Added OPML support

Jellyfin.Plugin.Jellypod/Services/IOpmlService.cs

@@ -0,0 +1,44 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Jellyfin.Plugin.Jellypod.Api.Models;
+using Jellyfin.Plugin.Jellypod.Models;
+
+namespace Jellyfin.Plugin.Jellypod.Services;
+
+/// <summary>
+/// Service for handling OPML import and export.
+/// </summary>
+public interface IOpmlService
+{
+    /// <summary>
+    /// Parses OPML content and extracts podcast outlines.
+    /// </summary>
+    /// <param name="opmlContent">The OPML XML content.</param>
+    /// <returns>List of parsed outlines.</returns>
+    IReadOnlyList<OpmlOutline> ParseOpml(string opmlContent);
+
+    /// <summary>
+    /// Parses OPML from a stream.
+    /// </summary>
+    /// <param name="stream">The input stream containing OPML XML.</param>
+    /// <returns>List of parsed outlines.</returns>
+    IReadOnlyList<OpmlOutline> ParseOpml(Stream stream);
+
+    /// <summary>
+    /// Imports podcasts from parsed OPML outlines.
+    /// </summary>
+    /// <param name="outlines">The parsed OPML outlines.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>Import result with statistics.</returns>
+    Task<OpmlImportResult> ImportPodcastsAsync(
+        IReadOnlyList<OpmlOutline> outlines,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Exports all subscribed podcasts to OPML format.
+    /// </summary>
+    /// <returns>OPML XML string.</returns>
+    Task<string> ExportToOpmlAsync();
+}