import { useEffect } from 'react';
import { MedicationStatement } from 'fhir/r4';
import { useMedicationStatementServiceContext, usePatientServiceContext, useWebSocketServiceContext } from '../services';
import { refersToPatient } from '../utils/writeThroughHold';

interface UseMedicationStatementWebSocketOptions {
    medicationStatement?: MedicationStatement;
    medicationStatementId?: string;
    isOpen?: boolean;
    onUpdate: (medicationStatement: MedicationStatement) => void;
    onDelete: () => void;
}

export const useFhirMedicationStatementTargetedBroadcast = ({
                                                                medicationStatement,
                                                                medicationStatementId,
                                                                isOpen = true,
                                                                onUpdate,
                                                                onDelete
                                                            }: UseMedicationStatementWebSocketOptions) => {
    const { subscribe, unsubscribe } = useWebSocketServiceContext();
    const { patientState } = usePatientServiceContext();
    // Admitted by the service's per-record floor, as the list is: an older, unordered or removed copy never reaches it.
    const { admitMedicationEvent } = useMedicationStatementServiceContext();

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

        const handleMedicationStatementEvent = (cloudEvent: any) => {
            const medicationStatementPayload: MedicationStatement = cloudEvent.data;
            const eventType = cloudEvent.type;

            const targetId = medicationStatementId || medicationStatement.id;

            // The same id about another patient is not this medication.
            if (medicationStatementPayload.id === targetId && refersToPatient(medicationStatementPayload, patientState.id)) {
                switch (eventType) {
                    case 'com.akashichealthrecords.fhir.medicationstatement.updated':
                        if (admitMedicationEvent(medicationStatementPayload, 'updated')) onUpdate(medicationStatementPayload);
                        break;
                    case 'com.akashichealthrecords.fhir.medicationstatement.deleted':
                        admitMedicationEvent(medicationStatementPayload, 'deleted');
                        onDelete();
                        break;
                }
            }
        };

        subscribe('com.akashichealthrecords.fhir.medicationstatement.updated', handleMedicationStatementEvent);
        subscribe('com.akashichealthrecords.fhir.medicationstatement.deleted', handleMedicationStatementEvent);

        return () => {
            unsubscribe('com.akashichealthrecords.fhir.medicationstatement.updated', handleMedicationStatementEvent);
            unsubscribe('com.akashichealthrecords.fhir.medicationstatement.deleted', handleMedicationStatementEvent);
        };
    }, [patientState, medicationStatement, medicationStatementId, isOpen, onUpdate, onDelete, subscribe, unsubscribe, admitMedicationEvent]);
};