// Author: Gockner, Simon
// Created: 2020-02-11
// Copyright(c) 2020 SimonG. All Rights Reserved.

using System;
using System.ServiceModel;
using System.Threading.Tasks;
using GBase.Api.Communication;
using GBase.Client.Interfaces;

namespace GBase.Client.Services
{
    /// <summary>
    /// Base class for services of the <see cref="IGBaseClient"/>
    /// </summary>
    /// <typeparam name="TService">The <see cref="Type"/> of the inheriting service</typeparam>
    public abstract class Service<TService> : IAsyncDisposable
    {
        /// <summary>
        /// Base class for services of the <see cref="IGBaseClient"/>
        /// </summary>
        /// <param name="serverProtocol">The <see cref="ServerProtocol"/></param>
        /// <param name="endpoint">The endpoint for this <typeparamref name="TService"/></param>
        protected Service(ServerProtocol serverProtocol, string endpoint)
        {
            ServiceFactory = OpenFactory(serverProtocol, endpoint);
        }

        /// <summary>
        /// The <see cref="ChannelFactory{TChannel}"/> for this <typeparamref name="TService"/>
        /// </summary>
        private ChannelFactory<TService> ServiceFactory { get; }

        /// <summary>
        /// Open a <see cref="ChannelFactory{TChannel}"/> for the given <see cref="ServerProtocol"/> and endpoint
        /// </summary>
        /// <param name="serverProtocol">The <see cref="ServerProtocol"/></param>
        /// <param name="endpoint">The endpoint for this <typeparamref name="TService"/></param>
        /// <returns></returns>
        private ChannelFactory<TService> OpenFactory(ServerProtocol serverProtocol, string endpoint)
        {
            ChannelFactory<TService> factory;
            if (serverProtocol == ServerProtocol.Http)
                factory = new ChannelFactory<TService>(new BasicHttpBinding(), new EndpointAddress(endpoint));
            else if (serverProtocol == ServerProtocol.Tcp)
                factory = new ChannelFactory<TService>(new NetTcpBinding(), new EndpointAddress(endpoint)); //TODO: Set security mode here?
            else
                throw new ArgumentOutOfRangeException(nameof(serverProtocol), serverProtocol, "Invalid server protocol used.");

            factory.Open();
            return factory;
        }

        /// <summary>
        /// Open an <see cref="IClientChannel"/> for this <typeparamref name="TService"/>
        /// </summary>
        /// <returns>The opened channel of type <typeparamref name="TService"/></returns>
        protected TService OpenChannel()
        {
            TService channel = ServiceFactory.CreateChannel();
            ((IClientChannel)channel).Open();

            return channel;
        }

        /// <summary>
        /// Close the <see cref="IClientChannel"/> for a given <typeparamref name="TService"/>
        /// </summary>
        /// <param name="service">The <typeparamref name="TService"/></param>
        protected void CloseChannel(TService service)
        {
            ((IClientChannel) service).Close();
        }

        /// <summary>
        /// Dispose used resources asynchronously
        /// </summary>
        /// <returns>A <see cref="ValueTask"/> to await</returns>
        public async ValueTask DisposeAsync()
        {
            ServiceFactory.Close();
        }
    }
}