import 'dart:async';
import 'dart:io';
import 'dart:math' as math;
import 'package:flutter/material.dart';
import 'package:pdfx/pdfx.dart';
import 'package:path_provider/path_provider.dart';
import 'package:qhd_prevention/customWidget/toast_util.dart';
import 'package:qhd_prevention/pages/my_appbar.dart';
import 'package:qhd_prevention/customWidget/custom_button.dart';
import 'package:dio/dio.dart';
import 'package:qhd_prevention/tools/tools.dart';

class RemoteFilePage extends StatefulWidget {
  final String fileUrl;
  final int countdownSeconds;

  const RemoteFilePage({
    Key? key,
    required this.fileUrl,
    this.countdownSeconds = 3,
  }) : super(key: key);

  @override
  _RemoteFilePageState createState() => _RemoteFilePageState();
}

class _RemoteFilePageState extends State<RemoteFilePage> {
  String? _localPath;
  bool _isLoading = true;
  bool _hasScrolledToBottom = false;
  bool _timerFinished = false;
  late int _secondsRemaining;
  Timer? _countdownTimer;
  PdfControllerPinch? _pdfController;
  int _totalPages = 0;

  // ========== 新增用于方案1的字段 ==========
  Size? _viewportSize; // 当前 viewport 大小，用于计算 scale
  final List<double> _pageTopOffsets = []; // 每页顶部偏移（相对于内容起点）
  double _totalContentHeight = 0; // 计算得到的滚动内容总高度
  double _pageSpacing = 0.0; // 如果你在 PdfViewPinch 布局里有页间距，可设置
  // ======================================

  @override
  void initState() {
    super.initState();
    _secondsRemaining = widget.countdownSeconds;
    _startCountdown();
    _downloadAndLoad();
    LoadingDialogHelper.hide();
  }

  Future<void> _downloadAndLoad() async {
    try {
      final url = widget.fileUrl;
      final filename = url.split('/').last;
      final dir = await getTemporaryDirectory();
      final filePath = '${dir.path}/$filename';

      final dio = Dio();
      final response = await dio.get<List<int>>(
        url,
        options: Options(responseType: ResponseType.bytes),
      );

      final file = File(filePath);
      await file.writeAsBytes(response.data!);

      // 直接传 Future<PdfDocument> 给 controller（不要 await）
      final futureDoc = PdfDocument.openFile(filePath); // Future<PdfDocument>
      _pdfController = PdfControllerPinch(document: futureDoc);

      // 注册 pageListenable listener（pageListenable 是 ValueListenable<int>，1-based）
      _pdfController!.pageListenable.addListener(_onPageListenableChanged);

      if (!mounted) return;
      setState(() {
        _localPath = filePath;
        _isLoading = false;
      });
    } catch (e) {
      if (mounted) {
        setState(() {
          _isLoading = false;
        });
        ToastUtil.showNormal(context, '文件加载失败: $e');
      }
    }
  }

  void _onPageListenableChanged() {
    // pageListenable.value 是当前页（1-based）
    final controller = _pdfController;
    if (controller == null) return;
    final currentPage = controller.pageListenable.value;
    // 如果 totalPages 已知且到达最后一页，则标记为已看完
    if (_totalPages > 0 && currentPage >= _totalPages - 3) {
      if (!_hasScrolledToBottom && mounted) {
        setState(() {
          _hasScrolledToBottom = true;
        });
      }
    }
  }

  void _startCountdown() {
    _countdownTimer = Timer.periodic(const Duration(seconds: 1), (timer) {
      if (!mounted) return;
      setState(() {
        if (_secondsRemaining > 1) {
          _secondsRemaining--;
        } else {
          _secondsRemaining = 0;
          _timerFinished = true;
          _countdownTimer?.cancel();
        }
      });
    });
  }

  @override
  void dispose() {
    _countdownTimer?.cancel();
    // 移除 listener 再释放 controller（注意 controller 和其 listenable 可能为 null）
    try {
      if (_pdfController != null) {
        _pdfController!.pageListenable.removeListener(_onPageListenableChanged);
        _pdfController!.dispose();
      }
    } catch (e) {
      // ignore dispose errors
    }
    super.dispose();
  }

  // 当滚动通知到达底部（或接近底部）时调用 — 作为备选方案/调试用
  bool _handleScrollNotification(ScrollNotification notification) {
    final metrics = notification.metrics;

    // 优先使用我们计算的 totalContentHeight + viewport 判断（更准确）
    if (_totalContentHeight > 0 && _viewportSize != null) {
      final viewportH = _viewportSize!.height;
      final threshold = math.min(50.0, viewportH * 0.1); // 灵活阈值
      final scrolledToBottom = (metrics.pixels + viewportH) >= (_totalContentHeight - threshold);

      if (scrolledToBottom) {
        if (!_hasScrolledToBottom && mounted) {
          setState(() {
            _hasScrolledToBottom = true;
          });
        }
      }
    } else {
      // 兜底：使用 maxScrollExtent 判断（保留你原来的逻辑）
      if ((metrics.maxScrollExtent - metrics.pixels) <= 5.0 ||
          (metrics.atEdge && metrics.pixels == metrics.maxScrollExtent)) {
        if (!_hasScrolledToBottom && mounted) {
          setState(() {
            _hasScrolledToBottom = true;
          });
        }
      }
    }
    return false; // 让事件继续传递
  }

  @override
  Widget build(BuildContext context) {
    final isButtonEnabled = _timerFinished && _hasScrolledToBottom;
    return Scaffold(
      appBar: MyAppbar(title: '资料学习'),
      backgroundColor: Colors.white,
      body: SafeArea(
        child: Column(
          children: [
            Expanded(
              child: _isLoading
                  ? const Center(child: CircularProgressIndicator())
                  : LayoutBuilder(builder: (context, constraints) {
                // 保存 viewport size（用于计算 scale）
                _viewportSize = Size(constraints.maxWidth, constraints.maxHeight);

                return NotificationListener<ScrollNotification>(
                  onNotification: _handleScrollNotification,
                  child: PdfViewPinch(
                    controller: _pdfController!,
                    scrollDirection: Axis.vertical,
                    onDocumentLoaded: (document) async {
                      // 原有行为：保存页数
                      _totalPages = document.pagesCount;

                      // ======= 新增：计算每页渲染高度并累加 totalContentHeight =======
                      // 注意：document.getPage(i) 后要 close()
                      try {
                        final viewportW = _viewportSize?.width ?? MediaQuery.of(context).size.width;
                        final viewportH = _viewportSize?.height ?? MediaQuery.of(context).size.height;

                        _pageTopOffsets.clear();
                        double acc = 0;
                        for (int i = 1; i <= _totalPages; i++) {
                          final page = await document.getPage(i);
                          // page.width / page.height 可能是 num/double
                          final pw = (page.width is num) ? (page.width as num).toDouble() : page.width.toDouble();
                          final ph = (page.height is num) ? (page.height as num).toDouble() : page.height.toDouble();

                          // 模拟 contained 缩放行为：scale = min(viewportW / pw, viewportH / ph)
                          final scale = math.min(viewportW / pw, viewportH / ph);
                          final renderedH = ph * scale;

                          _pageTopOffsets.add(acc);
                          acc += renderedH + _pageSpacing;

                          await page.close();
                        }
                        _totalContentHeight = acc;
                      } catch (e) {
                        // 计算失败则保留 _totalContentHeight 为 0，使用兜底判断
                        _totalContentHeight = 0;
                      }
                      // ==============================================================

                      // 保留你原来：如果页少，直接视为已看完
                      if (_totalPages <= 3) {
                        if (!_hasScrolledToBottom && mounted) {
                          setState(() => _hasScrolledToBottom = true);
                        }
                      }

                      if (mounted) setState(() {});
                    },
                    // 作为兜底：当 page 到最后一页时也标记为已看完（注意 page 是 1-based）
                    onPageChanged: (page) {
                      if (_totalPages > 0 && page == _totalPages) {
                        if (!_hasScrolledToBottom && mounted) {
                          setState(() => _hasScrolledToBottom = true);
                        }
                      }
                    },
                  ),
                );
              }),
            ),
            Padding(
              padding: const EdgeInsets.all(16),
              child: CustomButton(
                backgroundColor: isButtonEnabled ? Colors.blue : Colors.grey,
                text: isButtonEnabled
                    ? '我已学习完毕'
                    : _secondsRemaining == 0 ? '我已学习完毕' : '（$_secondsRemaining s）我已学习完毕',
                onPressed: isButtonEnabled
                    ? () {
                  Navigator.pop(context, true);
                }
                    : null,
              ),
            ),
          ],
        ),
      ),
    );
  }
}