namespace MessengerApi.Contracts
{
    /// <summary>
    /// Exists for mocking reason. This is implemented by <see cref="MessengerClient"/>.
    /// </summary>
    public interface IMessengerClient
    {
        /// <summary>
        /// Receives pending messages from the messenger API.
        /// </summary>
        /// <param name="credentials">Credentials to the API.</param>
        IEnumerable<InboxMessage> GetMessages();

        /// <summary>
        /// Acknowledges message reception to the server.
        /// </summary>
        void AckMessage(InboxMessage message);

        /// <summary>
        /// Sends a message.
        /// </summary>
        /// <param name="credentials">Credentials to the API.</param>
        void SendMessage(OutboxMessage outboxMessage);

        /// <summary>
        /// Returns user ids for allowed message recipients.
        /// </summary>
        Contact[] GetYellowPages();
    }
}