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

namespace Tango.Transport.Web
{
    public class StandardFileDownloader : IWebFileDownloader
    {
        private WebClient _client;
        private TaskCompletionSource<object> _completionSource;

        public String Address { get; private set; }

        public String FileName { get; private set; }

        public event EventHandler<WebFileDownloaderProgressEventArgs> Progress;

        public StandardFileDownloader(String address, String fileName)
        {
            Address = address;
            FileName = fileName;
            _client = new WebClient();
            _client.Proxy = null;
            _client.DownloadProgressChanged += _client_DownloadProgressChanged;
            _client.DownloadFileCompleted += _client_DownloadFileCompleted;

            _completionSource = new TaskCompletionSource<object>();
        }

        private void _client_DownloadFileCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
        {
            if (e.Error != null)
            {
                _completionSource.SetException(e.Error);
            }
            else
            {
                _completionSource.SetResult(true);
            }
        }

        public Task Download()
        {
            _client.DownloadFileAsync(new Uri(Address), FileName);
            return _completionSource.Task;
        }

        private void _client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            Progress?.Invoke(this, new WebFileDownloaderProgressEventArgs()
            {
                Current = e.BytesReceived,
                Total = e.TotalBytesToReceive,
            });
        }

        public Task<long> GetFileSize()
        {
            return Task.Factory.StartNew<long>(() =>
            {
                using (var client = new WebClient())
                {
                    client.OpenRead(Address);
                    Int64 bytes_total = Convert.ToInt64(client.ResponseHeaders["Content-Length"]);
                    return bytes_total;
                }
            });
        }

        public void Dispose()
        {
            _client.Dispose();
        }
    }
}