/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.g2d.utils;

import java.awt.geom.Path2D;
import java.awt.geom.PathIterator;
import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;

/**
 * Path Utils.
 * <p>
 * A line segment (linear, quadratic or cubic bezier) is described
 * with a double array. The length of the array describes its degree (4,6,8).
 * The first 2 elements define start point and last 2 the end point.
 * Points in the middle are bezier control points.
 * 
 * @author Toni Kalajainen
 */
public class PathUtils {

	/**
	 * Get tangent of an bezier
	 * @param lineSegment bezier of n degrees
	 * @param degree 1..3 
	 * @param t 0..1
	 * @return unit vector
	 */
	public static Point2D getLineTangent(double lineSegment[], double t)
	{
		int degree = getLineDegree(lineSegment);
		double x=0, y=0;
		if (degree==1)
		{
			x = lineSegment[2*1+0] - lineSegment[2*0+0];
			y = lineSegment[2*1+1] - lineSegment[2*0+1];
		} else {		
			if (degree==2) {
				x = 2*t*(lineSegment[2*0+0] - 2*lineSegment[2*1+0] + lineSegment[2*2+0]) + 2*(-lineSegment[2*0+0] + lineSegment[2*1+0]);
				y = 2*t*(lineSegment[2*0+1] - 2*lineSegment[2*1+1] + lineSegment[2*2+1]) + 2*(-lineSegment[2*0+1] + lineSegment[2*1+1]);
			} else if (degree==3) {
				x = 3*(1-t)*(1-t)*(lineSegment[2*1+0]-lineSegment[2*0+0]) + 3*(lineSegment[2*2+0]-lineSegment[2*1+0])*2*t*(1-t) + 3*(lineSegment[2*3+0]-lineSegment[2*2+0])*t*t;
				y = 3*(1-t)*(1-t)*(lineSegment[2*1+1]-lineSegment[2*0+1]) + 3*(lineSegment[2*2+1]-lineSegment[2*1+1])*2*t*(1-t) + 3*(lineSegment[2*3+1]-lineSegment[2*2+1])*t*t;
			}
		}		
		return new Point2D.Double(x, y);
	}
	
	/**
	 * 
	 * @param lineSegment
	 * @param t 0..1
	 * @return
	 */
	public static Point2D getLinePos(double lineSegment[], double t)
	{		
		assert(lineSegment!=null);
		int degree = getLineDegree(lineSegment);
		double x=0, y=0;
		
		if (degree==1) {
			double p0x = lineSegment[0];
			double p0y = lineSegment[1];
			double p1x = lineSegment[2];
			double p1y = lineSegment[3];
			
			x = p0x*(1-t) + t*p1x;
			y = p0y*(1-t) + t*p1y;
		} else if (degree==2) {
			double p0x = lineSegment[0];
			double p0y = lineSegment[1];
			double p1x = lineSegment[2];
			double p1y = lineSegment[3];
			double p2x = lineSegment[4];
			double p2y = lineSegment[5];			
			
			double c2x = p0x-2*p1x+p2x;
			double c2y = p0y-2*p1y+p2y;
			
			double c1x = -2*p0x+2*p1x;
			double c1y = -2*p0y+2*p1y;
			
			double c0x = p0x;
			double c0y = p0y;
			
			x = t*t*c2x+t*c1x+c0x;
			y = t*t*c2y+t*c1y+c0y;
		} else if (degree==3) {
			double p0x = lineSegment[0];
			double p0y = lineSegment[1];
			double p1x = lineSegment[2];
			double p1y = lineSegment[3];
			double p2x = lineSegment[4];
			double p2y = lineSegment[5];			
			double p3x = lineSegment[6];
			double p3y = lineSegment[7];			

			x = (1-t)*(1-t)*(1-t)*p0x + 3*t*(1-t)*(1-t)*p1x + 3*t*t*(1-t)*p2x + t*t*t*p3x;
			y = (1-t)*(1-t)*(1-t)*p0y + 3*t*(1-t)*(1-t)*p1y + 3*t*t*(1-t)*p2y + t*t*t*p3y;
		}
		
		return new Point2D.Double(x, y);
	}
	
	public static double getLineLength(double lineSegment[])
	{
		int degree = getLineDegree(lineSegment);		
		if (degree==1) {
			double dx = lineSegment[2]-lineSegment[0];
			double dy = lineSegment[3]-lineSegment[1];
			return Math.sqrt(dx*dx+dy*dy);
		}
		
		// Quick'n'dirty approximation 
		// TODO Replace with accurate value
		double result = 0;
		Point2D prevPos = getLinePos(lineSegment, 0.0); 
		for (int i=0; i<10; i++)
		{
			double t = (double)(i+1)/10;
			Point2D pos = getLinePos(lineSegment, t);
			result += pos.distance(prevPos);
			prevPos.setLocation(pos);
		}
		return result;
		/*
		if (degree==2) {
			double c2x = bezier[2*0+0]-2*bezier[2*1+0]+bezier[2*2+0];
			double c2y = bezier[2*0+1]-2*bezier[2*1+1]+bezier[2*2+1];
			
			double c1x = -2*bezier[2*0+0]+2*bezier[2*1+0];
			double c1y = -2*bezier[2*0+1]+2*bezier[2*1+1];
			
			double c0x = bezier[2*0+0];
			double c0y = bezier[2*0+1];
			
			double intg_x = c2x/3 + c1x/2 + c0x;
			double intg_y = c2y/3 + c1y/2 + c0y;
			System.out.println(intg_x +"\t" + intg_y);
			
			return intg_x + intg_y;
		}
		return 0;
		*/
	}
	
	public static int getLineDegree(double lineSegment[])
	{
		assert(lineSegment.length==4 || lineSegment.length==6 || lineSegment.length==8);
		return (lineSegment.length-2)/2;
	}
	
	/**
	 * Get first and last point & tangent of a path
	 * @param path
	 * @param begin
	 * @param beginDirection
	 * @param end
	 * @param endDirection
	 * @return true if pi contained atleast one line segment
	 */
	public static boolean getPathArrows(PathIterator pi, Point2D begin, Point2D beginDirection, Point2D end, Point2D endDirection)
	{
		Iterator<double[]> i = toLineIterator(pi);
		double first[]=null, last[]=null;
		while (i.hasNext()) {
			double[] current = i.next();
			if (first==null) first = current;
			if (!i.hasNext()) last = current;
		}
		if (first==null || last==null) return false;
		begin.setLocation( getLinePos(first, 0) );
		beginDirection.setLocation( getLineTangent(first, 0) );
		end.setLocation( getLinePos(last, 1) );
		Point2D endTangent = getLineTangent(last, 1);
		endDirection.setLocation( -endTangent.getX(), -endTangent.getY() );
		return true;
	}

	
	
	/**
	 * Interpolate two paths
	 * @param path1
	 * @param path2
	 * @param t phase 0..1, 0==path1, 1==path2
	 * @return
	 */
	public static Path2D interpolatePaths(PathIterator path1, PathIterator path2, double t)
	{
		Path2D result = new Path2D.Double();
				
		ArrayList<double[]> l1 = new ArrayList<double[]>(); 
		toLineSegments(path1, l1);
		ArrayList<double[]> l2 = new ArrayList<double[]>(); 
		toLineSegments(path2, l2);
		
		if (l1.size()==l2.size())
		{
			
		}
		
		result.append(path1, false);
		return result;
	}
	
	public static double[] interpolateLineSegment(double l1[], double l2[], double t)
	{
		assert(t>=0 && t<=1);
		if (t==0) return Arrays.copyOf(l1, l1.length);
		if (t==1) return Arrays.copyOf(l1, l1.length);
		
		int d1 = getLineDegree(l1);
		int d2 = getLineDegree(l2);
		
		if (d1==d2) {
			double result [] = new double[l1.length];		
			for (int i=0; i<l1.length; i++)			
				result[i] = l2[i]*t + l1[i]*(1-t); 
			return result;
		}
		
		if (d2<d1) {
			int d_ = d1;
			d1 = d2;
			d2 = d_;
			double[] l_ = l1;
			l1 = l2;
			l2 = l_;
			t = 1-t;
		}
		
		// d1 < d2
		double res[] = new double[l2.length];
		
		if (d1==1 && d2==2) {
			res[0] = l1[0]*(1-t) + l2[0]*t;
			res[1] = l1[1]*(1-t) + l2[1]*t;
			res[4] = l1[2]*(1-t) + l2[4]*t;
			res[5] = l1[3]*(1-t) + l2[5]*t;
			double cx  = (l1[0]+l1[2])/2;
			double cy  = (l1[0]+l1[2])/2;
			res[2] = cx*(1-t) + l2[2]*t;
			res[3] = cy*(1-t) + l2[3]*t;			
		}

		if (d1==1 && d2==3) {
			res[0] = l1[0]*(1-t) + l2[0]*t;
			res[1] = l1[1]*(1-t) + l2[1]*t;
			res[4] = l1[2]*(1-t) + l2[4]*t;
			res[5] = l1[3]*(1-t) + l2[5]*t;
			double cx  = (l1[0]+l1[2])/2;
			double cy  = (l1[0]+l1[2])/2;
			res[2] = cx*(1-t) + l2[2]*t;
			res[3] = cy*(1-t) + l2[3]*t;			
			res[4] = cx*(1-t) + l2[4]*t;
			res[5] = cy*(1-t) + l2[5]*t;			
		}
		
		if (d1==2 && d2==3) {
			res[0] = l1[0]*(1-t) + l2[0]*t;
			res[1] = l1[1]*(1-t) + l2[1]*t;
			res[2] = l1[2]*(1-t) + l2[2]*t;
			res[3] = l1[3]*(1-t) + l2[3]*t;			
			res[4] = l1[2]*(1-t) + l2[4]*t;
			res[5] = l1[3]*(1-t) + l2[5]*t;			
			res[6] = l1[4]*(1-t) + l2[6]*t;
			res[7] = l1[5]*(1-t) + l2[7]*t;
		}					
		
		return res;
	}
	
	/**
	 * Returns an iterator that constructs line segments by traversing a path iterator
	 * @param pi path iterator
	 * @return line segment iterator
	 */
	public static Iterator<double[]> toLineIterator(final PathIterator pi)
	{
		return new PathIteratorToSegmentIterator(pi);
	}
	
	public static void toLineSegments(PathIterator pi, Collection<double[]> result)
	{
		Iterator<double[]> i = toLineIterator(pi);
		while (i.hasNext()) {
			double[] segment = i.next();
			result.add(segment);
		}
	}
	
	private static class PathIteratorToSegmentIterator implements Iterator<double[]>
	{
		final PathIterator pi;
		double	lineTo[] = new double[6];
		double	startPos[] = new double[2];
		double	from[] = new double[2];
		int		degree = 0;
		PathIteratorToSegmentIterator(PathIterator pi) {
			this.pi = pi;
			while(!pi.isDone()) {
				int type = pi.currentSegment(lineTo);
				pi.next();
				if (type == PathIterator.SEG_MOVETO) {
					startPos[0] = from[0] = lineTo[0];
					startPos[1] = from[1] = lineTo[1];
				}
				if (type == PathIterator.SEG_CLOSE) {
					type = PathIterator.SEG_LINETO;
					lineTo[0] = startPos[0];
					lineTo[1] = startPos[1];
				}
				if (type>=PathIterator.SEG_LINETO && type<=PathIterator.SEG_CUBICTO)
				{
					degree = type;
					// from == xx
					break;
				}
			}
		}		
		@Override
		public boolean hasNext() {
			return degree>0;
		}
		@Override
		public double[] next() {
			if (degree==0) return null;
			double result[] = new double[degree*2+2]; 
			result[0] = from[0];
			result[1] = from[1];
			result[2] = lineTo[0];
			result[3] = lineTo[1];
			if (degree==2) {
				result[4] = lineTo[2];
				result[5] = lineTo[3];
			} else if (degree==3) {
				result[6] = lineTo[4];
				result[7] = lineTo[5];
			}
			// traverse path iterator until end or until next segment is known
			degree = 0;
			from[0] = lineTo[0];
			from[1] = lineTo[1];
			while(!pi.isDone()) {
				int type = pi.currentSegment(lineTo);
				pi.next();
				if (type == PathIterator.SEG_MOVETO) {
					startPos[0] = from[0] = lineTo[0];
					startPos[1] = from[1] = lineTo[1];
				}
				if (type == PathIterator.SEG_CLOSE) {
					type = PathIterator.SEG_LINETO;
					lineTo[0] = startPos[0];
					lineTo[1] = startPos[1];
				}
				if (type>=PathIterator.SEG_LINETO && type<=PathIterator.SEG_CUBICTO)
				{
					degree = type;
					break;
				}
			}
			return result;
		}
		@Override
		public void remove() {
			throw new UnsupportedOperationException();
		}
	}

	
	
	
	
	
	/**
	 * Finds intersection of two half-straight lines
	 * @param p0x
	 * @param p0y
	 * @param dir0
	 * @param p1x
	 * @param p1y
	 * @param dir1
	 * @return
	 */
	public static Point2D findIntersection(double p0x, double p0y, double dir0, double p1x, double p1y, double dir1)
	{
		Point2D uv = new Point2D.Double();
		GeometryUtils.toUnitVector(dir0, uv);
		double v0x = uv.getX();
		double v0y = uv.getY();
		GeometryUtils.toUnitVector(dir1, uv);
		double v1x = uv.getX();
		double v1y = uv.getY();
		return findIntersection(p0x, p0y, v0x, v0y, p1x, p1y, v1x, v1y);
	}
	
	/**
	 * Finds intersection of two half-straight lines
	 * @param p0
	 * @param v0
	 * @param p1
	 * @param v1
	 * @return
	 */
	public static Point2D findIntersection(Point2D p0, Point2D v0, Point2D p1, Point2D v1)
	{
		double v0x = v0.getX();
		double v0y = v0.getY();
		double v1x = v1.getX();
		double v1y = v1.getY();
		double p0x = p0.getX();
		double p0y = p0.getY();
		double p1x = p1.getX();
		double p1y = p1.getY();		
		return findIntersection(p0x, p0y, v0x, v0y, p1x, p1y, v1x, v1y);
	}
	
	/**
	 * Finds intersection of two half-straight lines
	 * @param p1
	 * @param v1 direction vector (unit vector)
	 * @param p2
	 * @param v2 direction vector (unit vector)
	 * @return
	 */
	public static Point2D findIntersection(double p0x, double p0y, double v0x, double v0y, double p1x, double p1y, double v1x, double v1y)
	{
		if (p0x==p1x && p0y==p1y) return new Point2D.Double(p0x, p0y);
		/*
		   i = Intersection point		  
		   i = p0 + t*v0 = p1 + r*v1;
		 */				
		double denominator	= v0y*v1x - v0x*v1y;
		// Straights are in same or opposite directions
		if (denominator == 0) {
			return null;
			/*
			// Do they overlap?
			boolean overlap		= v0x*(p1y-p0y) - v0y*(p1x-p1x) == 0;
			if (!overlap) return null;
			double t = v1x==0?(p1y-p0y)/v0y:(p1x-p0x)/v0x;
			double r = v0x==0?(p0y-p1y)/v1y:(p0x-p1x)/v1x;
			boolean parallel	= (v0x==v1x)&&(v0y==v1y);
			if (parallel) {
				if (t<0) return new Point2D.Double(p1x, p1y);
				if (r<0) return new Point2D.Double(p0x, p0y);
				return null;
			}
			return null;
			*/
		}
		
		double nominator 	= -v0x*p0y + v0x*p1y + v0y*p0x - v0y*p1x;
		double r			= nominator / denominator;
		if (r<0) return null;
		// XXX t on väärin
		//double t			= -p0x + p1x + v1x*r;
		//if (t<0) return null;
		
		double x			= p1x + r*v1x;
		double y			= p1y + r*v1y;
		return new Point2D.Double(x, y);
	}

	public static int findNearestPoints(Point2D p0, Point2D v0, Point2D p1, Point2D v1, Point2D cp1, Point2D cp2)
	{
		return findNearestPoints(p0.getX(), p0.getY(), v0.getX(), v0.getY(), p1.getX(), p1.getY(), v1.getX(), v1.getY(), cp1, cp2);
	}
	
	public static int findNearestPoints(double p0x, double p0y, double v0x, double v0y, double p1x, double p1y, double v1x, double v1y, Point2D cp1, Point2D cp2)
	{
		int result = 0;
		double r = -( v1x*(p1x-p0x) + v1y*(p1y-p0y) ) / (v1x*v1x+v1y*v1y);
		double t = -( v0x*(p0x-p1x) + v0y*(p0y-p1y) ) / (v0x*v0x+v0y*v0y);
		if (t>0) {
			cp1.setLocation( p0x + v0x*t, p0y + v0y*t );
			result |= 1;
		}
		if (r>0) {
			cp2.setLocation( p1x + v1x*r, p1y + v1y*r );
			result |= 2;
		}
		return result;
	}
	
	public static double[] subdiv_takeLeft(double line[], double t)
	{
		int 	degree	= getLineDegree(line); 
		
		double p0x = line[0];
		double p0y = line[1];
		double p1x = line[2];
		double p1y = line[3];
		double p1x_  = p0x*(1-t) + p1x*t;
		double p1y_  = p0y*(1-t) + p1y*t;
		if (degree==1) 			
			return new double[] {p0x, p0y, p1x_, p1y_};

		double p2x = line[4];
		double p2y = line[5];			

		double q0x = p0x*(1-t) + p1x*t;
		double q0y = p0y*(1-t) + p1y*t;

		double q1x = p1x*(1-t) + p2x*t;
		double q1y = p1y*(1-t) + p2y*t;
		
		double p2x_ = q0x*(1-t) + q1x*t;
		double p2y_ = q0y*(1-t) + q1y*t;
		if (degree==2) 		
			return new double[] {p0x, p0y, p1x_, p1y_, p2x_, p2y_};			
		
		
		double p3x = line[6];
		double p3y = line[7];
		
		double q2x = p2x*(1-t) + p3x*t;
		double q2y = p2y*(1-t) + p3y*t;

		double r0x = q0x*(1-t) + q1x*t;
		double r0y = q0y*(1-t) + q1y*t;
			
		double r1x = q1x*(1-t) + q2x*t;
		double r1y = q1y*(1-t) + q2y*t;
			
		double p3x_  = r0x*(1-t) + r1x*t;
		double p3y_  = r0y*(1-t) + r1y*t;

		if (degree==3) 
			return new double[] {p0x, p0y, p1x_, p1y_, p2x_, p2y_, p3x_, p3y_};
		
		return null;
	}
	
	public static double[] subdiv_takeRight(double line[], double t)
	{
		int 	degree	= getLineDegree(line); 
		
		double p0x = line[0];
		double p0y = line[1];
		double p1x = line[2];
		double p1y = line[3];

		double p0x_  = p0x*(1-t) + p1x*t;
		double p0y_  = p0y*(1-t) + p1y*t;
		if (degree==1) 			
			return new double[] {p0x_, p0y_, p1x, p1y};
		
		double p2x = line[4];
		double p2y = line[5];			

		double q0x = p0x*(1-t) + p1x*t;
		double q0y = p0y*(1-t) + p1y*t;

		double q1x = p1x*(1-t) + p2x*t;
		double q1y = p1y*(1-t) + p2y*t;
		
		double p2x_ = q0x*(1-t) + q1x*t;
		double p2y_ = q0y*(1-t) + q1y*t;	

		if (degree==2) 		
			return new double[] {p2x_, p2y_, q1x, q1y, p2x, p2y};			
				
		double p3x = line[6];
		double p3y = line[7];
		
		double q2x = p2x*(1-t) + p3x*t;
		double q2y = p2y*(1-t) + p3y*t;

		double r0x = q0x*(1-t) + q1x*t;
		double r0y = q0y*(1-t) + q1y*t;
			
		double r1x = q1x*(1-t) + q2x*t;
		double r1y = q1y*(1-t) + q2y*t;
			
		double p3x_  = r0x*(1-t) + r1x*t;
		double p3y_  = r0y*(1-t) + r1y*t;

		if (degree==3) 
			return new double[] {p3x_, p3y_, r1x, r1y, q2x, q2y, p3x, p3y};
		
		return null;
	}
	


	/**
	 * Crops line segment into a smaller line segment
	 * @param line line segment
	 * @param t0 begin t
	 * @param t1 end t
	 * @return cropped line segment
	 */
	public static double[] cropLine(double line[], double t0, double t1)
	{
		double temp[] = subdiv_takeLeft(line, t1);
		return subdiv_takeRight(temp, t0/t1);
	}
	
	@SuppressWarnings("unused")
	private static Point2D interpolateLine(double x0, double y0, double x1, double y1, double t)
	{
		double x = (x1-x0)*t + x0;
		double y = (y1-y0)*t + y0;
		return new Point2D.Double(x, y);
	}
	
	public static Path2D toPath(double lineSegment[])
	{
		int 	degree	= getLineDegree(lineSegment); 
		Path2D	p = new Path2D.Double();
		p.moveTo(lineSegment[0], lineSegment[1]);
		if (degree==1)
			p.lineTo(lineSegment[2], lineSegment[3]);
		if (degree==2)
			p.quadTo(lineSegment[2], lineSegment[3], lineSegment[4], lineSegment[5]);
		if (degree==3)
			p.curveTo(lineSegment[2], lineSegment[3], lineSegment[4], lineSegment[5], lineSegment[6], lineSegment[7]);		
		return p;
	}

	public static Path2D path(double ... pos)
	{
		assert(pos.length%2==0 && pos.length>=4);
		Path2D p = new Path2D.Double();
		p.moveTo(pos[0], pos[1]);
		for (int i=1; i<pos.length/2; i++)
		{
			p.lineTo(pos[i*2], pos[i*2+1]);
		}
		return p;
	}

	/**
	 * Create 3rd degree path. Every second point is a control point.
	 * @param positions
	 * @return
	 */
//	public static Path2D closePath3rdDeg(double ... pos)
//	{
//		assert(pos.length%2==0 && pos.length>=4);
//		Path2D p = new Path2D.Double();
//		p.moveTo(pos[0], pos[1]);
//		for (int i=1; i<pos.length/2; i++)
//		{
//			p.lineTo(pos[i*2], pos[i*2+1]);
//		}
//		return p;
//	}
//	
	
	public static Path2D closedPath(double ... pos)
	{
		Path2D p = path(pos);
		p.closePath();
		return p;
	}	
	
	public static void main(String[] args) {
		// test crop line
		double[] cubic = new double[] {0,0, 0, -1, 3, -1, 3,0};
		double[] cropped = cropLine(cubic, 0.2, 1);
		System.out.println(Arrays.toString(cropped));
		System.out.println(getLinePos(cubic, 0.5));
		System.out.println(getLinePos(cropped, 0.375));
		/*		
				Path2D p = new Path2D.Double();
				p.moveTo(4, 1);
				p.quadTo(6,1,6,3);
				p.quadTo(6,5,4,5);
				p.quadTo(2,5,2,3);
				p.quadTo(2,1,4,1);
				PathIterator pi = p.getPathIterator(null);
				double dada[] = new double[6];
				while (!pi.isDone()) {
					Arrays.fill(dada, 0);
					int type = pi.currentSegment(dada);
					System.out.println(type+":\t"+Arrays.toString(dada));
					pi.next();
				}*/
				
				assert(findIntersection(0,0,90,  10,1,270+45)!=null);
				assert(findIntersection(0,0,90,  1,1,89)!=null);
				assert(findIntersection(0,0,90,  1,1,270+45)==null);
				//System.out.println(findIntersection(0,0,270,  10,0,270));
				//System.out.println(findIntersection(0,0,90,  10,-10,180));		
				/*
				Point2D cp1 = new Point2D.Double();
				Point2D cp2 = new Point2D.Double();
				int i = findNearestPoints(0, 0, 0, 1, 2, 10, 0, -1, cp1, cp2);
				if (i>0)
					System.out.println(cp1+"\t"+cp2);
				else
					System.out.println("non posible");
*/
				/*
				double bezier[] = new double[] {100,1,102,1,105,1};  
				System.out.println(getLineLength(bezier, 2));
				for (int i=0; i<=10; i++)
				{
					double t = ((double)i)/10;
					System.out.println(GeometryUtils.getCompassDirection( getLineTangent(bezier, t) ));			
				}*/
			}
			
	
}