using System.Net;
using System.Security.Cryptography;
using MySql.Data.MySqlClient;

namespace Server;

public class Register : SecuredRoute
{
    private static void ValidateParams(Dictionary<string, string> paramsToValidate)
    {
        if (
            string.IsNullOrEmpty(paramsToValidate["username"])
            || paramsToValidate["username"].Length > 30
            || paramsToValidate["username"].Length < 4
            || string.IsNullOrEmpty(paramsToValidate["email"])
            || paramsToValidate["email"].Length > 50
            || paramsToValidate["email"].Length < 6
            || string.IsNullOrEmpty(paramsToValidate["password"])
            || paramsToValidate["password"].Length > 50
            || paramsToValidate["password"].Length < 10
        )
        {
            throw new Exception("Wrong parameters");
        }
    }

    public static void HandleRequest(HttpListenerRequest request, HttpListenerResponse response)
    {
        try
        {
            List<string> bodyParamNames = ["username", "email", "password"];
            var bodyParamValues = ExtractBody(request, bodyParamNames);
            ValidateParams(bodyParamValues);

            MySqlCommand cmd = new(CreateInsertQuery("user", bodyParamNames));
            bodyParamValues["password"] = HashPassword(bodyParamValues["password"]);
            cmd = AddValuesToCmd(bodyParamValues, cmd);
            using MySqlConnection conn = new(connectionString);
            conn.Open();
            cmd.Connection = conn;
            cmd.ExecuteNonQuery();

            SendSuccess(response);
        }
        catch (Exception ex)
        {
            SendError(response, ex);
        }
    }

    private static string HashPassword(string password)
    {
        byte[] salt = new byte[16];
        RandomNumberGenerator.Fill(salt);

        using var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 10000, HashAlgorithmName.SHA256);
        byte[] hash = pbkdf2.GetBytes(32);

        byte[] hashBytes = new byte[48]; // 16 (salt) + 32 (hash)
        Array.Copy(salt, 0, hashBytes, 0, 16);
        Array.Copy(hash, 0, hashBytes, 16, 32);

        return Convert.ToBase64String(hashBytes);
    }
}