using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Tango.Transport.Routing
{
    /// <summary>
    /// Represents a transport router capable of exchanging data between two <see cref="ITransportAdapter"/> of different types.
    /// </summary>
    /// <seealso cref="IDisposable" />
    public class TransportRoutingChannel : ITransportComponent
    {
        /// <summary>
        /// Gets or sets the name of the transport component.
        /// </summary>
        public String ComponentName { get; set; }

        /// <summary>
        /// Occurs when component state changes.
        /// </summary>
        public event EventHandler<TransportComponentState> StateChanged;

        /// <summary>
        /// Gets or sets the first adapter.
        /// </summary>
        public ITransportAdapter Adapter1 { get; private set; }

        /// <summary>
        /// Gets or sets the second adapter.
        /// </summary>
        public ITransportAdapter Adapter2 { get; private set; }

        private TransportComponentState _state;
        /// <summary>
        /// Gets the component state.
        /// </summary>
        public TransportComponentState State
        {
            get { return _state; }
            private set { _state = value; StateChanged?.Invoke(this, State); }
        }


        /// <summary>
        /// Initializes a new instance of the <see cref="TransportRoutingChannel"/> class.
        /// </summary>
        /// <param name="adapter1">The first adapter.</param>
        /// <param name="adapter2">The second adapter.</param>
        public TransportRoutingChannel(ITransportAdapter adapter1, ITransportAdapter adapter2)
        {
            ComponentName = "Routing Channel";

            Adapter1 = adapter1;
            Adapter2 = adapter2;

            Adapter1.DataAvailable += OnAdapter1DataAvailable;
            Adapter2.DataAvailable += OnAdapter2DataAvailable;

            Adapter1.StateChanged += OnAdapter1StateChanged;
            Adapter2.StateChanged += OnAdapter2StateChanged;
        }

        /// <summary>
        /// Called when the first adapter state has changed.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="state">The state.</param>
        protected virtual void OnAdapter1StateChanged(object sender, TransportComponentState state)
        {
            if (state == TransportComponentState.Failed)
            {
                State = TransportComponentState.Failed;
            }
        }

        /// <summary>
        /// Called when the second adapter state has changed.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="state">The state.</param>
        protected virtual void OnAdapter2StateChanged(object sender, TransportComponentState state)
        {
            if (state == TransportComponentState.Failed)
            {
                State = TransportComponentState.Failed;
            }
        }

        /// <summary>
        /// Called when the first adapter has available data.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="data">The data.</param>
        protected virtual void OnAdapter1DataAvailable(object sender, byte[] data)
        {
            Adapter2.Write(data);
        }

        /// <summary>
        /// Called when the second adapter has available data.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="data">The data.</param>
        protected virtual void OnAdapter2DataAvailable(object sender, byte[] data)
        {
            Adapter1.Write(data);
        }

        /// <summary>
        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
        /// </summary>
        public void Dispose()
        {
            if (Adapter1 != null) Adapter1.Dispose();
            if (Adapter2 != null) Adapter2.Dispose();
        }

        /// <summary>
        /// Connects the transport component.
        /// </summary>
        /// <returns></returns>
        public Task Connect()
        {
            var result = Task.WhenAll(Adapter1.Connect(), Adapter2.Connect());
            State = TransportComponentState.Connected;
            return result;
        }

        /// <summary>
        /// Disconnects the transport component.
        /// </summary>
        /// <returns></returns>
        public Task Disconnect()
        {
            var result = Task.WhenAll(Adapter1.Disconnect(), Adapter2.Disconnect());
            State = TransportComponentState.Disconnected;
            return result;
        }
    }
}