"""Deprecation middleware for legacy API routes.

Provides middleware to add deprecation warning headers to legacy /api/ routes
during the transition to /api/v1/.
"""
import logging
from datetime import datetime
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import Request

logger = logging.getLogger(__name__)


class DeprecationMiddleware(BaseHTTPMiddleware):
    """Middleware to add deprecation headers to legacy API routes.

    This middleware checks if a request is using a legacy /api/ route
    (instead of /api/v1/) and adds appropriate deprecation headers to
    encourage migration to the new versioned API.
    """

    # Sunset date for legacy routes (6 months from now, adjust as needed)
    SUNSET_DATE = "2026-07-01T00:00:00Z"

    async def dispatch(self, request: Request, call_next):
        response = await call_next(request)

        # Check if this is a legacy /api/ route (not /api/v1/)
        path = request.url.path
        if path.startswith("/api/") and not path.startswith("/api/v1/"):
            # Skip deprecation headers for health check endpoints
            if path in ["/health", "/health/ready", "/health/live", "/health/detailed"]:
                return response

            # Add deprecation headers (RFC 8594)
            response.headers["Deprecation"] = "true"
            response.headers["Sunset"] = self.SUNSET_DATE
            response.headers["Link"] = f'</api/v1{path[4:]}>; rel="successor-version"'
            response.headers["X-Deprecation-Notice"] = (
                "This API endpoint is deprecated. "
                "Please migrate to /api/v1/ prefix. "
                f"This endpoint will be removed after {self.SUNSET_DATE}."
            )

        return response