from dataclasses import dataclass
from time import perf_counter
from uuid import uuid4

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

REQUEST_ID_HEADER = "x-request-id"
TENANT_ID_HEADER = "x-tenant-id"
DEFAULT_TENANT_ID = "public"


@dataclass
class GatewayRequestContext:
    request_id: str
    tenant_id: str
    started_perf_counter: float
    target_service: str | None = None
    target_url: str | None = None


class GatewayRequestContextMiddleware(BaseHTTPMiddleware):
    async def dispatch(
        self,
        request: Request,
        call_next: RequestResponseEndpoint,
    ) -> Response:
        request_id = request.headers.get(REQUEST_ID_HEADER) or str(uuid4())
        tenant_id = resolve_tenant_id(request)
        request.state.gateway_context = GatewayRequestContext(
            request_id=request_id,
            tenant_id=tenant_id,
            started_perf_counter=perf_counter(),
        )
        try:
            response = await call_next(request)
        except Exception as exc:
            from app.infrastructure.audit import persist_gateway_audit

            persist_gateway_audit(
                request=request,
                session_factory=request.app.state.session_factory,
                status_code=500,
                error_message=str(exc),
            )
            raise

        from app.infrastructure.audit import persist_gateway_audit

        persist_gateway_audit(
            request=request,
            session_factory=request.app.state.session_factory,
            status_code=response.status_code,
        )
        response.headers[REQUEST_ID_HEADER] = request_id
        response.headers[TENANT_ID_HEADER] = tenant_id
        return response


def resolve_tenant_id(request: Request) -> str:
    header_tenant_id = request.headers.get(TENANT_ID_HEADER)
    if header_tenant_id:
        return header_tenant_id

    query_tenant_id = request.query_params.get("tenant_id")
    if query_tenant_id:
        return query_tenant_id

    return DEFAULT_TENANT_ID


def get_gateway_request_context(request: Request) -> GatewayRequestContext:
    context = getattr(request.state, "gateway_context", None)
    if isinstance(context, GatewayRequestContext):
        return context
    return GatewayRequestContext(
        request_id=str(uuid4()),
        tenant_id=DEFAULT_TENANT_ID,
        started_perf_counter=perf_counter(),
    )