#!/usr/bin/env bash
set -euo pipefail

: "${FILE:?FILE is required}"
: "${LATEST_RELEASE_URL:?LATEST_RELEASE_URL is required}"
: "${DOWNLOAD_URL_TEMPLATE:?DOWNLOAD_URL_TEMPLATE is required}"
: "${RELEASE_API_REPO:?RELEASE_API_REPO is required}"

version_strip_prefix="${LATEST_VERSION_STRIP_PREFIX:-v}"
release_tag_template="${RELEASE_TAG_TEMPLATE:-{version}}"

current_version=$(python - <<'PY'
import re
import os
p=os.environ['FILE']
s=open(p).read()
m=re.search(r'version\s*=\s*"([^"]+)";', s)
print(m.group(1) if m else "")
PY
)

latest_version=$(curl -fsSLI -o /dev/null -w '%{url_effective}' "$LATEST_RELEASE_URL" \
  | sed -E 's#.*/##')

if [ -n "$version_strip_prefix" ]; then
  latest_version="${latest_version#${version_strip_prefix}}"
fi

echo "current=$current_version"
echo "latest=$latest_version"

if [ -z "$latest_version" ] || [ "$latest_version" = "$current_version" ]; then
  echo "updated=false" >> "$GITHUB_OUTPUT"
  exit 0
fi

download_url="${DOWNLOAD_URL_TEMPLATE//\{version\}/$latest_version}"
new_hash=$(nix store prefetch-file --json "$download_url" | python -c 'import json,sys; print(json.load(sys.stdin)["hash"])')

export LATEST_VERSION="$latest_version"
export NEW_HASH="$new_hash"

python - <<'PY'
import os
import re
p=os.environ['FILE']
s=open(p).read()
s=re.sub(r'version\s*=\s*"[^"]+"', f'version = "{os.environ["LATEST_VERSION"]}"', s, count=1)
s=re.sub(r'hash\s*=\s*"[^"]+"', f'hash = "{os.environ["NEW_HASH"]}"', s, count=1)
open(p,'w').write(s)
PY

echo "updated=true" >> "$GITHUB_OUTPUT"
echo "version=$latest_version" >> "$GITHUB_OUTPUT"
echo "previous_version=$current_version" >> "$GITHUB_OUTPUT"

release_tag="${release_tag_template//\{version\}/$latest_version}"
release_notes=$(curl -fsSL "https://api.github.com/repos/${RELEASE_API_REPO}/releases/tags/${release_tag}" \
  | python -c 'import json,sys; d=json.load(sys.stdin); print((d.get("body") or "").strip())' \
  || true)

if [ -z "$release_notes" ]; then
  release_notes="_No changelog found in upstream release notes._"
fi

delimiter="CHANGELOG_$(date +%s%N)"
{
  echo "changelog<<${delimiter}"
  printf '%s\n' "$release_notes"
  echo "${delimiter}"
} >> "$GITHUB_OUTPUT"