/**
 * 随机从数组中选取一个元素
 * @param arr
 */
export function rollPick<T>(arr: T[]): T
export function rollPick<T>(arr: T[], pickCount: number): T[]
export function rollPick<T>(arr: T[], pickCount?: number): T | T[] {
    // 参数验证
    if (!Array.isArray(arr) || arr.length === 0) {
        throw new Error("Input array cannot be empty")
    }

    // 如果没有指定pickCount或pickCount为1,返回单个元素
    if (!pickCount || pickCount === 1) {
        const index = Math.floor(Math.random() * arr.length)
        return arr[index]
    }

    // 验证pickCount
    if (pickCount <= 0) {
        pickCount = 1
    }
    if (pickCount > arr.length) {
        pickCount = arr.length
    }

    // 复制原数组避免修改原数组
    const shuffled = [...arr]

    // Fisher-Yates洗牌算法选取多个元素
    for (let i = shuffled.length - 1; i > 0; i--) {
        const j = Math.floor(Math.random() * (i + 1))
        ;[shuffled[i], shuffled[j]] = [shuffled[j], shuffled[i]]
    }

    // 返回前pickCount个元素
    return shuffled.slice(0, pickCount)
}