app/security/middleware.py

from __future__ import annotations

import time
from typing import Any
from uuid import uuid4

from fastapi import Request
from fastapi.responses import JSONResponse
from starlette.middleware.base import BaseHTTPMiddleware, RequestResponseEndpoint
from starlette.responses import Response

from app.core.config import Settings
from app.core.logger import get_logger
from app.security.audit import AuditService
from app.security.context import AuthContext, auth_context, http_auth_applied
from app.security.errors import ForbiddenError, RateLimitError, UnauthorizedError
from app.security.policy import ScopePolicy
from app.security.rate_limit import APIKeyRateLimiter, RateLimitLease
from app.security.service import APIKeyService

logger = get_logger(__name__)


class APIKeyAuthenticationMiddleware(BaseHTTPMiddleware):
    """Authenticates, authorizes, rate-limits, and audits protected HTTP requests."""

    def __init__(
        self,
        app: Any,
        *,
        settings: Settings,
        api_keys: APIKeyService,
        rate_limiter: APIKeyRateLimiter,
        audit: AuditService,
    ) -> None:
        super().__init__(app)
        self.settings = settings
        self.api_keys = api_keys
        self.rate_limiter = rate_limiter
        self.audit = audit
        self.policy = ScopePolicy()

    async def dispatch(self, request: Request, call_next: RequestResponseEndpoint) -> Response:
        if not getattr(request.state, "request_id", None):
            request.state.request_id = str(uuid4())
        if not self.settings.auth_enabled or self.policy.is_public(request):
            return await call_next(request)
        started = time.monotonic()
        context: AuthContext | None = None
        lease: RateLimitLease | None = None
        context_token = None
        http_auth_token = None
        response_code = 500
        bytes_uploaded = self._content_length(request.headers.get("content-length"))
        bytes_downloaded = 0
        try:
            api_key = self._bearer_token(request.headers.get("authorization"))
            context = await self.api_keys.authenticate(api_key)
            request.state.auth = context
            context_token = auth_context.set(context)
            required_scope = await self.policy.required_scope(request)
            lease = await self.rate_limiter.acquire(
                context,
                is_job=self.policy.is_job(required_scope)
                or request.url.path.startswith("/v1/projects/")
                and "/renders" in request.url.path
                and request.method == "POST",
                is_upload=self.policy.is_upload(request, required_scope),
                uploaded_bytes=bytes_uploaded,
            )
            if context.membership_role == "viewer" and required_scope not in {
                "templates:read",
                "operations:read",
                "jobs:read",
                "assets:read",
                "mcp:read",
                "system:read",
                "social:accounts:read",
                "social:posts:read",
                "social:schedules:read",
                "social:analytics:read",
                "analytics:read",
                "generation:providers:read",
                "generation:requests:read",
                "ai:read",
                "copilot:read",
                "projects:read",
                "members:read",
                "teams:read",
                "projects:collaborate",
                "comments:read",
                "approvals:read",
            }:
                raise ForbiddenError
            self.api_keys.authorize(context, required_scope)
            await self._apply_social_rate_limit(request, context)
            await self.api_keys.mark_used(context)
            http_auth_token = http_auth_applied.set(True)
            response = await call_next(request)
            response_code = response.status_code
            bytes_downloaded = self._content_length(response.headers.get("content-length"))
            response.headers.setdefault("X-Request-ID", request.state.request_id)
            return response
        except UnauthorizedError:
            response_code = 401
            return self._error(
                401,
                "Unauthorized",
                "Invalid or expired API key.",
                request,
                {"WWW-Authenticate": "Bearer"},
            )
        except ForbiddenError:
            response_code = 403
            response = self._error(403, "Forbidden", "Missing required scope.", request)
            bytes_downloaded = len(response.body)
            return response
        except RateLimitError as exc:
            response_code = 429
            response = self._error(
                429,
                "Rate limit exceeded",
                "Retry later.",
                request,
                {"Retry-After": str(exc.retry_after)},
            )
            bytes_downloaded = len(response.body)
            return response
        finally:
            if lease is not None:
                await lease.release()
            if http_auth_token is not None:
                http_auth_applied.reset(http_auth_token)
            if context_token is not None:
                auth_context.reset(context_token)
            if context is not None:
                elapsed_ms = max(0, round((time.monotonic() - started) * 1000))
                await self._audit_request(
                    request,
                    context,
                    response_code,
                    elapsed_ms,
                    bytes_uploaded,
                    bytes_downloaded,
                )

    async def _apply_social_rate_limit(self, request: Request, context: AuthContext) -> None:
        path = request.url.path
        if path.startswith("/v1/analytics"):
            category = "analytics_sync" if path.endswith(("/sync", "/cancel")) else "analytics_read"
            limit = (
                max(1, self.settings.social_analytics_requests_per_minute // 6)
                if category == "analytics_sync"
                else self.settings.social_analytics_requests_per_minute
            )
            await self.rate_limiter.acquire_category(
                context,
                category,
                limit=limit,
                window_seconds=60,
            )
            return
        if not path.startswith("/v1/social"):
            return
        if "/analytics" in path:
            await self.rate_limiter.acquire_category(
                context,
                "social_analytics",
                limit=self.settings.social_analytics_requests_per_minute,
                window_seconds=60,
            )
        elif path.endswith("/connect") or path.endswith("/callback") or path.endswith("/refresh"):
            await self.rate_limiter.acquire_category(
                context,
                "social_oauth",
                limit=self.settings.social_oauth_requests_per_hour,
                window_seconds=3600,
            )
        elif path.endswith("/publish"):
            await self.rate_limiter.acquire_category(
                context,
                "social_publish",
                limit=self.settings.social_publish_requests_per_minute,
                window_seconds=60,
            )
        elif path.endswith("/schedule"):
            await self.rate_limiter.acquire_category(
                context,
                "social_schedule",
                limit=self.settings.social_schedule_requests_per_minute,
                window_seconds=60,
            )
        elif path.endswith("/reschedule"):
            await self.rate_limiter.acquire_category(
                context,
                "social_schedule",
                limit=self.settings.social_schedule_requests_per_minute,
                window_seconds=60,
            )
        elif path.endswith("/bulk"):
            await self.rate_limiter.acquire_category(
                context,
                "social_bulk",
                limit=max(1, self.settings.social_schedule_requests_per_minute // 4),
                window_seconds=60,
            )

    @staticmethod
    def _bearer_token(header: str | None) -> str:
        if not header:
            raise UnauthorizedError
        parts = header.strip().split()
        if len(parts) != 2 or parts[0].casefold() != "bearer" or not parts[1]:
            raise UnauthorizedError
        return parts[1]

    @staticmethod
    def _content_length(value: str | None) -> int:
        try:
            return max(0, int(value or 0))
        except ValueError:
            return 0

    @staticmethod
    def _error(
        status_code: int,
        error: str,
        message: str,
        request: Request,
        headers: dict[str, str] | None = None,
    ) -> JSONResponse:
        response_headers = dict(headers or {})
        request_id = getattr(request.state, "request_id", None)
        if request_id:
            response_headers["X-Request-ID"] = request_id
        return JSONResponse(
            {"error": error, "message": message},
            status_code=status_code,
            headers=response_headers,
        )

    def _client_ip(self, request: Request) -> str | None:
        if self.settings.auth_trust_proxy_headers:
            forwarded = request.headers.get("x-forwarded-for")
            if forwarded:
                return forwarded.split(",", 1)[0].strip()[:64]
        return request.client.host[:64] if request.client else None

    async def _audit_request(
        self,
        request: Request,
        context: AuthContext,
        response_code: int,
        elapsed_ms: int,
        bytes_uploaded: int,
        bytes_downloaded: int,
    ) -> None:
        data = {
            "request_id": getattr(request.state, "request_id", "-"),
            "api_key_id": context.api_key_id,
            "key_name": context.key_name,
            "ip_address": self._client_ip(request),
            "user_agent": request.headers.get("user-agent", "")[:512] or None,
            "endpoint": request.url.path,
            "http_method": request.method,
            "response_code": response_code,
            "processing_time_ms": elapsed_ms,
            "bytes_uploaded": bytes_uploaded,
            "bytes_downloaded": bytes_downloaded,
        }
        try:
            await self.audit.record(**data)
        except Exception:
            logger.exception(
                "authentication audit persistence failed",
                extra={"api_key_id": context.api_key_id},
            )
        logger.info("authenticated request", extra=data)