#!/bin/sh

domain="https://btxx.org"

# Check the operating system
os_name=$(uname -s)

if [ "$os_name" = "OpenBSD" ]; then
    alias sed=gsed
    alias date=gdate
    alias rsync=openrsync
elif [ "$os_name" = "Darwin" ]; then
    alias sed=gsed
    alias date=gdate
fi

set -eu
MARKDOWN=lowdown
IFS='	'

# Create tab separated file with filename, title, creation date, last update
index_tsv() {
	for f in "$1"/*.md
	do
		title=$(sed -n '/^# /{s/# //p; q}' "$f")
		printf '%s\t%s\t%s\t%s\n' "$f" "${title:="No Title"}"
	done
}

index_html() {
	# Print header
	title=$(sed -n '/^# /{s/# //p; q}' index.md)
	sed "s/{{TITLE}}/$title/" header.html

	# Intro text
	$MARKDOWN index.md

	echo "<ul>"

	# Posts
	while read -r f title created; do
		link=$(echo "$f" | sed -E 's|.*/(.*).md|\1/|')
		created=$(echo $(head -3 "$f" | tail -1))
		echo "<li>$created &middot; <a href=\"$link\">$title</a></li>"
	done < "$1" | sort -r

	echo "</ul>"

	# Print footer after post list
	cat footer.html
}

atom_xml() {
	uri=$(sed -rn '/atom.xml/ s/.*href="([^"]*)".*/\1/ p' header.html)
	first_commit_date=$(git log --pretty='format:%ai' . | cut -d ' ' -f1 | tail -1)

	cat <<EOF
<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
	<title>$(sed -n '/^# /{s/# //p; q}' index.md)</title>
	<link href="$domain/atom.xml" rel="self" />
	<updated>$(date +%FT%TZ)</updated>
	<author>
		<name>$(git config user.name)</name>
	</author>
	<id>$domain,$first_commit_date:default-atom-feed/</id>
EOF

	while read -r f title created; do

		content=$($MARKDOWN "$f" | sed 's/&/\&amp;/g; s/</\&lt;/g; s/>/\&gt;/g; s/"/\&quot;/g; s/'"'"'/\&#39;/g')
		post_link=$(echo "$f" | sed -E 's|posts/(.*).md|\1|')
		basic_date=$(echo $(head -3 "$f" | tail -1))
		published_date=$(date -d $basic_date -u +%Y-%m-%dT10:%M:%SZ)

		cat <<EOF
	<entry>
		<title>$title</title>
		<content type="html">$content</content>
		<link href="$domain/$post_link"/>
		<id>$domain/$post_link</id>
		<updated>$published_date</updated>
		<published>$published_date</published>
	</entry>
EOF
	done < "$1"

	echo '</feed>'
}

rss_xml() {
	uri=$(sed -rn '/rss.xml/ s/.*href="([^"]*)".*/\1/ p' header.html)
	first_commit_date=$(git log --pretty='format:%ai' . | cut -d ' ' -f1 | tail -1)

	cat <<EOF
<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0">
	<channel>
		<title>$(sed -n '/^# /{s/# //p; q}' index.md)</title>
		<link>$domain/rss.xml</link>
		<description>Feed description here</description>
		<lastBuildDate>$(date -u +"%a, %d %b %Y %H:%M:%S %z")</lastBuildDate>
		<pubDate>$(date -u +"%a, %d %b %Y %H:%M:%S %z")</pubDate>
		<generator>Custom RSS Generator</generator>
		<ttl>1800</ttl>
EOF

	while read -r f title created; do
		content=$($MARKDOWN "$f" | sed 's/&/\&amp;/g; s/</\&lt;/g; s/>/\&gt;/g; s/"/\&quot;/g; s/'"'"'/\&#39;/g')
		post_link=$(echo "$f" | sed -E 's|posts/(.*).md|\1|')
		basic_date=$(echo $(head -3 "$f" | tail -1))
		published_date=$(date -d "$basic_date" -u +"%a, %d %b %Y %H:%M:%S %z")

		cat <<EOF
		<item>
			<title>$title</title>
			<description>$content</description>
			<link>$domain/$post_link</link>
			<guid isPermaLink="false">$domain/$post_link</guid>
			<pubDate>$published_date</pubDate>
		</item>
EOF
	done < "$1"

	echo '</channel>'
	echo '</rss>'
}

write_page() {
	filename=$1
	directory=$(echo $(basename "$filename" .md))
	$(mkdir -p build/$directory)
	target=$(echo "$filename" | sed -r 's|\w+/(.*).md|build/\1/index.html|')
	created=$(echo $(head -3 "$filename" | tail -1))
	title=$2

	$MARKDOWN "$filename" | \
		cat header.html - |\
		sed "s|{{TITLE}}|$title|" \
		> "$target" && cat footer.html >> "$target"
}

rm -rf build && mkdir build

# Blog posts
index_tsv posts | sort -rt "	" -k 3 > build/posts.tsv
index_html build/posts.tsv > build/index.html
atom_xml build/posts.tsv > build/atom.xml
rss_xml build/posts.tsv > build/rss.xml
while read -r f title created; do
	write_page "$f" "$title" "$created"
done < build/posts.tsv

# Pages
index_tsv pages > build/pages.tsv
while read -r f title created; do
	write_page "$f" "$title" "$created"
done < build/pages.tsv