import { useEffect } from 'react';
import { Coverage } from 'fhir/r4';
import {
    useCoverageServiceContext,
    useFhirServiceContext,
    usePatientServiceContext,
    useWebSocketServiceContext
} from '../services';
import { isArchived } from '../utils/archivedResource';

const CREATED = 'com.akashichealthrecords.fhir.coverage.created';
const UPDATED = 'com.akashichealthrecords.fhir.coverage.updated';
const DELETED = 'com.akashichealthrecords.fhir.coverage.deleted';

// Keeps the insurance list of the patient on screen current; another patient's event is ignored.
export const useFhirCoverageBroadcast = () => {
    const { subscribe, unsubscribe } = useWebSocketServiceContext();
    const { setCoverageList } = useCoverageServiceContext();
    const { patientState } = usePatientServiceContext();
    const { extractReferenceId } = useFhirServiceContext();

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

        const handleCoverageEvent = (cloudEvent: any) => {
            const coverage: Coverage = cloudEvent.data;
            if (!coverage?.id || extractReferenceId(coverage.beneficiary) !== patientState.id) return;

            switch (cloudEvent.type) {
                case CREATED:
                    // The refetch after a save may already hold it; replace rather than append twice.
                    setCoverageList(prev =>
                        prev.some(p => p.id === coverage.id)
                            ? prev.map(p => p.id === coverage.id ? coverage : p)
                            : [...prev, coverage]
                    );
                    break;
                case UPDATED:
                    setCoverageList(prev => {
                        if (isArchived(coverage)) return prev.filter(p => p.id !== coverage.id);
                        return prev.some(p => p.id === coverage.id)
                            ? prev.map(p => p.id === coverage.id ? coverage : p)
                            : [...prev, coverage];
                    });
                    break;
                case DELETED:
                    setCoverageList(prev => prev.filter(p => p.id !== coverage.id));
                    break;
            }
        };

        subscribe(CREATED, handleCoverageEvent);
        subscribe(UPDATED, handleCoverageEvent);
        subscribe(DELETED, handleCoverageEvent);

        return () => {
            unsubscribe(CREATED, handleCoverageEvent);
            unsubscribe(UPDATED, handleCoverageEvent);
            unsubscribe(DELETED, handleCoverageEvent);
        };
    }, [patientState, subscribe, unsubscribe, extractReferenceId, setCoverageList]);
};