import 'package:oktoast/oktoast.dart' as ok;

import 'debug_log.dart';

/// Toast 位置
enum ToastGravity { top, center, bottom }

const _duration = Duration(seconds: 2);

/// Toast 队列：一条消失后回调里再弹下一条（时序由 oktoast 精确控制）
final _queue = <_ToastItem>[];
bool _isShowing = false;

class _ToastItem {
  final String message;
  final ToastGravity gravity;
  _ToastItem(this.message, this.gravity);
}

/// 显示 Toast 消息（连续调用会排队，一条消失后再弹下一条）
void showToast(String message, {ToastGravity? gravity}) {
  if (message.isEmpty) return;
  // 相邻重复的直接忽略，避免同一句刷屏
  if (_queue.isNotEmpty && _queue.last.message == message) return;
  _queue.add(_ToastItem(message, gravity ?? ToastGravity.center));
  _drain();
}

void _drain() {
  if (_isShowing || _queue.isEmpty) return;
  _isShowing = true;
  final item = _queue.removeAt(0);

  var done = false;
  void next() {
    if (done) return;
    done = true;
    _isShowing = false;
    _drain();
  }

  try {
    ok.showToast(
      item.message,
      duration: _duration,
      position: switch (item.gravity) {
        ToastGravity.top => ok.ToastPosition.top,
        ToastGravity.bottom => ok.ToastPosition.bottom,
        ToastGravity.center => ok.ToastPosition.center,
      },
      onDismiss: next,
    );
  } catch (e) {
    // OKToast 未挂载(启动早期)时 oktoast 直接抛错，不兜住的话 _isShowing 永久为 true → 全 App toast 静默失效
    debugLog("showToast()...error:$e");
    _queue.clear();
    _isShowing = false;
    return;
  }
  // 兜底：toast 被提前 dismiss 或 overlay 已销毁时 oktoast 不回调 onDismiss，超时自愈
  Future.delayed(_duration + const Duration(milliseconds: 500), next);
}