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

REPO_DIR="${REPO_DIR:-$(pwd)}"
TARGET_BRANCH="${TARGET_BRANCH:-thirdparty/skill}"
SNAPSHOT_DIR="${SNAPSHOT_DIR:-superpowers}"
SOURCE_FILE="${SOURCE_FILE:-${SNAPSHOT_DIR}/SOURCE.md}"
UPSTREAM_REPO="${UPSTREAM_REPO:-https://github.com/obra/superpowers.git}"
UPSTREAM_REF="${UPSTREAM_REF:-main}"
COMMIT_AUTHOR_NAME="${COMMIT_AUTHOR_NAME:-playbook-bot}"
COMMIT_AUTHOR_EMAIL="${COMMIT_AUTHOR_EMAIL:-playbook-bot@local}"

retry_cmd() {
  local retries="$1"
  shift
  local delay="$1"
  shift

  local attempt=1
  while true; do
    if "$@"; then
      return 0
    fi
    if [ "$attempt" -ge "$retries" ]; then
      return 1
    fi
    echo "Retry ($attempt/$retries): $*" >&2
    sleep "$delay"
    attempt=$((attempt + 1))
  done
}

github_owner_repo() {
  case "$1" in
    https://github.com/*)
      echo "$1" | sed -E 's#^https://github.com/([^/]+/[^/.]+)(\.git)?$#\1#'
      ;;
    http://github.com/*)
      echo "$1" | sed -E 's#^http://github.com/([^/]+/[^/.]+)(\.git)?$#\1#'
      ;;
    git@github.com:*)
      echo "$1" | sed -E 's#^git@github.com:([^/]+/[^/.]+)(\.git)?$#\1#'
      ;;
    *)
      return 1
      ;;
  esac
}

resolve_latest_sha() {
  local repo="$1"
  local ref="$2"
  local tmp_json="$3"
  local gh_repo="$4"
  local sha=""

  # Prefer GitHub API when possible to avoid git+gnutls handshake failures.
  if [ -n "$gh_repo" ]; then
    local api_url="https://api.github.com/repos/${gh_repo}/commits/${ref}"
    if retry_cmd 3 2 curl -fsSL --retry 3 --retry-delay 2 "$api_url" -o "$tmp_json"; then
      sha="$(sed -n 's/^[[:space:]]*"sha":[[:space:]]*"\([0-9a-f]\{40\}\)".*/\1/p' "$tmp_json" | head -n 1)"
      if [ -n "$sha" ]; then
        echo "$sha"
        return 0
      fi
    fi
  fi

  # Fallback to git transport.
  sha="$(retry_cmd 3 2 git -c http.version=HTTP/1.1 ls-remote "$repo" "refs/heads/$ref" | awk 'NR==1 {print $1}')"
  if [ -n "$sha" ]; then
    echo "$sha"
    return 0
  fi
  return 1
}

cd "$REPO_DIR"

git config user.name "$COMMIT_AUTHOR_NAME"
git config user.email "$COMMIT_AUTHOR_EMAIL"

git fetch origin "$TARGET_BRANCH"
git checkout -B "$TARGET_BRANCH" "origin/$TARGET_BRANCH"

tmp_dir="$(mktemp -d)"
cleanup() {
  rm -rf "$tmp_dir"
}
trap cleanup EXIT

gh_repo=""
if gh_repo="$(github_owner_repo "$UPSTREAM_REPO" 2>/dev/null)"; then
  :
fi

latest_sha="$(resolve_latest_sha "$UPSTREAM_REPO" "$UPSTREAM_REF" "$tmp_dir/latest.json" "$gh_repo" || true)"
if [ -z "$latest_sha" ]; then
  echo "ERROR: failed to resolve upstream ref: $UPSTREAM_REPO $UPSTREAM_REF" >&2
  exit 1
fi

current_sha=""
if [ -f "$SOURCE_FILE" ]; then
  current_sha="$(sed -n 's/^- Ref:[[:space:]]*//p' "$SOURCE_FILE" | head -n 1)"
fi

if [ "$latest_sha" = "$current_sha" ]; then
  echo "Third-party snapshot is up to date: $latest_sha"
  exit 0
fi

rm -rf "$SNAPSHOT_DIR"
mkdir -p "$SNAPSHOT_DIR"

snapshot_loaded=0

if [ -n "$gh_repo" ]; then
  tar_url="https://codeload.github.com/${gh_repo}/tar.gz/${latest_sha}"
  if retry_cmd 3 2 curl -fsSL --retry 3 --retry-delay 2 "$tar_url" -o "$tmp_dir/upstream.tar.gz"; then
    tar -xzf "$tmp_dir/upstream.tar.gz" -C "$SNAPSHOT_DIR" --strip-components=1
    snapshot_loaded=1
  fi
fi

if [ "$snapshot_loaded" -eq 0 ]; then
  upstream_dir="$tmp_dir/upstream"
  git init "$upstream_dir" >/dev/null
  git -C "$upstream_dir" remote add origin "$UPSTREAM_REPO"
  retry_cmd 3 2 git -C "$upstream_dir" fetch --depth 1 origin "$latest_sha"
  git -C "$upstream_dir" checkout --detach FETCH_HEAD
  git -C "$upstream_dir" archive --format=tar HEAD | tar -xf - -C "$SNAPSHOT_DIR"
fi

snapshot_date="$(date -u +%Y-%m-%d)"
cat > "$SOURCE_FILE" <<EOF
# Source

- Repo: ${UPSTREAM_REPO%".git"}
- Ref: $latest_sha
- Snapshot: $snapshot_date
- Notes: vendored into playbook branch $TARGET_BRANCH
EOF

git add "$SNAPSHOT_DIR"

if git diff --cached --quiet; then
  echo "No changes detected after snapshot refresh."
  exit 0
fi

git commit -m ":package: deps(superpowers): vendor snapshot"

TOKEN="${WORKFLOW:-}"
if [ -n "$TOKEN" ] && [ -n "${GITHUB_SERVER_URL:-}" ] && [ -n "${GITHUB_REPOSITORY:-}" ]; then
  git remote set-url origin "https://oauth2:${TOKEN}@${GITHUB_SERVER_URL#https://}/${GITHUB_REPOSITORY}.git"
fi

git push origin "$TARGET_BRANCH"