import 'dart:async';

import 'package:flutter/material.dart';

enum Toast {
  short,
  long,
}

enum ToastGravity {
  top,
  bottom,
  center,
  topLeft,
  topRight,
  bottomLeft,
  bottomRight,
  centerLEft,
  centerRight,
  snackBar,
}

typedef PositionedToastBuilder = Widget Function(BuildContext context, Widget child);

class FToast {
  late BuildContext context;

  static final FToast _instance = FToast._internal();

  factory FToast() {
    return _instance;
  }

  FToast init(BuildContext context) {
    _instance.context = context;
    return _instance;
  }

  FToast._internal();

  OverlayEntry? _entry;
  final List<_ToastEntry> _overlayQueue = [];
  Timer? _timer;

  void _showOverlay() {
    if (_overlayQueue.isEmpty) {
      _entry = null;
      return;
    }
    _ToastEntry toastEntry = _overlayQueue.removeAt(0);
    _entry = toastEntry.entry;
    Overlay.of(context)?.insert(_entry!);

    _timer = Timer(toastEntry.duration, () {
      Future.delayed(const Duration(milliseconds: 360), () {
        removeCustomToast();
      });
    });
  }

  void removeCustomToast() {
    _timer!.cancel();
    _timer = null;
    if (_entry != null) _entry!.remove();
    _entry = null;
    _showOverlay();
  }

  void removeQueuedCustomToasts() {
    _timer?.cancel();
    _timer = null;
    _overlayQueue.clear();
    if (_entry != null) _entry!.remove();
    _entry = null;
  }

  void showToast({
    required Widget child,
    PositionedToastBuilder? positionedToastBuilder,
    required Duration? toastDuration,
    required ToastGravity gravity,
    int fadeDuration = 350,
  }) {
    Widget newChild = _ToastStateFul(child, toastDuration ?? const Duration(seconds: 2), fadeDuration: fadeDuration);
    if (gravity == ToastGravity.bottom) {
      if (MediaQuery.of(context).viewInsets.bottom != 0) {
        gravity = ToastGravity.center;
      }
    }
    OverlayEntry newEntry = OverlayEntry(builder: (context) {
      if (positionedToastBuilder != null) return positionedToastBuilder(context, newChild);
      return _getPositionWidgetBasedOnGravity(newChild, gravity);
    });

    _overlayQueue.add(_ToastEntry(entry: newEntry, duration: toastDuration ?? const Duration(seconds: 2)));
    if (_timer == null) _showOverlay();
  }

  Positioned _getPositionWidgetBasedOnGravity(Widget child, ToastGravity gravity) {
    switch (gravity) {
      case ToastGravity.top:
        return Positioned(top: 100.0, left: 24.0, right: 24.0, child: child);
      case ToastGravity.topLeft:
        return Positioned(top: 100.0, left: 24.0, child: child);
      case ToastGravity.topRight:
        return Positioned(top: 100.0, right: 24.0, child: child);
      case ToastGravity.center:
        return Positioned(top: 50.0, bottom: 50.0, left: 24.0, right: 24.0, child: child);
      case ToastGravity.centerLEft:
        return Positioned(top: 50.0, bottom: 50.0, left: 24.0, child: child);
      case ToastGravity.centerRight:
        return Positioned(top: 50.0, bottom: 50.0, right: 24.0, child: child);
      case ToastGravity.bottomLeft:
        return Positioned(bottom: 50.0, left: 24.0, child: child);
      case ToastGravity.bottomRight:
        return Positioned(bottom: 50.0, right: 24.0, child: child);
      case ToastGravity.snackBar:
        return Positioned(bottom: MediaQuery.of(context).viewInsets.bottom, left: 0, right: 0, child: child);
      case ToastGravity.bottom:
      default:
        return Positioned(bottom: 50.0, left: 24.0, right: 24.0, child: child);
    }
  }
}

class _ToastEntry {
  final OverlayEntry entry;
  final Duration duration;

  _ToastEntry({required this.entry, required this.duration});
}

class _ToastStateFul extends StatefulWidget {
  const _ToastStateFul(this.child, this.duration, {Key? key, this.fadeDuration = 350}) : super(key: key);

  final Widget child;
  final Duration duration;
  final int fadeDuration;

  @override
  ToastStateFulState createState() => ToastStateFulState();
}

class ToastStateFulState extends State<_ToastStateFul> with SingleTickerProviderStateMixin {
  void showIt() {
    _animationController.forward();
  }

  void hideIt() {
    _animationController.reverse();
    _timer.cancel();
  }

  late AnimationController _animationController;
  late Animation _fadeAnimation;
  late Timer _timer;

  @override
  void initState() {
    _animationController = AnimationController(
      vsync: this,
      duration: Duration(milliseconds: widget.fadeDuration),
    );
    _fadeAnimation = CurvedAnimation(parent: _animationController, curve: Curves.easeIn);
    super.initState();
    showIt();
    _timer = Timer(widget.duration, () {
      hideIt();
    });
  }

  @override
  void deactivate() {
    _timer.cancel();
    _animationController.stop();
    super.deactivate();
  }

  @override
  void dispose() {
    _timer.cancel();
    _animationController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return FadeTransition(
      opacity: _fadeAnimation as Animation<double>,
      child: Center(
        child: Material(
          color: Colors.transparent,
          child: widget.child,
        ),
      ),
    );
  }
}