feat: Implement NFOService.update_tvshow_nfo()

- Parse existing NFO to extract TMDB ID from uniqueid or tmdbid element
- Fetch fresh metadata from TMDB API
- Regenerate NFO with updated data
- Optionally re-download media files
- Add comprehensive error handling (missing NFO, no TMDB ID, invalid XML)
- Add unit tests for XML parsing logic (4 tests, all passing)
- Add integration test script (requires TMDB API key)

src/core/services/nfo_service.py

@@ -12,6 +12,8 @@ import logging
 from pathlib import Path
 from typing import Any, Dict, List, Optional
 
+from lxml import etree
+
 from src.core.entities.nfo_models import (
     ActorInfo,
     ImageInfo,
@@ -158,21 +160,76 @@ class NFOService:
             
         Raises:
             FileNotFoundError: If NFO file doesn't exist
-            TMDBAPIError: If TMDB API fails
+            TMDBAPIError: If TMDB API fails or no TMDB ID found in NFO
         """
-        nfo_path = self.anime_directory / serie_folder / "tvshow.nfo"
+        folder_path = self.anime_directory / serie_folder
+        nfo_path = folder_path / "tvshow.nfo"
         
         if not nfo_path.exists():
             raise FileNotFoundError(f"NFO file not found: {nfo_path}")
         
-        # Parse existing NFO to get TMDB ID
-        # For simplicity, we'll recreate from scratch
-        # In production, you'd parse the XML to extract the ID
-        
         logger.info(f"Updating NFO for {serie_folder}")
-        # Implementation would extract serie name and call create_tvshow_nfo
-        # This is a simplified version
-        raise NotImplementedError("Update NFO not yet implemented")
+        
+        # Parse existing NFO to extract TMDB ID
+        try:
+            tree = etree.parse(str(nfo_path))
+            root = tree.getroot()
+            
+            # Try to find TMDB ID from uniqueid elements
+            tmdb_id = None
+            for uniqueid in root.findall(".//uniqueid"):
+                if uniqueid.get("type") == "tmdb":
+                    tmdb_id = int(uniqueid.text)
+                    break
+            
+            # Fallback: check for tmdbid element
+            if tmdb_id is None:
+                tmdbid_elem = root.find(".//tmdbid")
+                if tmdbid_elem is not None and tmdbid_elem.text:
+                    tmdb_id = int(tmdbid_elem.text)
+            
+            if tmdb_id is None:
+                raise TMDBAPIError(
+                    f"No TMDB ID found in existing NFO. "
+                    f"Delete the NFO and create a new one instead."
+                )
+            
+            logger.debug(f"Found TMDB ID: {tmdb_id}")
+            
+        except etree.XMLSyntaxError as e:
+            raise TMDBAPIError(f"Invalid XML in NFO file: {e}")
+        except ValueError as e:
+            raise TMDBAPIError(f"Invalid TMDB ID format in NFO: {e}")
+        
+        # Fetch fresh data from TMDB
+        async with self.tmdb_client:
+            logger.debug(f"Fetching fresh data for TMDB ID: {tmdb_id}")
+            details = await self.tmdb_client.get_tv_show_details(
+                tmdb_id,
+                append_to_response="credits,external_ids,images"
+            )
+            
+            # Convert TMDB data to TVShowNFO model
+            nfo_model = self._tmdb_to_nfo_model(details)
+            
+            # Generate XML
+            nfo_xml = generate_tvshow_nfo(nfo_model)
+            
+            # Save updated NFO file
+            nfo_path.write_text(nfo_xml, encoding="utf-8")
+            logger.info(f"Updated NFO: {nfo_path}")
+            
+            # Re-download media files if requested
+            if download_media:
+                await self._download_media_files(
+                    details,
+                    folder_path,
+                    download_poster=True,
+                    download_logo=True,
+                    download_fanart=True
+                )
+            
+            return nfo_path
     
     def _find_best_match(
         self,