angular.module('em-utils', [], function($provide) {

    var makeCRCTable = function(){
        var c;
        var crcTable = [];
        for(var n =0; n < 256; n++){
            c = n;
            for(var k =0; k < 8; k++){
                c = ((c&1) ? (0xEDB88320 ^ (c >>> 1)) : (c >>> 1));
            }
            crcTable[n] = c;
        }
        return crcTable;
    }
    var crcTable = makeCRCTable();

    var crc32 = function(str, init) {
        var crc = (typeof init === 'undefined') ? 0 ^ (-1) : init^0xFFFFFFFF;
        //var crc = 0 ^ (-1);
    
        for (var i = 0; i < str.length; i++ ) {
            crc = (crc >>> 8) ^ crcTable[(crc ^ str.charCodeAt(i)) & 0xFF];
        }
    
        return (crc ^ (-1)) >>> 0;
    };

	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
	/*  SHA-256 implementation in JavaScript | (c) Chris Veness 2002-2010 | www.movable-type.co.uk    */
	/*   - see http://csrc.nist.gov/groups/ST/toolkit/secure_hashing.html                             */
	/*         http://csrc.nist.gov/groups/ST/toolkit/examples.html                                   */
	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

	var Sha256 = {};  // Sha256 namespace

	/**
	 * Generates SHA-256 hash of string
	 *
	 * @param {String} msg                String to be hashed
	 * @param {Boolean} [utf8encode=true] Encode msg as UTF-8 before generating hash
	 * @returns {String}                  Hash of msg as hex character string
	 */
	Sha256.hash = function(msg, utf8encode) {
			utf8encode =  (typeof utf8encode == 'undefined') ? true : utf8encode;
			
			// convert string to UTF-8, as SHA only deals with byte-streams
			if (utf8encode) msg = Utf8.encode(msg);
			
			// constants [§4.2.2]
			var K = [0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
							 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
							 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
							 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
							 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
							 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
							 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
							 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2];
			// initial hash value [§5.3.1]
			var H = [0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19];

			// PREPROCESSING 
	 
			msg += String.fromCharCode(0x80);  // add trailing '1' bit (+ 0's padding) to string [§5.1.1]

			// convert string msg into 512-bit/16-integer blocks arrays of ints [§5.2.1]
			var l = msg.length/4 + 2;  // length (in 32-bit integers) of msg + '1' + appended length
			var N = Math.ceil(l/16);   // number of 16-integer-blocks required to hold 'l' ints
			var M = new Array(N);

			for (var i=0; i<N; i++) {
					M[i] = new Array(16);
					for (var j=0; j<16; j++) {  // encode 4 chars per integer, big-endian encoding
							M[i][j] = (msg.charCodeAt(i*64+j*4)<<24) | (msg.charCodeAt(i*64+j*4+1)<<16) | 
												(msg.charCodeAt(i*64+j*4+2)<<8) | (msg.charCodeAt(i*64+j*4+3));
					} // note running off the end of msg is ok 'cos bitwise ops on NaN return 0
			}
			// add length (in bits) into final pair of 32-bit integers (big-endian) [§5.1.1]
			// note: most significant word would be (len-1)*8 >>> 32, but since JS converts
			// bitwise-op args to 32 bits, we need to simulate this by arithmetic operators
			M[N-1][14] = ((msg.length-1)*8) / Math.pow(2, 32); M[N-1][14] = Math.floor(M[N-1][14])
			M[N-1][15] = ((msg.length-1)*8) & 0xffffffff;


			// HASH COMPUTATION [§6.1.2]

			var W = new Array(64); var a, b, c, d, e, f, g, h;
			for (var i=0; i<N; i++) {

					// 1 - prepare message schedule 'W'
					for (var t=0;  t<16; t++) W[t] = M[i][t];
					for (var t=16; t<64; t++) W[t] = (Sha256.sigma1(W[t-2]) + W[t-7] + Sha256.sigma0(W[t-15]) + W[t-16]) & 0xffffffff;

					// 2 - initialise working variables a, b, c, d, e, f, g, h with previous hash value
					a = H[0]; b = H[1]; c = H[2]; d = H[3]; e = H[4]; f = H[5]; g = H[6]; h = H[7];

					// 3 - main loop (note 'addition modulo 2^32')
					for (var t=0; t<64; t++) {
							var T1 = h + Sha256.Sigma1(e) + Sha256.Ch(e, f, g) + K[t] + W[t];
							var T2 = Sha256.Sigma0(a) + Sha256.Maj(a, b, c);
							h = g;
							g = f;
							f = e;
							e = (d + T1) & 0xffffffff;
							d = c;
							c = b;
							b = a;
							a = (T1 + T2) & 0xffffffff;
					}
					 // 4 - compute the new intermediate hash value (note 'addition modulo 2^32')
					H[0] = (H[0]+a) & 0xffffffff;
					H[1] = (H[1]+b) & 0xffffffff; 
					H[2] = (H[2]+c) & 0xffffffff; 
					H[3] = (H[3]+d) & 0xffffffff; 
					H[4] = (H[4]+e) & 0xffffffff;
					H[5] = (H[5]+f) & 0xffffffff;
					H[6] = (H[6]+g) & 0xffffffff; 
					H[7] = (H[7]+h) & 0xffffffff; 
			}

			return Sha256.toHexStr(H[0]) + Sha256.toHexStr(H[1]) + Sha256.toHexStr(H[2]) + Sha256.toHexStr(H[3]) + 
						 Sha256.toHexStr(H[4]) + Sha256.toHexStr(H[5]) + Sha256.toHexStr(H[6]) + Sha256.toHexStr(H[7]);
	}

	Sha256.ROTR = function(n, x) { return (x >>> n) | (x << (32-n)); }
	Sha256.Sigma0 = function(x) { return Sha256.ROTR(2,  x) ^ Sha256.ROTR(13, x) ^ Sha256.ROTR(22, x); }
	Sha256.Sigma1 = function(x) { return Sha256.ROTR(6,  x) ^ Sha256.ROTR(11, x) ^ Sha256.ROTR(25, x); }
	Sha256.sigma0 = function(x) { return Sha256.ROTR(7,  x) ^ Sha256.ROTR(18, x) ^ (x>>>3);  }
	Sha256.sigma1 = function(x) { return Sha256.ROTR(17, x) ^ Sha256.ROTR(19, x) ^ (x>>>10); }
	Sha256.Ch = function(x, y, z)  { return (x & y) ^ (~x & z); }
	Sha256.Maj = function(x, y, z) { return (x & y) ^ (x & z) ^ (y & z); }

	//
	// hexadecimal representation of a number 
	//   (note toString(16) is implementation-dependant, and  
	//   in IE returns signed numbers when used on full words)
	//
	Sha256.toHexStr = function(n) {
		var s="", v;
		for (var i=7; i>=0; i--) { v = (n>>>(i*4)) & 0xf; s += v.toString(16); }
		return s;
	}


	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
	/*  Utf8 class: encode / decode between multi-byte Unicode characters and UTF-8 multiple          */
	/*              single-byte character encoding (c) Chris Veness 2002-2010                         */
	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

	var Utf8 = {};  // Utf8 namespace

	/**
	 * Encode multi-byte Unicode string into utf-8 multiple single-byte characters 
	 * (BMP / basic multilingual plane only)
	 *
	 * Chars in range U+0080 - U+07FF are encoded in 2 chars, U+0800 - U+FFFF in 3 chars
	 *
	 * @param {String} strUni Unicode string to be encoded as UTF-8
	 * @returns {String} encoded string
	 */
	Utf8.encode = function(strUni) {
		// use regular expressions & String.replace callback function for better efficiency 
		// than procedural approaches
		var strUtf = strUni.replace(
				/[\u0080-\u07ff]/g,  // U+0080 - U+07FF => 2 bytes 110yyyyy, 10zzzzzz
				function(c) { 
					var cc = c.charCodeAt(0);
					return String.fromCharCode(0xc0 | cc>>6, 0x80 | cc&0x3f); }
			);
		strUtf = strUtf.replace(
				/[\u0800-\uffff]/g,  // U+0800 - U+FFFF => 3 bytes 1110xxxx, 10yyyyyy, 10zzzzzz
				function(c) { 
					var cc = c.charCodeAt(0); 
					return String.fromCharCode(0xe0 | cc>>12, 0x80 | cc>>6&0x3F, 0x80 | cc&0x3f); }
			);
		return strUtf;
	}

	/**
	 * Decode utf-8 encoded string back into multi-byte Unicode characters
	 *
	 * @param {String} strUtf UTF-8 string to be decoded back to Unicode
	 * @returns {String} decoded string
	 */
	Utf8.decode = function(strUtf) {
		// note: decode 3-byte chars first as decoded 2-byte strings could appear to be 3-byte char!
		var strUni = strUtf.replace(
				/[\u00e0-\u00ef][\u0080-\u00bf][\u0080-\u00bf]/g,  // 3-byte chars
				function(c) {  // (note parentheses for precence)
					var cc = ((c.charCodeAt(0)&0x0f)<<12) | ((c.charCodeAt(1)&0x3f)<<6) | ( c.charCodeAt(2)&0x3f); 
					return String.fromCharCode(cc); }
			);
		strUni = strUni.replace(
				/[\u00c0-\u00df][\u0080-\u00bf]/g,                 // 2-byte chars
				function(c) {  // (note parentheses for precence)
					var cc = (c.charCodeAt(0)&0x1f)<<6 | c.charCodeAt(1)&0x3f;
					return String.fromCharCode(cc); }
			);
		return strUni;
	}

	/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

	$provide.factory('crc32', function() {
		return crc32;
	});

	$provide.factory('sha256', function() {
		return Sha256;
	});
});