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

USAGE='[--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
'
. git-sh-setup

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\".
"

MRESOLVEMSG="
When you have resolved this problem run \"git rebase --continue\".
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

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 update-index?"
                die "$MRESOLVEMSG"
        fi

        if test -n "`git-diff-index HEAD`"
        then
                git-commit -C "`cat $dotest/current`"
        else
                echo "Previous merge succeeded automatically"
        fi

        prev_head=`git-rev-parse HEAD^0`

        # save the resulting commit so we can read-tree on it later
        echo "$prev_head" > "$dotest/`printf %0${prec}d $msgnum`.result"
        echo "$prev_head" > "$dotest/prev_head"

        # onto the next patch:
        msgnum=$(($msgnum + 1))
        printf "%0${prec}d" "$msgnum" > "$dotest/msgnum"
}

call_merge () {
        cmt="$(cat $dotest/`printf %0${prec}d $1`)"
        echo "$cmt" > "$dotest/current"
        git-merge-$strategy "$cmt^" -- HEAD "$cmt"
        rv=$?
        case "$rv" in
        0)
                git-commit -C "$cmt" || die "commit failed: $MRESOLVEMSG"
                ;;
        1)
                test -d "$GIT_DIR/rr-cache" && git-rerere
                die "$MRESOLVEMSG"
                ;;
        2)
                echo "Strategy: $rv $strategy failed, try another" 1>&2
                die "$MRESOLVEMSG"
                ;;
        *)
                die "Unknown exit code ($rv) from command:" \
                        "git-merge-$strategy $cmt^ -- HEAD $cmt"
                ;;
        esac
}

finish_rb_merge () {
        set -e

        msgnum=1
        echo "Finalizing rebased commits..."
        git-reset --hard "`cat $dotest/onto`"
        end="`cat $dotest/end`"
        while test "$msgnum" -le "$end"
        do
                msgnum=`printf "%0${prec}d" "$msgnum"`
                printf "%0${prec}d" "$msgnum" > "$dotest/msgnum"

                git-read-tree `cat "$dotest/$msgnum.result"`
                git-checkout-index -q -f -u -a
                git-commit -C "`cat $dotest/$msgnum`"

                echo "Committed $msgnum"
                echo '    '`git-rev-list --pretty=oneline -1 HEAD | \
                                        sed 's/^[a-f0-9]\+ //'`
                msgnum=$(($msgnum + 1))
        done
        rm -r "$dotest"
        echo "All done."
}

while case "$#" in 0) break ;; esac
do
        case "$1" in
        --continue)
                diff=$(git-diff-files)
                case "$diff" in
                ?*)     echo "You must edit all merge conflicts and then"
                        echo "mark them as resolved using git update-index"
                        exit 1
                        ;;
                esac
                if test -d "$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
                git am --resolved --3way --resolvemsg="$RESOLVEMSG"
                exit
                ;;
        --skip)
                if test -d "$dotest"
                then
                        die "--skip is not supported when using --merge"
                fi
                git am -3 --skip --resolvemsg="$RESOLVEMSG"
                exit
                ;;
        --abort)
                if test -d "$dotest"
                then
                        rm -r "$dotest"
                elif test -d .dotest
                then
                        rm -r .dotest
                else
                        die "No rebase in progress?"
                fi
                git reset --hard ORIG_HEAD
                exit
                ;;
        --onto)
                test 2 -le "$#" || 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 "$1" : '-[^=]*=\(.*\)'` ;;
                1,*)
                        usage ;;
                *)
                        strategy="$2"
                        shift ;;
                esac
                do_merge=t
                ;;
        -*)
                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 "$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"

# 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 "$2" || usage
        ;;
*)
        branch_name=`git symbolic-ref HEAD` || die "No current branch"
        branch_name=`expr "z$branch_name" : 'zrefs/heads/\(.*\)'`
        ;;
esac
branch=$(git-rev-parse --verify "${branch_name}^0") || exit

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

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

# Check if we are already based on $onto, but this should be
# done only when upstream and onto are the same.
if test "$upstream" = "$onto"
then
        mb=$(git-merge-base "$onto" "$branch")
        if test "$mb" = "$onto"
        then
                echo >&2 "Current branch $branch_name is up to date."
                exit 0
        fi
fi

# Rewind the head to "$onto"; this saves our current head in ORIG_HEAD.
git-reset --hard "$onto"

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

if test -z "$do_merge"
then
        git-format-patch -k --stdout --full-index "$upstream"..ORIG_HEAD |
        git am --binary -3 -k --resolvemsg="$RESOLVEMSG"
        exit $?
fi

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

mkdir -p "$dotest"
echo "$onto" > "$dotest/onto"
prev_head=`git-rev-parse HEAD^0`
echo "$prev_head" > "$dotest/prev_head"

msgnum=0
for cmt in `git-rev-list --no-merges "$upstream"..ORIG_HEAD \
                        | perl -e 'print reverse <>'`
do
        msgnum=$(($msgnum + 1))
        echo "$cmt" > "$dotest/`printf "%0${prec}d" $msgnum`"
done

printf "%0${prec}d" 1 > "$dotest/msgnum"
printf "%0${prec}d" "$msgnum" > "$dotest/end"

end=$msgnum
msgnum=1

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

finish_rb_merge