add possible solution for later

feat/ScriptInjectionMiddleware.cs

@@ -0,0 +1,102 @@
+using System;
+using System.IO;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+
+namespace Jellyfin.Plugin.Seasonals;
+
+/// <summary>
+/// Middleware to inject the Seasonals script into the Jellyfin web interface.
+/// </summary>
+public class ScriptInjectionMiddleware
+{
+    private readonly RequestDelegate _next;
+    private readonly ILogger<ScriptInjectionMiddleware> _logger;
+    private const string ScriptTag = "<script src=\"Seasonals/Resources/seasonals.js\"></script>";
+    private const string Marker = "</body>";
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptInjectionMiddleware"/> class.
+    /// </summary>
+    /// <param name="next">The next delegate in the pipeline.</param>
+    /// <param name="logger">The logger.</param>
+    public ScriptInjectionMiddleware(RequestDelegate next, ILogger<ScriptInjectionMiddleware> logger)
+    {
+        _next = next;
+        _logger = logger;
+    }
+
+    /// <summary>
+    /// Invokes the middleware.
+    /// </summary>
+    /// <param name="context">The HTTP context.</param>
+    /// <returns>A task representing the asynchronous operation.</returns>
+    public async Task InvokeAsync(HttpContext context)
+    {
+        if (IsIndexRequest(context.Request.Path))
+        {
+            var originalBodyStream = context.Response.Body;
+            using var responseBody = new MemoryStream();
+            context.Response.Body = responseBody;
+
+            try
+            {
+                await _next(context);
+
+                context.Response.Body = originalBodyStream;
+                responseBody.Seek(0, SeekOrigin.Begin);
+
+                if (context.Response.StatusCode == 200 &&
+                    context.Response.ContentType != null &&
+                    context.Response.ContentType.Contains("text/html", StringComparison.OrdinalIgnoreCase))
+                {
+                    using var reader = new StreamReader(responseBody);
+                    var content = await reader.ReadToEndAsync();
+
+                    if (!content.Contains(ScriptTag, StringComparison.Ordinal) && content.Contains(Marker, StringComparison.Ordinal))
+                    {
+                        var newContent = content.Replace(Marker, $"{ScriptTag}\n{Marker}", StringComparison.Ordinal);
+                        var bytes = Encoding.UTF8.GetBytes(newContent);
+                        
+                        context.Response.ContentLength = bytes.Length;
+                        await context.Response.Body.WriteAsync(bytes, 0, bytes.Length);
+                        return;
+                    }
+                }
+
+                responseBody.Seek(0, SeekOrigin.Begin);
+                await responseBody.CopyToAsync(originalBodyStream);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Error injecting Seasonals script via middleware.");
+                // Ensure we try to write back the original response if something failed
+                if (responseBody.Length > 0 && context.Response.Body == originalBodyStream)
+                {
+                    responseBody.Seek(0, SeekOrigin.Begin);
+                    await responseBody.CopyToAsync(originalBodyStream);
+                }
+            }
+        }
+        else
+        {
+            await _next(context);
+        }
+    }
+
+    private static bool IsIndexRequest(PathString path)
+    {
+        if (!path.HasValue)
+        {
+            return false;
+        }
+
+        var p = path.Value;
+        // Check for root, index.html, or web/index.html
+        return p.Equals("/", StringComparison.OrdinalIgnoreCase) ||
+               p.Equals("/index.html", StringComparison.OrdinalIgnoreCase) ||
+               p.EndsWith("/web/index.html", StringComparison.OrdinalIgnoreCase);
+    }
+}