// YAAHP - Yet Another AJAX History Plugin for jQuery
// by Andres Olivares (http://www.andyolivares.com - andyolivares@gmail.com)
// Version 0.1

// It uses some code available in different websites for Base64 and UTF-8 Encoding/Decoding

(function($)
{
	var lastLocation = "[]";
	var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
	var historyDefaults = {
		historyChanged: function(token) { },
		interval: 200,
		useJSON: true
	}
	
	$.putHistoryToken = function(token)
	{
		if (historyDefaults.useJSON)
		{
			var tokenJSON = $.toJSON(token);
			location.hash = $.base64encode(tokenJSON);
		}
		else
		{
			location.hash = token;
		}
	}
	
	$.getHistoryToken = function()
	{
		var token;
		
		if (historyDefaults.useJSON)
		{
			var tokenJSON = $.base64decode(location.hash);
			token = $.parseJSON(tokenJSON);
		}
		else
		{
			token = location.hash;
		}
		
		return token;
	}
	
	$.checkHistory = function()
	{
		var currentLocation = location.hash;
		
		if (lastLocation != currentLocation)
		{
			var token = $.getHistoryToken();
			
			lastLocation = currentLocation;
			historyDefaults.callback(token);
		}
	}
	
	$.initHistory = function(options)
	{
		historyDefaults = $.extend(historyDefaults, options);
		
		$.checkHistory();
		setInterval("$.checkHistory()", historyDefaults.interval);
	}
	
	$.base64encode = function(input)
	{
		var output = "";
		var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
		var i = 0;

		input = $.utf8_encode(input);

		while (i < input.length)
		{
			chr1 = input.charCodeAt(i++);
			chr2 = input.charCodeAt(i++);
			chr3 = input.charCodeAt(i++);

			enc1 = chr1 >> 2;
			enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
			enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
			enc4 = chr3 & 63;

			if (isNaN(chr2)) {
				enc3 = enc4 = 64;
			} else if (isNaN(chr3)) {
				enc4 = 64;
			}

			output = output + keyStr.charAt(enc1) + keyStr.charAt(enc2) + keyStr.charAt(enc3) + keyStr.charAt(enc4);
		}

		return output;
	}
	
	$.base64decode = function(input)
	{
		var output = "";
		var chr1, chr2, chr3;
		var enc1, enc2, enc3, enc4;
		var i = 0;

		input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

		while (i < input.length)
		{
			enc1 = keyStr.indexOf(input.charAt(i++));
			enc2 = keyStr.indexOf(input.charAt(i++));
			enc3 = keyStr.indexOf(input.charAt(i++));
			enc4 = keyStr.indexOf(input.charAt(i++));

			chr1 = (enc1 << 2) | (enc2 >> 4);
			chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
			chr3 = ((enc3 & 3) << 6) | enc4;

			output = output + String.fromCharCode(chr1);

			if (enc3 != 64) {
				output = output + String.fromCharCode(chr2);
			}
			if (enc4 != 64) {
				output = output + String.fromCharCode(chr3);
			}
		}

		output = $.utf8_decode(output);

		return output;
	}
	
	$.utf8_encode = function(string)
	{
		string = string.replace(/\r\n/g,"\n");
		var utftext = "";

		for (var n = 0; n < string.length; n++)
		{
			var c = string.charCodeAt(n);

			if (c < 128)
			{
				utftext += String.fromCharCode(c);
			}
			else if((c > 127) && (c < 2048))
			{
				utftext += String.fromCharCode((c >> 6) | 192);
				utftext += String.fromCharCode((c & 63) | 128);
			}
			else
			{
				utftext += String.fromCharCode((c >> 12) | 224);
				utftext += String.fromCharCode(((c >> 6) & 63) | 128);
				utftext += String.fromCharCode((c & 63) | 128);
			}
		}

		return utftext;
	}
	
	$.utf8_decode = function(utftext)
	{
		var string = "";
		var i = 0;
		var c = c1 = c2 = 0;

		while ( i < utftext.length )
		{
			c = utftext.charCodeAt(i);

			if (c < 128)
			{
				string += String.fromCharCode(c);
				i++;
			}
			else if((c > 191) && (c < 224))
			{
				c2 = utftext.charCodeAt(i+1);
				string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
				i += 2;
			}
			else
			{
				c2 = utftext.charCodeAt(i+1);
				c3 = utftext.charCodeAt(i+2);
				string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
				i += 3;
			}
		}

		return string;
	}
}
)(jQuery);