/*

Script: Fonts.js
	Contains a class for manipulating font sizes
 
License:
	MIT-style license.
 
Author:
	Adam Fisher
*/
 
/*
Class: Font
	Class to manipulate Font sizes. Inherits properties from both Fx.Style and Cookie
 
Arguments:
	els - the element(s) to apply the font change to. (can be a single element, 'myElement', $('myElement') or an array of elements eg. [$('element1'), $('element2')] or $$(a))
	sizes - an array of possible sizes for the font (integers). eg [11, 14, 18]
	options - object of options for the Font class
 
Options:
	useCookie - specify whether or not the class should save a cookie containing the users preference; true by default
	cookie - object of options for the Cookie. Inherits from Cookie.js
	start - index of the sizes array that should be used when the page loads (the default font size); cookie value will take higher precedent; defaults to 1
	fx - object containing options for the transition. Inherits from Fx.Base
 
Example:
	>var contentChange = new Font('myElement', [11, 14, 18], {useCookie: false, fx: {wait: false}});
	>contentChange.increase();//will change the font size of myElement to the next size up in the sizes array
 
Notes:
	units - The transition uses units of px by default, but em or pt can be used by specifying eg. fx: {unit: 'pt'} in the options argument
*/
 
var FontSizer = new Class({
	options: {
		useCookie: false,
		start: 1,
		fx: {
			duration: 200
		}
	},
 
	initialize: function(els, sizes, options){
		function sortArray(a, b){return a - b;}
		this.options = $merge({
    		useCookie: false,
    		start: 2,
    		fx: {
    			duration: 200
    		}
    	}, options);
		this.els = ($type(els) == 'array') ? els : [els];
		this.sizes = sizes.sort(sortArray);
        this.current = (this.options.useCookie && Cookie.get('fontSize')) ? Cookie.get('fontSize').toInt() : this.options['start'];
		this.fx = new Fx.Elements(this.els, this.options['fx']);
		this.set(this.options['start']);
	},
 
	/*
	Property: change
		changes the current index of the sizes array and transitions to the new size (used internally)
 
	Arguments:
		by - integer, current index of sizes array is changed by this amount, and font size is transitioned to new value if it exists
 
	Example:
		(start code)
		var fontChange = new Font([$('myElement'), $('anotherElement')], [11, 14, 18, 21]);
		fontChange.change(-2); //steps down font size of 'myElement' and 'anotherElement' by 2 in the sizes array
		(end)
	*/
 
	change: function(by){
		if (!this.sizes[this.current + by] || this.fx.timer){return;}
		this.current = this.current + by;
		var o = {};
		this.els.each(function(el, i){
			o[i] = {'fontSize': this.sizes[this.current] + '"' + this.options['units'] + '"'};
		}.bind(this));
		this.fx.start(o).chain(function(){this.busy = false;}.bind(this));
		if (this.options.useCookie) Cookie.set('fontSize', this.current, this.options['cookie']);
	},
 
	/*
	Property: increase
		Increases the font size by one 'step' (as specified in the sizes array)
 
	Example:
		(start code)
		var fontChange = new Font('myElement', [11, 14, 18, 21]);
		fontChange.increase(); //steps up font size of 'myElement'
		(end)
	*/
 
	increase: function() {
		this.change(1);
	},
 
	/*
	Property: decrease
		See increase - decreases the font size by one 'step' (as specified in the sizes array)
	*/
 
	decrease: function() {
		this.change(-1);
	},
 
	/*
	Property: max
		transitions the font size to the maximum value in the array
 
	Example:
		(start code)
		var fontChange = new Font('myElement', [11, 14, 18, 21]);
		fontChange.increase(); //steps up font size of 'myElement'
		(end)
	*/
 
	max: function() {
		this.change((this.sizes.length - 1) - this.current);
	},
 
	/*
	Property: min
		See max - transitions the font size to the minimum value in the array
	*/
 
	min: function() {
		this.change(-this.current);
	},
 
	/*
	Property: set
		transitions the font size to a specified value in the array
 
	Arguments:
		value - the index of the value you would like to transition to
 
	Example:
		(start code)
		var fontChange = new Font('myElement', [11, 14, 18, 21]);
		fontChange.set(2); //transitions the font size of myElement to 18px
		(end)
	*/
 
	set: function(value) {
		this.change(value - this.current);
	}
});