using System.Security.Cryptography;
using System.Text;

namespace Application.Helpers;

/// <summary>
/// 개발자 포털용 ClientID/Secret/PAT 생성 및 해시 헬퍼.
/// </summary>
public static class ApiTokenGenerator
{
    private const string Base62Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

    public static string GenerateClientID() => "dpot_client_" + RandomBase62(24);

    public static string GenerateClientSecret() => "dpot_secret_" + RandomBase62(40);

    public static string GeneratePat() => "dpot_pat_" + RandomBase62(40);

    public static string Hash(string token)
    {
        var bytes = Encoding.UTF8.GetBytes(token);
        var hash = SHA256.HashData(bytes);
        return Convert.ToHexString(hash).ToLowerInvariant();
    }

    public static string Hint(string token) => token.Length >= 4 ? token[^4..] : token;

    private static string RandomBase62(int length)
    {
        var sb = new StringBuilder(length);
        var bytes = RandomNumberGenerator.GetBytes(length);
        foreach (var b in bytes)
        {
            sb.Append(Base62Chars[b % Base62Chars.Length]);
        }
        return sb.ToString();
    }
}