/*
 * JFuncDiagraph v0.4.1
 * http://www.oglen.net/demo/JFuncDiagraph/
 *
 * Copyright 2011, Justin Fang
 *
 * Date: 2011-12-2
 */

function JFuncDiagraph(context, width, height, xp, yp, zoom, bg){
	
	this.context = context;
	this.width = width;
	this.height = height;

	this.xp = xp;
	this.yp = yp;

	this.zoom = zoom;
	this.brkMax = 800000;
	
	if(typeof JFuncDiagraph._initialized == "undefined"){

		JFuncDiagraph.prototype.drawEachFuncDiagraph = function(arr){

			var succArr = 1;
			var iBrk = 100;

			this.deltaSMax = 1;
			this.deltaSMin = 0.5;

			this.yMax = this.yp / this.zoom;
			this.yMin = (this.yp - this.height) / this.zoom;

			this.xMin = -this.xp / this.zoom;
			this.xMax = (-this.xp + this.width) / this.zoom;

			this.theMin = 2e-20;

			var tempA, tempB;

			if(Math.abs(this.xMax) > Math.abs(this.xMin)){
				tempA = Math.abs(this.xMax);
			}else{
				tempA = Math.abs(this.xMin);
			}

			if(Math.abs(this.yMax) > Math.abs(this.yMin)){
				tempB = Math.abs(this.yMax);
			}else{
				tempB = Math.abs(this.yMin);
			}

			this.rMax = Math.pow(Math.pow(tempA, 2) + Math.pow(tempB, 2), 0.5);

			for(var j = 0; j < arr.length; j++){
				
				var succ = 0;
				if(arr[j] && arr[j][2] == 1){
					try{
						this.context.fillStyle = arr[j][1];

						var sem;
						var exprs = arr[j][0];
						var expr = new Array();
						var n = 0;

						var qArea = new Array();

						do{
							sem = exprs.search(/;/);

							if(exprs.length > 0){
								if(sem == -1){
									expr[n] = $.trim(exprs.slice(0, exprs.length));
									break;
								}else{
									expr[n] = $.trim(exprs.slice(0, sem));
									exprs = exprs.slice(sem+1, exprs.length);
								}
							}else{
								break;
							}
							n++;
						}while(sem != -1)

						//****************************************************

						if(expr.length > 1){

							var para = 0;

							for(var l = 0; l < expr.length; l++){
								if(expr[l].search(/q/) != -1){
									if(para < 2){
										expr[l] = new Function('q', 'return ' + expr[l]);
									}else{
										qArea[0] =  new Function('return ' + $.trim(expr[l].slice(expr[l].search(/\(/)+1, expr[l].search(/,/))));
										qArea[1] =  new Function('return ' + $.trim(expr[l].slice(expr[l].search(/,/)+1, expr[l].search(/\)/))));
									}
									para++;
								}else{
									expr[l] = new Function('x', 'return ' + expr[l]);
									para--;
								}
							}

							if(para == expr.length){
								//parametric equation

								this.context.fillStyle = arr[j][1];

								if(typeof qArea[0] == 'function')
									var q = qArea[0]();
								else
									var q = 0;
								
								var tempQ = null;
								var tempX = null;
								var tempY = null;

								var deltaQ = 1 / this.zoom;
								var brk = 0;
								
								do {
									if(tempQ == null){

										var x = expr[0](q);
										var y = expr[1](q);

										tempX = x;
										tempY = y;
										tempQ = q;

									}else{
										var i = 0;
										tempQ = q;

										do{
											var x = expr[0](tempQ);
											var y = expr[1](tempQ);


											if(y > this.yMax || y < this.yMin){
												break;
											}

											deltaX = Math.abs(x - tempX);
											deltaY = Math.abs(y - tempY);

											var c = Math.pow(deltaY * this.zoom, 2) + Math.pow(deltaX * this.zoom, 2);
											var cMax = Math.pow(this.deltaSMax, 2);
											var cMin = Math.pow(this.deltaSMin, 2);

											if(c > cMax){

												if(deltaQ > this.theMin){
													deltaQ = deltaQ / 2;
													tempQ = q + deltaQ;
												}else{
													deltaQ = this.theMin;
													tempQ = q + deltaQ;
													break;
												}
											}

											if(c < cMin){
												deltaQ = deltaQ * 2;
												tempQ = q + deltaQ;
											}

											if(i > iBrk){
												break;
											}
											i++;

										}while(c > cMax || c < cMin)

										tempX = x;
										tempY = y;
										
									}
									
									if(typeof y != 'function' && y)
										succ = 1;

									xi = x * this.zoom;
									yi = y * this.zoom;

									this.context.fillRect(xi-1, yi, 1, 1);
									
									q += deltaQ;
									
									if(brk > this.brkMax)
										break;
									brk++;

									if(typeof qArea[1] == 'function'){
										if(q > qArea[1]())
											break;
									}else{
										if(!(Math.abs(x) < this.rMax && Math.abs(y) < this.rMax))
											break;
									}
								} while (1);

							}else if(para == -expr.length){

								for(var m = 0; m < expr.length; m++){


									this.context.fillStyle = arr[j][1];

									var x = this.xMin;

									var tempX = null;
									var tempY = null;

									var deltaX = 1 / this.zoom;
									var deltaY = null;

									var brk = 0;

									do {
										if(tempY == null){
											var y = expr[m](x);
											tempY = y;

										}else{
											var i = 0;
											tempX = x;

											do{
												y = expr[m](tempX);

												if(y > this.yMax || y < this.yMin){
													break;
												}

												deltaY = Math.abs(y - tempY);

												var c = Math.pow(deltaY * this.zoom, 2) + Math.pow(deltaX * this.zoom, 2);
												var cMax = Math.pow(this.deltaSMax, 2);
												var cMin = Math.pow(this.deltaSMin, 2);

												if(c > cMax){

													if(deltaX > this.theMin){
														deltaX = deltaX / 2;
														tempX = x + deltaX;
													}else{
														deltaX = this.theMin;
														tempX = x + deltaX;
														break;
													}
												}

												if(c < cMin){

													if(deltaX > 1 / this.zoom){
														deltaX = 1 / this.zoom;
														tempX = x + deltaX;
														break;
													}else{
														deltaX = deltaX * 2;
														tempX = x + deltaX;
													}
												}

												if(i > iBrk){
													break;
												}
												i++;

											}while(c > cMax || c < cMin)

											tempY = y;
											
										}
										
										if(typeof y != 'function' && y)
											succ = 1;

										xi = x * this.zoom;
										yi = y * this.zoom;

										this.context.fillRect(xi-1, yi, 1, 1);
										
										x += deltaX;
										
										if(brk > this.brkMax)
											break;
										brk++;

									} while (x <= this.xMax);
								}
							}else{

								return false;
							}

						}else{
							expr[0] = new Function('x', 'return ' + expr[0]);

							this.context.fillStyle = arr[j][1];

							var x = this.xMin;

							var tempX = null;
							var tempY = null;

							var deltaX = 1 / this.zoom;
							var deltaY = null;

							var brk = 0;

							do {

								if(tempY == null){
									var y = expr[0](x);
									tempY = y;

								}else{
									var i = 0;
									tempX = x;

									do{
										var y = expr[0](tempX);

										if(y > this.yMax || y < this.yMin){
											break;
										}

										deltaY = Math.abs(y - tempY);

										var c = Math.pow(deltaY * this.zoom, 2) + Math.pow(deltaX * this.zoom, 2);
										var cMax = Math.pow(this.deltaSMax, 2);
										var cMin = Math.pow(this.deltaSMin, 2);

										if(c > cMax){

											if(deltaX > this.theMin){
												deltaX = deltaX / 2;
												tempX = x + deltaX;
											}else{
												deltaX = this.theMin;
												tempX = x + deltaX;
												break;
											}
										}

										if(c < cMin){

											if(deltaX > 1 / this.zoom){
												deltaX = 1 / this.zoom;
												tempX = x + deltaX;
												break;
											}else{
												deltaX = deltaX * 2;
												tempX = x + deltaX;
											}
										}

										if(i > iBrk){
											break;
										}
										i++;

									}while(c > cMax || c < cMin)

									tempY = y;
									
								}
								
								if(typeof y != 'function' && y)
									succ = 1;

								xi = x * this.zoom;
								yi = y * this.zoom;

								this.context.fillRect(xi-1, yi, 1, 1);
								x += deltaX;
								
								if(brk > this.brkMax)
									break;
								brk++;

							} while (x <= this.xMax);
						}
					}catch(e){
						return false;
					}

				}else{
					succ = 1;
				}
				succArr &= succ;
				succ = 0;
			}
			return succArr;
		}
		JFuncDiagraph.prototype.position = function(xp, yp){
			this.xp = xp;
			this.yp = yp;

			this.xl = - xp;
			this.xr = - xp + this.width;

			this.clear(bg);
			this.context.save();
			this.context.translate(this.xp, this.yp);
			this.context.scale(1, -1);
		}

		JFuncDiagraph.prototype.zommInOut = function(zoom){
			this.zoom = zoom;

			this.clear(bg);
			this.context.save();
			this.context.translate(this.xp, this.yp);
			this.context.scale(1, -1);
		}

		JFuncDiagraph.prototype.clear = function(color){
			this.context.restore();
			this.context.fillStyle = color;
			this.context.fillRect(0, 0, this.width, this.height);
		}

		JFuncDiagraph.prototype.drawCoord = function(axisColor, gridColor){

			this.context.beginPath();
			this.context.strokeStyle = gridColor;

			for(var i = -1; i > (this.yp - this.height) / this.zoom; i--){
				this.context.moveTo(- this.xp, i * this.zoom + 0.5);
				this.context.lineTo(this.width - this.xp, i * this.zoom + 0.5);
			}
			for(var i = 1; i < this.yp / this.zoom; i++){
				this.context.moveTo(- this.xp, i * this.zoom + 0.5);
				this.context.lineTo(this.width - this.xp, i * this.zoom + 0.5);
			}
			for(var i = -1; i > - this.xp / this.zoom; i--){
				this.context.moveTo(i * this.zoom - 0.5, this.yp - this.height);
				this.context.lineTo(i * this.zoom - 0.5, this.yp);
			}
			for(var i = 1; i < (this.width - this.xp) / this.zoom; i++){
				this.context.moveTo(i * this.zoom - 0.5, this.yp - this.height);
				this.context.lineTo(i * this.zoom - 0.5, this.yp);
			}

			this.context.closePath();
			this.context.stroke();

			this.context.beginPath();
			this.context.strokeStyle = axisColor;

			this.context.moveTo(- this.xp, 0.5);
			this.context.lineTo(this.width - this.xp, 0.5);

			this.context.moveTo(-0.5, this.yp - this.height);
			this.context.lineTo(-0.5, this.yp);
			this.context.stroke();
		}

		JFuncDiagraph._initialized == true;
	}
	this.clear(bg);

	this.context.save();
	this.context.translate(this.xp, this.yp);
	this.context.scale(1, -1);

}