"""gRPC input adapter for on-demand tag reads (contract C4).

Thin adapter: unpack the request, call ActiveReadEngine.read_now, map the
result onto ReadTagResponse. Internal-only for now -- no auth/TLS, per the
feature owner (no consumer exists yet, likely a frontend later).
"""

import grpc
from sientia_do.observability.logger import Logger

from ingestor.engines.active_read import ActiveReadEngine
from ingestor.proto import opc_gateway_pb2, opc_gateway_pb2_grpc


class ReadTagServicer(opc_gateway_pb2_grpc.OpcGatewayServicer):
    def __init__(self, active_read: ActiveReadEngine, logger: Logger, slot_lookup=None):
        self.active_read = active_read
        self.logger = logger
        # ponytail: slot_lookup wiring (address -> names from the current slot)
        # lands at the SIENTIAPDE-1974 integration -- `names` only exist in slot v2,
        # which the Orchestrator produces after 1974. Until then ReadTag never
        # persists (persisted=False); optional callable keeps this servicer usable now.
        self.slot_lookup = slot_lookup

    async def ReadTag(self, request, context):
        names = None
        if self.slot_lookup is not None:
            names = self.slot_lookup(request.server_id, request.addr)
        try:
            result = await self.active_read.read_now(request.server_id, request.addr, names=names)
        except Exception as e:
            self.logger.error(f'ReadTag failed for {request.server_id}:{request.addr}: {e}')
            await context.abort(grpc.StatusCode.INTERNAL, f'read failed: {e}')
            return
        return opc_gateway_pb2.ReadTagResponse(
            value=str(result['value']),
            opc_status_code=result['opc_status_code'] or '',
            source_timestamp=result['source_timestamp'] or '',
            server_timestamp=result['server_timestamp'] or '',
            persisted=result['persisted'],
        )


class GrpcServer:
    def __init__(
        self,
        active_read: ActiveReadEngine,
        logger: Logger,
        port: int = 50051,
        slot_lookup=None,
    ):
        self.active_read = active_read
        self.logger = logger
        self.port = port
        self.slot_lookup = slot_lookup
        self.server: grpc.aio.Server | None = None

    async def start(self) -> None:
        self.server = grpc.aio.server()
        opc_gateway_pb2_grpc.add_OpcGatewayServicer_to_server(
            ReadTagServicer(self.active_read, self.logger, self.slot_lookup), self.server
        )
        self.server.add_insecure_port(f'[::]:{self.port}')
        await self.server.start()
        self.logger.info(f'GrpcServer started on port {self.port}')

    async def stop(self) -> None:
        if self.server is None:
            return
        await self.server.stop(grace=5)