using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;

namespace Turtle
{
    public class Canvas : IDisposable
    {
        protected int angle;
        public Bitmap Bitmap { get; protected set; }
        public Image Image { get; protected set; }

        public static readonly Pen TurtlePen = Pens.Black;

        public Point Position { get; set; }

        public int Angle
        {
            get { return angle; }
            set
            {
                angle = value;
                angle %= 360;

                if (angle < 0)
                {
                    angle += 360;
                }
            }
        }

        public bool PenState { get; set; }

        public int StepCount { get; set; }

        public int MaxStepCount { get; set; }

        public Canvas()
        {
            // initialize bitmap
            Bitmap = new Bitmap(700, 700);
            Image = Image.FromHbitmap(Bitmap.GetHbitmap());

            using (Graphics graphics = Graphics.FromImage(Image))
            {
                graphics.FillRectangle(Brushes.White, new Rectangle(0, 0, 700, 700));
            }

            // initialize state
            Position = new Point(350, 350);
            Angle = 0;
            PenState = false;
        }

        public void Dispose()
        {
            Bitmap.Dispose();
            Image.Dispose();
        }

        public void Execute(string name, int arg)
        {
            switch (name)
            {
                case "left": Angle -= arg; break;
                case "right": Angle += arg; break;
                case "pen": PenState = arg > 0; break;
                case "forward":

                    if (MaxStepCount != 0 && MaxStepCount < StepCount + 1)
                    {
                        break;
                    }

                    if (PenState)
                    {
                        StepCount++;
                    }

                    using (Graphics graphics = Graphics.FromImage(Image))
                    {
                        Point current = Position;
                        Point next = current;

                        /*double angle = Convert.ToDouble(Angle);
                        double radAngle = angle * Math.PI / 180;

                        if (angle < 90)
                        {
                            next.X += Convert.ToInt32(Math.Sin(radAngle) * arg);
                            next.Y += Convert.ToInt32(Math.Cos(radAngle) * arg);
                        }
                        else if (angle < 180)
                        {
                            next.X += Convert.ToInt32(Math.Sin(radAngle) * arg);
                            next.Y -= Convert.ToInt32(Math.Cos(radAngle) * arg);
                        }
                        else if (angle < 270)
                        {
                            next.X -= Convert.ToInt32(Math.Sin(radAngle) * arg);
                            next.Y -= Convert.ToInt32(Math.Cos(radAngle) * arg);
                        }
                        else
                        {
                            next.X -= Convert.ToInt32(Math.Sin(radAngle) * arg);
                            next.Y += Convert.ToInt32(Math.Cos(radAngle) * arg);
                        }*/

                        switch (angle)
                        {
                            case 0: next.Y -= arg; break;
                            case 90: next.X += arg; break;
                            case 180: next.Y += arg; break;
                            case 270: next.X -= arg; break;
                        }

                        if (PenState)
                        {
                            graphics.DrawLine(TurtlePen, current, next);
                        }

                        Position = next;
                    }

                    break;
            }
        }
    }
}