import { useEffect } from 'react';
import { useDeviceServiceContext, usePatientServiceContext, useWebSocketServiceContext } from '../services';
import { useSaveScope, type SaveOperation } from '../utils/saveOperation';

export const useFhirDeviceBroadcast = () => {
    const { subscribe, unsubscribe } = useWebSocketServiceContext();
    const { fetchDevicesWithPolling } = useDeviceServiceContext();
    const { patientState } = usePatientServiceContext();
    const patientId = patientState?.id;
    const scope = useSaveScope(patientId ? `Device-list/${patientId}` : undefined);

    useEffect(() => {
        if (!patientId || !patientState) return;
        const patient = { ...patientState, id: patientId };
        let live = true;
        let active: SaveOperation | undefined;
        const events = [
            'com.akashichealthrecords.fhir.device.created',
            'com.akashichealthrecords.fhir.device.updated',
            'com.akashichealthrecords.fhir.device.deleted',
        ];
        const handleDeviceEvent = async (event: { type?: string; data?: { id?: string; resourceType?: string } }) => {
            if (!live || !event?.type || !events.includes(event.type)
                || typeof event.data?.id !== 'string' || !/^[A-Za-z0-9.-]+$/.test(event.data.id)
                || (event.data.resourceType && event.data.resourceType !== 'Device')) return;
            active?.retire();
            const operation = scope.start();
            active = operation;
            try {
                // The service publishes only its authorized list; a pushed record never enters the cache.
                await operation.step(() => fetchDevicesWithPolling(patient, true, operation.transport));
            } catch {
                return;
            } finally {
                operation.retire();
                if (active === operation) active = undefined;
            }
        };
        for (const event of events) subscribe(event, handleDeviceEvent);
        return () => {
            live = false;
            active?.retire();
            for (const event of events) unsubscribe(event, handleDeviceEvent);
        };
    }, [patientId, patientState, fetchDevicesWithPolling, subscribe, unsubscribe, scope]);
};