#!/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}"

if command -v python >/dev/null 2>&1; then
  PYTHON_BIN=python
elif command -v python3 >/dev/null 2>&1; then
  PYTHON_BIN=python3
else
  echo "python is required but was not found"
  exit 1
fi

version_strip_prefix="${LATEST_VERSION_STRIP_PREFIX:-v}"
release_tag_template="${RELEASE_TAG_TEMPLATE:-{version}}"
release_tag_template="${release_tag_template//$'\r'/}"

current_version=$($PYTHON_BIN - <<'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_BIN" -c 'import json,sys; print(json.load(sys.stdin)["hash"])')

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

"$PYTHON_BIN" - <<'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

release_tag="${release_tag_template//\{version\}/$latest_version}"
release_tag="${release_tag#\{}"
release_tag="${release_tag%\}}"
release_tag="${release_tag#\'}"
release_tag="${release_tag%\'}"
release_url="${LATEST_RELEASE_URL%/latest}/tag/${release_tag}"

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