#!/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 [--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

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 log --no-color --abbrev-commit --pretty=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"

        # 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 $i_tree &&
                git add -u &&
                git write-tree &&
                rm -f "$TMP-index"
        ) ) ||
                die "Cannot save the current worktree state"

        # 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=
        while test $# != 0
        do
                case "$1" in
                --keep-index)
                        keep_index=t
                        ;;
                -q|--quiet)
                        GIT_QUIET=t
                        ;;
                *)
                        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"

        git reset --hard ${GIT_QUIET:+-q}

        if test -n "$keep_index" && test -n $i_tree
        then
                git read-tree --reset -u $i_tree
        fi
}

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

list_stash () {
        have_stash || return 0
        git log --no-color --pretty=oneline -g "$@" $ref_stash -- |
        sed -n -e 's/^[.0-9a-f]* refs\///p'
}

show_stash () {
        flags=$(git rev-parse --no-revs --flags "$@")
        if test -z "$flags"
        then
                flags=--stat
        fi

        w_commit=$(git rev-parse --verify --default $ref_stash "$@") &&
        b_commit=$(git rev-parse --verify "$w_commit^") &&
        git diff $flags $b_commit $w_commit
}

apply_stash () {
        unstash_index=

        while test $# != 0
        do
                case "$1" in
                --index)
                        unstash_index=t
                        ;;
                -q|--quiet)
                        GIT_QUIET=t
                        ;;
                *)
                        break
                        ;;
                esac
                shift
        done

        if test $# = 0
        then
                have_stash || die 'Nothing to apply'
        fi

        # stash records the work tree, and is a merge between the
        # base commit (first parent) and the index tree (second parent).
        s=$(git rev-parse --quiet --verify --default $ref_stash "$@") &&
        w_tree=$(git rev-parse --quiet --verify "$s:") &&
        b_tree=$(git rev-parse --quiet --verify "$s^1:") &&
        i_tree=$(git rev-parse --quiet --verify "$s^2:") ||
                die "$*: no valid stashed state found"

        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 "$unstash_index" && test "$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
                export GIT_MERGE_VERBOSITY=0
        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 "$unstash_index"
                then
                        echo >&2 'Index was not unstashed.'
                fi
                exit $status
        fi
}

drop_stash () {
        have_stash || die 'No stash entries to drop'

        while test $# != 0
        do
                case "$1" in
                -q|--quiet)
                        GIT_QUIET=t
                        ;;
                *)
                        break
                        ;;
                esac
                shift
        done

        if test $# = 0
        then
                set x "$ref_stash@{0}"
                shift
        fi
        # Verify supplied argument looks like a stash entry
        s=$(git rev-parse --verify "$@") &&
        git rev-parse --verify "$s:"   > /dev/null 2>&1 &&
        git rev-parse --verify "$s^1:" > /dev/null 2>&1 &&
        git rev-parse --verify "$s^2:" > /dev/null 2>&1 ||
                die "$*: not a valid stashed state"

        git reflog delete --updateref --rewrite "$@" &&
                say "Dropped $* ($s)" || die "$*: 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 () {
        have_stash || die 'Nothing to apply'

        test -n "$1" || die 'No branch name specified'
        branch=$1

        if test -z "$2"
        then
                set x "$ref_stash@{0}"
        fi
        stash=$2

        git checkout -b $branch $stash^ &&
        apply_stash --index $stash &&
        drop_stash $stash
}

# Main command set
case "$1" in
list)
        shift
        if test $# = 0
        then
                set x -n 10
                shift
        fi
        list_stash "$@"
        ;;
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
        if apply_stash "$@"
        then
                test -z "$unstash_index" || shift
                drop_stash "$@"
        fi
        ;;
branch)
        shift
        apply_to_branch "$@"
        ;;
*)
        if test $# -eq 0
        then
                save_stash &&
                say '(To restore them type "git stash apply")'
        else
                usage
        fi
        ;;
esac