/*
  MD5 code originally written by Joseph Myers
  (Public Domain per https://github.com/satazor/js-spark-md5/issues/45)
  http://www.myersdaily.org/joseph/javascript/md5-text.html
  http://www.myersdaily.org/joseph/javascript/md5.js

  Lightly cleaned up and otherwise modified by Tony Garnock-Jones
  <tonyg@leastfixedpoint.com>, August 2022, to work with Uint8Array and
  TypeScript.
*/

function md5cycle(x: Uint32Array, k: Uint32Array) {
    let a = x[0], b = x[1], c = x[2], d = x[3];

    a = ff(a, b, c, d, k[0], 7, -680876936);
    d = ff(d, a, b, c, k[1], 12, -389564586);
    c = ff(c, d, a, b, k[2], 17, 606105819);
    b = ff(b, c, d, a, k[3], 22, -1044525330);
    a = ff(a, b, c, d, k[4], 7, -176418897);
    d = ff(d, a, b, c, k[5], 12, 1200080426);
    c = ff(c, d, a, b, k[6], 17, -1473231341);
    b = ff(b, c, d, a, k[7], 22, -45705983);
    a = ff(a, b, c, d, k[8], 7, 1770035416);
    d = ff(d, a, b, c, k[9], 12, -1958414417);
    c = ff(c, d, a, b, k[10], 17, -42063);
    b = ff(b, c, d, a, k[11], 22, -1990404162);
    a = ff(a, b, c, d, k[12], 7, 1804603682);
    d = ff(d, a, b, c, k[13], 12, -40341101);
    c = ff(c, d, a, b, k[14], 17, -1502002290);
    b = ff(b, c, d, a, k[15], 22, 1236535329);

    a = gg(a, b, c, d, k[1], 5, -165796510);
    d = gg(d, a, b, c, k[6], 9, -1069501632);
    c = gg(c, d, a, b, k[11], 14, 643717713);
    b = gg(b, c, d, a, k[0], 20, -373897302);
    a = gg(a, b, c, d, k[5], 5, -701558691);
    d = gg(d, a, b, c, k[10], 9, 38016083);
    c = gg(c, d, a, b, k[15], 14, -660478335);
    b = gg(b, c, d, a, k[4], 20, -405537848);
    a = gg(a, b, c, d, k[9], 5, 568446438);
    d = gg(d, a, b, c, k[14], 9, -1019803690);
    c = gg(c, d, a, b, k[3], 14, -187363961);
    b = gg(b, c, d, a, k[8], 20, 1163531501);
    a = gg(a, b, c, d, k[13], 5, -1444681467);
    d = gg(d, a, b, c, k[2], 9, -51403784);
    c = gg(c, d, a, b, k[7], 14, 1735328473);
    b = gg(b, c, d, a, k[12], 20, -1926607734);

    a = hh(a, b, c, d, k[5], 4, -378558);
    d = hh(d, a, b, c, k[8], 11, -2022574463);
    c = hh(c, d, a, b, k[11], 16, 1839030562);
    b = hh(b, c, d, a, k[14], 23, -35309556);
    a = hh(a, b, c, d, k[1], 4, -1530992060);
    d = hh(d, a, b, c, k[4], 11, 1272893353);
    c = hh(c, d, a, b, k[7], 16, -155497632);
    b = hh(b, c, d, a, k[10], 23, -1094730640);
    a = hh(a, b, c, d, k[13], 4, 681279174);
    d = hh(d, a, b, c, k[0], 11, -358537222);
    c = hh(c, d, a, b, k[3], 16, -722521979);
    b = hh(b, c, d, a, k[6], 23, 76029189);
    a = hh(a, b, c, d, k[9], 4, -640364487);
    d = hh(d, a, b, c, k[12], 11, -421815835);
    c = hh(c, d, a, b, k[15], 16, 530742520);
    b = hh(b, c, d, a, k[2], 23, -995338651);

    a = ii(a, b, c, d, k[0], 6, -198630844);
    d = ii(d, a, b, c, k[7], 10, 1126891415);
    c = ii(c, d, a, b, k[14], 15, -1416354905);
    b = ii(b, c, d, a, k[5], 21, -57434055);
    a = ii(a, b, c, d, k[12], 6, 1700485571);
    d = ii(d, a, b, c, k[3], 10, -1894986606);
    c = ii(c, d, a, b, k[10], 15, -1051523);
    b = ii(b, c, d, a, k[1], 21, -2054922799);
    a = ii(a, b, c, d, k[8], 6, 1873313359);
    d = ii(d, a, b, c, k[15], 10, -30611744);
    c = ii(c, d, a, b, k[6], 15, -1560198380);
    b = ii(b, c, d, a, k[13], 21, 1309151649);
    a = ii(a, b, c, d, k[4], 6, -145523070);
    d = ii(d, a, b, c, k[11], 10, -1120210379);
    c = ii(c, d, a, b, k[2], 15, 718787259);
    b = ii(b, c, d, a, k[9], 21, -343485551);

    x[0] = add32(a, x[0]);
    x[1] = add32(b, x[1]);
    x[2] = add32(c, x[2]);
    x[3] = add32(d, x[3]);

}

function cmn(q: number, a: number, b: number, x: number, s: number, t: number): number {
    a = add32(add32(a, q), add32(x, t));
    return add32((a << s) | (a >>> (32 - s)), b);
}

function ff(a: number, b: number, c: number, d: number, x: number, s: number, t: number): number {
    return cmn((b & c) | ((~b) & d), a, b, x, s, t);
}

function gg(a: number, b: number, c: number, d: number, x: number, s: number, t: number): number {
    return cmn((b & d) | (c & (~d)), a, b, x, s, t);
}

function hh(a: number, b: number, c: number, d: number, x: number, s: number, t: number): number {
    return cmn(b ^ c ^ d, a, b, x, s, t);
}

function ii(a: number, b: number, c: number, d: number, x: number, s: number, t: number): number {
    return cmn(c ^ (b | (~d)), a, b, x, s, t);
}

function md51(s: Uint8Array): Uint8Array {
    const n = s.length;
    const state = Uint32Array.from([1732584193, -271733879, -1732584194, 271733878]);

    let i: number;

    for (i = 64; i <= s.length; i += 64) {
        md5cycle(state, md5blk(s.subarray(i - 64, i)));
    }
    s = s.subarray(i - 64);

    const tail = new Uint32Array(16);
    for (i = 0; i < s.length; i++) tail[i >> 2] |= s[i] << ((i % 4) << 3);
    tail[i >> 2] |= 0x80 << ((i % 4) << 3);

    if (i > 55) {
        md5cycle(state, tail);
        for (i = 0; i < 16; i++) tail[i] = 0;
    }
    tail[14] = n * 8;
    md5cycle(state, tail);

    return new Uint8Array(state.buffer);
}

function md5blk(s: Uint8Array): Uint32Array {
    const md5blks = new Uint32Array(16);
    let j = 0;
    for (let i = 0; i < md5blks.length; i++, j+=4) {
        md5blks[i] = s[j] + (s[j + 1] << 8) + (s[j + 2] << 16) + (s[j + 3] << 24);
    }
    return md5blks;
}

const HEX_CHR = '0123456789abcdef';
function rhex(digits: Array<string>, n: number): void {
    digits.push(HEX_CHR[(n >> 4) & 15]);
    digits.push(HEX_CHR[n & 15]);
}

export function hex(x: Uint8Array): string {
    const result: Array<string> = [];
    for (let i = 0; i < x.length; i++) rhex(result, x[i]);
    return result.join('');
}

export function md5(s: Uint8Array): string {
    return hex(md51(s));
}

function add32(a: number, b: number): number {
    return (a + b) & 0xFFFFFFFF;
}

if (md5(new TextEncoder().encode('hello')) != '5d41402abc4b2a76b9719d911017c592') {
    throw new Error('invalid md5 result');
}