/* tslint:disable:no-bitwise */
/* eslint no-invalid-this: "off" */

// Mersenne Twister from https://gist.github.com/banksean/300494
/*
  A C-program for MT19937, with initialization improved 2002/1/26.
  Coded by Takuji Nishimura and Makoto Matsumoto.

  Before using, initialize the state by using init_genrand(seed)
  or init_by_array(init_key, key_length).

  Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions
  are met:

  1. Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.

  2. Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.

  3. The names of its contributors may not be used to endorse or promote
  products derived from this software without specific prior written
  permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


  Any feedback is very welcome.
  http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
  email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
*/

export class MersenneTwister {
    private N: number

    private M: number

    private MATRIX_A: number

    private UPPER_MASK: number

    private LOWER_MASK: number

    private mt: any[]

    private mti: number

    constructor(seed: number) {
        if (seed === undefined) {
            // kept random number same size as time used previously to ensure no unexpected results downstream
            seed = Math.floor(Math.random() * Math.pow(10,13))
        }
        /* Period parameters */
        this.N = 624
        this.M = 397
        this.MATRIX_A = 0x9908b0df   /* constant vector a */
        this.UPPER_MASK = 0x80000000 /* most significant w-r bits */
        this.LOWER_MASK = 0x7fffffff /* least significant r bits */

        this.mt = new Array(this.N) /* the array for the state vector */
        this.mti = this.N + 1 /* mti==N + 1 means mt[N] is not initialized */

        this.init_genrand(seed)
    }

    /* generates a random number on [0,0xffffffff]-interval */
    public genrand_int32(): number {
        let y
        const mag01 = new Array(0x0, this.MATRIX_A)
        /* mag01[x] = x * MATRIX_A  for x=0,1 */

        if (this.mti >= this.N) { /* generate N words at one time */
            let kk

            if (this.mti === this.N + 1) {   /* if init_genrand() has not been called, */
                this.init_genrand(5489) /* a default initial seed is used */
            }
            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) ^ 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) ^ 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) ^ mag01[y & 0x1]

            this.mti = 0
        }

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

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

        return y >>> 0
    }

    /* generates a random number on [0,0x7fffffff]-interval */
    public genrand_int31 = (): number => (this.genrand_int32() >>> 1)

    /* generates a random number on [0,1]-real-interval */
    public genrand_real1 = (): number => this.genrand_int32() * (1.0 / 4294967295.0)
        /* divided by 2^32-1 */


    /* generates a random number on [0,1)-real-interval */
    public random = (): number => this.genrand_int32() * (1.0 / 4294967296.0)
        /* divided by 2^32 */


    /* generates a random number on (0,1)-real-interval */
    public genrand_real3 = (): number => (this.genrand_int32() + 0.5) * (1.0 / 4294967296.0)
        /* divided by 2^32 */


    /* generates a random number on [0,1) with 53-bit resolution*/
    public genrand_res53 = (): number => {
        const a = this.genrand_int32()>>>5
        const b = this.genrand_int32()>>>6
        return (a * 67108864.0 + b) * (1.0 / 9007199254740992.0)
    }

    /* initializes mt[N] with a seed */
    private init_genrand = (s: number) => {
        this.mt[0] = s >>> 0
        for (this.mti = 1; this.mti < this.N; this.mti++) {
            s = this.mt[this.mti - 1] ^ (this.mt[this.mti - 1] >>> 30)
            this.mt[this.mti] = (((((s & 0xffff0000) >>> 16) * 1812433253) << 16) + (s & 0x0000ffff) * 1812433253) + this.mti
            /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
            /* In the previous versions, MSBs of the seed affect   */
            /* only MSBs of the array mt[].                        */
            /* 2002/01/09 modified by Makoto Matsumoto             */
            this.mt[this.mti] >>>= 0
            /* for >32 bit machines */
        }
    }

    /* initialize by an array with array-length */
    /* init_key is the array for initializing keys */
    /* key_length is its length */
    /* slight change for C++, 2004/2/26 */
    private init_by_array = (init_key: number[], key_length: number) => {
        let i = 1
        let j = 0
        let k
        let s

        this.init_genrand(19650218)
        k = (this.N > key_length ? this.N : key_length)
        for (; k; k--) {
            s = this.mt[i - 1] ^ (this.mt[i - 1] >>> 30)
            this.mt[i] = (this.mt[i] ^ (((((s & 0xffff0000) >>> 16) * 1664525) << 16) + ((s & 0x0000ffff) * 1664525))) + init_key[j] + j /* non linear */
            this.mt[i] >>>= 0 /* for WORDSIZE > 32 machines */
            i++
            j++
            if (i >= this.N) { this.mt[0] = this.mt[this.N - 1]; i = 1 }
            if (j >= key_length) { j = 0 }
        }
        for (k = this.N - 1; k; k--) {
            s = this.mt[i - 1] ^ (this.mt[i - 1] >>> 30)
            this.mt[i] = (this.mt[i] ^ (((((s & 0xffff0000) >>> 16) * 1566083941) << 16) + (s & 0x0000ffff) * 1566083941)) - i /* non linear */
            this.mt[i] >>>= 0
            i++
            if (i >= this.N) { this.mt[0] = this.mt[this.N - 1]; i = 1 }
        }

        this.mt[0] = 0x80000000 /* MSB is 1; assuring non-zero initial array */
    }
}
