#!/bin/sh
# Copyright (c) 2007, Nanako Shiraishi

dashless=$(basename "$0" | sed -e 's/-/ /')
USAGE="list [<options>]
   or: $dashless show [<stash>]
   or: $dashless drop [-q|--quiet] [<stash>]
   or: $dashless ( pop | apply ) [--index] [-q|--quiet] [<stash>]
   or: $dashless branch <branchname> [<stash>]
   or: $dashless [save [--patch] [-k|--[no-]keep-index] [-q|--quiet] [<message>]]
   or: $dashless clear"

SUBDIRECTORY_OK=Yes
OPTIONS_SPEC=
. git-sh-setup
require_work_tree
cd_to_toplevel

TMP="$GIT_DIR/.git-stash.$$"
trap 'rm -f "$TMP-*"' 0

ref_stash=refs/stash

if git config --get-colorbool color.interactive; then
       help_color="$(git config --get-color color.interactive.help 'red bold')"
       reset_color="$(git config --get-color '' reset)"
else
       help_color=
       reset_color=
fi

no_changes () {
        git diff-index --quiet --cached HEAD --ignore-submodules -- &&
        git diff-files --quiet --ignore-submodules
}

clear_stash () {
        if test $# != 0
        then
                die "git stash clear with parameters is unimplemented"
        fi
        if current=$(git rev-parse --verify $ref_stash 2>/dev/null)
        then
                git update-ref -d $ref_stash $current
        fi
}

create_stash () {
        stash_msg="$1"

        git update-index -q --refresh
        if no_changes
        then
                exit 0
        fi

        # state of the base commit
        if b_commit=$(git rev-parse --verify HEAD)
        then
                head=$(git rev-list --oneline -n 1 HEAD --)
        else
                die "You do not have the initial commit yet"
        fi

        if branch=$(git symbolic-ref -q HEAD)
        then
                branch=${branch#refs/heads/}
        else
                branch='(no branch)'
        fi
        msg=$(printf '%s: %s' "$branch" "$head")

        # state of the index
        i_tree=$(git write-tree) &&
        i_commit=$(printf 'index on %s\n' "$msg" |
                git commit-tree $i_tree -p $b_commit) ||
                die "Cannot save the current index state"

        if test -z "$patch_mode"
        then

                # state of the working tree
                w_tree=$( (
                        rm -f "$TMP-index" &&
                        cp -p ${GIT_INDEX_FILE-"$GIT_DIR/index"} "$TMP-index" &&
                        GIT_INDEX_FILE="$TMP-index" &&
                        export GIT_INDEX_FILE &&
                        git read-tree -m $i_tree &&
                        git diff --name-only -z HEAD | git update-index -z --add --remove --stdin &&
                        git write-tree &&
                        rm -f "$TMP-index"
                ) ) ||
                        die "Cannot save the current worktree state"

        else

                rm -f "$TMP-index" &&
                GIT_INDEX_FILE="$TMP-index" git read-tree HEAD &&

                # find out what the user wants
                GIT_INDEX_FILE="$TMP-index" \
                        git add--interactive --patch=stash -- &&

                # state of the working tree
                w_tree=$(GIT_INDEX_FILE="$TMP-index" git write-tree) ||
                die "Cannot save the current worktree state"

                git diff-tree -p HEAD $w_tree > "$TMP-patch" &&
                test -s "$TMP-patch" ||
                die "No changes selected"

                rm -f "$TMP-index" ||
                die "Cannot remove temporary index (can't happen)"

        fi

        # create the stash
        if test -z "$stash_msg"
        then
                stash_msg=$(printf 'WIP on %s' "$msg")
        else
                stash_msg=$(printf 'On %s: %s' "$branch" "$stash_msg")
        fi
        w_commit=$(printf '%s\n' "$stash_msg" |
                git commit-tree $w_tree -p $b_commit -p $i_commit) ||
                die "Cannot record working tree state"
}

save_stash () {
        keep_index=
        patch_mode=
        while test $# != 0
        do
                case "$1" in
                -k|--keep-index)
                        keep_index=t
                        ;;
                --no-keep-index)
                        keep_index=
                        ;;
                -p|--patch)
                        patch_mode=t
                        keep_index=t
                        ;;
                -q|--quiet)
                        GIT_QUIET=t
                        ;;
                --)
                        shift
                        break
                        ;;
                -*)
                        echo "error: unknown option for 'stash save': $1"
                        echo "       To provide a message, use git stash save -- '$1'"
                        usage
                        ;;
                *)
                        break
                        ;;
                esac
                shift
        done

        stash_msg="$*"

        git update-index -q --refresh
        if no_changes
        then
                say 'No local changes to save'
                exit 0
        fi
        test -f "$GIT_DIR/logs/$ref_stash" ||
                clear_stash || die "Cannot initialize stash"

        create_stash "$stash_msg"

        # Make sure the reflog for stash is kept.
        : >>"$GIT_DIR/logs/$ref_stash"

        git update-ref -m "$stash_msg" $ref_stash $w_commit ||
                die "Cannot save the current status"
        say Saved working directory and index state "$stash_msg"

        if test -z "$patch_mode"
        then
                git reset --hard ${GIT_QUIET:+-q}

                if test -n "$keep_index" && test -n $i_tree
                then
                        git read-tree --reset -u $i_tree
                fi
        else
                git apply -R < "$TMP-patch" ||
                die "Cannot remove worktree changes"

                if test -z "$keep_index"
                then
                        git reset
                fi
        fi
}

have_stash () {
        git rev-parse --verify $ref_stash >/dev/null 2>&1
}

list_stash () {
        have_stash || return 0
        git log --format="%gd: %gs" -g "$@" $ref_stash --
}

show_stash () {
        assert_stash_like "$@"

        git diff ${FLAGS:---stat} $b_commit $w_commit
}

#
# Parses the remaining options looking for flags and
# at most one revision defaulting to ${ref_stash}@{0}
# if none found.
#
# Derives related tree and commit objects from the
# revision, if one is found.
#
# stash records the work tree, and is a merge between the
# base commit (first parent) and the index tree (second parent).
#
#   REV is set to the symbolic version of the specified stash-like commit
#   IS_STASH_LIKE is non-blank if ${REV} looks like a stash
#   IS_STASH_REF is non-blank if the ${REV} looks like a stash ref
#   s is set to the SHA1 of the stash commit
#   w_commit is set to the commit containing the working tree
#   b_commit is set to the base commit
#   i_commit is set to the commit containing the index tree
#   w_tree is set to the working tree
#   b_tree is set to the base tree
#   i_tree is set to the index tree
#
#   GIT_QUIET is set to t if -q is specified
#   INDEX_OPTION is set to --index if --index is specified.
#   FLAGS is set to the remaining flags
#
# dies if:
#   * too many revisions specified
#   * no revision is specified and there is no stash stack
#   * a revision is specified which cannot be resolve to a SHA1
#   * a non-existent stash reference is specified
#

parse_flags_and_rev()
{
        test "$PARSE_CACHE" = "$*" && return 0 # optimisation
        PARSE_CACHE="$*"

        IS_STASH_LIKE=
        IS_STASH_REF=
        INDEX_OPTION=
        s=
        w_commit=
        b_commit=
        i_commit=
        w_tree=
        b_tree=
        i_tree=

        REV=$(git rev-parse --no-flags --symbolic "$@") || exit 1

        FLAGS=
        for opt
        do
                case "$opt" in
                        -q|--quiet)
                                GIT_QUIET=-t
                        ;;
                        --index)
                                INDEX_OPTION=--index
                        ;;
                        -*)
                                FLAGS="${FLAGS}${FLAGS:+ }$opt"
                        ;;
                esac
        done

        set -- $REV

        case $# in
                0)
                        have_stash || die "No stash found."
                        set -- ${ref_stash}@{0}
                ;;
                1)
                        :
                ;;
                *)
                        die "Too many revisions specified: $REV"
                ;;
        esac

        REV=$(git rev-parse --quiet --symbolic --verify $1 2>/dev/null) || die "$1 is not valid reference"

        i_commit=$(git rev-parse --quiet --verify $REV^2 2>/dev/null) &&
        set -- $(git rev-parse $REV $REV^1 $REV: $REV^1: $REV^2: 2>/dev/null) &&
        s=$1 &&
        w_commit=$1 &&
        b_commit=$2 &&
        w_tree=$3 &&
        b_tree=$4 &&
        i_tree=$5 &&
        IS_STASH_LIKE=t &&
        test "$ref_stash" = "$(git rev-parse --symbolic-full-name "${REV%@*}")" &&
        IS_STASH_REF=t
}

is_stash_like()
{
        parse_flags_and_rev "$@"
        test -n "$IS_STASH_LIKE"
}

assert_stash_like() {
        is_stash_like "$@" || die "'$*' is not a stash-like commit"
}

is_stash_ref() {
        is_stash_like "$@" && test -n "$IS_STASH_REF"
}

assert_stash_ref() {
        is_stash_ref "$@" || die "'$*' is not a stash reference"
}

apply_stash () {

        assert_stash_like "$@"

        git update-index -q --refresh &&
        git diff-files --quiet --ignore-submodules ||
                die 'Cannot apply to a dirty working tree, please stage your changes'

        # current index state
        c_tree=$(git write-tree) ||
                die 'Cannot apply a stash in the middle of a merge'

        unstashed_index_tree=
        if test -n "$INDEX_OPTION" && test "$b_tree" != "$i_tree" &&
                        test "$c_tree" != "$i_tree"
        then
                git diff-tree --binary $s^2^..$s^2 | git apply --cached
                test $? -ne 0 &&
                        die 'Conflicts in index. Try without --index.'
                unstashed_index_tree=$(git write-tree) ||
                        die 'Could not save index tree'
                git reset
        fi

        eval "
                GITHEAD_$w_tree='Stashed changes' &&
                GITHEAD_$c_tree='Updated upstream' &&
                GITHEAD_$b_tree='Version stash was based on' &&
                export GITHEAD_$w_tree GITHEAD_$c_tree GITHEAD_$b_tree
        "

        if test -n "$GIT_QUIET"
        then
                GIT_MERGE_VERBOSITY=0 && export GIT_MERGE_VERBOSITY
        fi
        if git merge-recursive $b_tree -- $c_tree $w_tree
        then
                # No conflict
                if test -n "$unstashed_index_tree"
                then
                        git read-tree "$unstashed_index_tree"
                else
                        a="$TMP-added" &&
                        git diff-index --cached --name-only --diff-filter=A $c_tree >"$a" &&
                        git read-tree --reset $c_tree &&
                        git update-index --add --stdin <"$a" ||
                                die "Cannot unstage modified files"
                        rm -f "$a"
                fi
                squelch=
                if test -n "$GIT_QUIET"
                then
                        squelch='>/dev/null 2>&1'
                fi
                eval "git status $squelch" || :
        else
                # Merge conflict; keep the exit status from merge-recursive
                status=$?
                if test -n "$INDEX_OPTION"
                then
                        echo >&2 'Index was not unstashed.'
                fi
                exit $status
        fi
}

pop_stash() {
        assert_stash_ref "$@"

        apply_stash "$@" &&
        drop_stash "$@"
}

drop_stash () {
        assert_stash_ref "$@"

        git reflog delete --updateref --rewrite "${REV}" &&
                say "Dropped ${REV} ($s)" || die "${REV}: Could not drop stash entry"

        # clear_stash if we just dropped the last stash entry
        git rev-parse --verify "$ref_stash@{0}" > /dev/null 2>&1 || clear_stash
}

apply_to_branch () {
        test -n "$1" || die 'No branch name specified'
        branch=$1
        shift 1

        set -- --index "$@"
        assert_stash_like "$@"

        git checkout -b $branch $REV^ &&
        apply_stash "$@" && {
                test -z "$IS_STASH_REF" || drop_stash "$@"
        }
}

PARSE_CACHE='--not-parsed'
# The default command is "save" if nothing but options are given
seen_non_option=
for opt
do
        case "$opt" in
        -*) ;;
        *) seen_non_option=t; break ;;
        esac
done

test -n "$seen_non_option" || set "save" "$@"

# Main command set
case "$1" in
list)
        shift
        list_stash "$@"
        ;;
show)
        shift
        show_stash "$@"
        ;;
save)
        shift
        save_stash "$@"
        ;;
apply)
        shift
        apply_stash "$@"
        ;;
clear)
        shift
        clear_stash "$@"
        ;;
create)
        if test $# -gt 0 && test "$1" = create
        then
                shift
        fi
        create_stash "$*" && echo "$w_commit"
        ;;
drop)
        shift
        drop_stash "$@"
        ;;
pop)
        shift
        pop_stash "$@"
        ;;
branch)
        shift
        apply_to_branch "$@"
        ;;
*)
        case $# in
        0)
                save_stash &&
                say '(To restore them type "git stash apply")'
                ;;
        *)
                usage
        esac
        ;;
esac