class Md5 {
  private static _inst: Md5;
  public static get Instance(): Md5 {
    return this._inst || (this._inst = new Md5());
  }
  public get_md5(str: string): string {
    return this.md5(str);
  }
  split(target: string | any[], step: number, markString: boolean = typeof target === "string") {
    if (typeof target === "string") target = target.split("");
    let result: any[] = target.map(
      (_, index: number) =>
        index % step === 0
          ? Array.from(Array(step).keys()).map((x: number) => target[index + x])
          : []
    )
      .filter((x: any[]) => x.length > 0);
    if (markString) result = result.map((x: any[]) => x.join(""))
    return result;
  }
  padding(str: string | any[], length: number, char: string, tail: boolean = true, isArray: boolean = Array.isArray(str)) {
    let arr;
    if (Array.isArray(str)) {
      arr = str;
    } else {
      arr = str.split("");
    }
    const paddingStr: any[] = this.range(length - str.length).map(() => char);
    const result = tail ? arr.concat(paddingStr) : paddingStr.concat(arr);
    return isArray ? result : result.join("");
  }
  little_endian(charCode: number) {
    return this.split(this.padding(charCode.toString(16), 8, "0", false), 2).reverse().join("");
  }
  range(...args: number[]) {
    const start: number = args.length === 1 ? 0 : args[0];
    const end: number = args.length === 2 ? args[1] : args[0] - 1;
    return Array.from(Array(end - start + 1).keys()).map((x: number) => x + start);
  }
  to_binary(code: number, bit: number = 8, max: number = Math.pow(2, bit) - 1) {
    if (code < 0) throw new Error("code should be greater than: 0");
    if (code > max) throw new Error("code should be less than: " + max);
    return this.padding(code.toString(2), bit, "0", false);
  }
  to_hex(code: number, bit: number = 8, max: number = Math.pow(16, bit) - 1) {
    if (code < 0) throw new Error("code should be greater than: 0");
    if (code > max) throw new Error("code should be less than: " + max);
    return this.padding(code.toString(16), bit, "0", false);
  }
  to_code(str: string) {
    if (str.substr(0, 2).toLowerCase() === "0b") return parseInt(str.substr(2, 8), 2);
    if (str.substr(0, 2).toLowerCase() === "0x") return parseInt(str.substr(2, 8), 16);
  }
  utf16_to_utf8(str: string) {
    return str.split("").map((char: string) => this.utf8_encode(char)).join("");
  }
  utf8_encode(char: string) {
    let utftext = "";
    const c = char.charCodeAt(0);
    if (c < 128) {
      utftext += String.fromCharCode(c);
    } else if ((c > 127) && (c < 2048)) {
      utftext += String.fromCharCode((c >> 6) | 0b11000000);
      utftext += String.fromCharCode((c & 0b00111111) | 0b10000000);
    } else {
      utftext += String.fromCharCode((c >> 12) | 0b11100000);
      utftext += String.fromCharCode(((c >> 6) & 0b00111111) | 0b10000000);
      utftext += String.fromCharCode((c & 0b00111111) | 0b10000000);
    }
    return utftext;
  }
  uint_add(...args: number[]) {
    const t = Uint32Array.from([0]);
    const x = Uint32Array.from(args);
    x.forEach(n => t[0] = t[0] + n);
    return t[0];
  }
  loop_shift_left(n: number, bits: number) {
    return (n << bits) | (n >>> (32 - bits));
  }
  A = 0x67452301;
  B = 0xefcdab89;
  C = 0x98badcfe;
  D = 0x10325476;
  F(b: number, c: number, d: number) {
    return (b & c) | (~b & d);
  }
  G(b: number, c: number, d: number) {
    return (b & d) | (c & ~d);
  }
  H(b: number, c: number, d: number) {
    return b ^ c ^ d;
  }
  I(b: number, c: number, d: number) {
    return c ^ (b | ~d)
  }
  S = [
    7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
    5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20,
    4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
    6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21
  ]
  T(i: number) {
    return Math.floor(Math.pow(2, 32) * Math.abs(Math.sin(i + 1)));
  }
  x_index(i: number) {
    if (i >= 0 && i <= 15) return i;
    if (i >= 16 && i <= 31) return (5 * i + 1) % 16;
    if (i >= 32 && i <= 47) return (3 * i + 5) % 16;
    if (i >= 48 && i <= 63) return (7 * i) % 16;
    return 0;
  }
  wrap(m: any) {
    return (a: number, b: number, c: number, d: number, x: number, s: number, t: number) => {
      // 循环左移
      return this.uint_add(this.loop_shift_left(this.uint_add(a, m(b, c, d), x, t), s), b);
    };
  }
  porcess_message(str: string) {
    const length = str.length;
    const length_of_zero = Math.ceil(length / 64) * 64 - length - 8 - 1;
    str += String.fromCharCode(0b10000000);
    const strArray = this.padding(str.split(""), length + 1 + length_of_zero, String.fromCharCode(0));
    const tail = this.split(this.padding(this.to_binary(length * 8 % Math.pow(2, 64)), 64, "0"), 8).map(x => parseInt(x, 2));
    const head = (strArray as any[]).map(x => x.charCodeAt(0));
    return Uint32Array.from(
      this.split(head.concat(tail), 4)
        .map(x =>
          x.map((t: number) => this.padding(t.toString(16), 2, "0", false)).join("")
        )
        .map(x => parseInt(x, 16))
        .map(x => parseInt(this.little_endian(x), 16))
    )
  }
  fghi(i: number) {
    if (i >= 0 && i <= 15) return this.F;
    if (i >= 16 && i <= 31) return this.G;
    if (i >= 32 && i <= 47) return this.H;
    if (i >= 48 && i <= 63) return this.I;
  }
  fghi_wrapped(i: number) {
    return this.wrap(this.fghi(i));
  }
  //------------------------------------------------
  md5(str: string) {
    str = this.utf16_to_utf8(str);
    const uint32_array = this.porcess_message(str);
    const result = Uint32Array.from([this.A, this.B, this.C, this.D]);
    const chunks = this.split(Array.from(uint32_array), 16);
    for (const chunk of chunks) {
      const a = result[0];
      const b = result[1];
      const c = result[2];
      const d = result[3];
      for (let i = 0; i < 64; i++) {
        result[(4 - i % 4) % 4] = this.fghi_wrapped(i)(result[(4 - i % 4) % 4], result[((4 - i % 4) + 1) % 4], result[((4 - i % 4) + 2) % 4], result[((4 - i % 4) + 3) % 4], chunk[this.x_index(i)], this.S[i], this.T(i))
      }
      result[0] = a + result[0];
      result[1] = b + result[1];
      result[2] = c + result[2];
      result[3] = d + result[3];
    }
    return Array.from(result).map(x => this.little_endian(x)).join("").toLowerCase();
  }
}

export default Md5