using System.Text;
using System.Linq;

namespace FutGalaxy.EaApi.Helper
{
    public class HashConverter
    {
        private string _clearPhrase;

        private static readonly int[] r1Shifts = new int[] { 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22 };
        private static readonly int[] r2Shifts = new int[] { 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20 };
        private static readonly int[] r3Shifts = new int[] { 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23 };
        private static readonly int[] r4Shifts = new int[] { 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21 };


        public string Convert(string plainHash)
        {
            _clearPhrase = plainHash.Replace("/^\\s*/", "").Replace("/\\s*$/", "").Replace("/\\s{2,}/", " ");

            var x = chunkMessage(_clearPhrase);

            var a = 1732584193;
            var b = -271733879;
            var c = -1732584194;
            var d = 271733878;

            for (var i = 0; i < x.Count(); i += 16)
            {
                var tempA = a;
                var tempB = b;
                var tempC = c;
                var tempD = d;

                a = md5_f(a, b, c, d, x[i + 0], r1Shifts[0], -680876936);
                d = md5_f(d, a, b, c, x[i + 1], r1Shifts[1], -389564586);
                c = md5_f(c, d, a, b, x[i + 2], r1Shifts[2], 606105819);
                b = md5_f(b, c, d, a, x[i + 3], r1Shifts[3], -1044525330);
                a = md5_f(a, b, c, d, x[i + 4], r1Shifts[4], -176418897);
                d = md5_f(d, a, b, c, x[i + 5], r1Shifts[5], 1200080426);
                c = md5_f(c, d, a, b, x[i + 6], r1Shifts[6], -1473231341);
                b = md5_f(b, c, d, a, x[i + 7], r1Shifts[7], -45705983);
                a = md5_f(a, b, c, d, x[i + 8], r1Shifts[8], 1770035416);
                d = md5_f(d, a, b, c, x[i + 9], r1Shifts[9], -1958414417);
                c = md5_f(c, d, a, b, x[i + 10], r1Shifts[10], -42063);
                b = md5_f(b, c, d, a, x[i + 11], r1Shifts[11], -1990404162);
                a = md5_f(a, b, c, d, x[i + 12], r1Shifts[12], 1804603682);
                d = md5_f(d, a, b, c, x[i + 13], r1Shifts[13], -40341101);
                c = md5_f(c, d, a, b, x[i + 14], r1Shifts[14], -1502002290);
                b = md5_f(b, c, d, a, x[i + 15], r1Shifts[15], 1236535329);

                a = md5_g(a, b, c, d, x[i + 1], r2Shifts[0], -165796510);
                d = md5_g(d, a, b, c, x[i + 6], r2Shifts[1], -1069501632);
                c = md5_g(c, d, a, b, x[i + 11], r2Shifts[2], 643717713);
                b = md5_g(b, c, d, a, x[i + 0], r2Shifts[3], -373897302);
                a = md5_g(a, b, c, d, x[i + 5], r2Shifts[4], -701558691);
                d = md5_g(d, a, b, c, x[i + 10], r2Shifts[5], 38016083);
                c = md5_g(c, d, a, b, x[i + 15], r2Shifts[6], -660478335);
                b = md5_g(b, c, d, a, x[i + 4], r2Shifts[7], -405537848);
                a = md5_g(a, b, c, d, x[i + 9], r2Shifts[8], 568446438);
                d = md5_g(d, a, b, c, x[i + 14], r2Shifts[9], -1019803690);
                c = md5_g(c, d, a, b, x[i + 3], r2Shifts[10], -187363961);
                b = md5_g(b, c, d, a, x[i + 8], r2Shifts[11], 1163531501);
                a = md5_g(a, b, c, d, x[i + 13], r2Shifts[12], -1444681467);
                d = md5_g(d, a, b, c, x[i + 2], r2Shifts[13], -51403784);
                c = md5_g(c, d, a, b, x[i + 7], r2Shifts[14], 1735328473);
                b = md5_g(b, c, d, a, x[i + 12], r2Shifts[15], -1926607734);

                a = md5_h(a, b, c, d, x[i + 5], r3Shifts[0], -378558);
                d = md5_h(d, a, b, c, x[i + 8], r3Shifts[1], -2022574463);
                c = md5_h(c, d, a, b, x[i + 11], r2Shifts[2], 1839030562);
                b = md5_h(b, c, d, a, x[i + 14], r3Shifts[3], -35309556);
                a = md5_h(a, b, c, d, x[i + 1], r3Shifts[4], -1530992060);
                d = md5_h(d, a, b, c, x[i + 4], r3Shifts[5], 1272893353);
                c = md5_h(c, d, a, b, x[i + 7], r3Shifts[6], -155497632);
                b = md5_h(b, c, d, a, x[i + 10], r3Shifts[7], -1094730640);
                a = md5_h(a, b, c, d, x[i + 13], r3Shifts[8], 681279174);
                d = md5_h(d, a, b, c, x[i + 0], r3Shifts[9], -358537222);
                c = md5_h(c, d, a, b, x[i + 3], r3Shifts[10], -722521979);
                b = md5_h(b, c, d, a, x[i + 6], r3Shifts[11], 76029189);
                a = md5_h(a, b, c, d, x[i + 9], r3Shifts[12], -640364487);
                d = md5_h(d, a, b, c, x[i + 12], r3Shifts[13], -421815835);
                c = md5_h(c, d, a, b, x[i + 15], r3Shifts[14], 530742520);
                b = md5_h(b, c, d, a, x[i + 2], r3Shifts[15], -995338651);

                a = md5_i(a, b, c, d, x[i + 0], r4Shifts[0], -198630844);
                d = md5_i(d, a, b, c, x[i + 7], r4Shifts[1], 1126891415);
                c = md5_i(c, d, a, b, x[i + 14], r4Shifts[2], -1416354905);
                b = md5_i(b, c, d, a, x[i + 5], r4Shifts[3], -57434055);
                a = md5_i(a, b, c, d, x[i + 12], r4Shifts[4], 1700485571);
                d = md5_i(d, a, b, c, x[i + 3], r4Shifts[5], -1894986606);
                c = md5_i(c, d, a, b, x[i + 10], r4Shifts[6], -1051523);
                b = md5_i(b, c, d, a, x[i + 1], r4Shifts[7], -2054922799);
                a = md5_i(a, b, c, d, x[i + 8], r4Shifts[8], 1873313359);
                d = md5_i(d, a, b, c, x[i + 15], r4Shifts[9], -30611744);
                c = md5_i(c, d, a, b, x[i + 6], r4Shifts[10], -1560198380);
                b = md5_i(b, c, d, a, x[i + 13], r4Shifts[11], 1309151649);
                a = md5_i(a, b, c, d, x[i + 4], r4Shifts[12], -145523070);
                d = md5_i(d, a, b, c, x[i + 11], r4Shifts[13], -1120210379);
                c = md5_i(c, d, a, b, x[i + 2], r4Shifts[14], 718787259);
                b = md5_i(b, c, d, a, x[i + 9], r4Shifts[15], -343485551);
                b = md5_i(b, c, d, a, x[i + 9], r4Shifts[15], -343485551);

                a = add(a, tempA);
                b = add(b, tempB);
                c = add(c, tempC);
                d = add(d, tempD);
            }

            return numToHex(a) + numToHex(b) + numToHex(c) + numToHex(d);
        }

        private string numToHex(int num)
        {
            var sb = new StringBuilder();
            var hex_chr = "0123456789abcdef";
            for (var j = 0; j <= 3; j++)
            {
                sb.Append(hex_chr[((num >> (j * 8 + 4)) & 0x0F)]);
                sb.Append(hex_chr[(num >> (j * 8)) & 0x0F]);
            }

            return sb.ToString();
        }

        private int md5_i(int a, int b, int c, int d, int x, int s, int t)
        {
            return cmn(c ^ (b | (~d)), a, b, x, s, t);
        }

        private int md5_h(int a, int b, int c, int d, int x, int s, int t)
        {
            return cmn(b ^ c ^ d, a, b, x, s, t);
        }

        private int md5_g(int a, int b, int c, int d, int x, int s, int t)
        {
            return cmn((b & d) | (c & (~d)), a, b, x, s, t);
        }

        private int md5_f(int a, int b, int c, int d, int x, int s, int t)
        {
            return cmn((b & c) | ((~b) & d), a, b, x, s, t);
        }

        private int cmn(int q, int a, int b, int x, int s, int t)
        {
            return add(bitwiseRotate(add(add(a, q), add(x, t)), s), b);
        }

        private int add(int x, int y)
        {
            var lsw = (x & 0xFFFF) + (y & 0xFFFF);
            var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
            return (msw << 16) | (lsw & 0xFFFF);
        }

        private int bitwiseRotate(int x, int c)
        {
            //var unsigned = x < 0 ? x*(-1) : x ;

            return (x << c) | (int)((uint)x >> (32 - c));
        }

        private int[] chunkMessage(string clearPhrase)
        {
            var nblk = ((clearPhrase.Length + 8) >> 6) + 1;
            var blks = new int[nblk * 16];
            var i = 0;

            for (i = 0; i < nblk * 16; i++)
            {
                blks[i] = 0;
            }
            for (i = 0; i < clearPhrase.Length; i++)
            {
                blks[i >> 2] |= clearPhrase.Substring(i, 1).ToCharArray()[0] << ((i % 4) * 8);
            }

            blks[i >> 2] |= 0x80 << ((i % 4) * 8);
            blks[nblk * 16 - 2] = clearPhrase.Length * 8;

            return blks;
        }
    }
}