syncrow-web/lib/pages/analytics/modules/occupancy/widgets/interactive_heat_map.dart

import 'package:flutter/material.dart';
import 'package:syncrow_web/pages/analytics/modules/occupancy/widgets/heat_map_tooltip.dart';
import 'package:syncrow_web/pages/analytics/modules/occupancy/widgets/occupancy_painter.dart';

class InteractiveHeatMap extends StatefulWidget {
  const InteractiveHeatMap({
    required this.items,
    required this.maxValue,
    required this.cellSize,
    super.key,
  });

  final List<OccupancyPaintItem> items;
  final int maxValue;
  final double cellSize;

  @override
  State<InteractiveHeatMap> createState() => _InteractiveHeatMapState();
}

class _InteractiveHeatMapState extends State<InteractiveHeatMap> {
  OccupancyPaintItem? _hoveredItem;
  OverlayEntry? _overlayEntry;
  final LayerLink _layerLink = LayerLink();

  @override
  void dispose() {
    _removeOverlay();
    _overlayEntry?.dispose();
    super.dispose();
  }

  void _removeOverlay() {
    _overlayEntry?.remove();
    _overlayEntry = null;
  }

  void _showTooltip(OccupancyPaintItem item, Offset localPosition) {
    _removeOverlay();

    final column = item.index ~/ 7;
    final row = item.index % 7;
    final x = column * widget.cellSize;
    final y = row * widget.cellSize;

    _overlayEntry = OverlayEntry(
      builder: (context) => Positioned(
        child: CompositedTransformFollower(
          link: _layerLink,
          offset: Offset(x + widget.cellSize, y),
          child: Material(
            color: Colors.transparent,
            child: Transform.translate(
              offset: Offset(-(widget.cellSize * 2.5), -50),
              child: HeatMapTooltip(date: item.date.toUtc(), value: item.value),
            ),
          ),
        ),
      ),
    );

    Overlay.of(context).insert(_overlayEntry!);
  }

  @override
  Widget build(BuildContext context) {
    return CompositedTransformTarget(
      link: _layerLink,
      child: MouseRegion(
        onHover: (event) {
          final column = event.localPosition.dx ~/ widget.cellSize;
          final row = event.localPosition.dy ~/ widget.cellSize;
          final index = column * 7 + row;

          if (index >= 0 && index < widget.items.length) {
            final item = widget.items[index];
            if (_hoveredItem != item) {
              setState(() => _hoveredItem = item);
              _showTooltip(item, event.localPosition);
            }
          } else {
            _removeOverlay();
            setState(() => _hoveredItem = null);
          }
        },
        onExit: (_) {
          _removeOverlay();
          setState(() => _hoveredItem = null);
        },
        child: CustomPaint(
          isComplex: true,
          size: _painterSize,
          painter: OccupancyPainter(
            items: widget.items,
            maxValue: widget.maxValue,
            hoveredItem: _hoveredItem,
          ),
        ),
      ),
    );
  }

  Size get _painterSize {
    final height = 7 * widget.cellSize;
    final width = widget.items.length ~/ 7 * widget.cellSize;
    return Size(width, height);
  }
}