#!/bin/sh

# commit2quilt, based on patch2quilt
# Copyright (c) 2011, Frank Terbeck <ft@bewatermyfriend.org>
# Copyright (c) 2014, Axel Beckert <abe@debian.org>
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
# Often, we may want to backport a patch from upstream to our package. If
# that's just a matter of cherry-picking a patch from upstream, this script can
# help. We don't really want to git cherry-pick, but rather add a new patch to
# our quilt series. In short, this script automates doing that.
#
# Call it like this:
#   % git fetch zsh
#   % debian/bin/commit2quilt $commit_id
#
# `commit2quilt' requires `quilt', `git' and $GIT_EDITOR or
# emacsclient available.

set -e

for where in ./ ../ ../../ ../../../ ../../../../ ../../../../../; do
    if [ -e ${where}debian/rules -a -d ${where}debian/patches ]; then
        export QUILT_PATCHES=debian/patches
        break
    fi
done

export GIT_EDITOR=${GIT_EDITOR:-${VISUAL:-${EDITOR:-emacsclient}}}

if [ $# -ne 1 ]; then
    printf 'usage: patch2quilt <commit-id>\n'
    exit 1
fi

commitid="$1"
shortid="`echo -n $commitid | cut -c1-8`"
desc="`git show $commitid | egrep '^    [^ ]' | head -1 | sed -e 's/^[- *:]*//'`"
filename="cherry-pick-$shortid-`echo "$desc" | tr -c 'a-zA-Z0-9' '-' | tr 'A-Z' 'a-z' | sed -e 's/--*/-/g;s/-$//'`.patch"
echo "$filename"

if quilt series | fgrep -q "$filename"; then
    echo "Patch $filename ($commitid) already existing" 1>&2
    exit 1
fi

git show "$commitid" | filterdiff -x a/ChangeLog > "${where}debian/patches/$filename"
echo "$filename" >> "${where}debian/patches/series"
sed -e '1 s/^commit/Origin: commit/; 4 d; 5 s/^    /Description: /; 6 d' -i "${where}debian/patches/$filename"
"${GIT_EDITOR}" "${where}debian/patches/$filename"
git add "${where}debian/patches/$filename" "${where}debian/patches/series"
quilt push -a
quilt pop -a
git commit -m "Cherry-pick $shortid ($desc) from upstream" -v --edit

exit 0