using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace Parallel
{
    public enum Actions
    {
        TestParallelDownload,
        TestParallelSaveFile,
        TestAsyncDownload,
        TestAsyncSaveFile
    }

    public class Program
    {
        public static async Task Main(string[] args)
        {
            try
            {
                var stopWatch = Stopwatch.StartNew();
                var itemAmount = 5;

                await Test(Actions.TestParallelDownload, itemAmount);
                await Test(Actions.TestParallelSaveFile, itemAmount);

                await Test(Actions.TestAsyncDownload, itemAmount);
                await Test(Actions.TestAsyncSaveFile, itemAmount);

                stopWatch.Stop();
                Console.WriteLine("Finish {0}", stopWatch.Elapsed);
                Console.ReadLine();
            }
            catch (Exception ex)
            {
                Console.WriteLine("Err", ex.Message);
                Console.ReadLine();
            }
        }

        public static async Task Test(Actions action, int itemAmount)
        {
            string[] items = Enumerable.Range(0, itemAmount).Select(i => Guid.NewGuid().ToString()).ToArray();
            var stopWatch = Stopwatch.StartNew();

            switch (action)
            {
                case Actions.TestParallelDownload:
                    items.AsParallel().ForAll(item => DownloadAsync(item));
                    break;
                case Actions.TestParallelSaveFile:
                    items.AsParallel().ForAll(item => SaveAsync(item));
                    break;
                case Actions.TestAsyncDownload:
                    foreach (var item in items)
                        await DownloadAsync(item);
                    break;
                case Actions.TestAsyncSaveFile:
                    foreach (var item in items)
                        await SaveAsync(item);
                    break;
            }

            stopWatch.Stop();

            Console.WriteLine($"{action.ToString()} Call: Time: {stopWatch.Elapsed}");
        }

        public static async Task SaveAsync(string textToWrite)
        {
            string filePath = @"C:tempfile2.txt";
            byte[] encodedText = Encoding.Unicode.GetBytes(textToWrite);

            using (var sourceStream = new FileStream(filePath,
                FileMode.Append, FileAccess.Write, FileShare.None,
                bufferSize: 4096, useAsync: true))
            {
                await sourceStream.WriteAsync(encodedText, 0, encodedText.Length);
            };
        }

        public static async Task DownloadAsync(string name)
        {
            var uri = new Uri("https://images.sftcdn.net/images/t_app-logo-l,f_auto,dpr_auto/p/ce2ece60-9b32-11e6-95ab-00163ed833e7/2183169552/the-test-fun-for-friends-logo.png");
            using (var client = new WebClient())
            {
                await client.DownloadFileTaskAsync(uri, $"{name}.png");
            }
        }
    }
}