using System;
using Unity.UIWidgets.async;
using Unity.UIWidgets.service;
using Unity.UIWidgets.foundation;

namespace Unity.UIWidgets.ui {
    public delegate void VoidCallback();

    public delegate void FrameCallback(TimeSpan duration);

    public delegate void PointerDataPacketCallback(PointerDataPacket packet);

    public abstract class Window {
        public static Window instance {
            get {
                D.assert(_instance != null, "Window.instance is null");
                return _instance;
            }

            set {
                if (value == null) {
                    D.assert(_instance != null, "Window.instance is already cleared.");
                    _instance = null;
                } else {
                    D.assert(_instance == null, "Window.instance is already assigned.");
                    _instance = value;
                }
            }
        }

        public static bool hasInstance {
            get {
                return _instance != null;
            }
        }

        static Window _instance;

        public double devicePixelRatio {
            get { return this._devicePixelRatio; }
        }

        protected double _devicePixelRatio = 1.0;

        public Size physicalSize {
            get { return this._physicalSize; }
        }

        protected Size _physicalSize = Size.zero;

        public VoidCallback onMetricsChanged {
            get { return this._onMetricsChanged; }
            set { this._onMetricsChanged = value; }
        }

        VoidCallback _onMetricsChanged;

        public VoidCallback onLocaleChanged {
            get { return this._onLocaleChanged; }
            set { this._onLocaleChanged = value; }
        }

        private VoidCallback _onLocaleChanged;

        public FrameCallback onBeginFrame {
            get { return this._onBeginFrame; }
            set { this._onBeginFrame = value; }
        }

        FrameCallback _onBeginFrame;

        public VoidCallback onDrawFrame {
            get { return this._onDrawFrame; }
            set { this._onDrawFrame = value; }
        }

        VoidCallback _onDrawFrame;
        
        public PointerDataPacketCallback onPointerEvent {
            get { return this._onPointerEvent; }
            set { this._onPointerEvent = value; }
        }

        PointerDataPacketCallback _onPointerEvent;

        public abstract void scheduleFrame(bool regenerateLayerTree = true);

        public abstract void render(Scene scene);

        public abstract void scheduleMicrotask(Action callback);

        public abstract void flushMicrotasks();

        public abstract Timer run(TimeSpan duration, Action callback, bool periodic = false);
        
        public Timer run(Action callback) {
            return this.run(TimeSpan.Zero, callback);
        }

        public abstract TextInput textInput { get; }

        public abstract IDisposable getScope();
    }


    public class Locale : IEquatable<Locale> {
        public Locale(string languageCode, string countryCode = null) {
            D.assert(languageCode != null);
            this._languageCode = languageCode;
            this._countryCode = countryCode;
        }

        readonly string _languageCode;

        public string languageCode => this._languageCode;

        readonly string _countryCode;

        public string countryCode => this._countryCode;

        public bool Equals(Locale other) {
            if (ReferenceEquals(null, other)) return false;
            if (ReferenceEquals(this, other)) return true;
            return string.Equals(this._languageCode, other._languageCode) &&
                   string.Equals(this._countryCode, other._countryCode);
        }

        public override bool Equals(object obj) {
            if (ReferenceEquals(null, obj)) return false;
            if (ReferenceEquals(this, obj)) return true;
            if (obj.GetType() != this.GetType()) return false;
            return this.Equals((Locale) obj);
        }

        public override int GetHashCode() {
            unchecked {
                return ((this._languageCode != null ? this._languageCode.GetHashCode() : 0) * 397) ^
                       (this._countryCode != null ? this._countryCode.GetHashCode() : 0);
            }
        }

        public static bool operator ==(Locale left, Locale right) {
            return Equals(left, right);
        }

        public static bool operator !=(Locale left, Locale right) {
            return !Equals(left, right);
        }

        public override string ToString() {
            if (this.countryCode == null) {
                return this.languageCode;
            }

            return $"{this.languageCode}_{this.countryCode}";
        }
    }
}