#!/bin/sh
set -eu


usage() {
	cat <<-'EOF'
		Usage:
		  md2html.sh -T TITLE [-D TOC_DEPTH] < FILE.md
		  md2html.sh -h
	EOF
}

help() {
	cat <<-'EOF'

		Options:
		  -T TITLE        the required title of the generated HTML
		                  document
		  -D TOC_DEPTH    the depth of the generated table of
		                  contents (default: 2)
		  -h, --help      show this message


		Read markdown text from STDIN and emit HTML to STDOUT.
	EOF
}

for flag in "$@"; do
	case "$flag" in
		--)
			break
			;;
		--help)
			usage
			help
			exit
			;;
		*)
			;;
	esac
done

TOC_DEPTH=2
while getopts 'T:D:h' flag; do
	case "$flag" in
		T)
			TITLE="$OPTARG"
			;;
		D)
			TOC_DEPTH="$OPTARG"
			;;
		h)
			usage
			help
			exit
			;;
		*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))

eval "$(assert-arg "${TITLE:-}" '-T TITLE')"

pandoc \
	-s \
	--toc                     \
	--toc-depth="$TOC_DEPTH"  \
	--metadata lang=en        \
	--metadata title="$TITLE" \
	-H src/doc/head.html