export interface RNG {
    /** 设置随机数种子 */
    (seed: number): void;

    /** 获取一个 [0,1) 随机数 */
    next(max?: number):  number;

    /** 获取一个 [0,max) 随机整数 */
    nextInt(max: number): number;
}

/**
 * 使用 mulberry32 算法实现的伪随机数生成器
 * 这是一个快速、高质量的 32 位 PRNG
 */
export function createRNG(seed?: number): RNG {
    let currentSeed: number = seed ?? 1;

    function rng(seed: number): void {
        currentSeed = seed;
    }

    rng.next = function(max?: number): number {
        let t = (currentSeed += 0x6d2b79f5);
        t = Math.imul(t ^ (t >>> 15), t | 1);
        t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
        const result = ((t ^ (t >>> 14)) >>> 0) / 4294967296;
        return max !== undefined ? result * max : result;
    };

    rng.nextInt = function(max: number): number {
        return Math.floor(rng.next(max));
    };

    (rng as any).setSeed = function(seed: number): void {
        currentSeed = seed;
    };

    (rng as any).getSeed = function(): number {
        return currentSeed;
    };

    return rng;
}

/** Mulberry32RNG 类实现（用于类型兼容） */
export class Mulberry32RNG {
    private seed: number = 1;

    constructor(seed?: number) {
        if (seed !== undefined) {
            this.seed = seed;
        }
    }

    /** 设置随机数种子 */
    call(seed: number): void {
        this.seed = seed;
    }

    /** 获取一个 [0,1) 随机数 */
    next(max?: number): number {
        let t = (this.seed += 0x6d2b79f5);
        t = Math.imul(t ^ (t >>> 15), t | 1);
        t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
        const result = ((t ^ (t >>> 14)) >>> 0) / 4294967296;
        return max !== undefined ? result * max : result;
    }

    /** 获取一个 [0,max) 随机整数 */
    nextInt(max: number): number {
        return Math.floor(this.next(max));
    }

    /** 重新设置种子 */
    setSeed(seed: number): void {
        this.seed = seed;
    }

    /** 获取当前种子 */
    getSeed(): number {
        return this.seed;
    }
}