using System;
using System.Drawing;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
using Timer = System.Windows.Forms.Timer;

namespace AppCircularInterpolation
{
    public partial class Form1 : Form
    {
        // 圓弧插補關鍵參數  
        private float centerX, centerY;  // 圓心坐標  
        private float radius;            // 圓半徑  
        private float startAngle;        // 起始角度  
        private float endAngle;          // 結束角度  
        private bool clockwise;          // 旋轉方向  

        // 動畫相關參數  
        private Timer animationTimer;
        private float currentAnimationProgress = 0f;
        private const int AnimationDuration = 3000; // 動畫持續時間（毫秒）  
        private DateTime animationStartTime;

        public Form1()
        {
            InitializeComponent();
            this.DoubleBuffered = true;
            InitializeInterpolationParameters();
            InitializeAnimation();
        }

        private void InitializeInterpolationParameters()
        {
            // 設置圓弧基本參數  
            centerX = 250;
            centerY = 250;
            radius = 200;
            startAngle = 0;
            endAngle = 270;
            clockwise = true;
        }

        private void InitializeAnimation()
        {
            // 設置動畫計時器  
            animationTimer = new Timer();
            animationTimer.Interval = 16; // 約60幀/秒  
            animationTimer.Tick += AnimationTimer_Tick;
        }

        // 啟動動畫  
        private void StartAnimation()
        {
            currentAnimationProgress = 0f;
            animationStartTime = DateTime.Now;
            animationTimer.Start();
        }

        // 動畫計時器事件  
        private void AnimationTimer_Tick(object sender, EventArgs e)
        {
            // 計算動畫進度  
            TimeSpan elapsed = DateTime.Now - animationStartTime;
            currentAnimationProgress = Math.Min(1f, (float)elapsed.TotalMilliseconds / AnimationDuration);

            // 觸發重繪  
            Invalidate();

            // 動畫結束  
            if (currentAnimationProgress >= 1f)
            {
                animationTimer.Stop();
            }
        }

        // 圓弧插補核心算法（帶動畫進度）- 補差球  
        private PointF CalculateInterpolationBallPoint()
        {
            float currentEndAngle = startAngle + (endAngle - startAngle) * currentAnimationProgress;
            float interpolationAngle = startAngle + (currentEndAngle - startAngle) * currentAnimationProgress;
            float angleRad = interpolationAngle * (float)Math.PI / 180;

            return new PointF(
                centerX + radius * (float)Math.Cos(angleRad),
                centerY + radius * (float)Math.Sin(angleRad)
            );
        }

        // 勻速小球坐標計算  
        private PointF CalculateUniformMotionBallPoint()
        {
            float uniformAngle = startAngle + (endAngle - startAngle) * currentAnimationProgress;
            float angleRad = uniformAngle * (float)Math.PI / 180;

            return new PointF(
                centerX + radius * (float)Math.Cos(angleRad),
                centerY + radius * (float)Math.Sin(angleRad)
            );
        }

        // 圓弧插補核心算法（帶動畫進度）  
        private PointF[] CalculateArcPoints(int interpolationSteps)
        {
            PointF[] points = new PointF[interpolationSteps + 1];
            float currentEndAngle = startAngle + (endAngle - startAngle) * currentAnimationProgress;

            for (int i = 0; i <= interpolationSteps; i++)
            {
                // 計算當前插補角度  
                float currentAngle = startAngle +
                    (currentEndAngle - startAngle) * i / interpolationSteps;

                // 角度轉換為弧度  
                float angleRad = currentAngle * (float)Math.PI / 180;

                // 計算圓周上的坐標點  
                points[i] = new PointF(
                    centerX + radius * (float)Math.Cos(angleRad),
                    centerY + radius * (float)Math.Sin(angleRad)
                );
            }

            return points;
        }

        // 繪制圓弧軌跡  
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            Graphics g = e.Graphics;
            g.SmoothingMode = SmoothingMode.AntiAlias;

            // 獲取插補點  
            PointF[] interpolationPoints = CalculateArcPoints(100);

            // 繪制圓弧軌跡  
            using (Pen arcPen = new Pen(Color.Blue, 2))
            {
                g.DrawLines(arcPen, interpolationPoints);
            }

            // 繪制圓心和起止點  
            using (SolidBrush brush = new SolidBrush(Color.Red))
            {
                g.FillEllipse(brush, centerX - 5, centerY - 5, 10, 10);
            }

            // 繪制補差球（紅色）  
            PointF interpolationBallPoint = CalculateInterpolationBallPoint();
            using (SolidBrush interpolationBallBrush = new SolidBrush(Color.Red))
            {
                g.FillEllipse(interpolationBallBrush, interpolationBallPoint.X - 10, interpolationBallPoint.Y - 10, 20, 20);
            }

            // 繪制勻速小球（綠色）  
            PointF uniformMotionBallPoint = CalculateUniformMotionBallPoint();
            using (SolidBrush uniformMotionBallBrush = new SolidBrush(Color.Green))
            {
                g.FillEllipse(uniformMotionBallBrush, uniformMotionBallPoint.X - 10, uniformMotionBallPoint.Y - 10, 20, 20);
            }

            // 繪制動畫進度文本  
            using (Font font = new Font("Arial", 12))
            using (SolidBrush textBrush = new SolidBrush(Color.Black))
            {
                g.DrawString($"動畫進度: {currentAnimationProgress:P0}", font, textBrush, 10, 10);
            }
        }

        // 添加啟動動畫的按鈕事件  
        private void btnStart_Click(object sender, EventArgs e)
        {
            StartAnimation();
        }
    }
}