#!/bin/ksh -eu
f='sitemap.xml'
test $# -ne 2 && { echo "$f" && exit; }

SRC="$1"
DST="$2"

dst_pages=$(find "$DST" -type f -name '*.html')
if test -z "$dst_pages"; then exit; fi

diff_lines() { diff <(printf "%s\n" "$1") <(printf "%s\n" "$2") || :; }
if test -f "$DST/.ssg.dst"; then exit; fi
dst_pages_was=$(cut -d' ' -f2 "$DST/.ssg.dst" | grep '.html')
dst_pages_updated=$(diff_lines "$dst_pages_was" "$dst_pages")
if test -z "$dst_pages_updated"; then exit; fi

site=$(basename "$SRC")
{
	echo '<?xml version="1.0" encoding="UTF-8"?>
<urlset
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
	http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd"
	xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">'
	echo "$dst_pages" | sed -E '
			s,^$,,
			s,^'"$DST"',,
			s,index.html$,,
			s,^(.*)$,	<url><loc>https://'"$site"'\1</loc></url>,'
	echo '</urlset>'
} >"$DST/$f"
echo "$f"