#!/usr/bin/env bash
# Prints the release notes for a tag: the images it publishes, then the matching
# section of CHANGELOG.md (the commit log since the previous tag if the changelog
# has no section for that version).
#
#   scripts/release-notes.sh v1.2.3 git.example.com/owner/project
set -euo pipefail

tag=${1:?usage: release-notes.sh <tag> <image-namespace>}
namespace=${2:?usage: release-notes.sh <tag> <image-namespace>}
version=${tag#v}

echo "## Images"
echo
echo '```'
for service in protocols auth storage webmail migrations rspamd; do
  echo "$namespace/$service:$version"
done
echo '```'
echo

section=""
if [ -f CHANGELOG.md ]; then
  section=$(awk -v head="## [$version]" '
    index($0, head) == 1 { found = 1; next }
    found && /^## \[/ { exit }
    found && /^\[[^]]+\]: / { next }
    found { print }
  ' CHANGELOG.md)
fi

if [ -n "$(printf '%s' "$section" | tr -d '[:space:]')" ]; then
  printf '%s\n' "$section"
else
  previous=$(git describe --tags --abbrev=0 "$tag^" 2>/dev/null || true)
  echo "## Changes${previous:+ since $previous}"
  echo
  git log --no-merges --format='- %s (%h)' "${previous:+$previous..}$tag"
fi