export function generateStealthId(length: number = 32): string {
    const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    const base = chars.length;

    const randomChars = (count: number): string =>
        Array.from({ length: count }, () => chars.charAt(Math.floor(Math.random() * base))).join('');

    // 生成前 length - 1 位
    const body = randomChars(length - 1);

    // 将 body 每个字符的 charCode 累加，再 mod base，作为校验位
    const sum = body.split('').reduce((acc, c) => acc + c.charCodeAt(0), 0);
    const checksum = chars.charAt(sum % base);

    return body + checksum;
}

export function isStealthId(id: string): boolean {
    const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    const base = chars.length;

    if (!/^[A-Za-z0-9]{32}$/.test(id)) return false;

    const body = id.slice(0, -1);
    const expectedChecksum = id.slice(-1);

    const sum = body.split('').reduce((acc, c) => acc + c.charCodeAt(0), 0);
    const checksum = chars.charAt(sum % base);

    return checksum === expectedChecksum;
}