using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
using GeoSigma.SigmaDrawerUtil;

namespace GeoSigma.SigmaDrawerStyle
{
    public delegate void ItemColorChangedEventHandler(GradientColorItem item);
    public delegate void InsertNewColorItemEventHandler(double itemZ);
    public delegate void ResetColorItemEventHandler(int itemIndex, GradientColorItem item);
    public partial class GradientPanel : UserControl
    {
        public event ItemColorChangedEventHandler ItemColorChangedEvent;
        public event InsertNewColorItemEventHandler InsertNewColorEvent;
        public event ResetColorItemEventHandler ResetColorItemEvent;
        public event ItemColorChangedEventHandler ItemColorEditFinishedEvent;
        public List<GradientColorItem> Items { get; set; } = new List<GradientColorItem>();
        private double zMin = 0;
        private double zMax = 100;
        private int handleHeight = 30;
        private int paddingY = 2;
        private int paddingX = 4;

        private List<GradientHandler> handles { get; set; } = new List<GradientHandler>();
        private int selectedHandleIndex = -1;
        private SlowDownTimer _timer = new SlowDownTimer(20);
        /// <summary>
        /// Initializes a new instance of the <see cref="GradientPanel"/> class.
        /// </summary>
        public GradientPanel()
        {
            SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint, true);
            InitializeComponent();
        }
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            e.Graphics.SmoothingMode = SmoothingMode.HighQuality;

            Rectangle rectHandler = GetHandlerBound();
            foreach (var handler in handles)
            {
                handler.Draw(e.Graphics, rectHandler);
            }
        }

        protected override void OnPaintBackground(PaintEventArgs e)
        {
            base.OnPaintBackground(e);
            // ControlPaint.DrawBorder(e.Graphics, Bounds, SystemColors.ControlText, ButtonBorderStyle.Solid);
            PaintGradientValue(e.Graphics, GetGradientColorBounds(), Items);
        }

        public void DrawGradient(List<GradientColorItem> list)
        {
            Items = list;
            if (Items.Count == 0) { return; }
            zMin = Items.Min(r => r.Z);
            zMax = Items.Max(r => r.Z);
            handles = list.Select(item => new GradientHandler(item, zMin, zMax)).ToList();

            this.Invalidate();
        }

        private Rectangle GetGradientColorBounds()
        {
            var bounds = this.ClientRectangle;
            bounds.Inflate(-paddingX, (int)(-(paddingY + handleHeight) * 0.5));
            bounds.Y = paddingY;
            return bounds;
        }
        private Rectangle GetHandlerBound()
        {
            var bounds = this.ClientRectangle;
            // bounds.Inflate(cx, (int)(-(padingY + handleHeight) * 0.5));
            bounds.Inflate(-paddingX, 0);
            bounds.Y = this.ClientRectangle.Height - handleHeight;
            bounds.Height = handleHeight;
            return bounds;
        }
        /// <summary>
        /// 在指定画布的指定区域绘制渐变色
        /// </summary>
        /// <param name="g">画布</param>
        /// <param name="bounds">区域</param>
        /// <param name="list">颜色列表</param>
        public static void PaintGradientValue(Graphics g, RectangleF bounds, List<GradientColorItem> list)
        {
            if (list == null || list.Count < 2)
            {
                return;
            }
            double zmin = list.Min(r => r.Z);
            double zmax = list.Max(r => r.Z);
            if (zmin == zmax)
            {
                return;
            }
            LinearGradientBrush br = new LinearGradientBrush(bounds, Color.Black, Color.Black, 0, false);
            {
                RectangleF rectFill = bounds;
                rectFill.Inflate(-0.5f, 0);
                ColorBlend cb = new ColorBlend();
                cb.Colors = list.Select(model => Color.FromArgb(model.T, model.R, model.G, model.B)).ToArray();
                List<float> pos = new List<float>();
                cb.Positions = new float[cb.Colors.Length];
                cb.Positions[0] = 0.0f;
                cb.Positions[cb.Colors.Length - 1] = 1;
                for (int i = 1; i < list.Count - 1; i++)
                {
                    cb.Positions[i] = Convert.ToSingle((list[i].Z - zmin) / (zmax - zmin));
                }

                br.InterpolationColors = cb;
                // br.RotateTransform(45);
                g.FillRectangle(br, rectFill);
            }
            // 绘制突变
            for (int i = 0; i < list.Count - 1; i++)
            {
                var item1 = list[i];
                var item2 = list[i + 1];

                var x1 = Convert.ToInt32(((item1.Z - zmin) / (zmax - zmin) * bounds.Width) + bounds.Left);
                var x2 = Convert.ToInt32(((item2.Z - zmin) / (zmax - zmin) * bounds.Width) + bounds.Left);

                var rect = RectangleF.FromLTRB(x1, bounds.Top, x2, bounds.Bottom);

                if (rect.Width > 0)
                {
                    if (item1.C == 0)
                    {
                        var brush = new SolidBrush(item1.ColorValue);

                        g.FillRectangle(brush, rect);
                    }
                }
            }
        }
        /// <summary>
        /// 双击事件，插入控制点，或者修改颜色
        /// </summary>
        /// <param name="sender">当前控件</param>
        /// <param name="e">事件参数</param>
        private void GradientPanel_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            var bounds = GetHandlerBound();
            // 双击手柄时的处理
            for (int i = 1; i < handles.Count - 1; i++)
            {
                GradientHandler handle = handles[i];
                // 双击的是控制手柄时
                if (handle.GetBounds(bounds).Contains(e.Location))
                {
                    ColorDialog dlg = new ColorDialog();
                    dlg.Color = handle.Item.ColorValue;
                    if (dlg.ShowDialog() == DialogResult.OK)
                    {
                        handle.Item.ColorValue = dlg.Color;
                        ItemColorChangedEvent?.Invoke(handle.Item);
                        this.Invalidate();
                    }
                    return;
                }
            }
            // 双击其它区域，插入新控制点
            if (e.Location.X >= bounds.X && e.Location.X <= bounds.X + bounds.Width)
            {
                double dZInsert = (Convert.ToDouble(e.Location.X - bounds.Left) / bounds.Width * (zMax - zMin)) + zMin;
                InsertNewColorEvent?.Invoke(dZInsert);
            }
        }

        private void GradientPanel_MouseDown(object sender, MouseEventArgs e)
        {
            var rectHandleArea = GetHandlerBound();

            for (int i = 1; i < handles.Count - 1; i++)
            {
                GradientHandler handler = handles[i];

                if (handler.GetBounds(rectHandleArea).Contains(e.Location))
                {
                    selectedHandleIndex = i;
                    //selectedHandle = handler;

                    //_selected_z_begin = Items[i - 1].Z;
                    //_selected_z_end = Items[i + 1].Z;

                    break;
                }
            }
        }

        private void GradientPanel_MouseMove(object sender, MouseEventArgs e)
        {
            if (selectedHandleIndex > 0)
            { // 两端的控制点未处理
                var bounds = GetHandlerBound();
                GradientHandler handler = handles[selectedHandleIndex];
                GradientHandler handlerLeft = handles[selectedHandleIndex - 1];
                GradientHandler handlerRight = handles[selectedHandleIndex + 1];

                double newZ = (Convert.ToDouble(e.X - bounds.Left) / bounds.Width * (zMax - zMin)) + zMin;
                if (newZ > handlerLeft.Item.Z && newZ < handlerRight.Item.Z)
                {
                    handler.Item.Z = newZ;
                    this.Invalidate();
                    int index = selectedHandleIndex;
                    _timer.Invoke(this, () => ResetColorItemEvent(index, handler.Item));
                }
            }
        }
        private void ResetColorItem(int itemIndex, GradientColorItem item)
        {
            ResetColorItemEvent?.Invoke(selectedHandleIndex, item);
        }

        private void GradientPanel_MouseUp(object sender, MouseEventArgs e)
        {
            if (selectedHandleIndex > 0)
            {
                GradientHandler handle = handles[selectedHandleIndex];
                ItemColorEditFinishedEvent?.Invoke(handle.Item);
            }
            selectedHandleIndex = -1;
        }
    }

    #region GradientHandler

    public class GradientHandler
    {
        #region Shape

        private static GraphicsPath Shape;

        /// <summary>
        /// Initializes a new instance of the <see cref="GradientHandler"/> class.
        /// </summary>
        public GradientHandler()
        {
            if (Shape == null)
            {
                Shape = new GraphicsPath();
                Shape.AddLines(new PointF[]
                {
                    new PointF(0, 0),
                    new PointF(4f, 3f),
                    new PointF(4f, 13f),
                    new PointF(-4f, 13f),
                    new PointF(-4f, 3f),
                    new PointF(0, 0),
                });
            }
        }

        #endregion

        public GradientColorItem Item { get; set; }

        private SolidBrush _brush;
        private Pen _pen = new Pen(Color.Black, 1f);
        private double zMin;
        private double zMax;

        /// <summary>
        /// Initializes a new instance of the <see cref="GradientHandler"/> class.
        /// </summary>
        /// <param name="item"></param>
        /// <param name="zMin"></param>
        /// <param name="zMax"></param>
        public GradientHandler(GradientColorItem item, double zMin, double zMax)
            : this()
        {
            Item = item;

            this.zMin = zMin;
            this.zMax = zMax;

            _brush = new SolidBrush(item.ColorValue);
        }

        internal RectangleF GetBounds(Rectangle r)
        {
            return GetPath(r).GetBounds();
        }

        private GraphicsPath GetPath(Rectangle r)
        {
            var x = ((Item.Z - zMin) / (zMax - zMin) * r.Width) + r.Left;
            var y = r.Y;

            var tmp = (GraphicsPath)Shape.Clone();

            Matrix translateMatrix = new Matrix();
            translateMatrix.Translate((float)x, y);
            tmp.Transform(translateMatrix);

            return tmp;
        }

        public void Draw(Graphics g, Rectangle r)
        {
            var path = GetPath(r);
            _brush.Color = Item.ColorValue;
            g.FillPath(_brush, path);
            g.DrawPath(_pen, path);
        }

        public bool Update(Rectangle bounds, Point eLocation, double begin, double end)
        {
            double newZ = (Convert.ToDouble(eLocation.X - bounds.Left) / bounds.Width * (zMax - zMin)) + zMin;

            if (newZ >= begin && newZ <= end)
            {
                Item.Z = newZ;
                return true;
            }
            return false;
        }
    }

    #endregion

}