More changes to add Torrents automatically; Modified cache to 8 days; Modified season finale lookups for edge case

AnimeAnnouncer.Torrents/NyaaRssReader.cs

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+using System.Xml.Linq;
+
+namespace AnimeAnnouncer.Torrents
+{
+    public record NyaaRssItem(
+        String Title,
+        String Published,
+        String Category,
+        String CategoryID,
+        String Size,
+        String Link,
+        String Description,
+        String PostID);
+
+    /// <summary>
+    /// Reads Nyaa RSS feeds and downloads the .torrent files they link to.
+    /// </summary>
+    public class NyaaRssReader
+    {
+        private readonly HttpClient httpClient;
+
+        public NyaaRssReader(HttpClient? httpClient = null)
+        {
+            this.httpClient = httpClient ?? new HttpClient();
+        }
+
+        /// <summary>
+        /// Converts a Nyaa search URL into its RSS equivalent, if it isn't one already.
+        /// </summary>
+        public static String ToRssUrl(String url)
+        {
+            return url.Contains("rss") ? url : url + "&page=rss";
+        }
+
+        public async Task<List<NyaaRssItem>> ReadAsync(String url)
+        {
+            var response = await httpClient.GetStringAsync(ToRssUrl(url));
+            return Parse(response);
+        }
+
+        public static List<NyaaRssItem> Parse(String rssXml)
+        {
+            XDocument doc = XDocument.Parse(rssXml);
+            XNamespace nyaaNS = doc.Root!.GetNamespaceOfPrefix("nyaa") ?? XNamespace.None;
+            return (from item in doc.Descendants("channel").Elements("item")
+                    select new NyaaRssItem(
+                        Title: item.Element("title")?.Value ?? String.Empty,
+                        Published: item.Element("pubDate")?.Value ?? String.Empty,
+                        Category: item.Element(nyaaNS + "category")?.Value ?? String.Empty,
+                        CategoryID: item.Element(nyaaNS + "categoryId")?.Value ?? String.Empty,
+                        Size: item.Element(nyaaNS + "size")?.Value ?? String.Empty,
+                        Link: item.Element("link")?.Value ?? String.Empty,
+                        Description: item.Element("description")?.Value ?? String.Empty,
+                        PostID: item.Element("guid")?.Value ?? String.Empty
+                    )).ToList();
+        }
+
+        public Task<byte[]> DownloadTorrentAsync(NyaaRssItem item)
+        {
+            return httpClient.GetByteArrayAsync(item.Link);
+        }
+    }
+}

AnimeAnnouncer.Torrents/TorrentDirectoryNamer.cs

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+using System.Text.RegularExpressions;
+
+namespace AnimeAnnouncer.Torrents
+{
+    public static class TorrentDirectoryNamer
+    {
+        /// <summary>
+        /// Turns a release title into a dotted directory name, stripping the episode number
+        /// (keeping the resolution) and any trailing parenthesised suffix.
+        /// e.g. "Show Name S01E05 1080p WEB (Group)" -> "Show.Name.S01.1080p.WEB"
+        /// </summary>
+        public static String FromTitle(String title)
+        {
+            String name = title.Trim();
+            name = Regex.Replace(name, @"E\d{2,3}.*?(\d{3,4}p)", " $1");
+            name = Regex.Replace(name, @"\s\(.*?\)$", "");
+            return name.Replace(" ", ".");
+        }
+
+        public static String PrepareForURI(String title)
+        {
+            var titlePart = Regex.Replace(title, @"[^\w\s]+", String.Empty);
+            titlePart = Regex.Replace(titlePart, @"\s+", "+");
+            return titlePart;
+        }
+
+        /// <summary>
+        /// Builds the full save path for a release title under <paramref name="destinationFolder"/>.
+        /// </summary>
+        public static String FromTitle(String title, String destinationFolder)
+        {
+            return destinationFolder + (destinationFolder.EndsWith("/") ? String.Empty : "/") + FromTitle(title);
+        }
+    }
+}

AnimeAnnouncer.Torrents/TransmissionService.cs

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+using Transmission.API.RPC;
+using Transmission.API.RPC.Arguments;
+using Transmission.API.RPC.Entity;
+
+namespace AnimeAnnouncer.Torrents
+{
+    /// <summary>
+    /// Thin wrapper around the Transmission RPC client for adding torrents to the server.
+    /// </summary>
+    public class TransmissionService
+    {
+        public Client Client { get; }
+
+        private TransmissionService(Client client)
+        {
+            Client = client;
+        }
+
+        /// <summary>
+        /// Creates a client and verifies the server is reachable by requesting session information.
+        /// Throws <see cref="InvalidOperationException"/> if the server doesn't respond with a valid session.
+        /// </summary>
+        public static async Task<TransmissionService> ConnectAsync(String host, String? username, String? password)
+        {
+            var client = new Client(host, null, username, password);
+            var sessionInformation = await client.GetSessionInformationAsync();
+            if (sessionInformation == null || String.IsNullOrEmpty(sessionInformation.Version))
+                throw new InvalidOperationException($"An error occurred while receiving session information from the rpc server at {host}");
+
+            return new TransmissionService(client);
+        }
+
+        /// <summary>
+        /// Adds a .torrent file to the server, saving to <paramref name="saveLocation"/>, and applies a seed ratio limit.
+        /// </summary>
+        public async Task<NewTorrentInfo> AddNewTorrentFileToServerAsync(byte[] torrentFileData, String saveLocation, bool paused = true, double seedRatioLimit = 1.0)
+        {
+            NewTorrent newTorrent = new()
+            {
+                DownloadDirectory = saveLocation,
+                Paused = paused,
+                Metainfo = Convert.ToBase64String(torrentFileData)
+            };
+            var torrentInfo = await Client.TorrentAddAsync(newTorrent);
+            var seedSettings = new TorrentSettings()
+            {
+                SeedRatioLimit = seedRatioLimit,
+                SeedRatioMode = 1,
+                IDs = [torrentInfo.ID]
+            };
+
+            // TorrentSetAsync returns void in Transmission.API.RPC 2.1.2, so it can't be awaited
+            Client.TorrentSet(seedSettings);
+            return torrentInfo;
+        }
+    }
+}