using System;

using SharpVectors.Polynomials;

namespace SharpVectors.Dom.Svg
{
	public abstract class SvgPathSegCurveto : SvgPathSeg
	{
        #region constructors
		protected SvgPathSegCurveto(SvgPathSegType type) : base(type)
		{
		}
        #endregion

        #region abstract properties

        public abstract override SvgPointF AbsXY { get; }
        public abstract SvgPointF CubicX1Y1 { get; }
        public abstract SvgPointF CubicX2Y2 { get; }
        
        #endregion

        #region public properties
        public override double Length
        {
            get
            {
                return this.getArcLengthPolynomial().Simpson(0, 1);
            }
        }

        public override double StartAngle
		{
			get
			{
                SvgPointF p1 = PreviousSeg.AbsXY;
                SvgPointF p2 = CubicX1Y1;

                double dx = p2.X - p1.X;
                double dy = p2.Y - p1.Y;
                double a = (Math.Atan2(dy, dx) * 180 / Math.PI);
				a += 270;
				a %= 360;
				return a;
			}
		}

        public override double EndAngle
		{
			get
			{
                SvgPointF p1 = CubicX2Y2;
                SvgPointF p2 = AbsXY;

                double dx = p1.X - p2.X;
                double dy = p1.Y - p2.Y;
                double a = (Math.Atan2(dy, dx) * 180 / Math.PI);
				a += 270;
				a %= 360;
				return a;
			}
		}
        #endregion
	    
        protected abstract SqrtPolynomial getArcLengthPolynomial();
	}
}