import 'dart:async';
import 'dart:typed_data';

import 'package:chat/generated/i18n.dart';
import 'package:chat/photo/entity/options.dart';
import 'package:chat/photo/provider/asset_provider.dart';
import 'package:chat/photo/provider/config_provider.dart';
import 'package:chat/photo/provider/selected_provider.dart';
import 'package:chat/photo/ui/page/photo_main_page.dart';
import 'package:flutter/material.dart';
import 'package:photo_manager/photo_manager.dart';

class PhotoPreviewPage extends StatefulWidget {
  final SelectedProvider selectedProvider;

  final List<AssetEntity> list;

  final int initIndex;

  /// 这个参数是控制在内部点击check后是否实时修改provider状态
  final bool changeProviderOnCheckChange;

  /// 是否通过预览进来的
  final bool isPreview;

  /// 这里封装了结果
  final PhotoPreviewResult result;

  final AssetProvider assetProvider;

  const PhotoPreviewPage({
    Key key,
    @required this.selectedProvider,
    @required this.list,
    @required this.changeProviderOnCheckChange,
    @required this.result,
    @required this.assetProvider,
    this.initIndex = 0,
    this.isPreview = false,
  }) : super(key: key);

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

class _PhotoPreviewPageState extends State<PhotoPreviewPage> {
  PhotoPickerProvider get config => PhotoPickerProvider.of(context);
  AssetProvider get assetProvider => widget.assetProvider;

  Options get options => config.options;

  Color get themeColor => options.themeColor;

  Color get textColor => options.textColor;

  SelectedProvider get selectedProvider => widget.selectedProvider;

  List<AssetEntity> get list {
    if (!widget.isPreview) {
      return assetProvider.data;
    }
    return widget.list;
  }

  StreamController<int> pageChangeController = StreamController.broadcast();

  Stream<int> get pageStream => pageChangeController.stream;

  bool get changeProviderOnCheckChange => widget.changeProviderOnCheckChange;

  PhotoPreviewResult get result => widget.result;

  /// 缩略图用的数据
  ///
  /// 用于与provider数据联动
  List<AssetEntity> get previewList {
    return selectedProvider.selectedList;
  }

  /// 选中的数据
  List<AssetEntity> _selectedList = [];

  List<AssetEntity> get selectedList {
    if (changeProviderOnCheckChange) {
      return previewList;
    }
    return _selectedList;
  }

  PageController pageController;

  @override
  void initState() {
    super.initState();
    pageChangeController.add(0);
    pageController = PageController(
      initialPage: widget.initIndex,
    );

    _selectedList.clear();
    _selectedList.addAll(selectedProvider.selectedList);

    result.previewSelectedList = _selectedList;
  }

  @override
  void dispose() {
    pageChangeController.close();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    int totalCount  = 0;
 
    totalCount = assetProvider.current?.assetCount ?? 0;
    if (!widget.isPreview) {
      totalCount = assetProvider.current.assetCount;
    } else {
      totalCount = list.length;
    }

    var data = Theme.of(context);
 
    return Theme(
      data: data.copyWith(
        primaryColor: options.themeColor,
      ),
      child: Scaffold(
        appBar: AppBar(
          backgroundColor: config.options.themeColor,
          leading: BackButton(
            color: options.textColor,
          ),
          centerTitle: true,
          title: StreamBuilder(
            stream: pageStream,
            initialData: widget.initIndex,
            builder: (ctx, snap) {
              return Text(
                "${snap.data + 1}/$totalCount",
                style: TextStyle(
                  color: options.textColor,
                ),
              );
            },
          ),
          actions: <Widget>[
            Container(
                width: 60,
                height: 60,
                padding: EdgeInsets.only(right: 20),
                alignment: Alignment.center,
                child: StreamBuilder<int>(
                  builder: (ctx, snapshot) {
                    var index = snapshot.data;
                    var data = list[index];
                    var checked = selectedList.contains(data);
                    return Stack(
                      alignment: Alignment.center,
                      children: <Widget>[
                        IgnorePointer(
                          child: _buildCheckboxContent(checked, index),
                        ),
                        GestureDetector(
                          onTap: () => _changeSelected(!checked, index),
                          behavior: HitTestBehavior.translucent,
                          child: Container(),
                        ),
                      ],
                    );
                  },
                  initialData: widget.initIndex,
                  stream: pageStream,
                ))
          ],
        ),
        body: PageView.builder(
          controller: pageController,
          itemBuilder: _buildItem,
          itemCount: totalCount,
          onPageChanged: _onPageChanged,
        ),
        bottomSheet: _buildThumb(),
        bottomNavigationBar: _buildBottom(),
      ),
    );
  }

  Widget _buildBottom() {
    var textStyle = TextStyle(
      color: options.textColor,
      fontSize: 14.0,
    );

    return StreamBuilder(
        stream: pageStream,
        builder: (ctx, s) => Row(
              mainAxisSize: MainAxisSize.min,
              children: <Widget>[
                Expanded(child: SizedBox()),
                InkWell(
                    onTap: selectedList.length == 0 ? null : sure,
                    child: Container(
                      padding:
                          EdgeInsets.symmetric(vertical: 5, horizontal: 15),
                      margin: EdgeInsets.symmetric(vertical: 5, horizontal: 5),
                      decoration: BoxDecoration(
                          color: selectedList.length > 0
                              ? Color(0xFF2D81FF)
                              : Color(0xFFC7C7C7),
                          borderRadius: BorderRadius.circular(8)),
                      child: Text(
                        "${I18n.of(context).determine}(${selectedList.length})",
                        style: textStyle.copyWith(color: Colors.white),
                      ),
                    )),  Expanded(child: SizedBox()),
              ],
            ));
  }

  Widget _buildCheckboxContent(bool checked, int index) {
    Widget child;
    BoxDecoration decoration;
    if (checked) {
      child = Text(
        (index + 1).toString(),
        textAlign: TextAlign.center,
        style: TextStyle(
          fontSize: 12.0,
          color: Colors.white,
        ),
      );
      decoration =
          BoxDecoration(color: Color(0xFF2D81FF), shape: BoxShape.circle);
    } else {
      child = Icon(Icons.check);
      decoration = BoxDecoration(
          shape: BoxShape.circle,
          border: Border.all(
            color: Colors.black,
          ),
          color: Colors.white);
    }
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: AnimatedContainer(
        duration: Duration(milliseconds: 300),
        decoration: decoration,
        alignment: Alignment.center,
        child: child,
      ),
    );
  }

  void _changeSelected(bool isChecked, int index) {
    if (changeProviderOnCheckChange) {
      _onChangeProvider(isChecked, index);
    } else {
      _onCheckInOnlyPreview(isChecked, index);
    }
  }

  /// 仅仅修改预览时的状态,在退出时,再更新provider的顺序,这里无论添加与否不修改顺序
  void _onCheckInOnlyPreview(bool check, int index) {
    var item = list[index];
    if (check) {
      selectedList.add(item);
    } else {
      selectedList.remove(item);
    }
    pageChangeController.add(index);
  }

  /// 直接修改预览状态,会直接移除item
  void _onChangeProvider(bool check, int index) {
    var item = list[index];
    if (check) {
      selectedProvider.addSelectEntity(item);
    } else {
      selectedProvider.removeSelectEntity(item);
    }
    pageChangeController.add(index);
  }

  Widget _buildItem(BuildContext context, int index) {
    if (!widget.isPreview && index >= list.length - 5) {
      _loadMore();
    }

    var data = list[index];
    return BigPhotoImage(
      assetEntity: data,
      loadingWidget: _buildLoadingWidget(data),
    );
  }

  Future<void> _loadMore() async {
    assetProvider.loadMore();
  }

  Widget _buildLoadingWidget(AssetEntity entity) {
    return options.loadingDelegate
        .buildBigImageLoading(context, entity, themeColor);
  }

  void _onPageChanged(int value) {
    pageChangeController.add(value);
  }

  Widget _buildThumb() {
    return Container(
      height: 80.0,
      color: Color(0xFFF0F0F0),
      child: ListView.builder(
        padding: EdgeInsets.symmetric(horizontal: 10, vertical: 5),
        itemBuilder: _buildThumbItem,
        itemCount: previewList.length,
        scrollDirection: Axis.horizontal,
      ),
    );
  }

  Widget _buildThumbItem(BuildContext context, int index) {
    var item = previewList[index];

    return StreamBuilder<int>(
      initialData: widget.initIndex,
      builder: (ctx, snapshot) => RepaintBoundary(
        child: GestureDetector(
            onTap: () => changeSelected(item, index),
            child: Container(
              width: 80.0,
              child: Container(
                margin: EdgeInsets.all(10),
                decoration: BoxDecoration(
                    border: snapshot.data == index
                        ? Border.all(color: Colors.blue, width: 2)
                        : null),
                child: Stack(
                  children: <Widget>[
                    ImageItem(
                      themeColor: themeColor,
                      entity: item,
                      size: options.thumbSize,
                      loadingDelegate: options.loadingDelegate,
                    ),
                    IgnorePointer(
                        child: selectedList.contains(item)
                            ? Container()
                            : Container(
                                color: Colors.white.withOpacity(0.5),
                              )),
                  ],
                ),
              ),
            )),
      ),
      stream: pageStream,
    );
  }

  void changeSelected(AssetEntity entity, int index) {
    var itemIndex = list.indexOf(entity);
    if (itemIndex != -1) pageController.jumpToPage(itemIndex);
  }

  void sure() {
    Navigator.pop(context, selectedList);
  }
}

class BigPhotoImage extends StatefulWidget {
  final AssetEntity assetEntity;
  final Widget loadingWidget;

  const BigPhotoImage({
    Key key,
    this.assetEntity,
    this.loadingWidget,
  }) : super(key: key);

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

class _BigPhotoImageState extends State<BigPhotoImage>
    with AutomaticKeepAliveClientMixin {
  Widget get loadingWidget {
    return widget.loadingWidget ?? Container();
  }

  @override
  Widget build(BuildContext context) {
    super.build(context);
    var width = MediaQuery.of(context).size.width;
    var height = MediaQuery.of(context).size.height;
    return FutureBuilder(
      future:
          widget.assetEntity.thumbDataWithSize(width.floor(), height.floor()),
      builder: (BuildContext context, AsyncSnapshot<Uint8List> snapshot) {
        var file = snapshot.data;
        if (snapshot.connectionState == ConnectionState.done && file != null) {
          print(file.length);
          return Image.memory(
            file,
            fit: BoxFit.contain,
            width: double.infinity,
            height: double.infinity,
          );
        }
        return loadingWidget;
      },
    );
  }

  @override
  bool get wantKeepAlive => true;
}

class PhotoPreviewResult {
  List<AssetEntity> previewSelectedList = [];
}