#!/bin/bash
#
#   git-darcs - bidirectional operation between a darcs repo and git
#
#   Copyright (c) 2008, 2010 by Miklos Vajna <vmiklos@frugalware.org>
#
#   Based on git-bzr, which is
#
#   Copyright (c) 2008 Pieter de Bie <pdebie@ai.rug.nl>
#
#   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; either version 2 of the License, or
#   (at your option) any later version.
#
#   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
#   USA.
#

add()
{
	name="$1"
	shift
	location="$1"
	shift
	if ! [ -n "$name" -a -n "$location" ]; then
		echo "Usage: git darcs add name location [darcs-fast-export options]"
		return 1
	fi
	if git remote show |grep -q $name; then
		echo "There is already a remote with that name"
		return 1
	fi
	if [ -n "$(git config git-darcs.$name.location)" ]; then
		echo "There is already a darcs repo with that name"
		return 1
	fi
	repo=$location/_darcs
	if [ ! -d $repo ] && ! wget --quiet --spider $repo; then
		echo "Remote is not a darcs repository"
		return 1
	fi
	git config git-darcs.$name.location $location
	echo "Darcs repo $name added. You can fetch it with 'git darcs fetch $name'"
	if ! [ -z "$*" ]; then
		git config git-darcs.$name.darcs-fast-export-options "$*"
		echo "darcs-fast-export will get options: $*"
	fi
}

get_location()
{
	l=$(git config git-darcs.$remote.location)
	if [ -z "$l" ]; then
		echo "Cannot find darcs remote with name '$remote'." >&2
		return 1
	fi
	echo $l
}

fetch()
{
	remote="$1"
	shift
	if ! [ -n "$remote" -a -z "$*" ]; then
		echo "Usage: git darcs fetch reponame"
		return 1
	fi
	location=$(get_location $remote) || return $?
	git_map=$git_dir/darcs-git/$remote-git-map
	darcs_map=$git_dir/darcs-git/$remote-darcs-map
	common_opts="--working $git_dir/darcs-git/repo --logfile $git_dir/darcs-git/fetch.log --git-branch=refs/remotes/darcs/$remote"
        dfe_opts=$(git config git-darcs.$remote.darcs-fast-export-options)
	pre_fetch="$(git config git-darcs.$remote.pre-fetch)"
	if [ -n "$pre_fetch" ]; then
		$pre_fetch
	fi
	if [ ! -f $git_map -a ! -f $darcs_map ]; then
		echo "There doesn't seem to be an existing refmap."
		echo "Doing an initial import"
		mkdir -p $git_dir/darcs-git
		darcs-fast-export --export-marks=$darcs_map $common_opts $dfe_opts $location | \
			git fast-import --export-marks=$git_map
	elif [ -f $git_map -a -f $darcs_map ]; then
		echo "Updating remote $remote"
		old_rev=$(git rev-parse refs/remotes/darcs/$remote)
		darcs-fast-export --import-marks=$darcs_map --export-marks=$darcs_map $common_opts $dfe_opts $location | \
			git fast-import --quiet --import-marks=$git_map --export-marks=$git_map
		new_rev=$(git rev-parse refs/remotes/darcs/$remote)
		if [ "$old_rev" != "$new_rev" ]; then
			echo "Fetched the following updates:"
			git shortlog $old_rev..$new_rev
		else
			echo "Nothing fetched."
			return 0
		fi
	else
		echo "One of the mapfiles is missing! Something went wrong!"
		return 1
	fi
	post_fetch="$(git config git-darcs.$remote.post-fetch)"
	if [ -n "$post_fetch" ]; then
		$post_fetch
	fi
}

pull()
{
	remote="$1"
	shift
	if ! [ -n "$remote" -a -z "$*" ]; then
		echo "Usage: git darcs pull reponame"
		return 1
	fi
	fetch $remote || return $?
	# see if we need to merge or rebase
	branch=$(git symbolic-ref HEAD|sed 's|.*/||')
	if [ "$(git config branch.$branch.rebase)" = "true" ]; then
		git rebase refs/remotes/darcs/$remote
	else
		git merge refs/remotes/darcs/$remote
	fi
}

push()
{
	remote="$1"
	shift
	if ! [ -n "$remote" -a -z "$*" ]; then
		echo "Usage: git darcs push reponame"
		return 1
	fi
	location=$(get_location $remote) || return $?
	if [ -n "$(git rev-list --left-right HEAD...refs/remotes/darcs/$remote | sed -n '/^>/ p')" ]; then
		echo "HEAD is not a strict child of $remote, cannot push. Merge first"
		return 1
	fi
	if [ -z "$(git rev-list --left-right HEAD...refs/remotes/darcs/$remote | sed -n '/^</ p')" ]; then
		echo "Nothing to push. Commit something first"
		return 1
	fi
	git_map=$git_dir/darcs-git/$remote-git-map
	darcs_map=$git_dir/darcs-git/$remote-darcs-map
	if [ ! -f $git_map -o ! -f $darcs_map ]; then
		echo "We do not have refmapping yet. Then how can I push?"
		return 1
	fi
	pre_push="$(git config git-darcs.$remote.pre-push)"
	if [ -n "$pre_push" ]; then
		$pre_push
	fi
	echo "Pushing the following updates:"
	git shortlog refs/remotes/darcs/$remote..
	git fast-export --import-marks=$git_map --export-marks=$git_map HEAD | \
		(cd $location; darcs-fast-import --import-marks=$darcs_map --export-marks=$darcs_map \
		--logfile $git_dir/darcs-git/push.log)
	if [ $? == 0 ]; then
		git update-ref refs/remotes/darcs/$remote HEAD
		post_push="$(git config git-darcs.$remote.post-push)"
		if [ -n "$post_push" ]; then
			$post_push
		fi
	fi
}

# List the darcs remotes
list()
{
	if [ -z "$*" ]
	then
		git config -l | sed -n -e '/git-darcs\..*/ {s/git-darcs\.//; s/\.location=.*//p}'
		return 0
	elif [ "$#" -eq 1 ]
	then
		case $1 in
			-v|--verbose)
				git config -l | sed -n -e '/git-darcs\..*/ {s/git-darcs\.//; s/\.location=/\t/p}'
				return 0
				;;
		esac
	fi
	echo "Usage: git darcs list [-v|--verbose]"
	return 1
}

# Find the darcs commit(s) supporting a git SHA1 prefix
find_darcs()
{
	sha1="$1"
	shift
	if [ -z "$sha1" -o -n "$*" ]
	then
		echo "Usage: git darcs find-darcs <sha1-prefix>"
		return 1
	fi
	for remote in $(git for-each-ref --format='%(refname)' refs/remotes/darcs)
	do
		remote=`basename $remote`
		git_map=$git_dir/darcs-git/$remote-git-map
		darcs_map=$git_dir/darcs-git/$remote-darcs-map
		if [ ! -f $git_map -o ! -f $darcs_map ]
		then
			echo "Missing mappings for remote $remote"
			return 1
		fi
		for row in `sed -n -e "/:.* $sha1.*/ s/[^ ]*/&/p" $git_map`
		do
			sed -n -e "/$row / {s/[^ ]*//; s/.*/$remote\t&/p}" $darcs_map
		done
	done
}

# Find the git commit(s) supporting a darcs patch prefix
find_git()
{
	patch="$1"
	shift
	if [ -z "$patch" -o -n "$*" ]
	then
		echo "Usage: git darcs find-git <patch-prefix>"
		return 1
	fi
	for remote in $(git for-each-ref --format='%(refname)' refs/remotes/darcs)
	do
		remote=`basename $remote`
		git_map=$git_dir/darcs-git/$remote-git-map
		darcs_map=$git_dir/darcs-git/$remote-darcs-map
		if [ ! -f $git_map -o ! -f $darcs_map ]
		then
			echo "Missing mappings for remote $remote"
			return 1
		fi
		for row in `sed -n -e "/:.* $patch.*/ s/[^ ]*/&/p" $darcs_map`
		do
			sed -n -e "/$row / {s/[^ ]* \(.*\)/$remote\t\1/p}" $git_map
		done
	done
}

git rev-parse 2> /dev/null
if [ $? != 0 ]; then
	echo "Must be inside a git repository to work"
	exit 1
fi

git_dir=$(git rev-parse --git-dir)
# make it absolute
cd $git_dir
git_dir=$(pwd)
cd - >/dev/null
command="$1"
shift

case $command in
	add|push|fetch|pull|list)
		;;
	find-darcs)
		command=find_darcs
		;;
	find-git)
		command=find_git
		;;
	*)
		echo "Usage: git darcs [COMMAND] [OPTIONS]"
		echo "Commands: add, push, fetch, pull, list, find-darcs, find-git"
		exit 1
		;;
esac


up=$(git rev-parse --show-cdup)
[ -z "$up" ] && up="."
cd $up
$command "$@"