# Eggshell Linker entry point
#
# Copyright (C) 2015, 2016  Patrick "P. J." McDermott
#
# This file is part of the Eggshell Linker.
#
# The Eggshell Linker 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.
#
# The Eggshell Linker 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 the Eggshell Linker  If not, see
# <http://www.gnu.org/licenses/>.

set -u

VERSION='0.1.0'

usage()
{
	printf 'Usage: %s [option ...] <file>...\n' "${0}"
}

help()
{
	usage
	cat <<EOF
Options:
  -h           Display this information
  -V           Display linker version information
  -I <interp>  Use <interp> as the interpreter for your program, instead of the
               default of "/bin/sh"
  -e <entry>   Use <entry> as the function for beginning execution of your
               program, instead of the default of "main"
  -o <output>  Use <output> as the name of the program produced by eshld,
               instead of the default of "out.sh"
EOF
}

version()
{
	cat <<EOF
eshld ${VERSION}
Copyright (C) 2015  Patrick "P. J." McDermott
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
EOF
}

main()
{
	local opt=
	local interpreter=
	local entry_point=
	local output=
	local make_executable=
	local input=

	interpreter='/bin/sh'
	entry_point='main'
	output='out.sh'
	make_executable=true

	while getopts 'hVI:e:o:' opt; do
		case "${opt}" in
			'h')
				help
				return 0
				;;
			'V')
				version
				return 0
				;;
			'I')
				interpreter="${OPTARG}"
				;;
			'e')
				entry_point="${OPTARG}"
				;;
			'o')
				output="${OPTARG}"
				;;
		esac
	done
	shift $(($OPTIND - 1))

	if [ ${#} -lt 1 ]; then
		usage >&2
		return 1
	fi

	if ! link_begin "${interpreter}" "${entry_point}" "${output}" \
			${make_executable}; then
		return 1
	fi
	for input in "${@}"; do
		if ! link_file "${input}"; then
			return 1
		fi
	done
	if ! link_end; then
		return 1
	fi

	return 0
}