/**
   * Package: svedit.math
   *
   * Licensed under the Apache License, Version 2
   *
   * Copyright(c) 2010 Alexis Deveria
   * Copyright(c) 2010 Jeff Schiller
   */
  
  // Dependencies:
  // None.
  
  var svgedit = svgedit || {};
  
  (function() {
  
  if (!svgedit.math) {
  	svgedit.math = {};
  }
  
  // Constants
  var NEAR_ZERO = 1e-14;
  
  // Throw away SVGSVGElement used for creating matrices/transforms.
  var svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
  
  // Function: svgedit.math.transformPoint
  // A (hopefully) quicker function to transform a point by a matrix
  // (this function avoids any DOM calls and just does the math)
  // 
  // Parameters:
  // x - Float representing the x coordinate
  // y - Float representing the y coordinate
  // m - Matrix object to transform the point with
  // Returns a x,y object representing the transformed point
  svgedit.math.transformPoint = function(x, y, m) {
  	return { x: m.a * x + m.c * y + m.e, y: m.b * x + m.d * y + m.f};
  };
  
  
  // Function: svgedit.math.isIdentity
  // Helper function to check if the matrix performs no actual transform 
  // (i.e. exists for identity purposes)
  //
  // Parameters: 
  // m - The matrix object to check
  //
  // Returns:
  // Boolean indicating whether or not the matrix is 1,0,0,1,0,0
  svgedit.math.isIdentity = function(m) {
  	return (m.a === 1 && m.b === 0 && m.c === 0 && m.d === 1 && m.e === 0 && m.f === 0);
  };
  
  
  // Function: svgedit.math.matrixMultiply
  // This function tries to return a SVGMatrix that is the multiplication m1*m2.
  // We also round to zero when it's near zero
  // 
  // Parameters:
  // >= 2 Matrix objects to multiply
  //
  // Returns: 
  // The matrix object resulting from the calculation
  svgedit.math.matrixMultiply = function() {
  	var args = arguments, i = args.length, m = args[i-1];
  	
  	while(i-- > 1) {
  		var m1 = args[i-1];
  		m = m1.multiply(m);
  	}
  	if (Math.abs(m.a) < NEAR_ZERO) m.a = 0;
  	if (Math.abs(m.b) < NEAR_ZERO) m.b = 0;
  	if (Math.abs(m.c) < NEAR_ZERO) m.c = 0;
  	if (Math.abs(m.d) < NEAR_ZERO) m.d = 0;
  	if (Math.abs(m.e) < NEAR_ZERO) m.e = 0;
  	if (Math.abs(m.f) < NEAR_ZERO) m.f = 0;
  	
  	return m;
  };
  
  // Function: svgedit.math.hasMatrixTransform
  // See if the given transformlist includes a non-indentity matrix transform
  //
  // Parameters: 
  // tlist - The transformlist to check
  //
  // Returns: 
  // Boolean on whether or not a matrix transform was found
  svgedit.math.hasMatrixTransform = function(tlist) {
  	if(!tlist) return false;
  	var num = tlist.numberOfItems;
  	while (num--) {
  		var xform = tlist.getItem(num);
  		if (xform.type == 1 && !svgedit.math.isIdentity(xform.matrix)) return true;
  	}
  	return false;
  };
  
  // Function: svgedit.math.transformBox
  // Transforms a rectangle based on the given matrix
  //
  // Parameters:
  // l - Float with the box's left coordinate
  // t - Float with the box's top coordinate
  // w - Float with the box width
  // h - Float with the box height
  // m - Matrix object to transform the box by
  // 
  // Returns:
  // An object with the following values:
  // * tl - The top left coordinate (x,y object)
  // * tr - The top right coordinate (x,y object)
  // * bl - The bottom left coordinate (x,y object)
  // * br - The bottom right coordinate (x,y object)
  // * aabox - Object with the following values:
  // * Float with the axis-aligned x coordinate
  // * Float with the axis-aligned y coordinate
  // * Float with the axis-aligned width coordinate
  // * Float with the axis-aligned height coordinate
  svgedit.math.transformBox = function(l, t, w, h, m) {
  	var topleft = {x:l,y:t},
  		topright = {x:(l+w),y:t},
  		botright = {x:(l+w),y:(t+h)},
  		botleft = {x:l,y:(t+h)};
  	var transformPoint = svgedit.math.transformPoint;
  	topleft = transformPoint( topleft.x, topleft.y, m );
  	var minx = topleft.x,
  		maxx = topleft.x,
  		miny = topleft.y,
  		maxy = topleft.y;
  	topright = transformPoint( topright.x, topright.y, m );
  	minx = Math.min(minx, topright.x);
  	maxx = Math.max(maxx, topright.x);
  	miny = Math.min(miny, topright.y);
  	maxy = Math.max(maxy, topright.y);
  	botleft = transformPoint( botleft.x, botleft.y, m);
  	minx = Math.min(minx, botleft.x);
  	maxx = Math.max(maxx, botleft.x);
  	miny = Math.min(miny, botleft.y);
  	maxy = Math.max(maxy, botleft.y);
  	botright = transformPoint( botright.x, botright.y, m );
  	minx = Math.min(minx, botright.x);
  	maxx = Math.max(maxx, botright.x);
  	miny = Math.min(miny, botright.y);
  	maxy = Math.max(maxy, botright.y);
  
  	return {tl:topleft, tr:topright, bl:botleft, br:botright, 
  			aabox: {x:minx, y:miny, width:(maxx-minx), height:(maxy-miny)} };
  };
  
  // Function: svgedit.math.transformListToTransform
  // This returns a single matrix Transform for a given Transform List
  // (this is the equivalent of SVGTransformList.consolidate() but unlike
  //  that method, this one does not modify the actual SVGTransformList)
  // This function is very liberal with its min,max arguments
  // 
  // Parameters:
  // tlist - The transformlist object
  // min - Optional integer indicating start transform position
  // max - Optional integer indicating end transform position
  //
  // Returns:
  // A single matrix transform object
  svgedit.math.transformListToTransform = function(tlist, min, max) {
  	if(tlist == null) {
  		// Or should tlist = null have been prevented before this?
  		return svg.createSVGTransformFromMatrix(svg.createSVGMatrix());
  	}
  	var min = min == undefined ? 0 : min;
  	var max = max == undefined ? (tlist.numberOfItems-1) : max;
  	min = parseInt(min);
  	max = parseInt(max);
  	if (min > max) { var temp = max; max = min; min = temp; }
  	var m = svg.createSVGMatrix();
  	for (var i = min; i <= max; ++i) {
  		// if our indices are out of range, just use a harmless identity matrix
  		var mtom = (i >= 0 && i < tlist.numberOfItems ? 
  						tlist.getItem(i).matrix :
  						svg.createSVGMatrix());
  		m = svgedit.math.matrixMultiply(m, mtom);
  	}
  	return svg.createSVGTransformFromMatrix(m);
  };
  
  
  // Function: svgedit.math.getMatrix
  // Get the matrix object for a given element
  //
  // Parameters:
  // elem - The DOM element to check
  // 
  // Returns:
  // The matrix object associated with the element's transformlist
  svgedit.math.getMatrix = function(elem) {
  	var tlist = svgedit.transformlist.getTransformList(elem);
  	return svgedit.math.transformListToTransform(tlist).matrix;
  };
  
  
  // Function: svgedit.math.snapToAngle
  // Returns a 45 degree angle coordinate associated with the two given 
  // coordinates
  // 
  // Parameters:
  // x1 - First coordinate's x value
  // x2 - Second coordinate's x value
  // y1 - First coordinate's y value
  // y2 - Second coordinate's y value
  //
  // Returns: 
  // Object with the following values:
  // x - The angle-snapped x value
  // y - The angle-snapped y value
  // snapangle - The angle at which to snap
  svgedit.math.snapToAngle = function(x1,y1,x2,y2) {
  	var snap = Math.PI/4; // 45 degrees
  	var dx = x2 - x1;
  	var dy = y2 - y1;
  	var angle = Math.atan2(dy,dx);
  	var dist = Math.sqrt(dx * dx + dy * dy);
  	var snapangle= Math.round(angle/snap)*snap;
  	var x = x1 + dist*Math.cos(snapangle);	
  	var y = y1 + dist*Math.sin(snapangle);
  	//console.log(x1,y1,x2,y2,x,y,angle)
  	return {x:x, y:y, a:snapangle};
  };
  
  
  // Function: rectsIntersect
  // Check if two rectangles (BBoxes objects) intersect each other
  //
  // Paramaters:
  // r1 - The first BBox-like object
  // r2 - The second BBox-like object
  //
  // Returns:
  // Boolean that's true if rectangles intersect
  svgedit.math.rectsIntersect = function(r1, r2) {
  	return r2.x < (r1.x+r1.width) && 
  		(r2.x+r2.width) > r1.x &&
  		r2.y < (r1.y+r1.height) &&
  		(r2.y+r2.height) > r1.y;
  };
  
  
  })();