using Microsoft.WindowsAPICodePack.Net;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using Tango.Core;

namespace Tango.FSE.BL.Connectivity
{
    /// <summary>
    /// Represents the <see cref="IConnectivityProvider"/> default implementation.
    /// </summary>
    /// <seealso cref="Tango.Core.ExtendedObject" />
    /// <seealso cref="Tango.FSE.BL.Connectivity.IConnectivityProvider" />
    public class DefaultConnectivityProvider : ExtendedObject, IConnectivityProvider
    {
        private class TimeoutWebClient : WebClient
        {
            public int Timeout { get; set; }

            protected override WebRequest GetWebRequest(Uri uri)
            {
                WebRequest lWebRequest = base.GetWebRequest(uri);
                lWebRequest.Timeout = Timeout;
                ((HttpWebRequest)lWebRequest).ReadWriteTimeout = Timeout;
                return lWebRequest;
            }
        }

        /// <summary>
        /// Gets or sets the connectivity verification method.
        /// </summary>
        public ConnectivityVerificationMethod VerificationMethod { get; set; }

        private bool _isOnline;
        /// <summary>
        /// Gets a value indicating whether the system has an active Internet connection currently.
        /// </summary>
        public bool IsOnline
        {
            get { return _isOnline; }
            set
            {
                _isOnline = value;
                RaisePropertyChanged(nameof(IsOnline));
            }
        }

        /// <summary>
        /// Checks whether the system has an active Internet connection.
        /// </summary>
        /// <returns></returns>
        public bool CheckOnline()
        {
#if OFFLINE
            return false;
#endif
            try
            {
                if (VerificationMethod == ConnectivityVerificationMethod.Default)
                {
                    using (var client = new TimeoutWebClient())
                    {
                        client.Timeout = 1000;
                        client.OpenRead("http://google.com/generate_204");
                        IsOnline = true;
                        return true;
                    }
                }
                else if (VerificationMethod == ConnectivityVerificationMethod.Windows)
                {
                    if (NetworkListManager.GetNetworks(NetworkConnectivityLevels.Connected).Any(x => x.IsConnectedToInternet))
                    {
                        IsOnline = true;
                        return true;
                    }
                }
                else if (VerificationMethod == ConnectivityVerificationMethod.Gateway)
                {
                    return false; //Not implemented.
                }
                else if (VerificationMethod == ConnectivityVerificationMethod.AlwaysOnline)
                {
                    return true;
                }
                return false;
            }
            catch
            {
                IsOnline = false;
                return false;
            }
        }

        /// <summary>
        /// Checks whether the system has an active Internet connection.
        /// </summary>
        /// <returns></returns>
        public Task<bool> CheckOnlineAsync()
        {
            return Task.Factory.StartNew<bool>(CheckOnline);
        }

        /// <summary>
        /// Throws an exception if there is no Internet connection.
        /// </summary>
        public void ThrowIfNoInternet()
        {
            if (!CheckOnline())
            {
                throw new InternetConnectionException();
            }
        }
    }
}