#!/usr/bin/env bash
# runner.sh — Setup, manage, and tear down a GitHub Actions self-hosted runner.
#
# Supports two platforms:
#   - macOS: Installs the runner agent natively, manages it as a launchd service.
#   - Linux: Delegates to Docker-based runner infrastructure in infra/runners/.
#
# Typical flow:
#   1) ./scripts/runner.sh --mode setup          # install/configure runner
#   2) ./scripts/runner.sh --mode status          # verify runner is online
#   3) (push/PR triggers CI on the self-hosted runner)
#   4) ./scripts/runner.sh --mode stop            # stop runner
#   5) ./scripts/runner.sh --mode uninstall       # deregister and clean up

set -euo pipefail

MODE=""
RUNNER_DIR="${PERIODVAULT_RUNNER_DIR:-${HOME}/.periodvault-runner}"
RUNNER_LABELS="self-hosted,macOS,periodvault"
RUNNER_NAME=""
REPO_SLUG=""
REG_TOKEN=""
FORCE=false
FOREGROUND=false
PUSH_REGISTRY=""
BUILD_TARGET=""

PLIST_LABEL="com.periodvault.actions-runner"
PLIST_PATH="${HOME}/Library/LaunchAgents/${PLIST_LABEL}.plist"

# Resolved during Linux operations
INFRA_DIR=""

usage() {
  cat <<'EOF'
Usage:
  ./scripts/runner.sh --mode <setup|start|stop|status|build-image|uninstall> [options]

Required:
  --mode MODE              One of: setup, start, stop, status, build-image, uninstall

Options (macOS):
  --runner-dir DIR         Installation directory (default: ~/.periodvault-runner)
  --labels LABELS          Comma-separated labels (default: self-hosted,macOS,periodvault)
  --name NAME              Runner name (default: periodvault-<hostname>)
  --repo OWNER/REPO        GitHub repository (default: auto-detected from git remote)
  --token TOKEN            Registration/removal token (prompted if not provided)
  --force                  Force re-setup even if already configured
  --foreground             Start in foreground instead of launchd service

Options (Linux — Docker mode):
  On Linux, this script delegates to Docker Compose in infra/runners/.
  Configuration is managed via .env and envs/*.env files.
  See infra/runners/README.md for details.

Options (build-image):
  --target TARGET          Dockerfile target: slim or full (default: builds both)
  --push REGISTRY          Tag and push to a registry (e.g. localhost:5000)

Common:
  -h, --help               Show this help

Examples (macOS):
  ./scripts/runner.sh --mode setup
  ./scripts/runner.sh --mode setup --token ghp_xxxxx
  ./scripts/runner.sh --mode start
  ./scripts/runner.sh --mode start --foreground
  ./scripts/runner.sh --mode status
  ./scripts/runner.sh --mode stop
  ./scripts/runner.sh --mode uninstall

Examples (Linux):
  ./scripts/runner.sh --mode setup       # prompts for .env, starts runners
  ./scripts/runner.sh --mode start       # docker compose up -d
  ./scripts/runner.sh --mode stop        # docker compose down
  ./scripts/runner.sh --mode status      # docker compose ps + logs
  ./scripts/runner.sh --mode uninstall   # docker compose down -v --rmi local

Examples (build-image — works on any OS):
  ./scripts/runner.sh --mode build-image                              # build slim + full
  ./scripts/runner.sh --mode build-image --target slim                # build slim only
  ./scripts/runner.sh --mode build-image --push localhost:5000        # build + push to local registry

Environment overrides:
  PERIODVAULT_RUNNER_DIR   Runner installation directory (macOS only)
EOF
}

# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

log() {
  printf '[runner] %s\n' "$*"
}

warn() {
  printf '[runner] WARNING: %s\n' "$*" >&2
}

die() {
  printf '[runner] ERROR: %s\n' "$*" >&2
  exit 1
}

require_cmd() {
  local cmd="$1"
  command -v "$cmd" >/dev/null 2>&1 || die "required command not found: $cmd"
}

# ---------------------------------------------------------------------------
# Platform detection
# ---------------------------------------------------------------------------

detect_os() {
  case "$(uname -s)" in
    Darwin) printf 'darwin' ;;
    Linux)  printf 'linux' ;;
    *)      die "Unsupported OS: $(uname -s). This script supports macOS and Linux." ;;
  esac
}

ensure_macos() {
  [[ "$(detect_os)" == "darwin" ]] || die "This operation requires macOS."
}

find_infra_dir() {
  local script_dir
  script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
  local repo_root="${script_dir}/.."
  INFRA_DIR="$(cd "${repo_root}/infra/runners" 2>/dev/null && pwd)" || true

  if [[ -z "$INFRA_DIR" ]] || [[ ! -f "${INFRA_DIR}/docker-compose.yml" ]]; then
    die "Could not find infra/runners/docker-compose.yml. Ensure you are running from the periodvault repo."
  fi
}

# ---------------------------------------------------------------------------
# Argument parsing
# ---------------------------------------------------------------------------

parse_args() {
  while [[ $# -gt 0 ]]; do
    case "$1" in
      --mode)
        shift; [[ $# -gt 0 ]] || die "--mode requires a value"
        MODE="$1"; shift ;;
      --runner-dir)
        shift; [[ $# -gt 0 ]] || die "--runner-dir requires a value"
        RUNNER_DIR="$1"; shift ;;
      --labels)
        shift; [[ $# -gt 0 ]] || die "--labels requires a value"
        RUNNER_LABELS="$1"; shift ;;
      --name)
        shift; [[ $# -gt 0 ]] || die "--name requires a value"
        RUNNER_NAME="$1"; shift ;;
      --repo)
        shift; [[ $# -gt 0 ]] || die "--repo requires a value"
        REPO_SLUG="$1"; shift ;;
      --token)
        shift; [[ $# -gt 0 ]] || die "--token requires a value"
        REG_TOKEN="$1"; shift ;;
      --target)
        shift; [[ $# -gt 0 ]] || die "--target requires a value (slim or full)"
        BUILD_TARGET="$1"; shift ;;
      --force)
        FORCE=true; shift ;;
      --foreground)
        FOREGROUND=true; shift ;;
      --push)
        shift; [[ $# -gt 0 ]] || die "--push requires a registry address (e.g. localhost:5000)"
        PUSH_REGISTRY="$1"; shift ;;
      -h|--help)
        usage; exit 0 ;;
      *)
        die "unknown argument: $1" ;;
    esac
  done

  [[ -n "$MODE" ]] || die "--mode is required (setup|start|stop|status|build-image|uninstall)"
  case "$MODE" in
    setup|start|stop|status|build-image|uninstall) ;;
    *) die "invalid --mode: $MODE (expected setup|start|stop|status|build-image|uninstall)" ;;
  esac
}

# ---------------------------------------------------------------------------
# Repo detection
# ---------------------------------------------------------------------------

detect_repo() {
  if [[ -n "$REPO_SLUG" ]]; then
    return
  fi

  local remote_url=""
  remote_url="$(git remote get-url origin 2>/dev/null || true)"
  if [[ -z "$remote_url" ]]; then
    die "Could not detect repository from git remote. Use --repo OWNER/REPO."
  fi

  REPO_SLUG="$(printf '%s' "$remote_url" \
    | sed -E 's#^(https?://github\.com/|git@github\.com:)##' \
    | sed -E 's/\.git$//')"

  if [[ -z "$REPO_SLUG" ]] || ! printf '%s' "$REPO_SLUG" | grep -qE '^[^/]+/[^/]+$'; then
    die "Could not parse OWNER/REPO from remote URL: $remote_url. Use --repo OWNER/REPO."
  fi

  log "Auto-detected repository: $REPO_SLUG"
}

# ===========================================================================
# macOS: Native runner agent + launchd service
# ===========================================================================

detect_arch() {
  local arch
  arch="$(uname -m)"
  case "$arch" in
    arm64|aarch64) printf 'arm64' ;;
    x86_64)        printf 'x64' ;;
    *)             die "Unsupported architecture: $arch" ;;
  esac
}

download_runner() {
  require_cmd curl
  require_cmd shasum
  require_cmd tar

  local arch
  arch="$(detect_arch)"

  log "Fetching latest runner release metadata..."
  local release_json
  release_json="$(curl -fsSL "https://api.github.com/repos/actions/runner/releases/latest")"

  local version
  version="$(printf '%s' "$release_json" | grep '"tag_name"' | sed -E 's/.*"v([^"]+)".*/\1/')"
  if [[ -z "$version" ]]; then
    die "Could not determine latest runner version from GitHub API."
  fi
  log "Latest runner version: $version"

  local tarball="actions-runner-osx-${arch}-${version}.tar.gz"
  local download_url="https://github.com/actions/runner/releases/download/v${version}/${tarball}"

  local sha_marker="osx-${arch}"
  local expected_sha=""
  expected_sha="$(printf '%s' "$release_json" \
    | python3 -c "
import json,sys,re
body = json.load(sys.stdin).get('body','')
m = re.search(r'<!-- BEGIN SHA ${sha_marker} -->([0-9a-f]{64})<!-- END SHA ${sha_marker} -->', body)
print(m.group(1) if m else '')
" 2>/dev/null || true)"

  mkdir -p "$RUNNER_DIR"
  local dest="${RUNNER_DIR}/${tarball}"

  if [[ -f "$dest" ]]; then
    log "Tarball already exists: $dest"
  else
    log "Downloading: $download_url"
    curl -fSL -o "$dest" "$download_url"
  fi

  if [[ -n "$expected_sha" ]]; then
    log "Verifying SHA256 checksum..."
    local actual_sha
    actual_sha="$(shasum -a 256 "$dest" | awk '{print $1}')"
    if [[ "$actual_sha" != "$expected_sha" ]]; then
      rm -f "$dest"
      die "Checksum mismatch. Expected: $expected_sha, Got: $actual_sha"
    fi
    log "Checksum verified."
  else
    warn "Could not extract expected SHA256 from release metadata; skipping verification."
  fi

  log "Extracting runner into $RUNNER_DIR..."
  tar -xzf "$dest" -C "$RUNNER_DIR"
  rm -f "$dest"

  log "Runner extracted (version $version)."
}

prompt_token() {
  if [[ -n "$REG_TOKEN" ]]; then
    return
  fi

  log ""
  log "A registration token is required."
  log "Obtain one from: https://github.com/${REPO_SLUG}/settings/actions/runners/new"
  log "Or via the API:"
  log "  curl -X POST -H 'Authorization: token YOUR_PAT' \\"
  log "    https://api.github.com/repos/${REPO_SLUG}/actions/runners/registration-token"
  log ""
  printf '[runner] Enter registration token: '
  read -r REG_TOKEN
  [[ -n "$REG_TOKEN" ]] || die "No token provided."
}

register_runner() {
  if [[ -z "$RUNNER_NAME" ]]; then
    RUNNER_NAME="periodvault-$(hostname -s)"
  fi

  log "Registering runner '${RUNNER_NAME}' with labels '${RUNNER_LABELS}'..."

  local config_args=(
    --url "https://github.com/${REPO_SLUG}"
    --token "$REG_TOKEN"
    --name "$RUNNER_NAME"
    --labels "$RUNNER_LABELS"
    --work "${RUNNER_DIR}/_work"
    --unattended
  )

  if [[ "$FORCE" == "true" ]]; then
    config_args+=(--replace)
  fi

  "${RUNNER_DIR}/config.sh" "${config_args[@]}"
  log "Runner registered."
}

# ---------------------------------------------------------------------------
# launchd service management (macOS)
# ---------------------------------------------------------------------------

create_plist() {
  mkdir -p "${RUNNER_DIR}/logs"
  mkdir -p "$(dirname "$PLIST_PATH")"

  cat > "$PLIST_PATH" <<EOF
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>${PLIST_LABEL}</string>
    <key>ProgramArguments</key>
    <array>
        <string>${RUNNER_DIR}/run.sh</string>
    </array>
    <key>WorkingDirectory</key>
    <string>${RUNNER_DIR}</string>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <true/>
    <key>StandardOutPath</key>
    <string>${RUNNER_DIR}/logs/stdout.log</string>
    <key>StandardErrorPath</key>
    <string>${RUNNER_DIR}/logs/stderr.log</string>
    <key>EnvironmentVariables</key>
    <dict>
        <key>PATH</key>
        <string>/opt/homebrew/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin</string>
        <key>HOME</key>
        <string>${HOME}</string>
    </dict>
</dict>
</plist>
EOF

  log "Launchd plist created: $PLIST_PATH"
}

load_service() {
  if launchctl list 2>/dev/null | grep -q "$PLIST_LABEL"; then
    log "Service already loaded; unloading first..."
    launchctl unload "$PLIST_PATH" 2>/dev/null || true
  fi

  launchctl load "$PLIST_PATH"
  log "Service loaded."
}

unload_service() {
  if launchctl list 2>/dev/null | grep -q "$PLIST_LABEL"; then
    launchctl unload "$PLIST_PATH" 2>/dev/null || true
    log "Service unloaded."
  else
    log "Service is not loaded."
  fi
}

service_is_running() {
  launchctl list 2>/dev/null | grep -q "$PLIST_LABEL"
}

# ---------------------------------------------------------------------------
# macOS mode implementations
# ---------------------------------------------------------------------------

do_setup_darwin() {
  detect_repo

  if [[ -f "${RUNNER_DIR}/.runner" ]] && [[ "$FORCE" != "true" ]]; then
    log "Runner already configured at $RUNNER_DIR."
    log "Use --force to re-setup."
    do_status_darwin
    return
  fi

  download_runner
  prompt_token
  register_runner
  create_plist
  load_service

  log ""
  log "Setup complete. Runner is registered and running."
  log ""
  log "To activate self-hosted CI, set these repository variables:"
  log '  CI_RUNS_ON_MACOS: ["self-hosted", "macOS", "periodvault"]'
  log ""
  log "Via CLI:"
  log '  gh variable set CI_RUNS_ON_MACOS --body '"'"'["self-hosted","macOS","periodvault"]'"'"
  log ""
  log "Energy saver: ensure your Mac does not sleep while the runner is active."
  log "  System Settings > Energy Saver > Prevent automatic sleeping"
}

do_start_darwin() {
  [[ -f "${RUNNER_DIR}/.runner" ]] || die "Runner not configured. Run --mode setup first."

  if [[ "$FOREGROUND" == "true" ]]; then
    log "Starting runner in foreground (Ctrl-C to stop)..."
    exec "${RUNNER_DIR}/run.sh"
  fi

  if service_is_running; then
    log "Runner service is already running."
    return
  fi

  if [[ ! -f "$PLIST_PATH" ]]; then
    log "Plist not found; recreating..."
    create_plist
  fi

  load_service
  log "Runner started."
}

do_stop_darwin() {
  unload_service
  log "Runner stopped."
}

do_status_darwin() {
  log "Runner directory: $RUNNER_DIR"

  if [[ ! -f "${RUNNER_DIR}/.runner" ]]; then
    log "Status: NOT CONFIGURED"
    log "Run --mode setup to install and register the runner."
    return
  fi

  local runner_name=""
  if command -v python3 >/dev/null 2>&1; then
    runner_name="$(python3 -c "import json,sys; d=json.load(open(sys.argv[1])); print(d.get('agentName',''))" "${RUNNER_DIR}/.runner" 2>/dev/null || true)"
  fi
  if [[ -z "$runner_name" ]]; then
    runner_name="(could not parse)"
  fi

  log "Runner name: $runner_name"

  if service_is_running; then
    log "Service: RUNNING"
  else
    log "Service: STOPPED"
  fi

  if pgrep -f "Runner.Listener" >/dev/null 2>&1; then
    log "Process: ACTIVE (Runner.Listener found)"
  else
    log "Process: INACTIVE"
  fi

  local log_file="${RUNNER_DIR}/logs/stdout.log"
  if [[ -f "$log_file" ]]; then
    log ""
    log "Recent log output (last 10 lines):"
    tail -n 10 "$log_file" 2>/dev/null || true
  fi

  local diag_dir="${RUNNER_DIR}/_diag"
  if [[ -d "$diag_dir" ]]; then
    local latest_diag
    latest_diag="$(ls -t "${diag_dir}"/Runner_*.log 2>/dev/null | head -n1 || true)"
    if [[ -n "$latest_diag" ]]; then
      log ""
      log "Latest runner diagnostic (last 5 lines):"
      tail -n 5 "$latest_diag" 2>/dev/null || true
    fi
  fi
}

do_uninstall_darwin() {
  log "Uninstalling self-hosted runner..."

  unload_service

  if [[ -f "$PLIST_PATH" ]]; then
    rm -f "$PLIST_PATH"
    log "Removed plist: $PLIST_PATH"
  fi

  if [[ -f "${RUNNER_DIR}/config.sh" ]]; then
    if [[ -z "$REG_TOKEN" ]]; then
      detect_repo
      log ""
      log "A removal token is required to deregister the runner."
      log "Obtain one from: https://github.com/${REPO_SLUG}/settings/actions/runners"
      log "Or via the API:"
      log "  curl -X POST -H 'Authorization: token YOUR_PAT' \\"
      log "    https://api.github.com/repos/${REPO_SLUG}/actions/runners/remove-token"
      log ""
      printf '[runner] Enter removal token (or press Enter to skip deregistration): '
      read -r REG_TOKEN
    fi

    if [[ -n "$REG_TOKEN" ]]; then
      "${RUNNER_DIR}/config.sh" remove --token "$REG_TOKEN" || warn "Deregistration failed; you may need to remove the runner manually from GitHub settings."
      log "Runner deregistered from GitHub."
    else
      warn "Skipping deregistration. Remove the runner manually from GitHub settings."
    fi
  fi

  if [[ -d "$RUNNER_DIR" ]]; then
    log "Removing runner directory: $RUNNER_DIR"
    rm -rf "$RUNNER_DIR"
    log "Runner directory removed."
  fi

  log "Uninstall complete."
}

# ===========================================================================
# Linux: Docker-based runner via infra/runners/
# ===========================================================================

ensure_docker() {
  require_cmd docker

  if docker compose version >/dev/null 2>&1; then
    return
  fi

  if command -v docker-compose >/dev/null 2>&1; then
    warn "Found docker-compose (standalone). docker compose v2 plugin is recommended."
    return
  fi

  die "docker compose is required. Install Docker Compose v2: https://docs.docker.com/compose/install/"
}

compose() {
  docker compose -f "${INFRA_DIR}/docker-compose.yml" "$@"
}

do_build_image() {
  find_infra_dir
  ensure_docker

  local targets=()
  if [[ -n "$BUILD_TARGET" ]]; then
    targets+=("$BUILD_TARGET")
  else
    targets+=("slim" "full")
  fi

  for target in "${targets[@]}"; do
    local image_tag="periodvault-runner:${target}"
    if [[ -n "$PUSH_REGISTRY" ]]; then
      image_tag="${PUSH_REGISTRY}/periodvault-runner:${target}"
    fi

    log "Building runner image: ${image_tag} (target: ${target}, platform: linux/amd64)"
    DOCKER_BUILDKIT=1 docker build --platform linux/amd64 --pull \
      --target "$target" \
      -t "$image_tag" \
      "$INFRA_DIR"

    if [[ -n "$PUSH_REGISTRY" ]]; then
      log "Pushing ${image_tag}..."
      docker push "$image_tag"
      log "Image pushed: ${image_tag}"
    else
      log "Image built locally: ${image_tag}"
    fi
  done

  if [[ -z "$PUSH_REGISTRY" ]]; then
    log ""
    log "Use --push <registry> to push to a registry."
    log "Example: ./scripts/runner.sh --mode build-image --push localhost:5000"
  fi
}

do_setup_linux() {
  find_infra_dir
  ensure_docker

  log "Docker-based runner setup (infra/runners/)"
  log ""

  if [[ ! -f "${INFRA_DIR}/.env" ]]; then
    if [[ -f "${INFRA_DIR}/.env.example" ]]; then
      cp "${INFRA_DIR}/.env.example" "${INFRA_DIR}/.env"
      log "Created ${INFRA_DIR}/.env from template."
      log "Edit this file to set your GITHUB_PAT."
      log ""
      printf '[runner] Enter your GitHub PAT (or press Enter to edit .env manually later): '
      read -r pat_input
      if [[ -n "$pat_input" ]]; then
        sed -i "s/^GITHUB_PAT=.*/GITHUB_PAT=${pat_input}/" "${INFRA_DIR}/.env"
        log "GITHUB_PAT set in .env"
      fi
    else
      die "Missing .env.example template in ${INFRA_DIR}"
    fi
  else
    log ".env already exists; skipping."
  fi

  if [[ ! -f "${INFRA_DIR}/envs/periodvault.env" ]]; then
    if [[ -f "${INFRA_DIR}/envs/periodvault.env.example" ]]; then
      cp "${INFRA_DIR}/envs/periodvault.env.example" "${INFRA_DIR}/envs/periodvault.env"
      log "Created ${INFRA_DIR}/envs/periodvault.env from template."
      log "Edit this file to configure REPO_URL, RUNNER_NAME, and resource limits."
    else
      die "Missing envs/periodvault.env.example template in ${INFRA_DIR}"
    fi
  else
    log "envs/periodvault.env already exists; skipping."
  fi

  log ""
  log "Starting runners..."
  compose up -d

  log ""
  log "Setup complete. Verify with: ./scripts/runner.sh --mode status"
  log ""
  log "To activate self-hosted CI, set these repository variables:"
  log '  gh variable set CI_RUNS_ON --body '"'"'["self-hosted","Linux","X64"]'"'"
  log '  gh variable set CI_RUNS_ON_ANDROID --body '"'"'["self-hosted","Linux","X64","android-emulator"]'"'"
}

do_start_linux() {
  find_infra_dir
  ensure_docker

  log "Starting Docker runners..."
  compose up -d
  log "Runners started."
}

do_stop_linux() {
  find_infra_dir
  ensure_docker

  log "Stopping Docker runners..."
  compose down
  log "Runners stopped."
}

do_status_linux() {
  find_infra_dir
  ensure_docker

  log "Docker runner status (infra/runners/):"
  log ""
  compose ps
  log ""
  log "Recent logs (last 20 lines):"
  compose logs --tail 20 2>/dev/null || true
}

do_uninstall_linux() {
  find_infra_dir
  ensure_docker

  log "Uninstalling Docker runners..."
  compose down -v --rmi local 2>/dev/null || compose down -v
  log "Docker runners removed (containers, volumes, local images)."
  log ""
  log "Note: Runners should auto-deregister from GitHub (ephemeral mode)."
  log "If stale runners remain, remove them manually:"
  log "  gh api -X DELETE repos/OWNER/REPO/actions/runners/RUNNER_ID"
}

# ===========================================================================
# Entry point
# ===========================================================================

main() {
  parse_args "$@"

  local os
  os="$(detect_os)"

  case "$MODE" in
    setup)
      if [[ "$os" == "darwin" ]]; then do_setup_darwin; else do_setup_linux; fi ;;
    start)
      if [[ "$os" == "darwin" ]]; then do_start_darwin; else do_start_linux; fi ;;
    stop)
      if [[ "$os" == "darwin" ]]; then do_stop_darwin; else do_stop_linux; fi ;;
    status)
      if [[ "$os" == "darwin" ]]; then do_status_darwin; else do_status_linux; fi ;;
    build-image)
      do_build_image ;;
    uninstall)
      if [[ "$os" == "darwin" ]]; then do_uninstall_darwin; else do_uninstall_linux; fi ;;
    *)
      die "unexpected mode: $MODE" ;;
  esac
}

main "$@"