import 'dart:async';

import 'package:flutter/material.dart';
import 'package:venera/components/components.dart';
import 'package:venera/foundation/app.dart';
import 'package:venera/foundation/appdata.dart';
import 'package:venera/foundation/favorites.dart';
import 'package:venera/foundation/log.dart';
import 'package:venera/utils/data_sync.dart';
import 'package:venera/utils/translations.dart';
import '../foundation/global_state.dart';

class FollowUpdatesWidget extends StatefulWidget {
  const FollowUpdatesWidget({super.key});

  @override
  State<FollowUpdatesWidget> createState() => _FollowUpdatesWidgetState();
}

class _FollowUpdatesWidgetState
    extends AutomaticGlobalState<FollowUpdatesWidget> {
  int _count = 0;

  String? get folder => appdata.settings["followUpdatesFolder"];

  void getCount() {
    if (folder == null) {
      _count = 0;
      return;
    }
    if (!LocalFavoritesManager().folderNames.contains(folder)) {
      _count = 0;
      appdata.settings["followUpdatesFolder"] = null;
      Future.microtask(() {
        appdata.saveData();
      });
    } else {
      _count = LocalFavoritesManager().countUpdates(folder!);
    }
  }

  void updateCount() {
    setState(() {
      getCount();
    });
  }

  @override
  void initState() {
    super.initState();
    getCount();
  }

  @override
  Widget build(BuildContext context) {
    return SliverToBoxAdapter(
      child: Container(
        margin: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
        decoration: BoxDecoration(
          border: Border.all(
            color: Theme.of(context).colorScheme.outlineVariant,
            width: 0.6,
          ),
          borderRadius: BorderRadius.circular(8),
        ),
        child: InkWell(
          borderRadius: BorderRadius.circular(8),
          onTap: () {
            context.to(() => FollowUpdatesPage());
          },
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              SizedBox(
                height: 56,
                child: Row(
                  children: [
                    Center(
                      child: Text('Follow Updates'.tl, style: ts.s18),
                    ),
                    const Spacer(),
                    const Icon(Icons.arrow_right),
                  ],
                ),
              ).paddingHorizontal(16),
              if (_count > 0)
                Container(
                  padding:
                      const EdgeInsets.symmetric(horizontal: 16, vertical: 2),
                  margin: const EdgeInsets.only(bottom: 16, left: 16),
                  decoration: BoxDecoration(
                    borderRadius: BorderRadius.circular(8),
                    color: Theme.of(context).colorScheme.primaryContainer,
                  ),
                  child: Text(
                    '@c updates'.tlParams({
                      'c': _count,
                    }),
                    style: ts.s16,
                  ),
                ),
            ],
          ),
        ),
      ),
    );
  }

  @override
  Object? get key => 'FollowUpdatesWidget';
}

class FollowUpdatesPage extends StatefulWidget {
  const FollowUpdatesPage({super.key});

  @override
  State<FollowUpdatesPage> createState() => _FollowUpdatesPageState();
}

class _FollowUpdatesPageState extends AutomaticGlobalState<FollowUpdatesPage> {
  String? get folder => appdata.settings["followUpdatesFolder"];

  var updatedComics = <FavoriteItemWithUpdateInfo>[];
  var allComics = <FavoriteItemWithUpdateInfo>[];

  /// Sort comics by update time in descending order with nulls at the end.
  void sortComics() {
    allComics.sort((a, b) {
      if (a.updateTime == null && b.updateTime == null) {
        return 0;
      } else if (a.updateTime == null) {
        return -1;
      } else if (b.updateTime == null) {
        return 1;
      }
      try {
        var aNums = a.updateTime!.split('-').map(int.parse).toList();
        var bNums = b.updateTime!.split('-').map(int.parse).toList();
        for (int i = 0; i < aNums.length; i++) {
          if (aNums[i] != bNums[i]) {
            return bNums[i] - aNums[i];
          }
        }
        return 0;
      } catch (_) {
        return 0;
      }
    });
  }

  @override
  void initState() {
    super.initState();
    if (folder != null) {
      allComics = LocalFavoritesManager().getComicsWithUpdatesInfo(folder!);
      sortComics();
      updatedComics = allComics.where((c) => c.hasNewUpdate).toList();
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SmoothCustomScrollView(
        slivers: [
          SliverAppbar(title: Text('Follow Updates'.tl)),
          if (folder == null)
            buildNotConfigured(context)
          else
            buildConfigured(context),
          SliverPadding(padding: const EdgeInsets.only(top: 8)),
          buildUpdatedComics(),
          buildAllComics(),
        ],
      ),
    );
  }

  Widget buildNotConfigured(BuildContext context) {
    return SliverToBoxAdapter(
      child: Container(
        margin: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
        decoration: BoxDecoration(
          border: Border.all(
            color: Theme.of(context).colorScheme.outlineVariant,
            width: 0.6,
          ),
          borderRadius: BorderRadius.circular(8),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            ListTile(
              leading: Icon(Icons.info_outline),
              title: Text("Not Configured".tl),
            ),
            Text(
              "Choose a folder to follow updates.".tl,
              style: ts.s16,
            ).paddingHorizontal(16),
            const SizedBox(height: 8),
            FilledButton.tonal(
              onPressed: showSelector,
              child: Text("Choose Folder".tl),
            ).paddingHorizontal(16).toAlign(Alignment.centerRight),
            const SizedBox(height: 16),
          ],
        ),
      ),
    );
  }

  Widget buildConfigured(BuildContext context) {
    return SliverToBoxAdapter(
      child: Container(
        margin: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
        decoration: BoxDecoration(
          border: Border.all(
            color: Theme.of(context).colorScheme.outlineVariant,
            width: 0.6,
          ),
          borderRadius: BorderRadius.circular(8),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            ListTile(
              leading: Icon(Icons.stars_outlined),
              title: Text(folder!),
            ),
            Text(
              "Automatic update checking enabled.".tl,
              style: ts.s14,
            ).paddingHorizontal(16),
            Text(
              "The app will check for updates at most once a day.".tl,
              style: ts.s14,
            ).paddingHorizontal(16),
            const SizedBox(height: 8),
            Row(
              mainAxisAlignment: MainAxisAlignment.end,
              children: [
                TextButton(
                  onPressed: showSelector,
                  child: Text("Change Folder".tl),
                ),
                FilledButton.tonal(
                  onPressed: checkNow,
                  child: Text("Check Now".tl),
                ),
                const SizedBox(width: 16),
              ],
            ),
            const SizedBox(height: 16),
          ],
        ),
      ),
    );
  }

  Widget buildUpdatedComics() {
    return SliverMainAxisGroup(
      slivers: [
        SliverToBoxAdapter(
          child: Container(
            margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
            padding: const EdgeInsets.symmetric(vertical: 4),
            decoration: BoxDecoration(
              border: Border(
                bottom: BorderSide(
                  color: Theme.of(context).colorScheme.outlineVariant,
                  width: 0.6,
                ),
              ),
            ),
            child: Row(
              children: [
                Icon(Icons.update),
                const SizedBox(width: 8),
                Text(
                  "Updates".tl,
                  style: ts.s18,
                ),
                const Spacer(),
                if (updatedComics.isNotEmpty)
                  IconButton(
                    icon: Icon(Icons.clear_all),
                    onPressed: () {
                      showConfirmDialog(
                        context: App.rootContext,
                        title: "Mark all as read".tl,
                        content: "Do you want to mark all as read?".tl,
                        onConfirm: () {
                          for (var comic in updatedComics) {
                            LocalFavoritesManager().markAsRead(
                              comic.id,
                              comic.type,
                            );
                          }
                          updateFollowUpdatesUI();
                        },
                      );
                    },
                  ),
              ],
            ),
          ),
        ),
        if (updatedComics.isNotEmpty)
          SliverToBoxAdapter(
            child: Text(
                    "The comic will be marked as no updates as soon as you read it."
                        .tl)
                .paddingHorizontal(16)
                .paddingVertical(4),
          ),
        if (updatedComics.isNotEmpty)
          SliverGridComics(comics: updatedComics)
        else
          SliverToBoxAdapter(
            child: Row(
              children: [
                Container(
                  margin:
                      const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
                  padding:
                      const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
                  decoration: BoxDecoration(
                    color: Theme.of(context).colorScheme.surfaceContainerLow,
                    borderRadius: BorderRadius.circular(16),
                  ),
                  child: Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Text(
                        "No updates found".tl,
                        style: ts.s16,
                      ),
                    ],
                  ),
                )
              ],
            ),
          ),
      ],
    );
  }

  Widget buildAllComics() {
    return SliverMainAxisGroup(
      slivers: [
        SliverToBoxAdapter(
          child: Container(
            margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
            padding: const EdgeInsets.symmetric(vertical: 4),
            decoration: BoxDecoration(
              border: Border(
                bottom: BorderSide(
                  color: Theme.of(context).colorScheme.outlineVariant,
                  width: 0.6,
                ),
              ),
            ),
            child: Row(
              children: [
                Icon(Icons.list),
                const SizedBox(width: 8),
                Text(
                  "All Comics".tl,
                  style: ts.s18,
                ),
              ],
            ),
          ),
        ),
        SliverGridComics(comics: allComics),
      ],
    );
  }

  void showSelector() {
    var folders = LocalFavoritesManager().folderNames;
    if (folders.isEmpty) {
      context.showMessage(message: "No folders available".tl);
      return;
    }
    String? selectedFolder;
    showDialog(
      context: App.rootContext,
      builder: (context) {
        return StatefulBuilder(builder: (context, setState) {
          return ContentDialog(
            title: "Choose Folder".tl,
            content: Column(
              children: [
                ListTile(
                  title: Text("Folder".tl),
                  trailing: Select(
                    minWidth: 120,
                    current: selectedFolder,
                    values: folders,
                    onTap: (i) {
                      setState(() {
                        selectedFolder = folders[i];
                      });
                    },
                  ),
                ),
              ],
            ),
            actions: [
              if (appdata.settings["followUpdatesFolder"] != null)
                TextButton(
                  onPressed: () {
                    disable();
                    context.pop();
                  },
                  child: Text("Disable".tl),
                ),
              FilledButton(
                onPressed: selectedFolder == null
                    ? null
                    : () {
                        context.pop();
                        setFolder(selectedFolder!);
                      },
                child: Text("Confirm".tl),
              ),
            ],
          );
        });
      },
    );
  }

  void disable() {
    appdata.settings["followUpdatesFolder"] = null;
    appdata.saveData();
    updateFollowUpdatesUI();
  }

  void setFolder(String folder) async {
    FollowUpdatesService._cancelChecking?.call();
    LocalFavoritesManager().prepareTableForFollowUpdates(folder);

    var count = LocalFavoritesManager().count(folder);

    if (count > 0) {
      bool isCanceled = false;
      void onCancel() {
        isCanceled = true;
      }

      var loadingController = showLoadingDialog(
        App.rootContext,
        withProgress: true,
        cancelButtonText: "Cancel".tl,
        onCancel: onCancel,
        message: "Updating comics...".tl,
      );

      await for (var progress in _updateFolder(folder, true)) {
        if (isCanceled) {
          return;
        }
        loadingController.setProgress(progress.current / progress.total);
      }

      loadingController.close();
    }

    setState(() {
      appdata.settings["followUpdatesFolder"] = folder;
      updatedComics = [];
      allComics = LocalFavoritesManager().getComicsWithUpdatesInfo(folder);
      sortComics();
    });
    appdata.saveData();
  }

  void checkNow() async {
    FollowUpdatesService._cancelChecking?.call();

    bool isCanceled = false;
    void onCancel() {
      isCanceled = true;
    }

    var loadingController = showLoadingDialog(
      App.rootContext,
      withProgress: true,
      cancelButtonText: "Cancel".tl,
      onCancel: onCancel,
      message: "Updating comics...".tl,
    );

    int updated = 0;

    await for (var progress in _updateFolder(folder!, true)) {
      if (isCanceled) {
        return;
      }
      loadingController.setProgress(progress.current / progress.total);
      updated = progress.updated;
    }

    loadingController.close();

    if (updated > 0) {
      GlobalState.findOrNull<_FollowUpdatesWidgetState>()?.updateCount();
      updateComics();
    }
  }

  void updateComics() {
    if (folder == null) {
      setState(() {
        allComics = [];
        updatedComics = [];
      });
      return;
    }
    setState(() {
      allComics = LocalFavoritesManager().getComicsWithUpdatesInfo(folder!);
      sortComics();
      updatedComics = allComics.where((c) => c.hasNewUpdate).toList();
    });
  }

  @override
  Object? get key => 'FollowUpdatesPage';
}

class _UpdateProgress {
  final int total;
  final int current;
  final int errors;
  final int updated;

  _UpdateProgress(this.total, this.current, this.errors, this.updated);
}

void _updateFolderBase(
  String folder,
  StreamController<_UpdateProgress> stream,
  bool ignoreCheckTime,
) async {
  var comics = LocalFavoritesManager().getComicsWithUpdatesInfo(folder);
  int current = 0;
  int errors = 0;
  int updated = 0;
  var futures = <Future>[];
  const maxConcurrent = 5;

  for (int i = 0; i < comics.length; i++) {
    if (stream.isClosed) {
      return;
    }
    if (!ignoreCheckTime) {
      var lastCheckTime = comics[i].lastCheckTime;
      if (lastCheckTime != null &&
          DateTime.now().difference(lastCheckTime).inDays < 1) {
        current++;
        stream.add(_UpdateProgress(comics.length, current, errors, updated));
        continue;
      }
    }

    if (futures.length >= maxConcurrent) {
      await Future.any(futures);
    }

    var future = () async {
      int retries = 3;
      while (true) {
        try {
          var c = comics[i];
          var comicSource = c.type.comicSource;
          if (comicSource == null) return;
          var newInfo = (await comicSource.loadComicInfo!(c.id)).data;

          var newTags = <String>[];
          for (var entry in newInfo.tags.entries) {
            const shouldIgnore = ['author', 'artist', 'time'];
            var namespace = entry.key;
            if (shouldIgnore.contains(namespace.toLowerCase())) {
              continue;
            }
            for (var tag in entry.value) {
              newTags.add("$namespace:$tag");
            }
          }

          var item = FavoriteItem(
            id: c.id,
            name: newInfo.title,
            coverPath: newInfo.cover,
            author: newInfo.subTitle ??
                newInfo.tags['author']?.firstOrNull ??
                c.author,
            type: c.type,
            tags: newTags,
          );

          LocalFavoritesManager().updateInfo(folder, item);

          var updateTime = newInfo.findUpdateTime();
          if (updateTime != null && updateTime != c.updateTime) {
            LocalFavoritesManager().updateUpdateTime(
              folder,
              c.id,
              c.type,
              updateTime,
            );
          }
          updated++;
          return;
        } catch (e, s) {
          Log.error("Check Updates", e, s);
          retries--;
          if (retries == 0) {
            errors++;
            return;
          }
        } finally {
          current++;
          stream.add(_UpdateProgress(comics.length, current, errors, updated));
        }
      }
    }();

    future.then((_) {
      futures.remove(future);
    });

    futures.add(future);
  }

  await Future.wait(futures);

  stream.close();
}

Stream<_UpdateProgress> _updateFolder(String folder, bool ignoreCheckTime) {
  var stream = StreamController<_UpdateProgress>();
  _updateFolderBase(folder, stream, ignoreCheckTime);
  return stream.stream;
}

/// Background service for checking updates
abstract class FollowUpdatesService {
  static bool _isChecking = false;

  static void Function()? _cancelChecking;

  static bool _isInitialized = false;

  static void _check() async {
    if (_isChecking) {
      return;
    }
    var folder = appdata.settings["followUpdatesFolder"];
    if (folder == null) {
      return;
    }
    bool isCanceled = false;
    _cancelChecking = () {
      isCanceled = true;
    };

    _isChecking = true;

    while (DataSync().isDownloading) {
      await Future.delayed(const Duration(milliseconds: 100));
    }

    int updated = 0;
    try {
      await for (var progress in _updateFolder(folder, false)) {
        if (isCanceled) {
          return;
        }
        updated = progress.updated;
      }
    } finally {
      _cancelChecking = null;
      _isChecking = false;
      if (updated > 0) {
        updateFollowUpdatesUI();
      }
    }
  }

  /// Initialize the checker.
  static void initChecker() {
    if (_isInitialized) return;
    _isInitialized = true;
    _check();
    // A short interval will not affect the performance since every comic has a check time.
    Timer.periodic(const Duration(minutes: 5), (timer) {
      _check();
    });
  }
}

/// Update the UI of follow updates.
void updateFollowUpdatesUI() {
  GlobalState.findOrNull<_FollowUpdatesWidgetState>()?.updateCount();
  GlobalState.findOrNull<_FollowUpdatesPageState>()?.updateComics();
}