using System;

namespace Renci.SshNet
{
    /// <summary>
    /// Base class for all supported authentication methods.
    /// </summary>
    public abstract class AuthenticationMethod : IAuthenticationMethod
    {
        /// <summary>
        /// Gets the name of the authentication method.
        /// </summary>
        /// <value>
        /// The name of the authentication method.
        /// </value>
        public abstract string Name { get; }

        /// <summary>
        /// Gets connection username.
        /// </summary>
        public string Username { get; private set; }

        /// <summary>
        /// Gets or sets the list of allowed authentications.
        /// </summary>
        public string[] AllowedAuthentications { get; protected set; }

        /// <summary>
        /// Initializes a new instance of the <see cref="AuthenticationMethod"/> class.
        /// </summary>
        /// <param name="username">The username.</param>
        /// <exception cref="ArgumentException"><paramref name="username"/> is whitespace or <c>null</c>.</exception>
        protected AuthenticationMethod(string username)
        {
            if (string.IsNullOrWhiteSpace(username))
            {
                throw new ArgumentException("username");
            }

            Username = username;
        }

        /// <summary>
        /// Authenticates the specified session.
        /// </summary>
        /// <param name="session">The session to authenticate.</param>
        /// <returns>
        /// The result of the authentication process.
        /// </returns>
        public abstract AuthenticationResult Authenticate(Session session);

        /// <summary>
        /// Authenticates the specified session.
        /// </summary>
        /// <param name="session">The session to authenticate.</param>
        /// <returns>
        /// The result of the authentication process.
        /// </returns>
        AuthenticationResult IAuthenticationMethod.Authenticate(ISession session)
        {
            return Authenticate((Session) session);
        }
    }
}
