"""Shared legacy REST compat metering (routes and query params)."""
from __future__ import annotations

import logging

from fastapi import Request, Response
from sqlalchemy.ext.asyncio import AsyncSession

from api.services.legacy_meter import identity_from_request, record_legacy_usage

logger = logging.getLogger(__name__)

_LEGACY_OWNER = "state-hub.api"
# Planning horizon for legacy workstream interfaces; actual removal remains
# legacy-meter-gated per docs/workplan-terminology-transition.md.
_LEGACY_WORKSTREAM_SUNSET = "Wed, 30 Jun 2027 23:59:59 GMT"


def mark_legacy_response(response: Response | None, replacement_ref: str) -> None:
    if response is None:
        return
    response.headers["Deprecation"] = "true"
    response.headers["Sunset"] = _LEGACY_WORKSTREAM_SUNSET
    response.headers["X-StateHub-Replacement"] = replacement_ref
    response.headers.append("Link", f'<{replacement_ref}>; rel="successor-version"')


def legacy_query_param_key(method: str, route: str, param: str = "workstream_id") -> str:
    return f"rest_api:{method} {route}?{param}"


async def meter_legacy_query_param(
    *,
    session: AsyncSession,
    request: Request | None,
    response: Response | None,
    method: str,
    route: str,
    replacement_ref: str,
    param: str = "workstream_id",
) -> None:
    interface_key = legacy_query_param_key(method, route, param)
    mark_legacy_response(response, replacement_ref)
    try:
        await record_legacy_usage(
            session,
            interface_key=interface_key,
            interface_kind="rest_api",
            replacement_ref=replacement_ref,
            owner_component=_LEGACY_OWNER,
            replacement_verified=True,
            identity=identity_from_request(request),
        )
    except Exception:
        await session.rollback()
        logger.warning("legacy-meter failed to record %s", interface_key, exc_info=True)


def legacy_body_field_key(method: str, route: str, field: str = "workstream_id") -> str:
    return f"rest_api:{method} {route} {field}"


async def meter_legacy_body_field(
    *,
    session: AsyncSession,
    request: Request | None,
    response: Response | None,
    method: str,
    route: str,
    replacement_ref: str,
    field: str = "workstream_id",
) -> None:
    interface_key = legacy_body_field_key(method, route, field)
    mark_legacy_response(response, replacement_ref)
    try:
        await record_legacy_usage(
            session,
            interface_key=interface_key,
            interface_kind="rest_api",
            replacement_ref=replacement_ref,
            owner_component=_LEGACY_OWNER,
            replacement_verified=True,
            identity=identity_from_request(request),
        )
    except Exception:
        await session.rollback()
        logger.warning("legacy-meter failed to record %s", interface_key, exc_info=True)