import 'dart:async';

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

enum GestureType { RotateCamera, PanCamera, PanBackground }

class FilamentGestureDetector extends StatefulWidget {
  final Widget? child;
  final FilamentController controller;
  final bool showControls;

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

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

class _FilamentGestureDetectorState extends State<FilamentGestureDetector> {
  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 FilamentGestureDetector).showControls) {
      setState(() {});
    }

    super.didUpdateWidget(oldWidget);
  }

  Timer? _scrollTimer;

  @override
  Widget build(BuildContext context) {
    return Stack(children: [
      Positioned.fill(
          // pinch zoom on mobile
          // couldn't find any equivalent for pointerCount in Listener so we use two widgets:
          // - outer is a GestureDetector only for pinch zoom
          // - inner is a Listener for all other gestures
          child: GestureDetector(
              onScaleStart: (d) async {
                if (d.pointerCount == 2) {
                  await widget.controller.zoomEnd();
                  await widget.controller.zoomBegin();
                }
              },
              onScaleEnd: (d) async {
                if (d.pointerCount == 2) {
                  _lastScale = 0;
                  await widget.controller.zoomEnd();
                }
              },
              onScaleUpdate: (d) async {
                if (d.pointerCount == 2) {
                  if (_lastScale != 0) {
                    await widget.controller
                        .zoomUpdate(100 * (_lastScale - d.scale));
                  }
                }
                _lastScale = d.scale;
              },
              child: Listener(
                  onPointerSignal: (pointerSignal) async {
                    // scroll-wheel zoom on desktop
                    if (pointerSignal is PointerScrollEvent) {
                      _scrollTimer?.cancel();
                      await widget.controller.zoomBegin();
                      await widget.controller.zoomUpdate(
                          pointerSignal.scrollDelta.dy > 0 ? 100 : -100);
                      _scrollTimer = Timer(Duration(milliseconds: 100), () {
                        widget.controller.zoomEnd();
                        _scrollTimer = null;
                      });
                    } else {
                      print(pointerSignal);
                    }
                  },
                  onPointerPanZoomStart: (pzs) {},
                  onPointerDown: (d) async {
                    await _functionStart(
                        d.localPosition.dx, d.localPosition.dy);
                  },
                  onPointerMove: (d) async {
                    await _functionUpdate(
                        d.localPosition.dx, d.localPosition.dy);
                  },
                  onPointerUp: (d) async {
                    await _functionEnd();
                  },
                  child: widget.child))),
      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()
    ]);
  }
}