/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  SHA-1 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 Sha1 = {};  // Sha1 namespace

/**
* Generates SHA-1 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
*/
Sha1.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 [§4.2.1]
    var K = [0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xca62c1d6];

    // 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;

    // set initial hash value [§5.3.1]
    var H0 = 0x67452301;
    var H1 = 0xefcdab89;
    var H2 = 0x98badcfe;
    var H3 = 0x10325476;
    var H4 = 0xc3d2e1f0;

    // HASH COMPUTATION [§6.1.2]

    var W = new Array(80); var a, b, c, d, e;
    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 < 80; t++) W[t] = Sha1.ROTL(W[t - 3] ^ W[t - 8] ^ W[t - 14] ^ W[t - 16], 1);

        // 2 - initialise five working variables a, b, c, d, e with previous hash value
        a = H0; b = H1; c = H2; d = H3; e = H4;

        // 3 - main loop
        for (var t = 0; t < 80; t++) {
            var s = Math.floor(t / 20); // seq for blocks of 'f' functions and 'K' constants
            var T = (Sha1.ROTL(a, 5) + Sha1.f(s, b, c, d) + e + K[s] + W[t]) & 0xffffffff;
            e = d;
            d = c;
            c = Sha1.ROTL(b, 30);
            b = a;
            a = T;
        }

        // 4 - compute the new intermediate hash value
        H0 = (H0 + a) & 0xffffffff;  // note 'addition modulo 2^32'
        H1 = (H1 + b) & 0xffffffff;
        H2 = (H2 + c) & 0xffffffff;
        H3 = (H3 + d) & 0xffffffff;
        H4 = (H4 + e) & 0xffffffff;
    }

    return Sha1.toHexStr(H0) + Sha1.toHexStr(H1) +
    Sha1.toHexStr(H2) + Sha1.toHexStr(H3) + Sha1.toHexStr(H4);
}

//
// function 'f' [§4.1.1]
//
Sha1.f = function(s, x, y, z) {
    switch (s) {
        case 0: return (x & y) ^ (~x & z);           // Ch()
        case 1: return x ^ y ^ z;                    // Parity()
        case 2: return (x & y) ^ (x & z) ^ (y & z);  // Maj()
        case 3: return x ^ y ^ z;                    // Parity()
    }
}

//
// rotate left (circular left shift) value x by n positions [§3.2.5]
//
Sha1.ROTL = function(x, n) {
    return (x << n) | (x >>> (32 - n));
}

//
// hexadecimal representation of a number 
//   (note toString(16) is implementation-dependant, and  
//   in IE returns signed numbers when used on full words)
//
Sha1.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;
}

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