👀 preview docstring and docs

api/routes/documents/document.py

@@ -204,6 +204,24 @@ async def get_document_preview(
         metadata_repository: DocumentMetadataRepository = Depends(get_repository(DocumentMetadataRepository)),
         user: TokenData = Depends(get_current_user),
 ) -> FileResponse:
+
+    """
+    Get the preview of a document.
+
+    Args:
+        document (Union[str, UUID]): The ID or name of the document.
+        repository (DocumentRepository): The repository for accessing document data.
+        metadata_repository (DocumentMetadataRepository): The repository for accessing document metadata.
+        user (TokenData): The user token data.
+
+    Returns:
+        FileResponse: The file response containing the document preview.
+
+    Raises:
+        HTTP_404: If the document ID or name is not provided or if the document does not exist.
+        HTTP_400: If the file type is not supported for preview.
+    """
+
     if not document:
         raise HTTP_404(
             msg="Enter document id or name."
@@ -218,4 +236,4 @@ async def get_document_preview(
     except ValueError as e:
         raise HTTP_400(
             msg="File type is not supported for preview"
-        )
+        ) from e

docs/features/preview.md

@@ -0,0 +1,27 @@
+# Preview in Docflow
+
+Let's see how preview feature of DocFlow works. 🚀
+
+- 🎯 Endpoint:
+`GET /api/document/preview/:document`
+- ⚙️ Params:
+`{document: <docuent_id_or_name>}`
+- 🔐 Authorization:
+`Bearer <token>`
+
+Here in Preview we use two important models, `fastapi.response`'s `FileResponse` amd `tempfile`'s `NamedTemporaryFile`.
+
+`FileResponse` is used to return files.
+
+`NamedTemporaryFile` is a function in Python's `tempfile` module that creates a temporary file with a unique name in the 
+system's default location for temporary files. This function returns a file-like object that can be used in similar way 
+to other file objects.
+
+Here is the brief explanation on how it works:
+- When we call `NameTemporaryFile()`, it creates a new file in you system's temporary directory.
+- The temporary file is opened in binary mode (`wb+`) by default, and it can be read from and written to like any other
+file object.
+- The temporary file is deleted as soon as it is closed. This is controlled by the `delete` parameter, which is `True` 
+by default. This is important to set it `True`, as if not done then it could fill up the server's storage.
+
+The following figure describes how Preview in DocFlow works.