New: Add download client per indexer setting

src/NzbDrone.Core/Download/DownloadClientProvider.cs

@@ -2,13 +2,14 @@
 using System.Linq;
 using NLog;
 using NzbDrone.Common.Cache;
+using NzbDrone.Core.Download.Clients;
 using NzbDrone.Core.Indexers;
 
 namespace NzbDrone.Core.Download
 {
     public interface IProvideDownloadClient
     {
-        IDownloadClient GetDownloadClient(DownloadProtocol downloadProtocol);
+        IDownloadClient GetDownloadClient(DownloadProtocol downloadProtocol, int indexerId = 0);
         IEnumerable<IDownloadClient> GetDownloadClients();
         IDownloadClient Get(int id);
     }
@@ -18,17 +19,23 @@ namespace NzbDrone.Core.Download
         private readonly Logger _logger;
         private readonly IDownloadClientFactory _downloadClientFactory;
         private readonly IDownloadClientStatusService _downloadClientStatusService;
+        private readonly IIndexerFactory _indexerFactory;
         private readonly ICached<int> _lastUsedDownloadClient;
 
-        public DownloadClientProvider(IDownloadClientStatusService downloadClientStatusService, IDownloadClientFactory downloadClientFactory, ICacheManager cacheManager, Logger logger)
+        public DownloadClientProvider(IDownloadClientStatusService downloadClientStatusService,
+            IDownloadClientFactory downloadClientFactory,
+            IIndexerFactory indexerFactory,
+            ICacheManager cacheManager,
+            Logger logger)
         {
             _logger = logger;
             _downloadClientFactory = downloadClientFactory;
             _downloadClientStatusService = downloadClientStatusService;
+            _indexerFactory = indexerFactory;
             _lastUsedDownloadClient = cacheManager.GetCache<int>(GetType(), "lastDownloadClientId");
         }
 
-        public IDownloadClient GetDownloadClient(DownloadProtocol downloadProtocol)
+        public IDownloadClient GetDownloadClient(DownloadProtocol downloadProtocol, int indexerId = 0)
         {
             var availableProviders = _downloadClientFactory.GetAvailableProviders().Where(v => v.Protocol == downloadProtocol).ToList();
 
@@ -37,6 +44,23 @@ namespace NzbDrone.Core.Download
                 return null;
             }
 
+            if (indexerId > 0)
+            {
+                var indexer = _indexerFactory.Find(indexerId);
+
+                if (indexer is { DownloadClientId: > 0 })
+                {
+                    var client = availableProviders.SingleOrDefault(d => d.Definition.Id == indexer.DownloadClientId);
+
+                    if (client == null)
+                    {
+                        throw new DownloadClientUnavailableException("Indexer specified download client is not available");
+                    }
+
+                    return client;
+                }
+            }
+
             var blockedProviders = new HashSet<int>(_downloadClientStatusService.GetBlockedProviders().Select(v => v.ProviderId));
 
             if (blockedProviders.Any())
@@ -54,7 +78,7 @@ namespace NzbDrone.Core.Download
             }
 
             // Use the first priority clients first
-            availableProviders = availableProviders.GroupBy(v => (v.Definition as DownloadClientDefinition).Priority)
+            availableProviders = availableProviders.GroupBy(v => ((DownloadClientDefinition)v.Definition).Priority)
                                                    .OrderBy(v => v.Key)
                                                    .First().OrderBy(v => v.Definition.Id).ToList();