import { useEffect } from 'react';
import { Location } from 'fhir/r4';
import {
    useLocationServiceContext,
    useFhirServiceContext,
    useWebSocketServiceContext
} from '../services';

export const useFhirLocationBroadcast = () => {
    const { subscribe, unsubscribe } = useWebSocketServiceContext();
    const { locationsList, setLocationsList } = useLocationServiceContext();
    const { extractReferenceId } = useFhirServiceContext();

    useEffect(() => {
        const handleLocationEvent = (cloudEvent: any) => {
            const location: Location = cloudEvent.data;
            const eventType = cloudEvent.type;

            switch (eventType) {
                case 'com.akashichealthrecords.fhir.location.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.
                    setLocationsList(prev =>
                        prev.some(p => p.id === location.id)
                            ? prev.map(p => p.id === location.id ? location : p)
                            : [...prev, location]
                    );
                    break;
                case 'com.akashichealthrecords.fhir.location.updated':
                    setLocationsList(prev => prev.map(p => p.id === location.id ? location : p));
                    break;
                case 'com.akashichealthrecords.fhir.location.deleted':
                    setLocationsList(prev => prev.filter(p => p.id !== location.id));
                    break;
            }
        };

        subscribe('com.akashichealthrecords.fhir.location.created', handleLocationEvent);
        subscribe('com.akashichealthrecords.fhir.location.updated', handleLocationEvent);
        subscribe('com.akashichealthrecords.fhir.location.deleted', handleLocationEvent);

        return () => {
            unsubscribe('com.akashichealthrecords.fhir.location.created', handleLocationEvent);
            unsubscribe('com.akashichealthrecords.fhir.location.updated', handleLocationEvent);
            unsubscribe('com.akashichealthrecords.fhir.location.deleted', handleLocationEvent);
        };
    }, [subscribe, unsubscribe, extractReferenceId, locationsList]);
};