#!/usr/bin/env bash

set -euo pipefail

ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
RUNTIME_DIR="$ROOT_DIR/.dev-runtime"

BACKEND_PID_FILE="$RUNTIME_DIR/backend.pid"
FRONTEND_PID_FILE="$RUNTIME_DIR/frontend.pid"
BACKEND_LOG_FILE="$RUNTIME_DIR/backend.log"
FRONTEND_LOG_FILE="$RUNTIME_DIR/frontend.log"

BACKEND_HOST="127.0.0.1"
BACKEND_PORT="8000"
FRONTEND_HOST="127.0.0.1"
FRONTEND_PORT="5173"


usage() {
  cat <<'EOF'
Usage: scripts/dev.sh <start|stop|restart|status>
EOF
}


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


fail() {
  printf '[dev] %s\n' "$*" >&2
  exit 1
}


ensure_base_requirements() {
  [[ -x "$ROOT_DIR/backend/.venv/bin/uvicorn" ]] || fail "缺少 backend/.venv/bin/uvicorn"
  [[ -f "$ROOT_DIR/frontend/package.json" ]] || fail "缺少 frontend/package.json"
  [[ -d "$ROOT_DIR/frontend/node_modules" ]] || fail "缺少 frontend/node_modules，请先执行前端依赖安装"
  command -v npm >/dev/null 2>&1 || fail "当前环境缺少 npm"
  command -v setsid >/dev/null 2>&1 || fail "当前环境缺少 setsid"
}


ensure_runtime_dir() {
  mkdir -p "$RUNTIME_DIR"
}


pid_from_file() {
  local pid_file="$1"

  [[ -f "$pid_file" ]] || return 1

  local pid
  pid="$(tr -d '[:space:]' < "$pid_file")"
  [[ -n "$pid" ]] || return 1

  printf '%s\n' "$pid"
}


is_pid_running() {
  local pid="$1"
  kill -0 "$pid" 2>/dev/null
}


cleanup_stale_pid_file() {
  local service_name="$1"
  local pid_file="$2"
  local announce="${3:-true}"

  if pid="$(pid_from_file "$pid_file" 2>/dev/null)"; then
    if ! is_pid_running "$pid"; then
      rm -f "$pid_file"
      if [[ "$announce" == "true" ]]; then
        log "$service_name PID 文件已陈旧，已自动清理"
      fi
    fi
  elif [[ -f "$pid_file" ]]; then
    rm -f "$pid_file"
    if [[ "$announce" == "true" ]]; then
      log "$service_name PID 文件内容无效，已自动清理"
    fi
  fi
}


active_pid_from_file() {
  local pid_file="$1"

  if pid="$(pid_from_file "$pid_file" 2>/dev/null)"; then
    if is_pid_running "$pid"; then
      printf '%s\n' "$pid"
      return 0
    fi
  fi

  return 1
}


http_ready() {
  local url="$1"

  "$ROOT_DIR/backend/.venv/bin/python" - "$url" <<'PY'
import sys
import urllib.request

url = sys.argv[1]

try:
  with urllib.request.urlopen(url, timeout=1) as response:
    status = getattr(response, 'status', 200)
    raise SystemExit(0 if 200 <= status < 400 else 1)
except Exception:
  raise SystemExit(1)
PY
}


wait_for_service() {
  local service_name="$1"
  local pid_file="$2"
  local health_url="$3"
  local timeout_seconds="${4:-30}"

  local elapsed=0
  while (( elapsed < timeout_seconds )); do
    if http_ready "$health_url"; then
      return 0
    fi

    if ! active_pid_from_file "$pid_file" >/dev/null 2>&1; then
      log "$service_name 在就绪前已退出，请检查日志"
      return 1
    fi

    sleep 1
    elapsed=$((elapsed + 1))
  done

  log "$service_name 在 ${timeout_seconds}s 内未就绪"
  return 1
}


start_backend() {
  : > "$BACKEND_LOG_FILE"
  (
    cd "$ROOT_DIR"
    exec setsid "$ROOT_DIR/backend/.venv/bin/uvicorn" \
      backend.app.main:app \
      --app-dir . \
      --host "$BACKEND_HOST" \
      --port "$BACKEND_PORT" \
      --reload
  ) >>"$BACKEND_LOG_FILE" 2>&1 &
  echo "$!" > "$BACKEND_PID_FILE"
}


start_frontend() {
  : > "$FRONTEND_LOG_FILE"
  (
    cd "$ROOT_DIR/frontend"
    exec setsid npm run dev -- --host "$FRONTEND_HOST" --port "$FRONTEND_PORT"
  ) >>"$FRONTEND_LOG_FILE" 2>&1 &
  echo "$!" > "$FRONTEND_PID_FILE"
}


stop_service() {
  local service_name="$1"
  local pid_file="$2"

  cleanup_stale_pid_file "$service_name" "$pid_file" false

  if ! pid="$(active_pid_from_file "$pid_file" 2>/dev/null)"; then
    log "$service_name 未运行"
    return 0
  fi

  log "停止 $service_name (PID $pid)"
  kill -TERM -- "-$pid" 2>/dev/null || kill -TERM "$pid" 2>/dev/null || true

  local attempt=0
  while (( attempt < 10 )); do
    if ! is_pid_running "$pid"; then
      rm -f "$pid_file"
      log "$service_name 已停止"
      return 0
    fi
    sleep 1
    attempt=$((attempt + 1))
  done

  log "$service_name 未在预期时间内退出，强制结束"
  kill -KILL -- "-$pid" 2>/dev/null || kill -KILL "$pid" 2>/dev/null || true
  rm -f "$pid_file"
}


show_service_status() {
  local service_name="$1"
  local pid_file="$2"
  local port="$3"
  local log_file="$4"

  if pid="$(active_pid_from_file "$pid_file" 2>/dev/null)"; then
    printf '%s: running (PID %s, port %s, log %s)\n' "$service_name" "$pid" "$port" "$log_file"
    return 0
  fi

  if [[ -f "$pid_file" ]]; then
    rm -f "$pid_file"
    printf '%s: stale PID file removed, not running\n' "$service_name"
    return 0
  fi

  printf '%s: not running\n' "$service_name"
}


start_all() {
  ensure_base_requirements
  ensure_runtime_dir

  cleanup_stale_pid_file "backend" "$BACKEND_PID_FILE"
  cleanup_stale_pid_file "frontend" "$FRONTEND_PID_FILE"

  if active_pid_from_file "$BACKEND_PID_FILE" >/dev/null 2>&1 || active_pid_from_file "$FRONTEND_PID_FILE" >/dev/null 2>&1; then
    log "检测到已有开发服务在运行，请先执行 stop 或 restart"
    show_service_status "backend" "$BACKEND_PID_FILE" "$BACKEND_PORT" "$BACKEND_LOG_FILE"
    show_service_status "frontend" "$FRONTEND_PID_FILE" "$FRONTEND_PORT" "$FRONTEND_LOG_FILE"
    return 0
  fi

  log "启动 backend..."
  start_backend
  if ! wait_for_service "backend" "$BACKEND_PID_FILE" "http://$BACKEND_HOST:$BACKEND_PORT/api/health" 30; then
    stop_service "backend" "$BACKEND_PID_FILE" >/dev/null 2>&1 || true
    fail "backend 启动失败，请查看 $BACKEND_LOG_FILE"
  fi

  log "启动 frontend..."
  start_frontend
  if ! wait_for_service "frontend" "$FRONTEND_PID_FILE" "http://$FRONTEND_HOST:$FRONTEND_PORT" 30; then
    stop_service "frontend" "$FRONTEND_PID_FILE" >/dev/null 2>&1 || true
    stop_service "backend" "$BACKEND_PID_FILE" >/dev/null 2>&1 || true
    fail "frontend 启动失败，请查看 $FRONTEND_LOG_FILE"
  fi

  log "开发环境已启动"
  show_service_status "backend" "$BACKEND_PID_FILE" "$BACKEND_PORT" "$BACKEND_LOG_FILE"
  show_service_status "frontend" "$FRONTEND_PID_FILE" "$FRONTEND_PORT" "$FRONTEND_LOG_FILE"
}


stop_all() {
  stop_service "frontend" "$FRONTEND_PID_FILE"
  stop_service "backend" "$BACKEND_PID_FILE"
}


status_all() {
  show_service_status "backend" "$BACKEND_PID_FILE" "$BACKEND_PORT" "$BACKEND_LOG_FILE"
  show_service_status "frontend" "$FRONTEND_PID_FILE" "$FRONTEND_PORT" "$FRONTEND_LOG_FILE"
}


main() {
  local command="${1:-}"

  case "$command" in
    start)
      start_all
      ;;
    stop)
      stop_all
      ;;
    restart)
      stop_all
      start_all
      ;;
    status)
      status_all
      ;;
    *)
      usage
      exit 1
      ;;
  esac
}


main "$@"