#!/usr/bin/env zsh
# releases.atom.zsh -- releases.atom generator
# Copyright (C) 2022 Sergey Matveev <stargrave@stargrave.org>

set -e

[[ -n "$ATOM_ID" ]]
[[ -n "$NAME" ]]
[[ -n "$BASE_URL" ]]
[[ -n "$AUTHOR_EMAIL" ]]
export TZ=UTC
zmodload -F zsh/datetime b:strftime
UPDATED=$(strftime %FT%T)
ATOM=releases.atom
tmp=`mktemp`
trap "rm -f $tmp" HUP PIPE INT QUIT TERM EXIT

cat > $tmp <<EOF
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
  <title>$NAME releases</title>
  <id>urn:uuid:$ATOM_ID</id>
  <link rel="self" href="$BASE_URL/$ATOM"></link>
  <updated>$UPDATED</updated>
  <author>
    <email>$AUTHOR_EMAIL</email>
  </author>
EOF

zmodload -F zsh/stat b:zstat
for meta (*.meta4(om)) {
    fn=$meta:r
    title=${meta%.tar.*}
    updated=$(zstat -F %FT%T +mtime $meta)
    cat >> $tmp <<EOF
  <entry>
    <title>$title</title>
    <id>$BASE_URL/$fn</id>
    <link rel="alternate" type="application/metalink4+xml" href="$BASE_URL/$meta" />
    <updated>$updated</updated>
  </entry>
EOF
}

echo "</feed>" >> $tmp

size_our=$(zstat +size $tmp)
[[ -e $ATOM ]] && size_their=$(zstat +size $ATOM) || size_their=0
[[ $size_our = $size_their ]] || mv $tmp $ATOM