namespace DigitalData.Auth.Claims
{
    /// <summary>
    /// Provides helpers for building cookie names used in the DigitalData.Auth ecosystem.
    /// </summary>
    public static class CookieNames
    {
        private const string ReceiverSuffix = "SignFLOWReceiver.";

        /// <summary>
        /// Builds the cookie name for an envelope receiver token.
        /// </summary>
        /// <param name="defaultCookieName">The base cookie name configured in <c>AuthApiParams</c>.</param>
        /// <param name="key">The unique envelope receiver key.</param>
        /// <returns>A cookie name in the format <c>{defaultCookieName}SignFLOWReceiver.{key}</c>.</returns>
        public static string GetEnvelopeReceiverCookieName(string defaultCookieName, string key)
            => defaultCookieName + ReceiverSuffix + key;

        /// <summary>
        /// Extracts the envelope receiver key from a cookie name, or returns <see langword="null"/> if the cookie name does not match the expected format.
        /// </summary>
        /// <param name="cookieName">The full cookie name in the format <c>{defaultCookieName}SignFLOWReceiver.{key}</c>.</param>
        /// <param name="defaultCookieName">The base cookie name configured in <c>AuthApiParams</c>.</param>
        /// <returns>The envelope receiver key, or <see langword="null"/> if the cookie name does not match the expected format.</returns>
        public static string? GetEnvelopeReceiverKeyOrDefault(string cookieName, string defaultCookieName)
        {
            var prefix = defaultCookieName + ReceiverSuffix;
            return cookieName.StartsWith(prefix, StringComparison.Ordinal)
                ? cookieName[prefix.Length..]
                : null;
        }

        /// <summary>
        /// Tries to extract the envelope receiver key from a cookie name.
        /// </summary>
        /// <param name="cookieName">The full cookie name in the format <c>{defaultCookieName}SignFLOWReceiver.{key}</c>.</param>
        /// <param name="defaultCookieName">The base cookie name configured in <c>AuthApiParams</c>.</param>
        /// <param name="key">The extracted envelope receiver key if the cookie name matches the expected format; otherwise <see langword="null"/>.</param>
        /// <returns><see langword="true"/> if the key was successfully extracted; otherwise <see langword="false"/>.</returns>
        public static bool TryGetEnvelopeReceiverKey(string cookieName, string defaultCookieName, out string? key)
        {
            key = GetEnvelopeReceiverKeyOrDefault(cookieName, defaultCookieName);
            return key is not null;
        }
    }
}