Aves_mio0.88/lib/widgets/common/grid/item_tracker.dart

import 'dart:async';
import 'dart:math';
import 'dart:ui' show FlutterView;

import 'package:aves/model/highlight.dart';
import 'package:aves/theme/durations.dart';
import 'package:aves/widgets/common/grid/sections/list_layout.dart';
import 'package:aves_model/aves_model.dart';
import 'package:collection/collection.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

class GridItemTracker<T> extends StatefulWidget {
  final GlobalKey scrollableKey;
  final ValueNotifier<double> appBarHeightNotifier;
  final TileLayout tileLayout;
  final ScrollController scrollController;
  final Widget child;

  const GridItemTracker({
    super.key,
    required this.scrollableKey,
    required this.appBarHeightNotifier,
    required this.tileLayout,
    required this.scrollController,
    required this.child,
  });

  @override
  State<GridItemTracker<T>> createState() => _GridItemTrackerState<T>();
}

class _GridItemTrackerState<T> extends State<GridItemTracker<T>> with WidgetsBindingObserver {
  ValueNotifier<double> get appBarHeightNotifier => widget.appBarHeightNotifier;

  ScrollController get scrollController => widget.scrollController;

  final Set<StreamSubscription> _subscriptions = {};

  FlutterView? _view;
  ModalRoute<dynamic>? _route;
  HighlightInfo? _highlightInfo;
  SectionedListLayout<T>? _sectionedListLayout;

  bool _disposed = false;
  bool _hasSavedLayoutMetrics = false;

  late SectionedListLayout<T> _lastSectionedListLayout;
  late Size _lastScrollableSize;
  Orientation _lastOrientation = Orientation.portrait;

  @override
  Widget build(BuildContext context) {
    return widget.child;
  }

  Size? get scrollableSize {
    final scrollableContext = widget.scrollableKey.currentContext;
    if (scrollableContext == null) return null;

    try {
      final renderObject = scrollableContext.findRenderObject();
      if (renderObject is! RenderBox) return null;
      if (!renderObject.hasSize) return null;

      return renderObject.size;
    } catch (e, st) {
      debugPrint('GridItemTracker scrollableSize ignored: $e');
      debugPrint('$st');
      return null;
    }
  }

  bool get _canUseTracker {
    if (_disposed || !mounted) return false;

    final route = _route;
    if (route != null && !route.isCurrent) return false;

    return true;
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();

    _view = View.maybeOf(context);
    _route = ModalRoute.of(context);

    try {
      final highlightInfo = Provider.of<HighlightInfo>(
        context,
        listen: false,
      );

      if (!identical(_highlightInfo, highlightInfo)) {
        _subscriptions
          ..forEach((sub) => sub.cancel())
          ..clear();

        _highlightInfo = highlightInfo;
        _subscriptions.add(
          highlightInfo.eventBus.on<TrackEvent<T>>().listen(_trackItem),
        );
      }
    } catch (e, st) {
      debugPrint('GridItemTracker HighlightInfo lookup ignored: $e');
      debugPrint('$st');
    }

    try {
      _sectionedListLayout = Provider.of<SectionedListLayout<T>>(
        context,
        listen: false,
      );
    } catch (e, st) {
      debugPrint('GridItemTracker SectionedListLayout lookup ignored: $e');
      debugPrint('$st');
    }

    _saveLayoutMetrics();
  }

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void didUpdateWidget(covariant GridItemTracker<T> oldWidget) {
    super.didUpdateWidget(oldWidget);

    if (!_canUseTracker) return;

    if (oldWidget.tileLayout != widget.tileLayout) {
      _onLayoutChanged();
    }

    _saveLayoutMetrics();
  }

  @override
  void didChangeMetrics() {
    if (!_canUseTracker) return;

    final view = _view;
    if (view == null) return;

    final size = view.physicalSize;
    final orientation = size.width > size.height ? Orientation.landscape : Orientation.portrait;

    if (_lastOrientation == orientation) return;

    _lastOrientation = orientation;

    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!_canUseTracker) return;
      if (widget.scrollableKey.currentContext == null) return;

      try {
        _onLayoutChanged();
        _saveLayoutMetrics();
      } catch (e, st) {
        debugPrint('GridItemTracker didChangeMetrics ignored: $e');
        debugPrint('$st');
      }
    });
  }

  @override
  void dispose() {
    _disposed = true;

    WidgetsBinding.instance.removeObserver(this);

    _view = null;
    _route = null;
    _highlightInfo = null;
    _sectionedListLayout = null;

    _subscriptions
      ..forEach((sub) => sub.cancel())
      ..clear();

    super.dispose();
  }

  Future<void> _trackItem(TrackEvent event) async {
    if (!_canUseTracker) return;

    final sectionedListLayout = _sectionedListLayout;
    if (sectionedListLayout == null) return;

    try {
      final tileRect = sectionedListLayout.getTileRect(event.item);
      if (tileRect == null) return;

      final currentScrollableSize = scrollableSize;
      if (currentScrollableSize == null) return;

      if (scrollController.positions.length != 1) return;

      final viewportRect = Offset(0, scrollController.offset) & currentScrollableSize;

      final itemVisibility = max(0, tileRect.intersect(viewportRect).height) / tileRect.height;

      if (!event.predicate(itemVisibility)) return;

      double scrollOffset = tileRect.top + (tileRect.height - currentScrollableSize.height) * ((event.alignment.y + 1) / 2);

      scrollOffset += appBarHeightNotifier.value;
      scrollOffset = scrollOffset.clamp(0, scrollController.position.maxScrollExtent);

      if (scrollOffset > 0) {
        if (event.animate) {
          await scrollController.animateTo(
            scrollOffset,
            duration: Duration(
              milliseconds: (scrollOffset / 2).round().clamp(
                ADurations.highlightScrollAnimationMinMillis,
                ADurations.highlightScrollAnimationMaxMillis,
              ),
            ),
            curve: Curves.easeInOutCubic,
          );
        } else {
          scrollController.jumpTo(scrollOffset);
          await Future.delayed(ADurations.highlightJumpDelay);
        }
      }

      if (!_canUseTracker) return;

      final highlightItem = event.highlightItem;
      if (highlightItem != null) {
        _highlightInfo?.set(highlightItem);
      }
    } catch (e, st) {
      debugPrint('GridItemTracker _trackItem ignored: $e');
      debugPrint('$st');
    }
  }

  Future<void> _saveLayoutMetrics() async {
    await Future.delayed(const Duration(milliseconds: 500));

    if (!_canUseTracker) return;
    if (widget.scrollableKey.currentContext == null) return;

    final currentScrollableSize = scrollableSize;
    if (currentScrollableSize == null) return;

    final sectionedListLayout = _sectionedListLayout;
    if (sectionedListLayout == null) return;

    try {
      _lastSectionedListLayout = sectionedListLayout;
      _lastScrollableSize = currentScrollableSize;
      _hasSavedLayoutMetrics = true;
    } catch (e, st) {
      debugPrint('GridItemTracker _saveLayoutMetrics ignored: $e');
      debugPrint('$st');
    }
  }

  void _onLayoutChanged() {
    if (!_canUseTracker) return;
    if (!_hasSavedLayoutMetrics) return;
    if (scrollController.positions.length != 1) return;

    if (scrollController.offset == 0) return;

    try {
      final layout = _lastSectionedListLayout;
      final halfSize = _lastScrollableSize / 2;
      final center = Offset(
        halfSize.width,
        halfSize.height + scrollController.offset - appBarHeightNotifier.value,
      );

      var pivotItem = layout.getItemAt(center) ?? layout.getItemAt(Offset(0, center.dy));

      if (pivotItem == null) {
        final pivotSectionKey = layout.getSectionAt(center.dy)?.sectionKey;
        if (pivotSectionKey != null) {
          pivotItem = layout.sections[pivotSectionKey]?.firstOrNull;
        }
      }

      if (pivotItem != null) {
        WidgetsBinding.instance.addPostFrameCallback((_) {
          if (!_canUseTracker) return;

          try {
            _highlightInfo?.trackItem(
              pivotItem,
              animate: false,
            );
          } catch (e, st) {
            debugPrint('GridItemTracker _onLayoutChanged ignored: $e');
            debugPrint('$st');
          }
        });
      }
    } catch (e, st) {
      debugPrint('GridItemTracker _onLayoutChanged ignored: $e');
      debugPrint('$st');
    }
  }
}