#! /usr/bin/env bash

#  This script is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License version 2 as
#  published by the Free Software Foundation.
#
#  See the COPYING and AUTHORS files for more details.

: ${EDITOR:=vi}

usage()
{
	printf $"Usage: quilt header [-a|-r|-e] [--backup] [--strip-diffstat] [--strip-trailing-whitespace] [patch]\n"

	if [ x$1 = x-h ]
	then
		printf $"
Print or change the header of the topmost or specified patch.

-a, -r, -e
	Append to (-a) or replace (-r) the exiting patch header, or
	edit (-e) the header in \$EDITOR (%s). If none of these options is
	given, print the patch header.

--strip-diffstat
	Strip diffstat output from the header.

--strip-trailing-whitespace
	Strip trailing whitespace at the end of lines of the header.

--backup
	Create a backup copy of the old version of a patch as patch~.
" "$EDITOR"
		exit 0
	else
		exit 1
	fi
}

maybe_strip_trailing_whitespace()
{
	if [ -n "$opt_strip_trailing_whitespace" ]
	then
		sed -e 's:[ '$'\t'']*$::'
	else
		cat
	fi
}

maybe_strip_diffstat()
{
	if [ -n "$opt_strip_diffstat" ]
	then
		strip_diffstat
	else
		cat
	fi
}

options=`getopt -o areh --long backup,strip-trailing-whitespace,strip-diffstat -- "$@"`

if [ $? -ne 0 ]
then
	usage
fi

eval set -- "$options"

while true
do
	case "$1" in
	-a)
		opt_append=1
		shift ;;
	-r)
		opt_replace=1
		shift ;;
	-e)
		opt_edit=1
		shift ;;
	--backup)
		QUILT_BACKUP=1
		shift ;;
	--strip-diffstat)
		opt_strip_diffstat=1
		shift ;;
	--strip-trailing-whitespace)
		opt_strip_trailing_whitespace=1
		shift ;;
	-h)
		usage -h ;;
	--)
		shift
		break ;;
	esac
done

case "$opt_append$opt_replace$opt_edit"
in
''|1)	;;
*)	usage ;;
esac

if [ $# -gt 1 ]
then
	usage
fi

# Read in library functions
if ! [ -r $QUILT_DIR/scripts/patchfns ]
then
	echo "Cannot read library $QUILT_DIR/scripts/patchfns" >&2
	exit 1
fi
. $QUILT_DIR/scripts/patchfns

patch=$(find_patch_in_series "$1") || exit 1

patch_file=$(patch_file_name $patch)

if [ -z "$opt_replace" -a -z "$opt_append" -a -z "$opt_edit" ]
then
	[ -e "$patch_file" ] || exit 0

	setup_pager

	cat_file "$patch_file" \
	| patch_header \
	| maybe_strip_diffstat \
	| maybe_strip_trailing_whitespace
else
	patch_file_or_null=/dev/null
	[ -e "$patch_file" ] && patch_file_or_null=$patch_file

	tmp=$(gen_tempfile) || exit 1
	tmp2=$(gen_tempfile) || exit 1
	add_exit_handler "rm -f $tmp $tmp2"

	(	if [ -z "$opt_replace" ]
		then
			cat_file $patch_file_or_null | patch_header
		fi
		if [ -n "$opt_append" -o -n "$opt_replace" ]
		then
			cat
		fi
	) > $tmp

	if [ -n "$opt_edit" ]
	then
		LANG=$ORIGINAL_LANG $EDITOR "$tmp" || exit 1
	fi

	# Ensure there is a trailing newline before we append the rest
	ensure_trailing_newline $tmp

	maybe_strip_diffstat < $tmp \
	| maybe_strip_trailing_whitespace > $tmp2

	cat_file "$patch_file_or_null" | patch_body >> $tmp2 || exit 1

	if cat_to_new_file $patch_file $QUILT_BACKUP < $tmp2
	then
		if [ -z "$opt_append" ]
		then
			printf \
$"Replaced header of patch %s\n" "$(print_patch $patch)"
		else
			printf \
$"Appended text to header of patch %s\n" "$(print_patch $patch)"
		fi
	else
		exit 1
	fi
fi