using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using WPFDark.Controls.Effects;
using WPFDark.Internals;

namespace WPFDark.Controls
{
    internal class BiaHsvBoxBackground : Canvas
    {
        #region Hue

        public double Hue
        {
            get => hue;
            set
            {
                if (NumberHelper.AreClose(value, hue) == false)
                    SetValue(HueProperty, value);
            }
        }

        private double hue;

        public static readonly DependencyProperty HueProperty =
            DependencyProperty.Register(nameof(Hue), typeof(double), typeof(BiaHsvBoxBackground),
                new FrameworkPropertyMetadata(
                    0.0,
                    (s, e) =>
                    {
                        var self = (BiaHsvBoxBackground) s;
                        self.hue = (double) e.NewValue;
                    }));

        #endregion

        #region Saturation

        public double Saturation
        {
            get => saturation;
            set
            {
                if (NumberHelper.AreClose(value, saturation) == false)
                    SetValue(SaturationProperty, value);
            }
        }

        private double saturation;

        public static readonly DependencyProperty SaturationProperty =
            DependencyProperty.Register(nameof(Saturation), typeof(double), typeof(BiaHsvBoxBackground),
                new FrameworkPropertyMetadata(
                    0.0,
                    (s, e) =>
                    {
                        var self = (BiaHsvBoxBackground) s;
                        self.saturation = (double) e.NewValue;
                    }));

        #endregion

        #region Value

        public double Value
        {
            get => value;
            set
            {
                if (NumberHelper.AreClose(value, this.value) == false)
                    SetValue(ValueProperty, value);
            }
        }

        private double value;

        public static readonly DependencyProperty ValueProperty =
            DependencyProperty.Register(nameof(Value), typeof(double), typeof(BiaHsvBoxBackground),
                new FrameworkPropertyMetadata(
                    0.0,
                    FrameworkPropertyMetadataOptions.AffectsRender |
                    FrameworkPropertyMetadataOptions.SubPropertiesDoNotAffectRender,
                    (s, e) =>
                    {
                        var self = (BiaHsvBoxBackground) s;
                        self.value = (double) e.NewValue;

                        self.effect.Value = NumberHelper.Clamp01(self.value);
                    }));

        #endregion

        #region IsReadOnly

        public bool IsReadOnly
        {
            get => isReadOnly;
            set
            {
                if (value != isReadOnly)
                    SetValue(IsReadOnlyProperty, value);
            }
        }

        private bool isReadOnly;

        public static readonly DependencyProperty IsReadOnlyProperty =
            DependencyProperty.Register(nameof(IsReadOnly), typeof(bool), typeof(BiaHsvBoxBackground),
                new FrameworkPropertyMetadata(
                    false,
                    FrameworkPropertyMetadataOptions.AffectsRender |
                    FrameworkPropertyMetadataOptions.SubPropertiesDoNotAffectRender,
                    (s, e) =>
                    {
                        var self = (BiaHsvBoxBackground) s;
                        self.isReadOnly = (bool) e.NewValue;
                    }));

        #endregion

        #region StartedContinuousEditingCommand

        public ICommand? StartedContinuousEditingCommand
        {
            get => startedContinuousEditingCommand;
            set
            {
                if (value != startedContinuousEditingCommand)
                    SetValue(StartedContinuousEditingCommandProperty, value);
            }
        }

        private ICommand? startedContinuousEditingCommand;

        public static readonly DependencyProperty StartedContinuousEditingCommandProperty =
            DependencyProperty.Register(
                nameof(StartedContinuousEditingCommand),
                typeof(ICommand),
                typeof(BiaHsvBoxBackground),
                new PropertyMetadata(
                    default(ICommand),
                    (s, e) =>
                    {
                        var self = (BiaHsvBoxBackground) s;
                        self.startedContinuousEditingCommand = (ICommand) e.NewValue;
                    }));

        #endregion

        #region EndContinuousEditingCommand

        public ICommand? EndContinuousEditingCommand
        {
            get => endContinuousEditingCommand;
            set
            {
                if (value != endContinuousEditingCommand)
                    SetValue(EndContinuousEditingCommandProperty, value);
            }
        }

        private ICommand? endContinuousEditingCommand;

        public static readonly DependencyProperty EndContinuousEditingCommandProperty =
            DependencyProperty.Register(
                nameof(EndContinuousEditingCommand),
                typeof(ICommand),
                typeof(BiaHsvBoxBackground),
                new PropertyMetadata(
                    default(ICommand),
                    (s, e) =>
                    {
                        var self = (BiaHsvBoxBackground) s;
                        self.endContinuousEditingCommand = (ICommand) e.NewValue;
                    }));

        #endregion

        #region StartedBatchEditingCommand

        public ICommand? StartedBatchEditingCommand
        {
            get => startedBatchEditingCommand;
            set
            {
                if (value != startedBatchEditingCommand)
                    SetValue(StartedBatchEditingCommandProperty, value);
            }
        }

        private ICommand? startedBatchEditingCommand;

        public static readonly DependencyProperty StartedBatchEditingCommandProperty =
            DependencyProperty.Register(
                nameof(StartedBatchEditingCommand),
                typeof(ICommand),
                typeof(BiaHsvBoxBackground),
                new PropertyMetadata(
                    default(ICommand),
                    (s, e) =>
                    {
                        var self = (BiaHsvBoxBackground) s;
                        self.startedBatchEditingCommand = (ICommand) e.NewValue;
                    }));

        #endregion

        #region EndBatchEditingCommand

        public ICommand? EndBatchEditingCommand
        {
            get => endBatchEditingCommand;
            set
            {
                if (value != endBatchEditingCommand)
                    SetValue(EndBatchEditingCommandProperty, value);
            }
        }

        private ICommand? endBatchEditingCommand;

        public static readonly DependencyProperty EndBatchEditingCommandProperty =
            DependencyProperty.Register(
                nameof(EndBatchEditingCommand),
                typeof(ICommand),
                typeof(BiaHsvBoxBackground),
                new PropertyMetadata(
                    default(ICommand),
                    (s, e) =>
                    {
                        var self = (BiaHsvBoxBackground) s;
                        self.endBatchEditingCommand = (ICommand) e.NewValue;
                    }));

        #endregion

        private readonly HsvBoxBackgroundEffect effect = new ();

        // ReSharper disable once PrivateFieldCanBeConvertedToLocalVariable
        private readonly PropertyChangeNotifier isEnabledChangeNotifier;

        static BiaHsvBoxBackground()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(BiaHsvBoxBackground),
                new FrameworkPropertyMetadata(typeof(BiaHsvBoxBackground)));
        }

        public BiaHsvBoxBackground()
        {
            Effect = effect;

            RenderOptions.SetEdgeMode(this, EdgeMode.Aliased);
            effect.DisableColor = ((ByteColor)ThemeManager.Current.TryFindResource("InactiveColorPickerColorKey")).ToPoint3D();

            isEnabledChangeNotifier = new PropertyChangeNotifier(this, IsEnabledProperty);
            isEnabledChangeNotifier.ValueChanged += (_, _) =>
            {
                effect.IsEnabled = IsEnabled ? 1.0f : 0.0f;
                InvalidateVisual();
            };
        }

        protected override void OnRender(DrawingContext dc)
        {
            base.OnRender(dc);

            if (ActualWidth <= 1 ||
                ActualHeight <= 1)
                return;
            
            var rounder = new LayoutRounder(this);

            var rect = rounder.RoundRenderRectangle(true);

            dc.DrawRectangle(Brushes.Transparent, null, rect);
        }

        private void UpdateParams(in LayoutRounder rounder, MouseEventArgs e)
        {
            var pos = e.GetPosition(this);

            var s = rounder.RoundLayoutValue(1);
            var x = (pos.X - s) / (ActualWidth - s * 2);
            var y = (pos.Y - s) / (ActualHeight - s * 2);

            x = NumberHelper.Clamp01(x);
            y = NumberHelper.Clamp01(y);

            Hue = x;
            Saturation = 1 - y;
        }

        private bool isMouseDown;
        private bool isContinuousEdited;
        private (double, double) continuousEditingStartValue;

        protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonDown(e);

            if (IsReadOnly)
                return;

            isMouseDown = true;
            GuiHelper.HideCursor();

            var rounder = new LayoutRounder(this);

            continuousEditingStartValue = (Hue, Saturation);
            isContinuousEdited = true;

            StartedContinuousEditingCommand?.ExecuteIfCan(null);

            UpdateParams(rounder, e);

            CaptureMouse();

            this.SetMouseClipping();

            e.Handled = true;
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);

            if (IsReadOnly)
                return;

            if (isMouseDown == false)
                return;
            
            var rounder = new LayoutRounder(this);

            UpdateParams(rounder, e);

            e.Handled = true;
        }

        protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonUp(e);

            if (IsReadOnly)
                return;

            if (isMouseDown == false)
                return;

            // マウス位置を補正する
            {
                var rounder = new LayoutRounder(this);
                
                var pos = BiaHsvBoxCursor.MakeCursorRenderPos(rounder, ActualWidth, ActualHeight, Hue, Saturation);

                var mousePos = PointToScreen(Unsafe.As<ImmutableVec2_double, Point>(ref pos));
                Win32Helper.SetCursorPos((int) mousePos.X, (int) mousePos.Y);
            }

            isMouseDown = false;
            GuiHelper.ShowCursor();
            this.ResetMouseClipping();
            ReleaseMouseCapture();

            if (isContinuousEdited)
            {
                if (EndContinuousEditingCommand != null)
                {
                    if (EndContinuousEditingCommand.CanExecute(null))
                    {
                        var changedValue = (Hue, Saturation);
                        (Hue, Saturation) = continuousEditingStartValue;

                        EndContinuousEditingCommand.Execute(null);

                        StartedBatchEditingCommand?.ExecuteIfCan(null);

                        (Hue, Saturation) = changedValue;

                        EndBatchEditingCommand?.ExecuteIfCan(null);
                    }
                }

                isContinuousEdited = false;
            }


            e.Handled = true;
        }

        protected override void OnMouseLeave(MouseEventArgs e)
        {
            base.OnMouseLeave(e);

            if (isMouseDown)
            {
                isMouseDown = false;
                ReleaseMouseCapture();
                GuiHelper.ShowCursor();
                this.ResetMouseClipping();
            }

            e.Handled = true;
        }
    }
}