#!@bash@

# Copyright (C) 2014, 2016-2017 Luke Shumaker <lukeshu@sbcglobal.net>
#
# This file is not considered part of GNU Emacs.
#
# 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 3 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, see <http://www.gnu.org/licenses/>.

m4_include(common.sh.in)

usage() {
	print 'Usage: %q [OPTIONS] FILE_A FILE_B' "$0"
	print '   or: %q -3 [OPTIONS] FILE_A FILE_B FILE_C|FILE_ANCESTOR' "$0"
	print "Use Emacs' ediff-mode to compare two files"
	echo
	print 'The following OPTIONS are accepted:'
	emacs_usage
	flag '-r, -R REGEXP, --recursive[=REGEXP]' \
	     'Diff directories recursively,
excluding filenames not matching REGEXP'

	flag '-3' \
	     'Do a 3-way diff instead of 2-way
When used in the context of a --merge,
the 3rd file is the common ancestor between A and B'

	flag '-m OUTFILE, --merge=OUTFILE' \
	     'Merge files A and B, saving the output in OUTFILE'
}

main() {
	declare -a flags=()
	declare mode=normal

	# The functions that we currently make available are:
	#   (ediff                     FILE-A FILE-B               &optional STARTUP-HOOKS)
	#   (ediff3                    FILE-A FILE-B FILE-C        &optional STARTUP-HOOKS)
	#   (ediff-merge               FILE-A FILE-B               &optional STARTUP-HOOKS MERGE-BUFFER-FILE)
	#   (ediff-merge-with-ancestor FILE-A FILE-B FILE-ANCESTOR &optional STARTUP-HOOKS MERGE-BUFFER-FILE)
	# and their recursive equivalents:
	#   (edirs                     DIR1 DIR2              REGEXP)
	#   (edirs3                    DIR1 DIR2 DIR3         REGEXP)
	#   (edirs-merge               DIR1 DIR2              REGEXP &optional MERGE-AUTOSTORE-DIR)
	#   (edirs-merge-with-ancestor DIR1 DIR2 ANCESTOR-DIR REGEXP &optional MERGE-AUTOSTORE-DIR)
	#
	# This list is currently missing the "revision" commands:
	#   (ediff-revision &optional FILE STARTUP-HOOKS)
	#   (edir-revisions                     DIR1 REGEXP)
	#   (edir-merge-revisions               DIR1 REGEXP &optional MERGE-AUTOSTORE-DIR)
	#   (edir-merge-revisions-with-ancestor DIR1 REGEXP &optional MERGE-AUTOSTORE-DIR)
	# and the epatch command:
	#   (epatch &optional ARG PATCH-BUF)

	declare cmd=ediff
	declare -i cnt=2
	declare -a files=()
	declare extra=nil # STARTUP-HOOKS for cmd=ediff, REGEXP for cmd=edirs
	declare merge=''

	emacs_getopt_init
	declare args
	if ! args="$(emacs_getopt rR:3m: recursive::,merge: "$@")"; then
		mode=error
	else
		eval set -- "$args"
		while true; do
			case "$1" in
				-V|--version) shift; mode=version;;
				-H|--help) shift; mode=usage;;

				-r) shift; cmd=edirs;;
				-R|--recursive)
					cmd=edirs
					[[ -z "$2" ]] || extra="$(emacs_quote "$2")"
					shift 2
					;;

				-3) shift; cnt=3;;

				-m|--merge) merge="$(emacs_quote "$2")"; shift 2;;

				--) shift; break;;
				*)
					if [[ $1 =~ $emacs_getopt_2 ]]; then
						flags+=("$1" "$2"); shift 2
					else
						flags+=("$1"); shift 1
					fi
					;;
			esac
		done
		files=("$@")
		if [[ $mode == normal ]]; then
			[[ ${#files[@]} = ${cnt} ]] || mode=error
		fi
	fi

	if [[ -z "$merge" ]]; then
		[[ $cnt == 2 ]] || cmd+='3'
	else
		cmd+='-merge'
		[[ $cnt == 2 ]] || cmd+='-with-ancestor'
	fi
	next "$mode" \
	     emacsclient "${flags[@]}" --eval \
	     "(${cmd} $(emacs_quote "${files[@]}") $extra $merge)"
}

main "$@"