/*
 * Jsgauge 0.4.1
 * http://code.google.com/p/jsgauge/
 *
 * Licensed under the MIT license:
 * http://www.opensource.org/licenses/mit-license.php
 */
/*jslint browser: true */
function Gauge( canvas, options ) {
	var that = this;
	this.canvas = canvas;
	options = options || {};

	// Gauge settings
	this.settings = {
		value: options.value || 0,
		pointerValue: options.value || 0,
		label: options.label || '',
		unitsLabel: options.unitsLabel || '',
		min: options.min || 0,
		max: options.max || 100,
		majorTicks: options.majorTicks || 5,
		minorTicks: options.minorTicks || 2, // small ticks inside each major tick
		bands: [].concat(options.bands || []),

		// START - Deprecated
		greenFrom: [].concat(options.greenFrom || 0),
		greenTo: [].concat(options.greenTo || 0),
		yellowFrom: [].concat(options.yellowFrom || 0),
		yellowTo: [].concat(options.yellowTo || 0),
		redFrom: [].concat(options.redFrom || 0),
		redTo: [].concat(options.redTo || 0)
		// END - Deprecated
	};

	// settings normalized to a [0, 100] interval
	function normalize( settings ) {
		var i,
		span = settings.max - settings.min,
		spanPct = span/100,
		normalized;

		// Restrict pointer to range of values
		if (settings.pointerValue > settings.max){
			settings.pointerValue = settings.max;
		} else if(settings.pointerValue < settings.min){
			settings.pointerValue = settings.min;
		}

		normalized = {
			min: 0,
			max: 100,
			value: ( settings.value - settings.min ) / spanPct,
			pointerValue: ( settings.pointerValue - settings.min ) / spanPct,
			label: settings.label || '',
			greenFrom: [],
			greenTo: [],
			yellowFrom: [],
			yellowTo: [],
			redFrom: [],
			redTo: [],
			bands: [],
			// also fix some possible invalid settings
		
			decimals: Math.max( 0, 3 - ( settings.max - settings.min ).toFixed( 0 ).length )
		};

		for(i=settings.bands.length;i--;) {
			var band = settings.bands[i];
			normalized.bands[i] = {
				color: band.color,
				from: (band.from - settings.min)/spanPct,
				to: (band.to - settings.min)/spanPct
			};
		}

		return normalized;
	}


	// Colors used to render the gauge
	this.colors = {
		text:    options.colorOfText || 'rgb(0, 0, 0)',
		warningText:    options.colorOfWarningText || 'rgb(255, 0, 0)',
		fill:    options.colorOfFill || [ '#111', '#ccc', '#ddd', '#eee' ],
		pointerFill:    options.colorOfPointerFill || 'rgba(0, 0, 0)',
	
		centerCircleFill:    options.colorOfCenterCircleFill || 'rgba(0, 0, 0)',
	

		// START - Deprecated
		redBand: options.colorOfRedBand || options.redColor || 'rgba(255, 0, 0, 0.2)',
		yelBand: options.colorOfYellowBand || options.yellowColor || 'rgba(255, 215, 0, 0.2)',
		grnBand: options.colorOfGreenBand || options.greenColor || 'rgba(0, 255, 0, 0.2)'
		// END - Deprecated
	};

	// Add colors to the bands object
	for(var i=this.settings.redFrom.length; i--;){
		this.settings.bands.push({ // Red
			color: this.colors.redBand,
			from: this.settings.redFrom[i],
			to: this.settings.redTo[i]
		});
	}
	for(i=this.settings.yellowFrom.length; i--;){
		this.settings.bands.push({ // Yellow
			color: this.colors.yelBand,
			from: this.settings.yellowFrom[i],
			to: this.settings.yellowTo[i]
		});
	}
	for(i=this.settings.greenFrom.length; i--;){
		this.settings.bands.push({ // Green
			color: this.colors.grnBand,
			from: this.settings.greenFrom[i],
			to: this.settings.greenTo[i]
		});
	}

	// draw context contains a set of values useful for
	// most drawing operations.
	this.relSettings = normalize( this.settings );

	// Private helper functions
	function styleText( context, style ) {
		context.font = style;
		context.mozTextStyle = style; // FF3
	}

	function measureText(context, text) {
		if (context.measureText) {
			return context.measureText(text).width; //-->
		} else if (context.mozMeasureText) { //FF < 3.5
			return context.mozMeasureText(text); //-->
		}
		throw "measureText() not supported!";
	}

	function fillText(context, text, px, py) {
		var width;
		if (context.fillText) {
			return context.fillText(text, px, py);
		} else if (context.mozDrawText) { //FF < 3.5
			context.save();
			context.translate(px, py);
			width = context.mozDrawText(text);
			context.restore();
			return width;
		}
		throw "fillText() not supported!";
	}

	this.drawBackground = function( ) {
		var fill = that.colors.fill,
		rad = [ this.radius, this.radius - 1, this.radius * 0.98, this.radius * 0.95 ],
		i;

		this.c2d.rotate( this.startDeg );
		for ( i = 0; i < fill.length; i++ ) {
			this.c2d.fillStyle = fill[ i ];
			this.c2d.beginPath();
			this.c2d.arc( 0, 0, rad[ i ], 0, this.spanDeg, false );
			
		}
	};

	this.drawRange = function( from, to, style ) {
		if ( to > from ) {
			var span = this.spanDeg * ( to - from ) / 100;

			this.c2d.rotate( this.startDeg );
			this.c2d.fillStyle = style;
			this.c2d.rotate( this.spanDeg * from / 100 );
			this.c2d.beginPath();
			this.c2d.moveTo( this.innerRadius, 0 );
			this.c2d.lineTo( this.outerRadius, 0 );
			this.c2d.arc( 0, 0, this.outerRadius, 0, span, false );
			this.c2d.rotate( span );
			this.c2d.lineTo( this.innerRadius, 0 );
			this.c2d.arc( 0, 0, this.innerRadius, 0, - span, true );
			this.c2d.fill();
		}
	};

	this.drawTicks = function( majorTicks, minorTicks ) {
		var majorSpan,
		i, j;
		// major ticks
		this.c2d.rotate( this.startDeg );
		this.c2d.lineWidth = this.radius * 0.025;
		majorSpan = this.spanDeg / ( majorTicks - 1 );
		for ( i = 0; i < majorTicks; i++ ) {
			this.c2d.beginPath();
			this.c2d.moveTo( this.innerRadius,0 );
			this.c2d.lineTo( this.outerRadius,0 );
			this.c2d.stroke();

			// minor ticks
			if ( i + 1 < majorTicks ) {
				this.c2d.save();
				this.c2d.lineWidth = this.radius * 0.01;
				var minorSpan = majorSpan / ( minorTicks + 1 );
				for ( j = 0; j < minorTicks; j++ ) {
					this.c2d.rotate( minorSpan );
					this.c2d.beginPath();
					this.c2d.moveTo( this.innerRadius + ( this.outerRadius - this.innerRadius ) / 3, 0 );
					this.c2d.lineTo( this.outerRadius, 0 );
					this.c2d.stroke();
				}
				this.c2d.restore();
			}
			this.c2d.rotate( majorSpan );
		}
	};

	this.drawPointer = function( value ) {
		function pointer( ctx ) {
			ctx.c2d.beginPath();
			ctx.c2d.moveTo( - ctx.radius * 0.05, 0 );
			ctx.c2d.lineTo(	0, ctx.radius * 0.05 );
			ctx.c2d.lineTo( ctx.radius * 0.8, 0 );
			ctx.c2d.lineTo( 0, - ctx.radius * 0.05 );
			ctx.c2d.lineTo( - ctx.radius * 0.05, 0 );
		}
		this.c2d.rotate( this.startDeg );
		this.c2d.rotate( this.spanDeg * value / 100 );
		this.c2d.lineWidth = this.radius * 0.015;
		this.c2d.fillStyle = that.colors.pointerFill;
		pointer( this );
		this.c2d.fill();
		this.c2d.strokeStyle = that.colors.pointerStroke; 
		pointer( this );
		this.c2d.stroke();
		// center circle
		
		this.c2d.beginPath();
		this.c2d.arc( 0, 0, this.radius * 0.08, 0, Math.PI * 2, true );
		this.c2d.fill();
		
		this.c2d.beginPath();
		this.c2d.arc( 0, 0, this.radius * 0.08, 0, Math.PI * 2, true );
		this.c2d.stroke();
	};

	this.drawCaption = function( label ) {
		if ( label ) {
			var fontSize = this.radius / 5;
			styleText( this.c2d, fontSize.toFixed(0) + 'px sans-serif');
			var metrics = measureText( this.c2d, label );
			this.c2d.fillStyle = that.colors.text;
			var px = - metrics/ 2;
			var py = - this.radius * 0.4 + fontSize / 2;
			fillText( this.c2d, label, px, py );
		}
	};

	this.drawValues = function( min, max, value, decimals ) {
		var deg, fontSize, metrics, valueText;
		function formatNum( value, decimals ) {
			var ret = value.toFixed( decimals );
			while ( ( decimals > 0 ) && ret.match( /^\d+\.(\d+)?0$/ ) ) {
				decimals -= 1;
				ret = value.toFixed( decimals );
			}
			return ret;
		}

		
		
	};

	this.draw();

	return this;
}

	Gauge.prototype.setValue = function( value ) {
		var that = this,
		pointerValue = (value > that.settings.max) ?
		that.settings.max :  // Nomalize to max value
		(value < that.settings.min) ?
		that.settings.min :  // Nomalize to min value
		value,
		increment = Math.abs( that.settings.pointerValue - pointerValue ) / 20;

		function adjustValue() {
			var span;
			if ( that.settings.pointerValue < pointerValue ) {
				that.settings.pointerValue += increment;
				if ( that.settings.pointerValue + increment >= pointerValue ) {
					that.settings.pointerValue = pointerValue;
				}
			} else {
				that.settings.pointerValue -= increment;
				if ( that.settings.pointerValue - increment <= pointerValue ) {
					that.settings.pointerValue = pointerValue;
				}
			}
			span = that.settings.max - that.settings.min;
			that.relSettings.pointerValue = (that.settings.pointerValue -
			that.settings.min) / (span / 100);
			that.draw();
			if (that.settings.pointerValue != pointerValue) {
				setTimeout(adjustValue, 50); // Draw another frame
			}
		}

		if ( !isNaN(value) && this.settings.value !== value ) {
			this.settings.value = value;
			adjustValue();
		}
	};

	Gauge.prototype.draw = function() {
		var r, g, y;

		if ( ! this.canvas.getContext ) {
			return; //-->
		}

		var drawCtx = {
			c2d: this.canvas.getContext( '2d' ),
			startDeg: Math.PI * 5.5 / 6,
			spanDeg: Math.PI * 13 / 12,
			save: function() {
				this.c2d.save();
			},
			restore: function() {
				this.c2d.restore();
			},
			call: function( fn ) {
				var args = Array.prototype.slice.call( arguments );
				this.save();
				this.translateCenter();
				fn.apply( this, args.slice( 1 ) );
				this.restore();
			},
			clear: function() {
				this.c2d.clearRect( 0, 0, this.width, this.height );
			},
			translateCenter: function() {
				this.c2d.translate( this.centerX, this.centerY );
			}
		};

		drawCtx.width = drawCtx.c2d.canvas.width;
		drawCtx.height = drawCtx.c2d.canvas.height;
		drawCtx.radius = Math.min( drawCtx.width / 2 - 4, drawCtx.height / 2 - 4 );
		drawCtx.innerRadius = drawCtx.radius * 0.7;
		drawCtx.outerRadius = drawCtx.radius * 0.9;
		drawCtx.centerX = drawCtx.radius + 4;
		drawCtx.centerY = drawCtx.radius + 4 + ( drawCtx.radius -
			drawCtx.radius * Math.sin( drawCtx.startDeg ) ) / 2;

		// draw everything
		drawCtx.clear();
		drawCtx.call( this.drawBackground );
		for(var i = this.relSettings.bands.length; i--;) {
			var band = this.relSettings.bands[i];
			drawCtx.call(this.drawRange, band.from, band.to, band.color);

		}
		drawCtx.call( this.drawTicks, this.relSettings.majorTicks, this.relSettings.minorTicks );
		drawCtx.call( this.drawPointer, this.relSettings.pointerValue );
		drawCtx.call( this.drawCaption, this.relSettings.label );
		drawCtx.call( this.drawValues, 
			this.settings.min,
			this.settings.max,
			this.settings.value,
			this.relSettings.decimals );
	};