#!/bin/sh
#
# Copyright (C) 2009 Canonical
#
# Authors:
#  Daniel Holbach
#   Michael Vogt
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; version 3.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

set -e


PATCHSYSTEM="unknown"
PATCHNAME="no-patch-name"

PATCH_DESC=$(cat<<EOF
## Description: add some description\
\n## Origin/Author: add some origin or author\
\n## Bug: bug URL
EOF
)

fatal_error() {
    echo "$@" >&2
    exit 1
}

# check if the given binary is installed and give a error if not
# arg1: binary
# arg2: error message
require_installed() {
    if ! which "$1" >/dev/null; then
	fatal_error "$2"
    fi 
}    

ensure_debian_dir() {
    if [ ! -e debian/control ] || [ ! -e debian/rules ]; then
	fatal_error "Can not find debian/rules or debian/control. Not in a debian dir?"
    fi

}

detect_patchsystem() {
    CDBS_PATCHSYS="^[^#]*simple-patchsys.mk"

    if grep -q "$CDBS_PATCHSYS" debian/rules; then
	PATCHSYSTEM="cdbs"
	require_installed cdbs-edit-patch "no cdbs-edit-patch found, is 'cdbs' installed?"
    elif [ -e debian/patches/00list ]; then
	PATCHSYSTEM="dpatch"
	require_installed dpatch-edit-patch "no dpatch-edit-patch found, is 'dpatch' installed?"
    elif [ -e debian/patches/series ]; then
	PATCHSYSTEM="quilt"
	require_installed quilt "no quilt found, is 'quilt' installed?"
    else
	fatal_error "Patch system can not be detected (no quilt, cdbs or dpatch?)"
    fi
}

# remove full path if given
normalize_patch_path() {
    PATCHNAME=${PATCHNAME##*/}
    echo "Normalizing patch path to $PATCHNAME"
}

# ensure (for new patches) that:
# - dpatch ends with .dpatch
# - cdbs/quilt with .patch
normalize_patch_extension() {
    # check if we have a patch already
    if [ -e debian/patches/$PATCHNAME ]; then
	echo "Patch $PATCHNAME exists, not normalizing"
	return
    fi

    # normalize name for new patches
    PATCHNAME=${PATCHNAME%.*}
    if [ "$PATCHSYSTEM" = "quilt" ]; then
	PATCHNAME="${PATCHNAME}.patch"
    elif [ "$PATCHSYSTEM" = "cdbs" ]; then
	PATCHNAME="${PATCHNAME}.patch"
    elif [ "$PATCHSYSTEM" = "dpatch" ]; then
	PATCHNAME="${PATCHNAME}.dpatch"
    fi

    echo "Normalizing patch name to $PATCHNAME"
}

edit_patch_cdbs() {
    cdbs-edit-patch $PATCHNAME
    vcs_add debian/patches/$1
}

edit_patch_dpatch() {
    dpatch-edit-patch $PATCHNAME
    # add if needed
    if ! grep -q $1 debian/patches/00list; then
	echo "$1" >> debian/patches/00list
    fi
    vcs_add debian/patches/00list debian/patches/$1
}

edit_patch_quilt() {
    export QUILT_PATCHES=debian/patches
    if [ -e debian/patches/$1 ]; then
	# if its a existing patch and we are at the end of the stack,
	# go back at the beginning
	if ! quilt unapplied; then
	    quilt pop -a
	fi
	quilt push $1
    else
	# if its a new patch make sure we are at the end of the stack
	if quilt unapplied >/dev/null; then
		quilt push -a
	fi
	quilt new $1
    fi
    # use a sub-shell
    quilt shell
    quilt refresh
    quilt pop -a
    vcs_add debian/patches/$1 debian/patches/series
}

vcs_add() {
    if [ -d .bzr ]; then
	bzr add $@
    elif [ -d .git ];then
	git add $@
    else
	echo "Remember to add $@ to a VCS if you use one"
    fi
}

vcs_commit() {
    # check if debcommit is happy
    if ! debcommit --noact 2>/dev/null; then
	return
    fi
    # commit (if the user confirms)
    debcommit --confirm
}

add_changelog() {
    S="debian/patches/$1: [DESCRIBE CHANGES HERE]"
    if head -n1 debian/changelog|grep UNRELEASED; then
	dch --append "$S"
    else
	dch --increment "$S"
    fi
    # let the user edit it
    dch --edit
}

add_patch_tagging() {
    # check if we have a descripton already
    if grep "## Description:" debian/patches/$1; then
	return
    fi
    # if not, add one
    RANGE=1,1
    # make sure we keep the first line (for dpatch)
    if head -n1 debian/patches/$1|grep -q '^#'; then
	RANGE=2,2
    fi
    sed -i ${RANGE}i"$PATCH_DESC" debian/patches/$1
}


# TODO:
# - edit-patch --remove implementieren
# - dbs patch system
# - handle no patch system

main() {
    # parse args
    if [ $# -ne 1 ]; then
	fatal_error "Need exactly one patch name"
    fi
    PATCHNAME="$1"
    # do the work
    ensure_debian_dir
    detect_patchsystem
    normalize_patch_path
    normalize_patch_extension
    edit_patch_$PATCHSYSTEM $PATCHNAME
    add_patch_tagging $PATCHNAME
    add_changelog $PATCHNAME
    vcs_commit
}

main $@