package lighting;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Polygon;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.Collections;

import javax.swing.JPanel;

public class Screen extends JPanel {

	private Graphics g;

	private int w;
	private int h;
	private int count = 0;

	private ArrayList<Ray> rays;

	public Screen(int w, int h) {
		this.w = w;
		this.h = h;
		this.rays = new ArrayList<Ray>();
		repaint();
	}

	public void paint(Graphics g) {
		this.g = g;
		paint();
	}

	public void paint() {
		count++;
		g.setColor(Color.getHSBColor(1f, 0f, 1f));
		g.fillRect(0, 0, w, h);
		rays.clear();
		renderObsc();
		renderLines();
	}
	private void renderObsc() {
		for(Obscurer o : Main.obscList) {
			g.setColor(Color.DARK_GRAY);
			Polygon profile = o.getProfile();
			g.fillPolygon(profile);
		}
	}

	private void renderLines() {
		for(Obscurer o : Main.obscList) {
			Line2D.Double[] segments = o.lineSegments();
			for(Line2D.Double segment : segments) {

				g.setColor(Color.MAGENTA);
				g.drawLine((int)segment.getX1(), (int)segment.getY1(), (int)segment.getX2(), (int)segment.getY2());

				calculateLines(segment);
			}
		}

		double[][] screenEdgePoints = new double[][]
				{{0,0},{Main.screenWidth,0},{Main.screenWidth,Main.screenHeight},{0,Main.screenHeight}};
		for(double[] point : screenEdgePoints) {
			double dx = point[0]-Main.light.position.getX();
			double dy = point[1]-Main.light.position.getY();
			double angle = Math.atan2(dy, dx);
			angle = (angle+Math.PI*6)%(Math.PI*2);
			calculateLine(angle);
		}


		Collections.sort(rays, new CustomComparator());
		Polygon p = new Polygon();
		for(int i = 0; i < rays.size(); i++) {
			Ray ray0 = rays.get(i);
			double[] endpoint0 = new double[] {Main.light.position.getX()+(Math.cos(ray0.getRad())*ray0.getT2()),Main.light.position.getY()+(Math.sin(ray0.getRad())*ray0.getT2())};
			p.addPoint((int)endpoint0[0], (int)endpoint0[1]);
		}
		g.setColor(Color.getHSBColor(1, .5f, 0.85f));
		g.fillPolygon(p);
	}

	private void calculateLines(Line2D.Double segment) {
		double ldx = segment.getX1()-Main.light.position.getX();
		double ldy = segment.getY1()-Main.light.position.getY();
		double lightAngle = Math.atan2(ldy, ldx);
		calculateLine(lightAngle-0.00001);
		calculateLine(lightAngle);
		calculateLine(lightAngle+0.00001);

	}
	private void calculateLine(double rad) {
		rad = (rad+=6*Math.PI)%(2*Math.PI);
		double cos = Math.cos(rad);
		double sin = Math.sin(rad);
		double[] p = new double[] {Main.light.position.getX(),Main.light.position.getY()};
		double[] r = new double[] {cos,sin};

		double lowest_t2 = Main.light.radius;

		for(Obscurer o : Main.obscList) {
			Line2D.Double[] segments = o.lineSegments();
			for(Line2D.Double seg : segments) {
				double dy = seg.getY2()-seg.getY1();
				double dx = seg.getX2()-seg.getX1();
				double[] q = new double[] {seg.getX1(),seg.getY1()};
				double[] s = new double[] {dx,dy};

				double r_cross_s = cross(r,s);
				double[] q_minus_p = {q[0]-p[0],q[1]-p[1]};
				double q_minus_p__cross_s = cross(q_minus_p,s);
				double q_minus_p__cross_r = cross(q_minus_p,r);

				double u2 = q_minus_p__cross_r/r_cross_s;
				double t2 = q_minus_p__cross_s/r_cross_s;

				if(u2 >= 0 && u2 <= 1 && t2 >= 0 && t2 <= Main.light.radius) {
					if(t2<lowest_t2) {
						lowest_t2 = t2;
					}

				}
			}
		}
		rays.add(new Ray(rad,lowest_t2));
	}
	private double cross(double[] first, double[] second) {
		return first[0]*second[1] - first[1]*second[0];
	}
}