#!/bin/sh
#
# Generate a patch to add M+ fbcon fonts to Linux(-libre)
#
# Copyright (C) 2019  Patrick McDermott
#
# 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, see <http://www.gnu.org/licenses/>.

set -eu

VARIANTS='
	1m  regular 16 22
	1m  bold    16 22
	1mn regular 16 22
	1mn bold    16 22
	'
LF='
'

backup_orig()
{
	local f=

	for f in include/linux/font.h lib/fonts/Kconfig lib/fonts/Makefile \
			lib/fonts/fonts.c; do
		if ! [ -e "tmp/src/${f}.orig" ]; then
			mv "tmp/src/${f}" "tmp/src/${f}.orig"
		fi
	done
}

edit_font_h()
{
	local state=
	local i=
	local line=
	local ft=

	exec 3>'tmp/src/include/linux/font.h'
	state='want_defs'
	i=0
	while IFS='' read -r line; do
		if [ x"${state}" = x'want_defs' ] || [ x"${state}" = x'defs' ]
		then
			case "${line}" in '#define '*'_IDX'*)
				state='defs'
				printf '%s\n' "${line}" 1>&3
				: $((i += 1))
				continue
			esac
		fi
		if [ x"${state}" = x'defs' ]; then  # End of defines
			while read fc wt wd ht; do
				[ -z "${fc}" ] && continue
				ft="MPLUS_$(printf '%s_%s' "${fc}" "${wt}" | \
					tr '[a-z]' '[A-Z]')_${wd}x${ht}_IDX"
				printf '#define %s\t%d\n' "${ft}" ${i} 1>&3
				: $((i += 1))
			done <<-EOF
				${VARIANTS}
				EOF
			state='want_decls'
		fi
		if [ x"${state}" = x'want_decls' ]; then
			case "${line}" in *'struct font_desc'*)
				state='decls'
			esac
		fi
		if [ x"${state}" = x'decls' ]; then
			case "${line}" in *';')
				printf '%s\n' "${line%;}" 1>&3
				while read fc wt wd ht; do
					[ -z "${fc}" ] && continue
					printf ',\t\t\tfont_mplus_%s_%s'"$(: \
						)"'_%dx%d' "${fc}" "${wt}" \
						"${wd}" "${ht}" 1>&3
				done <<-EOF
					${VARIANTS}
					EOF
				printf ';\n' 1>&3
				state='end'
				continue
			esac
			printf '%s\n' "${line}" 1>&3
		fi
		printf '%s\n' "${line}" 1>&3
	done 0<'tmp/src/include/linux/font.h.orig'

	if ! [ x"${state}" = x'end' ]; then
		printf 'Error editing include/linux/font.h\n' 1>&2
		return 1
	fi

	return 0
}

edit_kconfig()
{
}

edit_makefile()
{
}

edit_fonts_c()
{
}


gen_headers()
{
	local mplus_dir="${1}"
	shift 1
	local mplus_ver=

	mplus_ver="$(tr '\0' '\n' <"${mplus_dir}/mplus-1m-regular.ttf" | \
		sed -n 's/^Version 1.//p')"
	cat <<-EOF
	Author: Patrick McDermott <patrick.mcdermott@libiquity.com>
	Subject: Add M+ fonts

	Generated from M+ version ${mplus_ver} by ${0}
	EOF
	return 0
}

gen_diff()
{
	local headers="${1}"
	shift 1
	local files=
	local fc=
	local wt=
	local wd=
	local ht=
	local f=
	local diff=
	local a=
	local b=

	files="include/linux/font.h${LF}lib/fonts/Kconfig${LF}"
	files="${files}lib/fonts/Makefile${LF}"
	while read fc wt wd ht; do
		[ -z "${fc}" ] && continue
		f="lib/fonts/font_mplus_${fc}_${wt}_${wd}x${ht}.c"
		files="${files}${f}${LF}"
	done <<-EOF
		${VARIANTS}
		EOF
	files="${files}lib/fonts/fonts.c${LF}"

	diff=''
	for f in ${files}; do
		a="tmp/src/${f}"
		b="tmp/src/${f}.orig"
		case "${f}" in lib/fonts/font_*.c) a='/dev/null';; esac
		diff="${diff}diff -Naurp a/${f} b/${f}${LF}"
		diff="${diff}--- a/${f}${LF}"
		diff="${diff}+++ a/${f}${LF}"
		diff="${diff}$(diff -up "${a}" "${b}" | tail -n +3)${LF}"
	done
	diff="${headers}${LF}---${LF}$(printf '%s' "${diff}" | \
		diffstat)${LF}${diff}"

	return 0
}

main()
{
	local mplus_dir=
	local bdf2fbcon=

	if [ ${#} -ne 2 ]; then
		printf 'Usage: %s <mplus-dir> <bdf2fbcon>\n' "${0}" 1>&2
		return 1
	fi
	mplus_dir="${1}"
	bdf2fbcon="${2}"
	shift 2

	conv_fonts "${mplus_dir}" "${bdf2fbcon}"
	backup_orig
	edit_font_h
	edit_kconfig
	edit_makefile
	edit_fonts_c
	gen_diff "$(gen_headers "${mplus_dir}")"

	return 0
}

main "${@}"