wabbajack/Wabbajack.Lib/Downloaders/AbstractIPS4Downloader.cs

using System;
using System.IO;
using System.Linq;
using System.Net;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Web;
using Newtonsoft.Json;
using Wabbajack.Common;
using Wabbajack.Lib.Validation;
using File = System.IO.File;

namespace Wabbajack.Lib.Downloaders
{
    // IPS4 is the site used by LoversLab, VectorPlexus, etc. the general mechanics of each site are the 
    // same, so we can fairly easily abstract the state.
    // Pass in the state type via TState
    public abstract class AbstractIPS4Downloader<TDownloader, TState> : AbstractNeedsLoginDownloader, IDownloader 
        where TState : AbstractIPS4Downloader<TDownloader, TState>.State<TDownloader>, new() 
        where TDownloader : IDownloader
    {
        public override string SiteName { get; }
        public override Uri SiteURL { get; }

        public async Task<AbstractDownloadState> GetDownloaderState(dynamic archiveINI)
        {
            Uri url = DownloaderUtils.GetDirectURL(archiveINI);

            var absolute = true;
            if (url == null || url.Host != SiteURL.Host) return null;
            if (!url.PathAndQuery.StartsWith("/files/file/"))
            {
                if (string.IsNullOrWhiteSpace(url.Query)) return null;
                if (!url.Query.Substring(1).StartsWith("/files/file/")) return null;
                absolute = false;
            }

            var id = HttpUtility.ParseQueryString(url.Query)["r"];
            var file = absolute
                ? url.AbsolutePath.Split('/').Last(s => s != "")
                : url.Query.Substring(1).Split('/').Last(s => s != "");
            
            return new TState
            {
                FileID = id,
                FileName = file
            };
        }


        public class State<TDownloader> : AbstractDownloadState where TDownloader : IDownloader
        {
            public string FileID { get; set; }
            public string FileName { get; set; }

            private static bool IsHTTPS => Downloader.SiteURL.AbsolutePath.StartsWith("https://");
            private static string URLPrefix => IsHTTPS ? "https://" : "http://";

            private static string Site => string.IsNullOrWhiteSpace(Downloader.SiteURL.Query)
                ? $"{URLPrefix}{Downloader.SiteURL.Host}"
                : Downloader.SiteURL.ToString();

            public override object[] PrimaryKey
            {
                get
                {
                    return FileID == null
                        ? new object[] {Downloader.SiteURL, FileName}
                        : new object[] {Downloader.SiteURL, FileName, FileID};
                }
            }

            public override bool IsWhitelisted(ServerWhitelist whitelist)
            {
                return true;
            }

            public override async Task<bool> Download(Archive a, string destination)
            {
                var stream = await ResolveDownloadStream();
                using (var file = File.Open(destination, FileMode.Create))
                {
                    stream.CopyTo(file);
                }
                return true;
            }

            private async Task<Stream> ResolveDownloadStream()
            {
                var downloader = (AbstractNeedsLoginDownloader)(object)DownloadDispatcher.GetInstance<TDownloader>();

                TOP:
                var csrfurl = FileID == null
                    ? $"{Site}/files/file/{FileName}/?do=download"
                    : $"{Site}/files/file/{FileName}/?do=download&r={FileID}";
                var html = await downloader.AuthedClient.GetStringAsync(csrfurl);

                var pattern = new Regex("(?<=csrfKey=).*(?=[&\"\'])|(?<=csrfKey: \").*(?=[&\"\'])");
                var matches = pattern.Matches(html).Cast<Match>();
                    
                    var csrfKey = matches.Where(m => m.Length == 32).Select(m => m.ToString()).FirstOrDefault();

                if (csrfKey == null)
                    return null;

                var url = FileID == null
                    ? $"{Site}/files/file/{FileName}/?do=download&confirm=1&t=1&csrfKey={csrfKey}"
                    : $"{Site}/files/file/{FileName}/?do=download&r={FileID}&confirm=1&t=1&csrfKey={csrfKey}";
                    

                var streamResult = await downloader.AuthedClient.GetAsync(url);
                if (streamResult.StatusCode != HttpStatusCode.OK)
                {
                    Utils.Error(new InvalidOperationException(), $"{downloader.SiteName} servers reported an error for file: {FileID}");
                }

                var contentType = streamResult.Content.Headers.ContentType;

                if (contentType.MediaType != "application/json")
                    return await streamResult.Content.ReadAsStreamAsync();

                // Sometimes LL hands back a json object telling us to wait until a certain time
                var times = (await streamResult.Content.ReadAsStringAsync()).FromJSONString<WaitResponse>();
                var secs = times.Download - times.CurrentTime;
                for (int x = 0; x < secs; x++)
                {
                    Utils.Status($"Waiting for {secs} at the request of {downloader.SiteName}", x * 100 / secs);
                    await Task.Delay(1000);
                }
                Utils.Status("Retrying download");
                goto TOP;
            }

            private class WaitResponse
            {
                [JsonProperty("download")]
                public int Download { get; set; }
                [JsonProperty("currentTime")]
                public int CurrentTime { get; set; }
            }

            public override async Task<bool> Verify(Archive a)
            {
                var stream = await ResolveDownloadStream();
                if (stream == null)
                    return false;

                stream.Close();
                return true;
            }

            public override IDownloader GetDownloader()
            {
                return DownloadDispatcher.GetInstance<TDownloader>();
            }

            public override string GetReportEntry(Archive a)
            {
                return $"* {((INeedsLogin)GetDownloader()).SiteName} - [{a.Name}]({Site}/files/file/{FileName}/?do=download&r={FileID})";
            }

            public override string[] GetMetaIni()
            {
                if (FileID != null)
                    return new[]
                    {
                        "[General]",
                        $"directURL={Site}/files/file/{FileName}/?do=download&r={FileID}&confirm=1&t=1"
                    };
                return new[]
                {
                    "[General]",
                    $"directURL={Site}/files/file/{FileName}"
                };
            }

            private static AbstractNeedsLoginDownloader Downloader => (AbstractNeedsLoginDownloader)(object)DownloadDispatcher.GetInstance<TDownloader>();
        }

        protected AbstractIPS4Downloader(Uri loginUri, string encryptedKeyName, string cookieDomain) : 
            base(loginUri, encryptedKeyName, cookieDomain, "ips4_member_id")
        {
        }


    }
}