import 'dart:collection';

import 'package:flutter/widgets.dart';
import 'package:get/src/instance/get_instance.dart';
import 'package:get/src/navigation/root/smart_management.dart';
import 'package:get/src/state_manager/rx/rx_core/rx_interface.dart';
import 'package:get/state_manager.dart';

import 'simple_builder.dart';

typedef Disposer = void Function();

class GetxController extends DisposableInterface {
  final HashSet<StateSetter> _updaters = HashSet<StateSetter>();

  final HashMap<String, StateSetter> _updatersIds =
      HashMap<String, StateSetter>();

  /// Update GetBuilder with update();
  void update([List<String> ids, bool condition = true]) {
    if (!condition) return;
    (ids == null)
        ? _updaters.forEach((rs) => rs(() {}))
        : ids.forEach((element) {
            _updatersIds[element]?.call(() {});
          });
  }

  Disposer addListener(StateSetter listener) {
    _updaters.add(listener);
    return () => _updaters.remove(listener);
  }

  // void removeListener(StateSetter listener) {
  //   _updaters.remove(listener);
  // }

  Disposer addListenerId(String key, StateSetter listener) {
    _updatersIds[key] = listener;
    return () => _updatersIds.remove(key);
  }

  void disposeKey(String key) => _updatersIds.remove(key);
}

class GetBuilder<T extends GetxController> extends StatefulWidget {
  final Widget Function(T) builder;
  final bool global;
  final String id;
  final String tag;
  final bool autoRemove;
  final bool assignId;
  final void Function(State state) initState, dispose, didChangeDependencies;
  final void Function(GetBuilder oldWidget, State state) didUpdateWidget;
  final T init;
  const GetBuilder({
    Key key,
    this.init,
    this.global = true,
    @required this.builder,
    this.autoRemove = true,
    this.assignId = false,
    this.initState,
    this.tag,
    this.dispose,
    this.id,
    this.didChangeDependencies,
    this.didUpdateWidget,
  })  : assert(builder != null),
        super(key: key);
  @override
  _GetBuilderState<T> createState() => _GetBuilderState<T>();
}

class _GetBuilderState<T extends GetxController> extends State<GetBuilder<T>> {
  GetxController controller;
  bool isCreator = false;
  final HashSet<Disposer> disposers = HashSet<Disposer>();
  Disposer remove;

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

    if (widget.initState != null) widget.initState(this);
    if (widget.global) {
      final isPrepared = GetInstance().isPrepared<T>(tag: widget.tag);
      final isRegistered = GetInstance().isRegistered<T>(tag: widget.tag);

      if (isPrepared) {
        if (GetConfig.smartManagement != SmartManagement.keepFactory) {
          isCreator = true;
        }
        controller = GetInstance().find<T>(tag: widget.tag);
      } else if (isRegistered) {
        controller = GetInstance().find<T>(tag: widget.tag);
        isCreator = false;
      } else {
        controller = widget.init;
        isCreator = true;
        GetInstance().put<T>(controller, tag: widget.tag);
      }
    } else {
      controller = widget.init;
      isCreator = true;
      controller?.onStart();
    }

    if (widget.global &&
        GetConfig.smartManagement == SmartManagement.onlyBuilder) {
      controller?.onStart();
    }
    remove = (widget.id == null)
        ? controller?.addListener(setState)
        : controller?.addListenerId(widget.id, setState);
  }

  @override
  void dispose() {
    super.dispose();
    if (widget.dispose != null) widget.dispose(this);
    if (isCreator || widget.assignId) {
      if (widget.autoRemove && GetInstance().isRegistered<T>(tag: widget.tag)) {
        if (remove != null) remove();

        GetInstance().delete<T>(tag: widget.tag);
      }
    } else {
      if (remove != null) remove();
    }

    disposers.forEach((element) {
      element();
    });
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    if (widget.didChangeDependencies != null) {
      widget.didChangeDependencies(this);
    }
  }

  @override
  void didUpdateWidget(GetBuilder oldWidget) {
    super.didUpdateWidget(oldWidget as GetBuilder<T>);
    if (widget.didUpdateWidget != null) widget.didUpdateWidget(oldWidget, this);
  }

  @override
  Widget build(BuildContext context) => widget.builder(controller);
}

/// This is a experimental feature.
/// Meant to be used with SimpleBuilder, it auto-registers the variable
/// like Rx() does with Obx().
class Value<T> extends GetxController {
  Value([this._value]);
  T _value;

  T get value {
    TaskManager.instance.notify(_updaters);
    return _value;
  }

  set value(T newValue) {
    if (_value == newValue) return;
    _value = newValue;
    update();
  }
}