feat: add form-urlencoded body parsing for Feishin compatibility

octo-fiesta/Controllers/SubSonicController.cs

@@ -51,8 +51,40 @@ public class SubsonicController : ControllerBase
             parameters[query.Key] = query.Value.ToString();
         }
 
-        // Get body parameters (JSON)
+        // Get body parameters
-        if (Request.ContentLength > 0 && Request.ContentType?.Contains("application/json") == true)
+        if (Request.ContentLength > 0 || Request.ContentType != null)
+        {
+            // Handle application/x-www-form-urlencoded (OpenSubsonic formPost extension)
+            if (Request.HasFormContentType)
+            {
+                try
+                {
+                    var form = await Request.ReadFormAsync();
+                    foreach (var field in form)
+                    {
+                        parameters[field.Key] = field.Value.ToString();
+                    }
+                }
+                catch
+                {
+                    // Fall back to manual parsing if ReadFormAsync fails
+                    Request.EnableBuffering();
+                    using var reader = new StreamReader(Request.Body, leaveOpen: true);
+                    var body = await reader.ReadToEndAsync();
+                    Request.Body.Position = 0;
+                    
+                    if (!string.IsNullOrEmpty(body))
+                    {
+                        var formParams = Microsoft.AspNetCore.WebUtilities.QueryHelpers.ParseQuery(body);
+                        foreach (var param in formParams)
+                        {
+                            parameters[param.Key] = param.Value.ToString();
+                        }
+                    }
+                }
+            }
+            // Handle application/json
+            else if (Request.ContentType?.Contains("application/json") == true)
             {
                 using var reader = new StreamReader(Request.Body);
                 var body = await reader.ReadToEndAsync();
@@ -76,6 +108,7 @@ public class SubsonicController : ControllerBase
                     }
                 }
             }
+        }
 
         return parameters;
     }