#!/bin/sh
# ht.sh
# *.ht -> *html

# config
header_file=header.htm
footer_file=footer.htm
meta_file=meta.sh

# state
HTDAT="$(date +%s)"
HT_TMPL_COUNT=0

print() {
	printf '%s\n' "$*"
}

htt() { # htt FILE
	# Like `cat`, but with templating.
	ht_end="ht_main_${HTDAT}_${HT_TMPL_COUNT}" # be extra double sure
	eval "$(
		print "cat <<$ht_end"
		cat "$@"
		print
		print "$ht_end"
	)"
	HT_TMPL_COUNT=$((HT_TMPL_COUNT + 1))
}

htmeta_clear() {
	# Generate metadata-clearing commands from $meta_file.
	while read -r line; do
		case "$line" in
		*'()'*) # function
			unset -f "${line%()*}"
			;;
		*=*) # variable assignment
			unset -v "${line%=*}"
			;;
		*) # other -- XXX: Don't know what to do
			;;
		esac
	done <"$meta_file"
}

htmeta() { # htmeta FILE
	# Collect metadata from FILE.
	# Metadata looks like this: `;;@<SHELL_EXPRESSION>`
	sed -n 's/^;;@//p' "$1" | tee "$meta_file"
}

main() {
	# Make two passes over each input file, collecting metadata and content.
	:
	# Of course, this isn't safe, but you trust yourself, right?
	for file; do
		eval "$(htmeta_clear)"
		eval "$(htmeta "$file")"

		./ht.awk <"$file" | htt "$header_file" - "$footer_file" >"${file}ml"
	done
}