import { useEffect } from 'react';
import { CareTeam } from 'fhir/r4';
import {
    useAuthServiceContext,
    useCareTeamServiceContext,
    useFhirServiceContext,
    usePatientServiceContext,
    useWebSocketServiceContext
} from '../services';
import { isArchived } from '../utils/archivedResource';
import { useCareTeamReadScope } from './useCareTeamReadScope';

export const useFhirCareTeamBroadcast = () => {
    const { subscribe, unsubscribe } = useWebSocketServiceContext();
    const { openListWriter, writeCareTeamsList } = useCareTeamServiceContext();
    const { patientState } = usePatientServiceContext();
    const { currentOrganization } = useAuthServiceContext();
    const scope = useCareTeamReadScope(patientState?.id);
    const organizationId = currentOrganization?.id;
    const { extractReferenceId } = useFhirServiceContext();

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

        // This subscription writes only into the list read for its own scope, and not at all once it ends.
        const writer = openListWriter(scope, patientState.id, organizationId);

        const handleCareTeamEvent = (cloudEvent: any) => {
            const careTeam: CareTeam = cloudEvent.data;
            const eventType = cloudEvent.type;
            const patientId = extractReferenceId(careTeam.subject);

            if (patientState.id === patientId) {
                const setCareTeamsList = (update: (prev: CareTeam[]) => CareTeam[], removed = false) =>
                    writeCareTeamsList(writer, update, { resource: careTeam, removed });
                switch (eventType) {
                    case 'com.akashichealthrecords.fhir.careteam.created':
                        // The list has two writers: this broadcast, and the service's own refetch after a write
                        // (several of which POLL until the new id appears). Refetch first and the list already holds
                        // the record, so an unconditional append put a SECOND copy of it on screen - observed on a
                        // patient's questionnaire answers, where one submission rendered as two completed forms.
                        // Keeping the broadcast's copy rather than skipping: its body is at least as fresh.
                        setCareTeamsList(prev =>
                            prev.some(p => p.id === careTeam.id)
                                ? prev.map(p => p.id === careTeam.id ? careTeam : p)
                                : [...prev, careTeam]
                        );
                        break;
                    case 'com.akashichealthrecords.fhir.careteam.updated':
                        setCareTeamsList(prev =>
                            isArchived(careTeam)
                                ? prev.filter(p => p.id !== careTeam.id)
                                : prev.map(p => p.id === careTeam.id ? careTeam : p),
                            isArchived(careTeam)
                        );
                        break;
                    case 'com.akashichealthrecords.fhir.careteam.deleted':
                        setCareTeamsList(prev => prev.filter(p => p.id !== careTeam.id), true);
                        break;
                }
            }
        };

        subscribe('com.akashichealthrecords.fhir.careteam.created', handleCareTeamEvent);
        subscribe('com.akashichealthrecords.fhir.careteam.updated', handleCareTeamEvent);
        subscribe('com.akashichealthrecords.fhir.careteam.deleted', handleCareTeamEvent);

        return () => {
            writer.retired = true;
            unsubscribe('com.akashichealthrecords.fhir.careteam.created', handleCareTeamEvent);
            unsubscribe('com.akashichealthrecords.fhir.careteam.updated', handleCareTeamEvent);
            unsubscribe('com.akashichealthrecords.fhir.careteam.deleted', handleCareTeamEvent);
        };
    }, [patientState, scope, organizationId, subscribe, unsubscribe, extractReferenceId, openListWriter, writeCareTeamsList]);
};