fase 4 afgerond

app/api/session.py

@@ -137,3 +137,13 @@ def reorder_selected_files(
         raise HTTPException(status_code=400, detail=str(exc))
 
     return {"session_id": normalized_session_id, "items": items}
+
+
+@router.get("/mapping-preview")
+def get_mapping_preview(session_id: str = Query("default", min_length=1)):
+    service = SessionService()
+    normalized_session_id = _normalize_session_id(session_id)
+    try:
+        return service.build_mapping_preview(normalized_session_id)
+    except ValueError as exc:
+        raise HTTPException(status_code=400, detail=str(exc))

app/services/session_service.py

@@ -316,3 +316,34 @@ class SessionService:
                     (position, session_id, item["selection_id"]),
                 )
         return self.list_selected_files(session_id)
+
+    def build_mapping_preview(self, session_id: str) -> dict:
+        episodes = self.list_selected_episodes(session_id)
+        files = self.list_selected_files(session_id)
+
+        if len(episodes) != len(files):
+            raise ValueError(
+                "Selected episodes and selected files count mismatch: "
+                f"{len(episodes)} episodes vs {len(files)} files"
+            )
+
+        mappings = []
+        for index, (episode_item, file_item) in enumerate(zip(episodes, files)):
+            mappings.append(
+                {
+                    "index": index,
+                    "episode_selection_id": episode_item["selection_id"],
+                    "file_selection_id": file_item["selection_id"],
+                    "episode": episode_item["episode"],
+                    "file": file_item["file"],
+                }
+            )
+
+        return {
+            "session_id": session_id,
+            "counts": {
+                "episodes": len(episodes),
+                "files": len(files),
+            },
+            "mappings": mappings,
+        }