#!/bin/sh
#-
# Copyright (c) 2020 Daniel Morante
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
#

set -e

progname=${0##*/}

#
# Print an error message and exit.
#
error() {
	echo "$progname: $*" >&2
	exit 1
}

#
# Print a usage string and exit.
#
usage() {
	echo "usage: $progname [-hbfo]" >&2
	exit 1
}

#
# Merge all files into one if directory was given, or just the single file
#
build_section() {
	if [ -d $1 ]; then 
		for f in ${1%/}/*.$2; do (cat "${f}"; echo; echo); done
	else
		(cat "${1}"; echo; echo)
	fi
}

#
# Main program.
#
main() {
	# Default file extension
	opt_e='conf'

	# parse command-line arguments
	while getopts "h:f:b:o:e:" option ; do
		case $option in
		h)
			opt_h=$OPTARG
			;;
		b)
			opt_b=$OPTARG
			;;
		f)
			opt_f=$OPTARG
			;;
		o)
			opt_o=$OPTARG
			;;
		e)
			opt_e=$OPTARG
			;;
		*)
			usage
			;;
		esac
	done
	shift $((OPTIND-1))

	if [ $OPTIND -le $# ] ; then
		usage
	fi

	conf_header=""
	conf_body=""
	conf_footer=""

	# Build the header
	if [ ! -z $opt_h ] ; then
		conf_header="$(build_section ${opt_h} ${opt_e})"
	fi

	# Build body
	if [ ! -z $opt_b ] ; then
		conf_body="$(build_section ${opt_b} ${opt_e})"
	fi

	# Build footer
	if [ ! -z $opt_f ] ; then
		conf_footer="$(build_section ${opt_f} ${opt_e})"
	fi

	output=""

	if [ ! -z "$conf_header" ]; then 
		output="$(echo "${output}"; echo "${conf_header}"; echo)"
	fi
	if [ ! -z "$conf_body" ]; then 
		output="$(echo "${output}"; echo "${conf_body}"; echo)"
	fi
	if [ ! -z "$conf_footer" ]; then 
		output="$(echo "${output}"; echo "${conf_footer}"; echo)"
	fi		
	
	if [ -z $opt_o ] || [ $opt_o == '-' ] ; then
		echo "${output}"
	else
		echo "${output}" > $opt_o
	fi
	
}

main "$@"