import "dart:async";

import "package:flutter/foundation.dart";
import "package:flutter/material.dart";
import "package:logging/logging.dart";
import "package:photos/core/constants.dart";
import "package:photos/core/event_bus.dart";
import "package:photos/events/files_updated_event.dart";
import "package:photos/events/people_changed_event.dart";
import "package:photos/events/tab_changed_event.dart";
import "package:photos/models/search/search_result.dart";
import "package:photos/models/search/search_types.dart";
import "package:photos/utils/standalone/debouncer.dart";

class AllSectionsExamplesProvider extends StatefulWidget {
  final Widget child;
  const AllSectionsExamplesProvider({super.key, required this.child});

  @override
  State<AllSectionsExamplesProvider> createState() =>
      _AllSectionsExamplesProviderState();
}

class _AllSectionsExamplesProviderState
    extends State<AllSectionsExamplesProvider> {
  //Some section results in [allSectionsExamplesFuture] can be out of sync
  //with what is displayed on UI. This happens when some section is
  //independently listening to some set of events and is rebuilt. Sections
  //can listen to a list of events and rebuild (see sectionUpdateEvents()
  //in search_types.dart) and new results will not reflect in
  //[allSectionsExamplesFuture] unless reloadAllSections() is called.
  Future<List<List<SearchResult>>> allSectionsExamplesFuture = Future.value([]);

  late StreamSubscription<FilesUpdatedEvent> _filesUpdatedEvent;
  late StreamSubscription<PeopleChangedEvent> _onPeopleChangedEvent;
  late StreamSubscription<TabChangedEvent> _tabChangeEvent;
  bool hasPendingUpdate = false;
  bool isOnSearchTab = false;
  bool _firstLoadInProgressOrComplete = false;
  final _logger = Logger("AllSectionsExamplesProvider");

  final _debouncer = Debouncer(
    const Duration(seconds: 3),
    executionInterval: const Duration(seconds: 12),
    leading: true,
  );

  @override
  void initState() {
    super.initState();
    //add all common events for all search sections to reload to here.
    _filesUpdatedEvent = Bus.instance.on<FilesUpdatedEvent>().listen((event) {
      onDataUpdate();
    });
    _onPeopleChangedEvent =
        Bus.instance.on<PeopleChangedEvent>().listen((event) {
      onDataUpdate();
    });
    _tabChangeEvent = Bus.instance.on<TabChangedEvent>().listen((event) {
      if (event.source == TabChangedEventSource.pageView &&
          event.selectedIndex == 3) {
        isOnSearchTab = true;
        if (hasPendingUpdate) {
          hasPendingUpdate = false;
          reloadAllSections();
        }
      } else {
        isOnSearchTab = false;
      }
    });

    Future.delayed(const Duration(seconds: 3), () {
      if (!_firstLoadInProgressOrComplete) {
        reloadAllSections();
      }
    });
  }

  void onDataUpdate() {
    if (!isOnSearchTab) {
      if (kDebugMode) {
        _logger.finest('Skip reload till user clicks on search tab');
      }
      hasPendingUpdate = true;
    } else {
      hasPendingUpdate = false;
      reloadAllSections();
    }
  }

  void reloadAllSections() {
    _firstLoadInProgressOrComplete = true;
    _logger.info('queue reload all sections');
    _debouncer.run(() async {
      setState(() {
        _logger.info("'_debounceTimer: reloading all sections in search tab");
        final allSectionsExamples = <Future<List<SearchResult>>>[];
        for (SectionType sectionType in SectionType.values) {
          allSectionsExamples.add(
            sectionType.getData(context, limit: kSearchSectionLimit),
          );
        }
        try {
          allSectionsExamplesFuture = Future.wait<List<SearchResult>>(
            allSectionsExamples,
            eagerError: false,
          );
        } catch (e) {
          _logger.severe("Error reloading all sections: $e");
        }
      });
    });
  }

  @override
  void dispose() {
    _onPeopleChangedEvent.cancel();
    _filesUpdatedEvent.cancel();
    _tabChangeEvent.cancel();
    _debouncer.cancelDebounceTimer();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return InheritedAllSectionsExamples(
      allSectionsExamplesFuture,
      _debouncer.debounceActiveNotifier,
      child: widget.child,
    );
  }
}

class InheritedAllSectionsExamples extends InheritedWidget {
  final Future<List<List<SearchResult>>> allSectionsExamplesFuture;
  final ValueNotifier<bool> isDebouncingNotifier;
  const InheritedAllSectionsExamples(
    this.allSectionsExamplesFuture,
    this.isDebouncingNotifier, {
    super.key,
    required super.child,
  });

  static InheritedAllSectionsExamples of(BuildContext context) {
    return context
        .dependOnInheritedWidgetOfExactType<InheritedAllSectionsExamples>()!;
  }

  @override
  bool updateShouldNotify(covariant InheritedAllSectionsExamples oldWidget) {
    return !identical(
      oldWidget.allSectionsExamplesFuture,
      allSectionsExamplesFuture,
    );
  }
}