[UPDATE]: add docstring

src/api/routers/rerank.py

@@ -1,11 +1,12 @@
 """
-Rerank endpoint
+Rerank Endpoint Module
 
-This module provides routes for rerank documents
+This module provides routes for reranking documents based on a query.
+It accepts a list of documents and returns a ranked list based on relevance to the query.
 """
 
 import time
-from typing import Union
+from typing import Union, List
 from fastapi import APIRouter, Depends, HTTPException, status
 from loguru import logger
 
@@ -21,21 +22,39 @@ from src.core.exceptions import (
 from src.api.dependencies import get_model_manager
 from src.utils.validators import extract_embedding_kwargs
 
-router = APIRouter(prefix="rerank", tags=["rerank"])
+router = APIRouter(tags=["rerank"]) 
 
 
 @router.post(
-    "/", response_model=RerankResponse, summary="reranking documents", description=""
+    "/rerank", response_model=RerankResponse, summary="Rerank documents", description="Reranks the provided documents based on the given query."
 )
 async def rerank_documents(
     request: RerankRequest,
     manager: ModelManager = Depends(get_model_manager),
-) -> Union[RerankResponse, HTTPException]:
-    """"""
+) -> RerankResponse:
+    """
+    Rerank documents based on a query.
+
+    This endpoint processes a list of documents and returns them ranked according to their relevance to the query.
+    
+    Args:
+        request (RerankRequest): The request object containing the query and documents to rank.
+        manager (ModelManager): The model manager dependency to access the model.
+
+    Returns:
+        RerankResponse: The response containing the ranked documents and processing time.
+
+    Raises:
+        HTTPException: If there are validation errors, model loading issues, or unexpected errors.
+    """
     # Filter out empty documents and keep original indices
     valid_docs = [
         (i, doc.strip()) for i, doc in enumerate(request.documents) if doc.strip()
     ]
+
+    if not valid_docs:
+        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="No valid documents provided.")
+
     try:
         kwargs = extract_embedding_kwargs(request)
         model = manager.get_model(request.model_id)
@@ -44,26 +63,26 @@ async def rerank_documents(
         start = time.time()
         if config.type == "rerank":
             scores = model.rank_document(
-                request.query, request.documents, request.top_k, **kwargs
+                request.query, [doc for _, doc in valid_docs], request.top_k, **kwargs
             )
             processing_time = time.time() - start
 
             original_indices, documents_list = zip(*valid_docs)
-            results: list[RerankResult] = []
+            results: List[RerankResult] = []
 
             for i, (orig_idx, doc) in enumerate(zip(original_indices, documents_list)):
                 results.append(RerankResult(text=doc, score=scores[i], index=orig_idx))
 
-            # Sort by score descending
+            # Sort results by score in descending order
             results.sort(key=lambda x: x.score, reverse=True)
 
-        logger.info(f"Rerank documents in {processing_time:.3f} seconds")
-        return RerankResponse(
-            model_id=request.model_id,
-            processing_time=processing_time,
-            query=request.query,
-            results=results,
-        )
+            logger.info(f"Reranked documents in {processing_time:.3f} seconds")
+            return RerankResponse(
+                model_id=request.model_id,
+                processing_time=processing_time,
+                query=request.query,
+                results=results,
+            )
 
     except (ValidationError, ModelNotFoundError) as e:
         raise HTTPException(status_code=e.status_code, detail=e.message)