#!/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 restore 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_SPEC=
. git-sh-setup
set_reflog_action rebase
require_work_tree
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 restore 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
prec=4
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=

read_state () {
        if test "$type" = merge
        then
                onto_name=$(cat "$state_dir"/onto_name) &&
                end=$(cat "$state_dir"/end) &&
                msgnum=$(cat "$state_dir"/msgnum)
        fi &&
        head_name=$(cat "$state_dir"/head-name) &&
        onto=$(cat "$state_dir"/onto) &&
        orig_head=$(cat "$state_dir"/orig-head) &&
        GIT_QUIET=$(cat "$state_dir"/quiet)
}

continue_merge () {
        test -d "$merge_dir" || die "$merge_dir 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 "$merge_dir/current"`
        if ! git diff-index --quiet --ignore-submodules HEAD --
        then
                if ! git commit --no-verify -C "$cmt"
                then
                        echo "Commit failed, please do not call \"git commit\""
                        echo "directly, but instead do one of the following: "
                        die "$resolvemsg"
                fi
                if test -z "$GIT_QUIET"
                then
                        printf "Committed: %0${prec}d " $msgnum
                fi
                echo "$cmt $(git rev-parse HEAD^0)" >> "$merge_dir/rewritten"
        else
                if test -z "$GIT_QUIET"
                then
                        printf "Already applied: %0${prec}d " $msgnum
                fi
        fi
        test -z "$GIT_QUIET" &&
        GIT_PAGER='' git log --format=%s -1 "$cmt"

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

call_merge () {
        cmt="$(cat "$merge_dir/cmt.$1")"
        echo "$cmt" > "$merge_dir/current"
        hd=$(git rev-parse --verify HEAD)
        cmt_name=$(git symbolic-ref HEAD 2> /dev/null || echo HEAD)
        msgnum=$(cat "$merge_dir/msgnum")
        eval GITHEAD_$cmt='"${cmt_name##refs/heads/}~$(($end - $msgnum))"'
        eval GITHEAD_$hd='$onto_name'
        export GITHEAD_$cmt GITHEAD_$hd
        if test -n "$GIT_QUIET"
        then
                GIT_MERGE_VERBOSITY=1 && export GIT_MERGE_VERBOSITY
        fi
        test -z "$strategy" && strategy=recursive
        eval 'git-merge-$strategy' $strategy_opts '"$cmt^" -- "$hd" "$cmt"'
        rv=$?
        case "$rv" in
        0)
                unset GITHEAD_$cmt GITHEAD_$hd
                return
                ;;
        1)
                git rerere $allow_rerere_autoupdate
                die "$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 () {
        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
        git notes copy --for-rewrite=rebase < "$merge_dir"/rewritten
        if test -x "$GIT_DIR"/hooks/post-rewrite &&
                test -s "$merge_dir"/rewritten; then
                "$GIT_DIR"/hooks/post-rewrite rebase < "$merge_dir"/rewritten
        fi
        rm -r "$merge_dir"
        say All done.
}

is_interactive () {
        while test $# != 0
        do
                case "$1" in
                        -i|--interactive)
                                interactive_rebase=explicit
                                break
                        ;;
                        -p|--preserve-merges)
                                interactive_rebase=implied
                        ;;
                esac
                shift
        done

        if [ "$interactive_rebase" = implied ]; then
                GIT_EDITOR=:
                export GIT_EDITOR
        fi

        test -n "$interactive_rebase" || test -f "$merge_dir"/interactive
}

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.'

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

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 $total_argc -eq 1 || usage
                action=${1##--}
                ;;
        --onto)
                test 2 -le "$#" || usage
                onto="$2"
                shift
                ;;
        -M|-m|--m|--me|--mer|--merg|--merge)
                do_merge=t
                ;;
        -X*|--strategy-option*)
                case "$#,$1" in
                1,-X|1,--strategy-option)
                        usage ;;
                *,-X|*,--strategy-option)
                        newopt="$2"
                        shift ;;
                *,--strategy-option=*)
                        newopt="$(expr " $1" : ' --strategy-option=\(.*\)')" ;;
                *,-X*)
                        newopt="$(expr " $1" : ' -X\(.*\)')" ;;
                1,*)
                        usage ;;
                esac
                strategy_opts="$strategy_opts $(git rev-parse --sq-quote "--$newopt")"
                do_merge=t
                test -z "$strategy" && strategy=recursive
                ;;
        -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
                --strateg=*|--strategy=*|\
        -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
                case "$#,$1" in
                *,*=*)
                        strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
                1,*)
                        usage ;;
                *)
                        strategy="$2"
                        shift ;;
                esac
                do_merge=t
                ;;
        -n|--no-stat)
                diffstat=
                ;;
        --stat)
                diffstat=t
                ;;
        -v|--verbose)
                verbose=t
                diffstat=t
                GIT_QUIET=
                ;;
        -q|--quiet)
                GIT_QUIET=t
                git_am_opt="$git_am_opt -q"
                verbose=
                diffstat=
                ;;
        --whitespace=*)
                git_am_opt="$git_am_opt $1"
                case "$1" in
                --whitespace=fix|--whitespace=strip)
                        force_rebase=t
                        ;;
                esac
                ;;
        --ignore-whitespace)
                git_am_opt="$git_am_opt $1"
                ;;
        --committer-date-is-author-date|--ignore-date)
                git_am_opt="$git_am_opt $1"
                force_rebase=t
                ;;
        -C*)
                git_am_opt="$git_am_opt $1"
                ;;
        --root)
                rebase_root=t
                ;;
        -f|--f|--fo|--for|--forc|--force|--force-r|--force-re|--force-reb|--force-reba|--force-rebas|--force-rebase|--no-ff)
                force_rebase=t
                ;;
        --rerere-autoupdate|--no-rerere-autoupdate)
                allow_rerere_autoupdate="$1"
                ;;
        -*)
                usage
                ;;
        *)
                break
                ;;
        esac
        shift
done
test $# -gt 2 && usage

test -n "$action" && test -z "$in_progress" && die "No rebase in progress?"

case "$action" in
continue)
        git update-index --ignore-submodules --refresh &&
        git diff-files --quiet --ignore-submodules || {
                echo "You must edit all merge conflicts and then"
                echo "mark them as resolved using git add"
                exit 1
        }
        read_state
        if test -d "$merge_dir"
        then
                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" &&
        move_to_original_branch
        exit
        ;;
skip)
        git reset --hard HEAD || exit $?
        read_state
        if test -d "$merge_dir"
        then
                git rerere clear
                msgnum=$(($msgnum + 1))
                while test "$msgnum" -le "$end"
                do
                        call_merge "$msgnum"
                        continue_merge
                done
                finish_rb_merge
                exit
        fi
        git am -3 --skip --resolvemsg="$resolvemsg" &&
        move_to_original_branch
        exit
        ;;
abort)
        git rerere clear
        read_state
        case "$head_name" in
        refs/*)
                git symbolic-ref HEAD $head_name ||
                die "Could not move back to $head_name"
                ;;
        esac
        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

test $# -eq 0 && test -z "$rebase_root" && usage

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

if test -z "$rebase_root"
then
        # The upstream head must be given.  Make sure it is valid.
        upstream_name="$1"
        shift
        upstream=`git rev-parse --verify "${upstream_name}^0"` ||
        die "invalid upstream $upstream_name"
        unset root_flag
        upstream_arg="$upstream_name"
else
        test -z "$onto" && die "--root must be used with --onto"
        unset upstream_name
        unset upstream
        root_flag="--root"
        upstream_arg="$root_flag"
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") || exit
        ;;
esac

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

# 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/$1" &&
           branch=$(git rev-parse -q --verify "refs/heads/$1")
        then
                head_name="refs/heads/$1"
        elif branch=$(git rev-parse -q --verify "$1")
        then
                head_name="detached HEAD"
        else
                echo >&2 "fatal: no such branch: $1"
                usage
        fi
        ;;
*)
        # Do not need to switch branches, we are already on it.
        if branch_name=`git symbolic-ref -q HEAD`
        then
                head_name=$branch_name
                branch_name=`expr "z$branch_name" : 'zrefs/heads/\(.*\)'`
        else
                head_name="detached HEAD"
                branch_name=HEAD ;# detached
        fi
        branch=$(git rev-parse --verify "${branch_name}^0") || exit
        ;;
esac
orig_head=$branch

# Now we are rebasing commits $upstream..$branch (or with --root,
# everything leading up to $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" | 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

# 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 $branch

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

# If the $onto is a proper descendant of the tip of the branch, then
# we just fast-forwarded.
if test "$mb" = "$branch"
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

if test -z "$do_merge"
then
        git format-patch -k --stdout --full-index --ignore-if-in-upstream \
                --src-prefix=a/ --dst-prefix=b/ \
                --no-renames $root_flag "$revisions" |
        git am $git_am_opt --rebasing --resolvemsg="$resolvemsg" &&
        move_to_original_branch
        ret=$?
        test 0 != $ret -a -d "$apply_dir" &&
                echo $head_name > "$apply_dir/head-name" &&
                echo $onto > "$apply_dir/onto" &&
                echo $orig_head > "$apply_dir/orig-head" &&
                echo "$GIT_QUIET" > "$apply_dir/quiet"
        exit $ret
fi

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

mkdir -p "$merge_dir"
echo "$onto_name" > "$merge_dir/onto_name"
echo "$head_name" > "$merge_dir/head-name"
echo "$onto" > "$merge_dir/onto"
echo "$orig_head" > "$merge_dir/orig-head"
echo "$GIT_QUIET" > "$merge_dir/quiet"

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

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

end=$msgnum
msgnum=1

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

finish_rb_merge