_opt="$git_am_opt $1"
                force_rebase=t
                ;;
        -C)
                shift
                git_am_opt="$git_am_opt -C$1"
                ;;
        --root)
                rebase_root=t
                ;;
        -f|--no-ff)
                force_rebase=t
                ;;
        --rerere-autoupdate|--no-rerere-autoupdate)
                allow_rerere_autoupdate="$1"
                ;;
        --)
                shift
                break
                ;;
        esac
        shift
done
test $# -gt 2 && usage

if test -n "$action"
then
        test -z "$in_progress" && die "No rebase in progress?"
        # Only interactive rebase uses detailed reflog messages
        if test "$type" = interactive && test "$GIT_REFLOG_ACTION" = rebase
        then
                GIT_REFLOG_ACTION="rebase -i ($action)"
                export GIT_REFLOG_ACTION
        fi
fi

case "$action" in
continue)
        # Sanity check
        git rev-parse --verify HEAD >/dev/null ||
                die "Cannot read HEAD"
        git update-index --ignore-submodules --refresh &&
        git diff-files --quiet --ignore-submodules || {
                echo "You must edit all merge conflicts and then"
                echo "mark them as resolved using git add"
                exit 1
        }
        read_basic_state
        run_specific_rebase
        ;;
skip)
        output git reset --hard HEAD || exit $?
        read_basic_state
        run_specific_rebase
        ;;
abort)
        git rerere clear
        read_basic_state
        case "$head_name" in
        refs/*)
                git symbolic-ref -m "rebase: aborting" HEAD $head_name ||
                die "Could not move back to $head_name"
                ;;
        esac
        output git reset --hard $orig_head
        rm -r "$state_dir"
        exit
        ;;
esac

# Make sure no rebase is in progress
if test -n "$in_progress"
then
        die '
It seems that there is already a '"${state_dir##*/}"' directory, and
I wonder if you are in the middle of another rebase.  If that is the
case, please try
        git rebase (--continue | --abort | --skip)
If that is not the case, please
        rm -fr '"$state_dir"'
and run me again.  I am stopping in case you still have something
valuable there.'
fi

if test -n "$interactive_rebase"
then
        type=interactive
        state_dir="$merge_dir"
elif test -n "$do_merge"
then
        type=merge
        state_dir="$merge_dir"
else
        type=am
        state_dir="$apply_dir"
fi

if test -z "$rebase_root"
then
        case "$#" in
        0)
                if ! upstream_name=$(git rev-parse --symbolic-full-name \
                        --verify -q @{upstream} 2>/dev/null)
                then
                        . git-parse-remote
                        error_on_missing_default_upstream "rebase" "rebase" \
                                "against" "git rebase <branch>"
                fi
                ;;
        *)      upstream_name="$1"
                shift
                ;;
        esac
        upstream=`git rev-parse --verify "${upstream_name}^0"` ||
        die "invalid upstream $upstream_name"
        upstream_arg="$upstream_name"
else
        test -z "$onto" && die "You must specify --onto when using --root"
        unset upstream_name
        unset upstream
        upstream_arg=--root
fi

# Make sure the branch to rebase onto is valid.
onto_name=${onto-"$upstream_name"}
case "$onto_name" in
*...*)
        if      left=${onto_name%...*} right=${onto_name#*...} &&
                onto=$(git merge-base --all ${left:-HEAD} ${right:-HEAD})
        then
                case "$onto" in
                ?*"$LF"?*)
                        die "$onto_name: there are more than one merge bases"
                        ;;
                '')
                        die "$onto_name: there is no merge base"
                        ;;
                esac
        else
                die "$onto_name: there is no merge base"
        fi
        ;;
*)
        onto=$(git rev-parse --verify "${onto_name}^0") ||
        die "Does not point to a valid commit: $onto_name"
        ;;
esac

# If the branch to rebase is given, that is the branch we will rebase
# $branch_name -- branch being rebased, or HEAD (already detached)
# $orig_head -- commit object name of tip of the branch before rebasing
# $head_name -- refs/heads/<that-branch> or "detached HEAD"
switch_to=
case "$#" in
1)
        # Is it "rebase other $branchname" or "rebase other $commit"?
        branch_name="$1"
        switch_to="$1"

        if git show-ref --verify --quiet -- "refs/heads/$1" &&
           orig_head=$(git rev-parse -q --verify "refs/heads/$1")
        then
                head_name="refs/heads/$1"
        elif orig_head=$(git rev-parse -q --verify "$1")
        then
                head_name="detached HEAD"
        else
                die "fatal: no such branch: $1"
        fi
        ;;
*)
        # Do not need to switch branches, we are already on it.
        if branch_name=`git symbolic-ref -q HEAD`
        then
                head_name=$branch_name
                branch_name=`expr "z$branch_name" : 'zrefs/heads/\(.*\)'`
        else
                head_name="detached HEAD"
                branch_name=HEAD ;# detached
        fi
        orig_head=$(git rev-parse --verify "${branch_name}^0") || exit
        ;;
esac

require_clean_work_tree "rebase" "Please commit or stash them."

# Now we are rebasing commits $upstream..$orig_head (or with --root,
# everything leading up to $orig_head) on top of $onto

# Check if we are already based on $onto with linear history,
# but this should be done only when upstream and onto are the same
# and if this is not an interactive rebase.
mb=$(git merge-base "$onto" "$orig_head")
if test "$type" != interactive && test "$upstream" = "$onto" &&
        test "$mb" = "$onto" &&
        # linear history?
        ! (git rev-list --parents "$onto".."$orig_head" | sane_grep " .* ") > /dev/null
then
        if test -z "$force_rebase"
        then
                # Lazily switch to the target branch if needed...
                test -z "$switch_to" || git checkout "$switch_to" --
                say "Current branch $branch_name is up to date."
                exit 0
        else
                say "Current branch $branch_name is up to date, rebase forced."
        fi
fi

# If a hook exists, give it a chance to interrupt
run_pre_rebase_hook "$upstream_arg" "$@"

if test -n "$diffstat"
then
        if test -n "$verbose"
        then
                echo "Changes from $mb to $onto:"
        fi
        # We want color (if set), but no pager
        GIT_PAGER='' git diff --stat --summary "$mb" "$onto"
fi

test "$type" = interactive && run_specific_rebase

# Detach HEAD and reset the tree
say "First, rewinding head to replay your work on top of it..."
git checkout -q "$onto^0" || die "could not detach HEAD"
git update-ref ORIG_HEAD $orig_head

# If the $onto is a proper descendant of the tip of the branch, then
# we just fast-forwarded.
if test "$mb" = "$orig_head"
then
        say "Fast-forwarded $branch_name to $onto_name."
        move_to_original_branch
        exit 0
fi

if test -n "$rebase_root"
then
        revisions="$onto..$orig_head"
else
        revisions="$upstream..$orig_head"
fi

run_specific_rebase