audit/middleware.py

"""
Audit Log Middleware

Automatically logs every mutating request (POST/PUT/PATCH/DELETE)
to sensitive paths. Read (GET) requests to admin/audit paths are
also captured for compliance tracing.
"""

import logging
import json
from django.conf import settings
from django.utils.deprecation import MiddlewareMixin

logger = logging.getLogger('audit')

SENSITIVE_PATHS = getattr(settings, 'AUDIT_LOG_SENSITIVE_PATHS', [
    '/api/admin/',
    '/api/auth/',
    '/api/caregivers/',
    '/api/bookings/',
    '/admin/',
])

LOG_METHODS = {'POST', 'PUT', 'PATCH', 'DELETE'}
# Also log GETs on these extra paths
LOG_GET_PATHS = ['/admin/', '/api/audit/']


def _get_client_ip(request):
    x_forwarded = request.META.get('HTTP_X_FORWARDED_FOR')
    if x_forwarded:
        return x_forwarded.split(',')[0].strip()
    return request.META.get('REMOTE_ADDR')


def _is_sensitive(path):
    return any(path.startswith(p) for p in SENSITIVE_PATHS)


def _is_log_get(path):
    return any(path.startswith(p) for p in LOG_GET_PATHS)


class AuditLogMiddleware(MiddlewareMixin):
    """
    Captures mutating requests on sensitive endpoints after the response
    is generated. Only imports AuditLog lazily to avoid AppRegistryNotReady
    errors during startup.
    """

    def process_response(self, request, response):
        method = request.method
        path = request.path

        should_log = (method in LOG_METHODS and _is_sensitive(path)) or \
                     (method == 'GET' and _is_log_get(path))

        if not should_log:
            return response

        try:
            from audit.models import AuditLog, AuditAction

            user = getattr(request, 'user', None)
            actor = user if (user and user.is_authenticated) else None

            # Derive action from method
            action_map = {
                'POST': AuditAction.CREATE,
                'PUT': AuditAction.UPDATE,
                'PATCH': AuditAction.UPDATE,
                'DELETE': AuditAction.DELETE,
                'GET': AuditAction.VIEW,
            }
            action = action_map.get(method, AuditAction.VIEW)

            # Specialise for known paths
            if '/caregivers/' in path:
                if method == 'POST':
                    action = AuditAction.CAREGIVER_ADD
                elif method in ('PUT', 'PATCH'):
                    action = AuditAction.CAREGIVER_UPDATE
                elif method == 'DELETE':
                    action = AuditAction.CAREGIVER_DELETE
            elif '/bookings/' in path:
                if method == 'POST':
                    action = AuditAction.BOOKING_CREATE
                elif method in ('PUT', 'PATCH'):
                    action = AuditAction.BOOKING_UPDATE
            elif '/auth/login' in path:
                action = AuditAction.LOGIN if response.status_code < 400 else AuditAction.LOGIN_FAILED
            elif '/auth/logout' in path:
                action = AuditAction.LOGOUT
            elif '/auth/register' in path:
                action = AuditAction.REGISTER

            # Build description
            description = f'{method} {path} → {response.status_code}'

            AuditLog.objects.create(
                actor=actor,
                action=action,
                description=description,
                request_path=path,
                request_method=method,
                response_status=response.status_code,
                ip_address=_get_client_ip(request),
                user_agent=request.META.get('HTTP_USER_AGENT', '')[:500],
            )
        except Exception as exc:   # noqa: BLE001 — never break the response
            logger.warning('AuditLogMiddleware error: %s', exc)

        return response