let crypto = { __disabled__: null };
try {
  crypto = require("crypto");
  // eslint-disable-next-line no-unused-vars
} catch (err) {
  // Crypto support is disabled.
}

// SHA256 function
function sha256(s) {
  if (crypto.__disabled__ === undefined) {
    let hash = crypto.createHash("SHA256");
    hash.update(s);
    return hash.digest("hex");
  } else {
    const chrsz = 8;
    const hexcase = 0;

    const safeAdd = (x, y) => {
      const lsw = (x & 0xffff) + (y & 0xffff);
      const msw = (x >> 16) + (y >> 16) + (lsw >> 16);
      return (msw << 16) | (lsw & 0xffff);
    };

    const S = (X, n) => (X >>> n) | (X << (32 - n));
    const R = (X, n) => X >>> n;
    const Ch = (x, y, z) => (x & y) ^ (~x & z);
    const Maj = (x, y, z) => (x & y) ^ (x & z) ^ (y & z);
    const Sigma0256 = (x) => S(x, 2) ^ S(x, 13) ^ S(x, 22);
    const Sigma1256 = (x) => S(x, 6) ^ S(x, 11) ^ S(x, 25);
    const Gamma0256 = (x) => S(x, 7) ^ S(x, 18) ^ R(x, 3);
    const Gamma1256 = (x) => S(x, 17) ^ S(x, 19) ^ R(x, 10);

    function coreSha256(m, l) {
      const K = new Array(
        0x428a2f98,
        0x71374491,
        0xb5c0fbcf,
        0xe9b5dba5,
        0x3956c25b,
        0x59f111f1,
        0x923f82a4,
        0xab1c5ed5,
        0xd807aa98,
        0x12835b01,
        0x243185be,
        0x550c7dc3,
        0x72be5d74,
        0x80deb1fe,
        0x9bdc06a7,
        0xc19bf174,
        0xe49b69c1,
        0xefbe4786,
        0xfc19dc6,
        0x240ca1cc,
        0x2de92c6f,
        0x4a7484aa,
        0x5cb0a9dc,
        0x76f988da,
        0x983e5152,
        0xa831c66d,
        0xb00327c8,
        0xbf597fc7,
        0xc6e00bf3,
        0xd5a79147,
        0x6ca6351,
        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
      );
      let HASH = new Array(
        0x6a09e667,
        0xbb67ae85,
        0x3c6ef372,
        0xa54ff53a,
        0x510e527f,
        0x9b05688c,
        0x1f83d9ab,
        0x5be0cd19
      );
      let W = new Array(64);
      let a, b, c, d, e, f, g, h;
      let T1, T2;

      m[l >> 5] |= 0x80 << (24 - (l % 32));
      m[(((l + 64) >> 9) << 4) + 15] = l;

      for (let i = 0; i < m.length; i += 16) {
        a = HASH[0];
        b = HASH[1];
        c = HASH[2];
        d = HASH[3];
        e = HASH[4];
        f = HASH[5];
        g = HASH[6];
        h = HASH[7];

        for (let j = 0; j < 64; j++) {
          if (j < 16) W[j] = m[j + i];
          else
            W[j] = safeAdd(
              safeAdd(
                safeAdd(Gamma1256(W[j - 2]), W[j - 7]),
                Gamma0256(W[j - 15])
              ),
              W[j - 16]
            );

          T1 = safeAdd(
            safeAdd(safeAdd(safeAdd(h, Sigma1256(e)), Ch(e, f, g)), K[j]),
            W[j]
          );
          T2 = safeAdd(Sigma0256(a), Maj(a, b, c));

          h = g;
          g = f;
          f = e;
          e = safeAdd(d, T1);
          d = c;
          c = b;
          b = a;
          a = safeAdd(T1, T2);
        }

        HASH[0] = safeAdd(a, HASH[0]);
        HASH[1] = safeAdd(b, HASH[1]);
        HASH[2] = safeAdd(c, HASH[2]);
        HASH[3] = safeAdd(d, HASH[3]);
        HASH[4] = safeAdd(e, HASH[4]);
        HASH[5] = safeAdd(f, HASH[5]);
        HASH[6] = safeAdd(g, HASH[6]);
        HASH[7] = safeAdd(h, HASH[7]);
      }
      return HASH;
    }

    const str2binb = (str) => {
      let bin = Array();
      const mask = (1 << chrsz) - 1;
      for (let i = 0; i < str.length * chrsz; i += chrsz) {
        bin[i >> 5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - (i % 32));
      }
      return bin;
    };

    const Utf8Encode = (string) => {
      string = string.replace(/\r\n/g, "\n");
      let utftext = "";

      for (let n = 0; n < string.length; n++) {
        let 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;
    };

    const binb2hex = (binarray) => {
      const hexTab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
      let str = "";
      for (let i = 0; i < binarray.length * 4; i++) {
        str +=
          hexTab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8 + 4)) & 0xf) +
          hexTab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8)) & 0xf);
      }
      return str;
    };

    s = Utf8Encode(s);
    return binb2hex(coreSha256(str2binb(s), s.length * chrsz));
  }
}

module.exports = sha256;