import { useEffect } from 'react';
import { Goal } from 'fhir/r4';
import {
    useGoalServiceContext,
    useFhirServiceContext,
    usePatientServiceContext,
    useWebSocketServiceContext
} from '../services';

export const useFhirGoalBroadcast = () => {
    const { subscribe, unsubscribe } = useWebSocketServiceContext();
    const { goalsList, publishGoal, readGoalForEvent } = useGoalServiceContext();
    const { patientState } = usePatientServiceContext();
    const { extractReferenceId } = useFhirServiceContext();

    useEffect(() => {
        if (!patientState) {
            return;
        }

        const handleGoalEvent = (cloudEvent: any) => {
            const goal: Goal = cloudEvent.data;
            const eventType = cloudEvent.type;
            const patientId = extractReferenceId(goal.subject);

            if (patientState.id !== patientId || !goal.id) return;
            // A deletion clears it at once; any other change is read again, since what an event carries is not shown.
            if (eventType === 'com.akashichealthrecords.fhir.goal.deleted') publishGoal(goal, 'deleted');
            else void readGoalForEvent(goal.id, cloudEvent);
        };

        subscribe('com.akashichealthrecords.fhir.goal.created', handleGoalEvent);
        subscribe('com.akashichealthrecords.fhir.goal.updated', handleGoalEvent);
        subscribe('com.akashichealthrecords.fhir.goal.deleted', handleGoalEvent);

        return () => {
            unsubscribe('com.akashichealthrecords.fhir.goal.created', handleGoalEvent);
            unsubscribe('com.akashichealthrecords.fhir.goal.updated', handleGoalEvent);
            unsubscribe('com.akashichealthrecords.fhir.goal.deleted', handleGoalEvent);
        };
    }, [patientState, subscribe, unsubscribe, extractReferenceId, goalsList, publishGoal, readGoalForEvent]);
};