thi-ng/umbrella

import type { IRandom } from "./api.js";

const INV_MAX = 1 / 2 ** 32;

export abstract class ARandom implements IRandom {
    abstract int(): number;

    float(norm = 1) {
        return this.int() * INV_MAX * norm;
    }

    probability(p: number) {
        return this.float() < p;
    }

    norm(norm = 1) {
        return (this.int() * INV_MAX - 0.5) * 2 * norm;
    }

    normMinMax(min: number, max: number) {
        const x = this.minmax(min, max);
        return this.float() < 0.5 ? x : -x;
    }

    minmax(min: number, max: number) {
        return this.float() * (max - min) + min;
    }

    minmaxInt(min: number, max: number) {
        min |= 0;
        const range = (max | 0) - min;
        return range ? min + (this.int() % range) : min;
    }

    minmaxUint(min: number, max: number) {
        min >>>= 0;
        const range = (max >>> 0) - min;
        return range ? min + (this.int() % range) : min;
    }
}