import 'package:flutter/material.dart';
import 'filament_controller.dart';
import 'filament_widget.dart';

enum GestureType {
  RotateCamera,
  PanCamera,
  PanBackground
}

class GestureDetectingFilamentView extends StatefulWidget {
  
  final FilamentController controller;
  final bool showControls;

  const GestureDetectingFilamentView(
      {Key? key, required this.controller, this.showControls = false})
      : super(key: key);

  @override
  State<StatefulWidget> createState() => _GestureDetectingFilamentViewState();
}

class _GestureDetectingFilamentViewState
    extends State<GestureDetectingFilamentView> {
  
  GestureType gestureType = GestureType.PanCamera;

  final _icons = {
    GestureType.PanBackground:Icons.image,
    GestureType.PanCamera:Icons.pan_tool,
    GestureType.RotateCamera:Icons.rotate_90_degrees_ccw
  };

  // to avoid duplicating code for pan/rotate (panStart, panUpdate, panEnd, rotateStart, rotateUpdate etc) 
  // we have only a single function for start/update/end.
  // when the gesture type is changed, these properties are updated to point to the correct function.
  late Future Function(double x, double y) _functionStart;
  late Future Function(double x, double y) _functionUpdate;
  late Future Function() _functionEnd;

  double _lastScale = 0;

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

  void _setFunction() {
    switch(gestureType) {
      case GestureType.RotateCamera:
        _functionStart = widget.controller.rotateStart;
        _functionUpdate = widget.controller.rotateUpdate;
        _functionEnd = widget.controller.rotateEnd;
        break;
      case GestureType.PanCamera:
        _functionStart = widget.controller.panStart;
        _functionUpdate = widget.controller.panUpdate;
        _functionEnd = widget.controller.panEnd;
        break;
      // TODO 
      case GestureType.PanBackground:
        _functionStart = (x,y) async {

        };
        _functionUpdate = (x,y) async  {

        };
        _functionEnd = () async {
          
        };
    }
  }

  @override
  void didUpdateWidget(Widget oldWidget) {
    if (widget.showControls !=
        (oldWidget as GestureDetectingFilamentView).showControls) {
      setState(() {});
    }

    super.didUpdateWidget(oldWidget);
  }

  @override
  Widget build(BuildContext context) {
    return Stack(children: [
      Positioned.fill(
          child: GestureDetector(
              behavior: HitTestBehavior.opaque,
              onScaleStart: (d) async {
                if (d.pointerCount == 2) {
                  await widget.controller.zoomEnd();
                  await widget.controller.zoomBegin();
                } else {
                  await _functionStart(d.focalPoint.dx, d.focalPoint.dy); 
                }
              },
              onScaleEnd: (d) async {
                if (d.pointerCount == 2) {
                  _lastScale = 0;
                  await widget.controller.zoomEnd();
                } else {
                  await _functionEnd();
                }
              },
              onScaleUpdate: (d) async {
                if (d.pointerCount == 2) {
                  if (_lastScale != 0) {
                    await widget.controller.zoomUpdate(100 * (d.scale -_lastScale));
                  }
                } else {
                  await _functionUpdate(d.focalPoint.dx, d.focalPoint.dy);  
                }
                _lastScale = d.scale;
              },
              child: FilamentWidget(controller: widget.controller))),
      widget.showControls
          ? Align(
              alignment: Alignment.bottomRight,
              child: GestureDetector(
                onTap: () {
                  setState(() {
                    var curIdx = GestureType.values.indexOf(gestureType);
                    var nextIdx = curIdx == GestureType.values.length - 1 ? 0 : curIdx + 1 ;
                    gestureType = GestureType.values[nextIdx];
                    _setFunction();
                  });
                },
                child: Container(
                    padding: const EdgeInsets.all(50),
                    child: Icon(_icons[gestureType], color:Colors.green)),
              ))
          : Container()
    ]);
  }
}