using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.Logging;
using Tango.PMR.Common;
using Tango.Core.Commands;
using Tango.Transport;
using Tango.Core;

namespace Tango.Emulations
{
    /// <summary>
    /// Represents an <see cref="IEmulator"/> base class.
    /// </summary>
    /// <seealso cref="Tango.SharedUI.ExtendedObject" />
    /// <seealso cref="Tango.Emulations.IEmulator" />
    public abstract class EmulatorBase : ExtendedObject, IEmulator
    {
        #region Properties

        private bool _isStarted;
        /// <summary>
        /// Gets or sets a value indicating whether the emulator is started.
        /// </summary>
        public bool IsStarted
        {
            get { return _isStarted; }
            set { _isStarted = value; RaisePropertyChanged(nameof(IsStarted)); InvalidateRelayCommands(); }
        }

        private ITransporter _transporter;
        /// <summary>
        /// Gets or sets the transporter.
        /// </summary>
        public ITransporter Transporter
        {
            get { return _transporter; }
            set
            {
                _transporter = value;
                SetTransporter(_transporter);
            }
        }

        #endregion

        #region Commands

        /// <summary>
        /// Gets or sets the start command.
        /// </summary>
        public RelayCommand StartCommand { get; set; }

        /// <summary>
        /// Gets or sets the stop command.
        /// </summary>
        public RelayCommand StopCommand { get; set; }

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="EmulatorBase"/> class.
        /// </summary>
        public EmulatorBase()
        {
            StartCommand = new RelayCommand(async () => { await Start(); }, (x) => !IsStarted);
            StopCommand = new RelayCommand(async () => { await Stop(); }, (x) => IsStarted);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="EmulatorBase"/> class.
        /// </summary>
        /// <param name="transporter">The transporter.</param>
        public EmulatorBase(ITransporter transporter) : this()
        {
            Transporter = transporter;
        }

        #endregion

        #region Private Methods

        /// <summary>
        /// Sets the transporter.
        /// </summary>
        /// <param name="transporter">The transporter.</param>
        private void SetTransporter(ITransporter transporter)
        {
            if (_transporter != null)
            {
                _transporter.StateChanged -= OnTransporterStateChanged;
            }

            _transporter = transporter;
            _transporter.RequestReceived += OnTransporterRequestReceived;

            _transporter.StateChanged += OnTransporterStateChanged;
        }

        #endregion

        #region Public Methods

        /// <summary>
        /// Stops this instance.
        /// </summary>
        public virtual async Task Stop()
        {
            if (IsStarted)
            {
                await _transporter.Disconnect();
                IsStarted = false;
            }
        }

        /// <summary>
        /// Starts this instance.
        /// </summary>
        public virtual async Task Start()
        {
            if (!IsStarted)
            {
                await _transporter.Connect();
                IsStarted = true;
            }
        }

        #endregion

        #region Virtual Methods

        /// <summary>
        /// Called when transporter state has changed.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The e.</param>
        protected virtual void OnTransporterStateChanged(object sender, TransportComponentState e)
        {
            LogManager.Log("Transporter state changed: " + e.ToString());
        }

        #endregion

        #region Abstract Methods

        /// <summary>
        /// Called on new request message.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="container">The container.</param>
        protected abstract void OnTransporterRequestReceived(object sender, RequestReceivedEventArgs e);

        #endregion

        #region Dispose

        /// <summary>
        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
        /// </summary>
        public void Dispose()
        {
            Stop().Wait();
            if (Transporter != null) Transporter.Dispose();
        }

        #endregion
    }
}