using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading;

using Renci.SshNet.Common;

using Renci.SshNet.Messages.Authentication;

using Renci.SshNet.Messages;



namespace Renci.SshNet

{

    /// <summary>

    /// Provides functionality to perform password authentication.

    /// </summary>

    public partial class PasswordAuthenticationMethod : AuthenticationMethod, IDisposable

    {

        private AuthenticationResult _authenticationResult = AuthenticationResult.Failure;



        private Session _session;



        private EventWaitHandle _authenticationCompleted = new AutoResetEvent(false);



        private Exception _exception;



        private RequestMessage _requestMessage;



        private string _password;



        /// <summary>

        /// Gets authentication method name

        /// </summary>

        public override string Name

        {

            get { return this._requestMessage.MethodName; }

        }



        /// <summary>

        /// Occurs when user's password has expired and needs to be changed.

        /// </summary>

        public event EventHandler<AuthenticationPasswordChangeEventArgs> PasswordExpired;



        /// <summary>

        /// Initializes a new instance of the <see cref="PasswordAuthenticationMethod"/> class.

        /// </summary>

        /// <param name="host">The host.</param>

        /// <param name="port">The port.</param>

        /// <param name="username">The username.</param>

        /// <param name="password">The password.</param>

        public PasswordAuthenticationMethod(string username, string password)

            : base(username)

        {

            if (password == null)

                throw new ArgumentNullException("password");



            this._password = password;



            this._requestMessage = new RequestMessagePassword(ServiceName.Connection, this.Username, password);

        }



        /// <summary>

        /// Authenticates the specified session.

        /// </summary>

        /// <param name="session">The session to authenticate.</param>

        /// <returns></returns>

        public override AuthenticationResult Authenticate(Session session)

        {

            this._session = session;



            session.UserAuthenticationSuccessReceived += Session_UserAuthenticationSuccessReceived;

            session.UserAuthenticationFailureReceived += Session_UserAuthenticationFailureReceived;

            session.MessageReceived += Session_MessageReceived;



            session.RegisterMessage("SSH_MSG_USERAUTH_PASSWD_CHANGEREQ");



            session.SendMessage(this._requestMessage);



            session.WaitHandle(this._authenticationCompleted);



            session.UserAuthenticationSuccessReceived -= Session_UserAuthenticationSuccessReceived;

            session.UserAuthenticationFailureReceived -= Session_UserAuthenticationFailureReceived;

            session.MessageReceived -= Session_MessageReceived;





            if (this._exception != null)

            {

                throw this._exception;

            }



            return this._authenticationResult;

        }



        private void Session_UserAuthenticationSuccessReceived(object sender, MessageEventArgs<SuccessMessage> e)

        {

            this._authenticationResult = AuthenticationResult.Success;



            this._authenticationCompleted.Set();

        }



        private void Session_UserAuthenticationFailureReceived(object sender, MessageEventArgs<FailureMessage> e)

        {

            if (e.Message.PartialSuccess)

                this._authenticationResult = AuthenticationResult.PartialSuccess;

            else

                this._authenticationResult = AuthenticationResult.Failure;



            //  Copy allowed authentication methods

            this.AllowedAuthentications = e.Message.AllowedAuthentications.ToList();



            this._authenticationCompleted.Set();

        }



        private void Session_MessageReceived(object sender, MessageEventArgs<Message> e)

        {

            if (e.Message is PasswordChangeRequiredMessage)

            {

                this._session.UnRegisterMessage("SSH_MSG_USERAUTH_PASSWD_CHANGEREQ");



                this.ExecuteThread(() =>

                {

                    try

                    {

                        var eventArgs = new AuthenticationPasswordChangeEventArgs(this.Username);



                        //  Raise an event to allow user to supply a new password

                        if (this.PasswordExpired != null)

                        {

                            this.PasswordExpired(this, eventArgs);

                        }



                        //  Send new authentication request with new password

                        this._session.SendMessage(new RequestMessagePassword(ServiceName.Connection, this.Username, this._password, eventArgs.NewPassword));

                    }

                    catch (Exception exp)

                    {

                        this._exception = exp;

                        this._authenticationCompleted.Set();

                    }

                });

            }

        }



        partial void ExecuteThread(Action action);



        #region IDisposable Members



        private bool isDisposed = false;



        /// <summary>

        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

        /// </summary>

        public void Dispose()

        {

            Dispose(true);



            GC.SuppressFinalize(this);

        }



        /// <summary>

        /// Releases unmanaged and - optionally - managed resources

        /// </summary>

        /// <param name="disposing"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>

        protected virtual void Dispose(bool disposing)

        {

            // Check to see if Dispose has already been called.

            if (!this.isDisposed)

            {

                // If disposing equals true, dispose all managed

                // and unmanaged resources.

                if (disposing)

                {

                    // Dispose managed resources.

                    if (this._authenticationCompleted != null)

                    {

                        this._authenticationCompleted.Dispose();

                        this._authenticationCompleted = null;

                    }

                }



                // Note disposing has been done.

                isDisposed = true;

            }

        }



        /// <summary>

        /// Releases unmanaged resources and performs other cleanup operations before the

        /// <see cref="PasswordConnectionInfo"/> is reclaimed by garbage collection.

        /// </summary>

        ~PasswordAuthenticationMethod()

        {

            // Do not re-create Dispose clean-up code here.

            // Calling Dispose(false) is optimal in terms of

            // readability and maintainability.

            Dispose(false);

        }



        #endregion



    }

}