app/middleware/logging_middleware.py

"""Author RAG Chatbot SaaS — Structured Logging Middleware (Pure ASGI).

Logs every request with: method, path, status, duration_ms, client_ip.
Uses structlog for JSON-formatted structured logging.

Uses pure ASGI to avoid BaseHTTPMiddleware request body consumption issues.
"""

import time

import structlog
from starlette.types import ASGIApp, Receive, Scope, Send

logger = structlog.get_logger(__name__)


class LoggingMiddleware:
    """Log all HTTP requests with timing and status (pure ASGI)."""

    def __init__(self, app: ASGIApp) -> None:
        self.app = app

    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
        if scope["type"] != "http":
            await self.app(scope, receive, send)
            return

        start_time = time.monotonic()
        status_code = 500  # Default in case of unhandled error

        async def send_with_logging(message):
            nonlocal status_code
            if message["type"] == "http.response.start":
                status_code = message["status"]
            await send(message)

        try:
            await self.app(scope, receive, send_with_logging)
        finally:
            duration_ms = int((time.monotonic() - start_time) * 1000)
            path = scope.get("path", "")

            # Skip health check noise in logs
            if path != "/health":
                client = scope.get("client")
                ip = client[0] if client else "unknown"
                log = logger.bind(
                    method=scope.get("method", ""),
                    path=path,
                    status=status_code,
                    duration_ms=duration_ms,
                    ip=ip,
                )
                if status_code >= 500:
                    log.error("Request failed")
                elif status_code >= 400:
                    log.warning("Client error")
                else:
                    log.info("Request completed")