From 6d62744667c9242807e30666e4ba729355f08b6c Mon Sep 17 00:00:00 2001
From: Qstick <qstick@gmail.com>
Date: Sat, 4 Dec 2021 12:26:55 -0600
Subject: [PATCH] Fixed: (Cardigann) Magnet generation for public indexers with
 InfoHash

Fixes #668
---
 src/NzbDrone.Core/Indexers/IndexerBase.cs     | 21 ++++++++++++++++---
 .../Indexers/MagnetLinkBuilder.cs             | 16 ++++++++++++++
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/src/NzbDrone.Core/Indexers/IndexerBase.cs b/src/NzbDrone.Core/Indexers/IndexerBase.cs
index 75717c1b5..cd123f4ad 100644
--- a/src/NzbDrone.Core/Indexers/IndexerBase.cs
+++ b/src/NzbDrone.Core/Indexers/IndexerBase.cs
@@ -132,10 +132,25 @@ protected virtual IList<ReleaseInfo> CleanupReleases(IEnumerable<ReleaseInfo> re
                 c.DownloadProtocol = Protocol;
                 c.IndexerPriority = ((IndexerDefinition)Definition).Priority;
 
-                //Add common flags
-                if (Protocol == DownloadProtocol.Torrent && ((TorrentInfo)c).DownloadVolumeFactor == 0)
+                if (Protocol == DownloadProtocol.Torrent)
                 {
-                    c.IndexerFlags.Add(IndexerFlag.FreeLeech);
+                    // generate magnet link from info hash (not allowed for private sites)
+                    if (((TorrentInfo)c).MagnetUrl == null && !string.IsNullOrWhiteSpace(((TorrentInfo)c).InfoHash) && ((IndexerDefinition)Definition).Privacy != IndexerPrivacy.Private)
+                    {
+                        ((TorrentInfo)c).MagnetUrl = MagnetLinkBuilder.BuildPublicMagnetLink(((TorrentInfo)c).InfoHash, c.Title);
+                    }
+
+                    // generate info hash from magnet link
+                    if (((TorrentInfo)c).MagnetUrl != null && string.IsNullOrWhiteSpace(((TorrentInfo)c).InfoHash))
+                    {
+                        ((TorrentInfo)c).InfoHash = MagnetLinkBuilder.GetInfoHashFromMagnet(((TorrentInfo)c).MagnetUrl);
+                    }
+
+                    //Add common flags
+                    if (((TorrentInfo)c).DownloadVolumeFactor == 0)
+                    {
+                        ((TorrentInfo)c).IndexerFlags.Add(IndexerFlag.FreeLeech);
+                    }
                 }
             });
 
diff --git a/src/NzbDrone.Core/Indexers/MagnetLinkBuilder.cs b/src/NzbDrone.Core/Indexers/MagnetLinkBuilder.cs
index 5732c3dcf..a41d64b98 100644
--- a/src/NzbDrone.Core/Indexers/MagnetLinkBuilder.cs
+++ b/src/NzbDrone.Core/Indexers/MagnetLinkBuilder.cs
@@ -1,5 +1,8 @@
+using System;
 using System.Collections.Generic;
+using System.Linq;
 using MonoTorrent;
+using NzbDrone.Core.Parser;
 
 namespace NzbDrone.Core.Indexers
 {
@@ -33,5 +36,18 @@ public static string BuildPublicMagnetLink(string infoHash, string releaseTitle)
         {
             return new MagnetLink(InfoHash.FromHex(infoHash), releaseTitle, _trackers).ToV1String();
         }
+
+        public static string GetInfoHashFromMagnet(string magnet)
+        {
+            try
+            {
+                var xt = ParseUtil.GetArgumentFromQueryString(magnet.ToString(), "xt");
+                return xt.Split(':').Last(); // remove prefix urn:btih:
+            }
+            catch (Exception)
+            {
+                return null;
+            }
+        }
     }
 }