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

USAGE='[--interactive | -i] [-v] [--onto <newbase>] <upstream> [<branch>]'
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 restore the
original <branch> and remove the .dotest 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.  You must be in the top
directory of your project to start (or continue) a rebase.

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_SPEC=
. git-sh-setup
set_reflog_action rebase
require_work_tree
cd_to_toplevel

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 restore the original branch and stop rebasing run \"git rebase --abort\".
"
unset newbase
strategy=recursive
do_merge=
dotest=$GIT_DIR/.dotest-merge
prec=4
verbose=
git_am_opt=

continue_merge () {
        test -n "$prev_head" || die "prev_head must be defined"
        test -d "$dotest" || die "$dotest directory does not exist"

        unmerged=$(git ls-files -u)
        if test -n "$unmerged"
        then
                echo "You still have unmerged paths in your index"
                echo "did you forget to use git add?"
                die "$RESOLVEMSG"
        fi

        cmt=`cat "$dotest/current"`
        if ! git diff-index --quiet HEAD --
        then
                if ! git-commit -C "$cmt"
                then
                        echo "Commit failed, please do not call \"git commit\""
                        echo "directly, but instead do one of the following: "
                        die "$RESOLVEMSG"
                fi
                printf "Committed: %0${prec}d " $msgnum
        else
                printf "Already applied: %0${prec}d " $msgnum
        fi
        git rev-list --pretty=oneline -1 "$cmt" | sed -e 's/^[^ ]* //'

        prev_head=`git rev-parse HEAD^0`
        # save the resulting commit so we can read-tree on it later
        echo "$prev_head" > "$dotest/prev_head"

        # onto the next patch:
        msgnum=$(($msgnum + 1))
        echo "$msgnum" >"$dotest/msgnum"
}

call_merge () {
        cmt="$(cat "$dotest/cmt.$1")"
        echo "$cmt" > "$dotest/current"
        hd=$(git rev-parse --verify HEAD)
        cmt_name=$(git symbolic-ref HEAD 2> /dev/null || echo HEAD)
        msgnum=$(cat "$dotest/msgnum")
        end=$(cat "$dotest/end")
        eval GITHEAD_$cmt='"${cmt_name##refs/heads/}~$(($end - $msgnum))"'
        eval GITHEAD_$hd='$(cat "$dotest/onto_name")'
        export GITHEAD_$cmt GITHEAD_$hd
        git-merge-$strategy "$cmt^" -- "$hd" "$cmt"
        rv=$?
        case "$rv" in
        0)
                unset GITHEAD_$cmt GITHEAD_$hd
                return
                ;;
        1)
                git rerere
                die "$RESOLVEMSG"
                ;;
        2)
                echo "Strategy: $rv $strategy failed, try another" 1>&2
                die "$RESOLVEMSG"
                ;;
        *)
                die "Unknown exit code ($rv) from command:" \
                        "git-merge-$strategy $cmt^ -- HEAD $cmt"
                ;;
        esac
}

move_to_original_branch () {
        test -z "$head_name" &&
                head_name="$(cat "$dotest"/head-name)" &&
                onto="$(cat "$dotest"/onto)" &&
                orig_head="$(cat "$dotest"/orig-head)"
        case "$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 HEAD $head_name ||
                die "Could not move back to $head_name"
                ;;
        esac
}

finish_rb_merge () {
        move_to_original_branch
        rm -r "$dotest"
        echo "All done."
}

is_interactive () {
        test -f "$dotest"/interactive ||
        while :; do case $#,"$1" in 0,|*,-i|*,--interactive) break ;; esac
                shift
        done && test -n "$1"
}

is_interactive "$@" && exec git-rebase--interactive "$@"

while test $# != 0
do
        case "$1" in
        --continue)
                git diff-files --quiet || {
                        echo "You must edit all merge conflicts and then"
                        echo "mark them as resolved using git add"
                        exit 1
                }
                if test -d "$dotest"
                then
                        prev_head=$(cat "$dotest/prev_head")
                        end=$(cat "$dotest/end")
                        msgnum=$(cat "$dotest/msgnum")
                        onto=$(cat "$dotest/onto")
                        continue_merge
                        while test "$msgnum" -le "$end"
                        do
                                call_merge "$msgnum"
                                continue_merge
                        done
                        finish_rb_merge
                        exit
                fi
                head_name=$(cat .dotest/head-name) &&
                onto=$(cat .dotest/onto) &&
                orig_head=$(cat .dotest/orig-head) &&
                git am --resolved --3way --resolvemsg="$RESOLVEMSG" &&
                move_to_original_branch
                exit
                ;;
        --skip)
                git reset --hard HEAD || exit $?
                if test -d "$dotest"
                then
                        git rerere clear
                        prev_head=$(cat "$dotest/prev_head")
                        end=$(cat "$dotest/end")
                        msgnum=$(cat "$dotest/msgnum")
                        msgnum=$(($msgnum + 1))
                        onto=$(cat "$dotest/onto")
                        while test "$msgnum" -le "$end"
                        do
                                call_merge "$msgnum"
                                continue_merge
                        done
                        finish_rb_merge
                        exit
                fi
                head_name=$(cat .dotest/head-name) &&
                onto=$(cat .dotest/onto) &&
                orig_head=$(cat .dotest/orig-head) &&
                git am -3 --skip --resolvemsg="$RESOLVEMSG" &&
                move_to_original_branch
                exit
                ;;
        --abort)
                git rerere clear
                if test -d "$dotest"
                then
                        move_to_original_branch
                elif test -d .dotest
                then
                        dotest=.dotest
                        move_to_original_branch
                else
                        die "No rebase in progress?"
                fi
                git reset --hard $(cat $dotest/orig-head)
                rm -r "$dotest"
                exit
                ;;
        --onto)
                test 2 -le "$#" || usage
                newbase="$2"
                shift
                ;;
        -M|-m|--m|--me|--mer|--merg|--merge)
                do_merge=t
                ;;
        -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
                --strateg=*|--strategy=*|\
        -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
                case "$#,$1" in
                *,*=*)
                        strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
                1,*)
                        usage ;;
                *)
                        strategy="$2"
                        shift ;;
                esac
                do_merge=t
                ;;
        -v|--verbose)
                verbose=t
                ;;
        --whitespace=*)
                git_am_opt="$git_am_opt $1"
                ;;
        -C*)
                git_am_opt="$git_am_opt $1"
                ;;
        -*)
                usage
                ;;
        *)
                break
                ;;
        esac
        shift
done

# Make sure we do not have .dotest
if test -z "$do_merge"
then
        if mkdir .dotest
        then
                rmdir .dotest
        else
                echo >&2 '
It seems that I cannot create a .dotest directory, and I wonder if you
are in the middle of patch application or another rebase.  If that is not
the case, please rm -fr .dotest and run me again.  I am stopping in case
you still have something valuable there.'
                exit 1
        fi
else
        if test -d "$dotest"
        then
                die "previous dotest directory $dotest still exists." \
                        'try git-rebase < --continue | --abort >'
        fi
fi

# The tree must be really really clean.
git update-index --refresh || exit
diff=$(git diff-index --cached --name-status -r HEAD --)
case "$diff" in
?*)     echo "cannot rebase: your index is not up-to-date"
        echo "$diff"
        exit 1
        ;;
esac

# The upstream head must be given.  Make sure it is valid.
upstream_name="$1"
upstream=`git rev-parse --verify "${upstream_name}^0"` ||
    die "invalid upstream $upstream_name"

# Make sure the branch to rebase onto is valid.
onto_name=${newbase-"$upstream_name"}
onto=$(git rev-parse --verify "${onto_name}^0") || exit

# If a hook exists, give it a chance to interrupt
if test -x "$GIT_DIR/hooks/pre-rebase"
then
        "$GIT_DIR/hooks/pre-rebase" ${1+"$@"} || {
                echo >&2 "The pre-rebase hook refused to rebase."
                exit 1
        }
fi

# If the branch to rebase is given, first switch to it.
case "$#" in
2)
        branch_name="$2"
        git-checkout "$2" || usage
        ;;
*)
        if branch_name=`git symbolic-ref -q HEAD`
        then
                branch_name=`expr "z$branch_name" : 'zrefs/heads/\(.*\)'`
        else
                branch_name=HEAD ;# detached
        fi
        ;;
esac
branch=$(git rev-parse --verify "${branch_name}^0") || exit

# Now we are rebasing commits $upstream..$branch on top of $onto

# Check if we are already based on $onto with linear history,
# but this should be done only when upstream and onto are the same.
mb=$(git merge-base "$onto" "$branch")
if test "$upstream" = "$onto" && test "$mb" = "$onto" &&
        # linear history?
        ! git rev-list --parents "$onto".."$branch" | grep " .* " > /dev/null
then
        echo >&2 "Current branch $branch_name is up to date."
        exit 0
fi

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

# move to a detached HEAD
orig_head=$(git rev-parse HEAD^0)
head_name=$(git symbolic-ref HEAD 2> /dev/null)
case "$head_name" in
'')
        head_name="detached HEAD"
        ;;
*)
        git checkout "$orig_head" > /dev/null 2>&1 ||
                die "could not detach HEAD"
        ;;
esac

# Rewind the head to "$onto"; this saves our current head in ORIG_HEAD.
echo "First, rewinding head to replay your work on top of it..."
git-reset --hard "$onto"

# If the $onto is a proper descendant of the tip of the branch, then
# we just fast forwarded.
if test "$mb" = "$branch"
then
        echo >&2 "Fast-forwarded $branch_name to $onto_name."
        move_to_original_branch
        exit 0
fi

if test -z "$do_merge"
then
        git format-patch -k --stdout --full-index --ignore-if-in-upstream "$upstream"..ORIG_HEAD |
        git am $git_am_opt --binary -3 -k --resolvemsg="$RESOLVEMSG" &&
        move_to_original_branch
        ret=$?
        test 0 != $ret -a -d .dotest &&
                echo $head_name > .dotest/head-name &&
                echo $onto > .dotest/onto &&
                echo $orig_head > .dotest/orig-head
        exit $ret
fi

# start doing a rebase with git-merge
# this is rename-aware if the recursive (default) strategy is used

mkdir -p "$dotest"
echo "$onto" > "$dotest/onto"
echo "$onto_name" > "$dotest/onto_name"
prev_head=$orig_head
echo "$prev_head" > "$dotest/prev_head"
echo "$orig_head" > "$dotest/orig-head"
echo "$head_name" > "$dotest/head-name"

msgnum=0
for cmt in `git rev-list --reverse --no-merges "$upstream"..ORIG_HEAD`
do
        msgnum=$(($msgnum + 1))
        echo "$cmt" > "$dotest/cmt.$msgnum"
done

echo 1 >"$dotest/msgnum"
echo $msgnum >"$dotest/end"

end=$msgnum
msgnum=1

while test "$msgnum" -le "$end"
do
        call_merge "$msgnum"
        continue_merge
done

finish_rb_merge