codekingpro/portable-devtools

1"""Client middleware support."""
2
3from collections.abc import Awaitable, Callable, Sequence
4
5from .client_reqrep import ClientRequest, ClientResponse
6
7__all__ = ("ClientMiddlewareType", "ClientHandlerType", "build_client_middlewares")
8
9# Type alias for client request handlers - functions that process requests and return responses
10ClientHandlerType = Callable[[ClientRequest], Awaitable[ClientResponse]]
11
12# Type for client middleware - similar to server but uses ClientRequest/ClientResponse
13ClientMiddlewareType = Callable[
14    [ClientRequest, ClientHandlerType], Awaitable[ClientResponse]
15]
16
17
18def build_client_middlewares(
19    handler: ClientHandlerType,
20    middlewares: Sequence[ClientMiddlewareType],
21) -> ClientHandlerType:
22    """
23    Apply middlewares to request handler.
24
25    The middlewares are applied in reverse order, so the first middleware
26    in the list wraps all subsequent middlewares and the handler.
27
28    This implementation avoids using partial/update_wrapper to minimize overhead
29    and doesn't cache to avoid holding references to stateful middleware.
30    """
31    # Optimize for single middleware case
32    if len(middlewares) == 1:
33        middleware = middlewares[0]
34
35        async def single_middleware_handler(req: ClientRequest) -> ClientResponse:
36            return await middleware(req, handler)
37
38        return single_middleware_handler
39
40    # Build the chain for multiple middlewares
41    current_handler = handler
42
43    for middleware in reversed(middlewares):
44        # Create a new closure that captures the current state
45        def make_wrapper(
46            mw: ClientMiddlewareType, next_h: ClientHandlerType
47        ) -> ClientHandlerType:
48            async def wrapped(req: ClientRequest) -> ClientResponse:
49                return await mw(req, next_h)
50
51            return wrapped
52
53        current_handler = make_wrapper(middleware, current_handler)
54
55    return current_handler
56