/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * JavaScript version of Mersenne Twister
 *
 * @author Yasuharu Okada
 *
 */

export default class MersenneTwister {
  N = 624;
  M = 397;
  UPPER_MASK = 0x80000000;
  LOWER_MASK = 0x7fffffff;
  MAG01 = new Int32Array([0, 0x9908b0df]);
  mt = new Int32Array(this.N);
  mti = 625; // The array for the state vector.

  constructor() {}

  seed(s) {
    this.mt[0] = s | 0;
    for (this.mti = 1; this.mti < this.N; this.mti++) {
      this.mt[this.mti] =
        Math.imul(
          1812433253,
          this.mt[this.mti - 1] ^ (this.mt[this.mti - 1] >>> 30)
        ) + this.mti;
    }
  }

  export_state() {
    // eslint-disable-line camelcase
    return [this.mt, this.mti];
  }

  import_state(s) {
    // eslint-disable-line camelcase
    this.mt = s[0];
    this.mti = s[1];
  }

  export_mta() {
    // eslint-disable-line camelcase
    return this.mt;
  }

  import_mta(_mta) {
    // eslint-disable-line camelcase
    this.mt = _mta;
  }

  export_mti() {
    // eslint-disable-line camelcase
    return this.mti;
  }

  import_mti(_mti) {
    // eslint-disable-line camelcase
    this.mti = _mti;
  }

  int32() {
    let y, kk;

    if (this.mti >= this.N) {
      /* generate N words at one time */
      for (kk = 0; kk < this.N - this.M; kk++) {
        y =
          (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK);
        this.mt[kk] = this.mt[kk + this.M] ^ (y >>> 1) ^ this.MAG01[y & 0x1];
      }
      for (; kk < this.N - 1; kk++) {
        y =
          (this.mt[kk] & this.UPPER_MASK) | (this.mt[kk + 1] & this.LOWER_MASK);
        this.mt[kk] =
          this.mt[kk + (this.M - this.N)] ^ (y >>> 1) ^ this.MAG01[y & 0x1];
      }
      y =
        (this.mt[this.N - 1] & this.UPPER_MASK) |
        (this.mt[0] & this.LOWER_MASK);
      this.mt[this.N - 1] =
        this.mt[this.M - 1] ^ (y >>> 1) ^ this.MAG01[y & 0x1];
      this.mti = 0;
    }

    y = this.mt[this.mti++];

    /* Tempering */
    y = y ^ (y >>> 11);
    y = y ^ ((y << 7) & 0x9d2c5680);
    y = y ^ ((y << 15) & 0xefc60000);
    y = y ^ (y >>> 18);

    return y >>> 0;
  }

  real2() {
    return (
      ((this.int32() >>> 5) * 67108864.0 + (this.int32() >>> 6)) /
      9007199254740992.0
    );
  }
}