using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;

namespace Num
{
    public class Program
    {
        static Program()
        {
            Task.Run(() =>
            {
                while(true)
                {
                    if(_stack.Count > 0)
                    {
                        Console.WriteLine(_stack.Pop());
                    }
                }
            });
        }

        private static HttpClient _client = new HttpClient();
        private static readonly Stack<string> _stack = new Stack<string>();

        public static async Task Main(string[] args)
        {
            int threadSize = 30;
            if (args.Length > 0)
            {
                threadSize = int.Parse(args[0]);
            }

            string rawFiles = await _client.GetStringAsync("https://reiyo.kibii.org/~/dump/reiyo-full-dump.txt");
            string[] urls = rawFiles.Split('\n').Where(f => !f.StartsWith("#") && !string.IsNullOrWhiteSpace(f)).Select(c => c.Trim()).ToArray();

            if (!Directory.Exists("out/"))
            {
                Directory.CreateDirectory("out/");
            }

            IList<Task> tasks = new List<Task>();
            string[][] uriLists = urls.SliceArray(threadSize).Select(u => u.ToArray()).ToArray();

            for (int i = 0; i < uriLists.Length; i++)
            {
                Task localTask = await Task.Factory.StartNew(async () => await DownloadAndSaveFiles(uriLists[i], i));
                tasks.Add(localTask);
            }

            Task.WaitAll(tasks.ToArray());
            Console.WriteLine("All images have been downloaded.");
            Console.ReadKey();
        }

        public static async Task DownloadAndSaveFiles(string[] urls, int batchId)
        {
            for (int i = 0; i < urls.Length; i++)
            {
                await Task.Run(async () =>
                {
                    try
                    {
                        Uri uri = new Uri(urls[i]);
                        string originalFileName = uri.AbsolutePath.Split('/')?.Last().Trim();
                        if (string.IsNullOrWhiteSpace(originalFileName) || Guid.TryParse(originalFileName, out Guid res1))
                            originalFileName = "no-file-name-available";

                        string fileId = uri.AbsolutePath.Split('/').FirstOrDefault(u => Guid.TryParse(u, out Guid res2)) ?? Guid.NewGuid().ToString("N");

                        HttpResponseMessage res = await _client.GetAsync(uri);
                        string newFileName = originalFileName + "_" + fileId + "." + res.Content.Headers.ContentType.MediaType.Split('/').Last();
                        string filePath = Path.Combine(Path.Combine(Directory.GetCurrentDirectory(), "out/"), newFileName);

                        using (Stream outStr = File.Create(filePath))
                        {
                            Stream inStr = await res.Content.ReadAsStreamAsync();
                            await inStr.CopyToAsync(outStr);
                        }

                        QueueOut("[B" + batchId + "] File DL'd (" + i.ToString() + "/" + urls.Length + "): '" + newFileName + "'");
                    }
                    catch
                    {
                        QueueOut("[B" + batchId + "] ERR (" + i.ToString() + "/" + urls.Length + ").");
                    }
                });
            }
        }

        private static void QueueOut(string message)
        {
            Task.Run(() => _stack.Push(message));
        }
    }

    public static class EnumerbleExtensions
    {
        public static IEnumerable<IEnumerable<T>> SliceArray<T>(this T[] array, int groupSize)
        {
            List<T> locations = array.ToList();
            int nSize = array.Length / groupSize;

            for (int i = 0; i < locations.Count; i += nSize)
            {
                yield return locations.GetRange(i, Math.Min(nSize, locations.Count - i));
            }
        }
    }
}