using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;

namespace XP.Common.Controls
{
    /// <summary>
    /// 虚拟摇杆 UserControl，提供圆形区域内的鼠标拖拽操控能力 | Virtual joystick UserControl providing mouse drag interaction within a circular area
    /// </summary>
    /// <remarks>
    /// 支持双轴/单轴 Y 模式、死区配置、归一化比例输出（-1.0 ~ 1.0）、鼠标左右键区分及四向功能图标切换。
    /// Supports dual-axis/single-axis Y mode, dead zone configuration, normalized proportional output (-1.0 ~ 1.0),
    /// left/right mouse button differentiation, and four-directional icon switching.
    /// </remarks>
    public partial class VirtualJoystick : UserControl
    {
        #region 私有字段 | Private Fields

        /// <summary>是否正在拖拽 | Whether dragging is in progress</summary>
        private bool _isDragging;

        /// <summary>控件中心点坐标 | Control center point coordinates</summary>
        private Point _centerPoint;

        /// <summary>操控点的平移变换 | Translate transform for thumb element</summary>
        private readonly TranslateTransform _thumbTransform = new TranslateTransform();

        /// <summary>操控点元素引用 | Thumb element reference</summary>
        private Ellipse? _thumbElement;

        #endregion

        #region 构造函数 | Constructor

        public VirtualJoystick()
        {
            InitializeComponent();

            // 控件加载完成后绑定操控点的 TranslateTransform | Bind thumb TranslateTransform after control loaded
            Loaded += (s, e) =>
            {
                _thumbElement = FindName("PART_Thumb") as Ellipse;
                if (_thumbElement != null)
                    _thumbElement.RenderTransform = _thumbTransform;

                // 初始化时更新背景和图标可见性 | Update background and icon visibility on init
                UpdateIconVisibility();
            };
        }

        #endregion

        #region JoystickMode 依赖属性 | JoystickMode Dependency Property

        public static readonly DependencyProperty JoystickModeProperty =
            DependencyProperty.Register(nameof(JoystickMode), typeof(JoystickMode), typeof(VirtualJoystick),
                new PropertyMetadata(JoystickMode.DualAxis, OnJoystickModeChanged));

        /// <summary>获取或设置摇杆轴模式 | Gets or sets the joystick axis mode</summary>
        public JoystickMode JoystickMode
        {
            get => (JoystickMode)GetValue(JoystickModeProperty);
            set => SetValue(JoystickModeProperty, value);
        }

        private static void OnJoystickModeChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is VirtualJoystick joystick)
                joystick.UpdateIconVisibility();
        }

        #endregion

        #region OutputX/OutputY 只读依赖属性 | OutputX/OutputY Read-Only Dependency Properties

        private static readonly DependencyPropertyKey OutputXPropertyKey =
            DependencyProperty.RegisterReadOnly(nameof(OutputX), typeof(double), typeof(VirtualJoystick), new PropertyMetadata(0.0));
        public static readonly DependencyProperty OutputXProperty = OutputXPropertyKey.DependencyProperty;

        /// <summary>X 轴归一化输出值 [-1.0, 1.0] | X-axis normalized output</summary>
        public double OutputX
        {
            get => (double)GetValue(OutputXProperty);
            internal set => SetValue(OutputXPropertyKey, value);
        }

        private static readonly DependencyPropertyKey OutputYPropertyKey =
            DependencyProperty.RegisterReadOnly(nameof(OutputY), typeof(double), typeof(VirtualJoystick), new PropertyMetadata(0.0));
        public static readonly DependencyProperty OutputYProperty = OutputYPropertyKey.DependencyProperty;

        /// <summary>Y 轴归一化输出值 [-1.0, 1.0] | Y-axis normalized output</summary>
        public double OutputY
        {
            get => (double)GetValue(OutputYProperty);
            internal set => SetValue(OutputYPropertyKey, value);
        }

        #endregion

        #region DeadZone 依赖属性 | DeadZone Dependency Property

        public static readonly DependencyProperty DeadZoneProperty =
            DependencyProperty.Register(nameof(DeadZone), typeof(double), typeof(VirtualJoystick), new PropertyMetadata(0.05));

        /// <summary>死区比例 [0.0, 1.0]，默认 0.05 | Dead zone ratio, default 0.05</summary>
        public double DeadZone
        {
            get => (double)GetValue(DeadZoneProperty);
            set => SetValue(DeadZoneProperty, value);
        }

        #endregion

        #region ActiveMouseButton 只读依赖属性 | ActiveMouseButton Read-Only Dependency Property

        private static readonly DependencyPropertyKey ActiveMouseButtonPropertyKey =
            DependencyProperty.RegisterReadOnly(nameof(ActiveMouseButton), typeof(MouseButtonType), typeof(VirtualJoystick),
                new PropertyMetadata(MouseButtonType.None, OnActiveMouseButtonChanged));
        public static readonly DependencyProperty ActiveMouseButtonProperty = ActiveMouseButtonPropertyKey.DependencyProperty;

        /// <summary>当前激活的鼠标按键 | Currently active mouse button</summary>
        public MouseButtonType ActiveMouseButton
        {
            get => (MouseButtonType)GetValue(ActiveMouseButtonProperty);
            internal set => SetValue(ActiveMouseButtonPropertyKey, value);
        }

        private static void OnActiveMouseButtonChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is VirtualJoystick joystick)
                joystick.UpdateIconVisibility();
        }

        #endregion

        #region 四向图标依赖属性 | Directional Icon Dependency Properties

        // 左键图标 | Left button icons
        public static readonly DependencyProperty LeftButtonTopIconProperty = DependencyProperty.Register(nameof(LeftButtonTopIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? LeftButtonTopIcon { get => GetValue(LeftButtonTopIconProperty); set => SetValue(LeftButtonTopIconProperty, value); }

        public static readonly DependencyProperty LeftButtonBottomIconProperty = DependencyProperty.Register(nameof(LeftButtonBottomIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? LeftButtonBottomIcon { get => GetValue(LeftButtonBottomIconProperty); set => SetValue(LeftButtonBottomIconProperty, value); }

        public static readonly DependencyProperty LeftButtonLeftIconProperty = DependencyProperty.Register(nameof(LeftButtonLeftIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? LeftButtonLeftIcon { get => GetValue(LeftButtonLeftIconProperty); set => SetValue(LeftButtonLeftIconProperty, value); }

        public static readonly DependencyProperty LeftButtonRightIconProperty = DependencyProperty.Register(nameof(LeftButtonRightIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? LeftButtonRightIcon { get => GetValue(LeftButtonRightIconProperty); set => SetValue(LeftButtonRightIconProperty, value); }

        // 右键图标 | Right button icons
        public static readonly DependencyProperty RightButtonTopIconProperty = DependencyProperty.Register(nameof(RightButtonTopIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? RightButtonTopIcon { get => GetValue(RightButtonTopIconProperty); set => SetValue(RightButtonTopIconProperty, value); }

        public static readonly DependencyProperty RightButtonBottomIconProperty = DependencyProperty.Register(nameof(RightButtonBottomIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? RightButtonBottomIcon { get => GetValue(RightButtonBottomIconProperty); set => SetValue(RightButtonBottomIconProperty, value); }

        public static readonly DependencyProperty RightButtonLeftIconProperty = DependencyProperty.Register(nameof(RightButtonLeftIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? RightButtonLeftIcon { get => GetValue(RightButtonLeftIconProperty); set => SetValue(RightButtonLeftIconProperty, value); }

        public static readonly DependencyProperty RightButtonRightIconProperty = DependencyProperty.Register(nameof(RightButtonRightIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? RightButtonRightIcon { get => GetValue(RightButtonRightIconProperty); set => SetValue(RightButtonRightIconProperty, value); }

        // 默认图标 | Default icons
        public static readonly DependencyProperty DefaultTopIconProperty = DependencyProperty.Register(nameof(DefaultTopIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? DefaultTopIcon { get => GetValue(DefaultTopIconProperty); set => SetValue(DefaultTopIconProperty, value); }

        public static readonly DependencyProperty DefaultBottomIconProperty = DependencyProperty.Register(nameof(DefaultBottomIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? DefaultBottomIcon { get => GetValue(DefaultBottomIconProperty); set => SetValue(DefaultBottomIconProperty, value); }

        public static readonly DependencyProperty DefaultLeftIconProperty = DependencyProperty.Register(nameof(DefaultLeftIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? DefaultLeftIcon { get => GetValue(DefaultLeftIconProperty); set => SetValue(DefaultLeftIconProperty, value); }

        public static readonly DependencyProperty DefaultRightIconProperty = DependencyProperty.Register(nameof(DefaultRightIcon), typeof(object), typeof(VirtualJoystick), new PropertyMetadata(null));
        public object? DefaultRightIcon { get => GetValue(DefaultRightIconProperty); set => SetValue(DefaultRightIconProperty, value); }

        #endregion

        #region 鼠标交互事件处理 | Mouse Interaction Event Handlers

        protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonDown(e);
            if (_isDragging || !IsEnabled) return;
            StartDrag(MouseButtonType.Left);
            e.Handled = true;
        }

        protected override void OnMouseRightButtonDown(MouseButtonEventArgs e)
        {
            base.OnMouseRightButtonDown(e);
            if (_isDragging || !IsEnabled) return;
            StartDrag(MouseButtonType.Right);
            e.Handled = true;
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);
            if (!_isDragging) return;

            try
            {
                var mousePosition = e.GetPosition(this);
                var dx = mousePosition.X - _centerPoint.X;
                var dy = mousePosition.Y - _centerPoint.Y;

                // SingleAxisY 模式下强制水平位移为零，操控点只能上下移动 | Force dx=0 in SingleAxisY mode, thumb moves vertically only
                if (JoystickMode == JoystickMode.SingleAxisY)
                    dx = 0;

                var radius = GetRadius();
                if (radius <= 0) return;

                var (clampedDx, clampedDy) = JoystickCalculator.ClampToRadius(dx, dy, radius);
                var (outputX, outputY) = JoystickCalculator.CalculateOutput(dx, dy, radius, DeadZone, JoystickMode);

                OutputX = outputX;
                OutputY = outputY;
                _thumbTransform.X = clampedDx;
                _thumbTransform.Y = clampedDy;
            }
            catch
            {
                ResetToCenter();
            }
            e.Handled = true;
        }

        protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonUp(e);
            if (!_isDragging || ActiveMouseButton != MouseButtonType.Left) return;
            EndDrag();
            e.Handled = true;
        }

        protected override void OnMouseRightButtonUp(MouseButtonEventArgs e)
        {
            base.OnMouseRightButtonUp(e);
            if (!_isDragging || ActiveMouseButton != MouseButtonType.Right) return;
            EndDrag();
            e.Handled = true;
        }

        #endregion

        #region 拖拽辅助方法 | Drag Helper Methods

        private void StartDrag(MouseButtonType buttonType)
        {
            CaptureMouse();
            ActiveMouseButton = buttonType;
            _centerPoint = new Point(ActualWidth / 2.0, ActualHeight / 2.0);
            _isDragging = true;
        }

        private void EndDrag()
        {
            ResetToCenter();
            ReleaseMouseCapture();
        }

        /// <summary>重置操控点到中心位置 | Reset thumb to center</summary>
        internal void ResetToCenter()
        {
            OutputX = 0.0;
            OutputY = 0.0;
            ActiveMouseButton = MouseButtonType.None;
            _isDragging = false;
            _thumbTransform.X = 0.0;
            _thumbTransform.Y = 0.0;
        }

        /// <summary>
        /// 获取可用半径（限制为控件尺寸的 80%）| Get usable radius (limited to 80% of control size)
        /// 双轴取宽高最小值的一半，单轴取高度的一半 | DualAxis uses min(W,H)/2, SingleAxisY uses H/2
        /// </summary>
        private double GetRadius()
        {
            var raw = JoystickMode == JoystickMode.SingleAxisY
                ? ActualHeight / 2.0
                : Math.Min(ActualWidth, ActualHeight) / 2.0;
            return raw * 0.8;
        }

        #endregion

        #region 图标可见性切换 | Icon Visibility Switching

        /// <summary>
        /// 根据 ActiveMouseButton 和 JoystickMode 更新图标可见性 | Update icon visibility based on ActiveMouseButton and JoystickMode
        /// </summary>
        private void UpdateIconVisibility()
        {
            // 查找命名元素 | Find named elements
            var defaultTop = FindName("DefaultTopPresenter") as UIElement;
            var defaultBottom = FindName("DefaultBottomPresenter") as UIElement;
            var defaultLeft = FindName("DefaultLeftPresenter") as UIElement;
            var defaultRight = FindName("DefaultRightPresenter") as UIElement;
            var leftTop = FindName("LeftTopPresenter") as UIElement;
            var leftBottom = FindName("LeftBottomPresenter") as UIElement;
            var leftLeft = FindName("LeftLeftPresenter") as UIElement;
            var leftRight = FindName("LeftRightPresenter") as UIElement;
            var rightTop = FindName("RightTopPresenter") as UIElement;
            var rightBottom = FindName("RightBottomPresenter") as UIElement;
            var rightLeft = FindName("RightLeftPresenter") as UIElement;
            var rightRight = FindName("RightRightPresenter") as UIElement;
            var dualBg = FindName("DualAxisBackground") as UIElement;
            var singleBg = FindName("SingleAxisBackground") as UIElement;
            var hLine = FindName("HorizontalLine") as UIElement;

            if (defaultTop == null) return; // 控件尚未加载 | Control not yet loaded

            // 切换背景形状：双轴=圆形，单轴=腰圆 | Switch background: DualAxis=circle, SingleAxisY=capsule
            var isSingleAxis = JoystickMode == JoystickMode.SingleAxisY;
            if (dualBg != null) dualBg.Visibility = isSingleAxis ? Visibility.Collapsed : Visibility.Visible;
            if (singleBg != null) singleBg.Visibility = isSingleAxis ? Visibility.Visible : Visibility.Collapsed;
            if (hLine != null) hLine.Visibility = isSingleAxis ? Visibility.Collapsed : Visibility.Visible;

            // 先全部隐藏 | Hide all first
            SetVisibility(Visibility.Collapsed, leftTop, leftBottom, leftLeft, leftRight, rightTop, rightBottom, rightLeft, rightRight);
            SetVisibility(Visibility.Visible, defaultTop, defaultBottom, defaultLeft, defaultRight);

            // 根据 ActiveMouseButton 切换 | Switch based on ActiveMouseButton
            switch (ActiveMouseButton)
            {
                case MouseButtonType.Left:
                    SetVisibility(Visibility.Collapsed, defaultTop, defaultBottom, defaultLeft, defaultRight);
                    SetVisibility(Visibility.Visible, leftTop, leftBottom, leftLeft, leftRight);
                    if (_thumbElement != null) _thumbElement.Fill = new SolidColorBrush(Color.FromRgb(0x3A, 0x7B, 0xC8));
                    break;
                case MouseButtonType.Right:
                    SetVisibility(Visibility.Collapsed, defaultTop, defaultBottom, defaultLeft, defaultRight);
                    SetVisibility(Visibility.Visible, rightTop, rightBottom, rightLeft, rightRight);
                    if (_thumbElement != null) _thumbElement.Fill = new SolidColorBrush(Color.FromRgb(0x5B, 0xA8, 0x5B));
                    break;
                default:
                    if (_thumbElement != null) _thumbElement.Fill = new SolidColorBrush(Color.FromRgb(0x4A, 0x90, 0xD9));
                    break;
            }

            // SingleAxisY 模式下隐藏左右图标 | Hide left/right icons in SingleAxisY mode
            if (isSingleAxis)
            {
                SetVisibility(Visibility.Collapsed, defaultLeft, defaultRight, leftLeft, leftRight, rightLeft, rightRight);
            }
        }

        private static void SetVisibility(Visibility visibility, params UIElement?[] elements)
        {
            foreach (var element in elements)
                if (element != null) element.Visibility = visibility;
        }

        #endregion
    }
}