using System;
using System.Windows;
using System.Windows.Media;

namespace DrawFigureLibrary.Figures
{
    public class PolygonFigure : Figure
    {
        public Point[] Points { get; private set; }

        public PolygonFigure(string name, Point[] points) : base(name, 0, 0, 0, 0)
        {
            if (points == null || points.Length < 3)
                throw new ArgumentException("Многоугольник должен иметь минимум 3 точки.");

            Points = points;
            RecalcBounds();
        }

        protected void RecalcBounds()
        {
            double minX = Points.Min(p => p.X);
            double minY = Points.Min(p => p.Y);
            double maxX = Points.Max(p => p.X);
            double maxY = Points.Max(p => p.Y);

            x = (int)minX;
            y = (int)minY;
            w = (int)(maxX - minX);
            h = (int)(maxY - minY);
        }

        public override void Draw(DrawingContext drawingContext)
        {
            StreamGeometry g = new StreamGeometry();
            using (var ctx = g.Open())
            {
                ctx.BeginFigure(Points[0], isFilled: true, isClosed: true);
                ctx.PolyLineTo(Points.Skip(1).ToArray(), isStroked: true, isSmoothJoin: false);
            }
            drawingContext.DrawGeometry(null, Init.pen, g);
        }

        public override void MoveBy(int deltaX, int deltaY)
        {
            if (Init.DrawingImage == null) return;

            if (Check(this, deltaX, deltaY, Init.DrawingImage))
            {
                for (int i = 0; i < Points.Length; i++)
                    Points[i] = new Point(Points[i].X + deltaX, Points[i].Y + deltaY);

                RecalcBounds();
            }
        }

        public override void ResizeTo(int newW, int newH)
        {
            if (newW <= 0 || newH <= 0) throw new ArgumentException("Размеры должны быть > 0");

            double oldW = w;
            double oldH = h;

            if (oldW <= 0 || oldH <= 0)
            {
                RecalcBounds();
                oldW = w;
                oldH = h;

                if (oldW <= 0 || oldH <= 0) throw new ArgumentException("Нельзя изменить размер: вырожденный многоугольник.");
            }

            double sx = newW / oldW;
            double sy = newH / oldH;

            double ox = x;
            double oy = y;

            for (int i = 0; i < Points.Length; i++)
            {
                double px = Points[i].X;
                double py = Points[i].Y;

                double nx = ox + (px - ox) * sx;
                double ny = oy + (py - oy) * sy;

                Points[i] = new Point(nx, ny);
            }

            RecalcBounds();
        }
    }
}