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

export const useFhirEncounterBroadcast = () => {
    const { subscribe, unsubscribe } = useWebSocketServiceContext();
    const { encountersList, setEncountersList } = useEncounterServiceContext();
    const { patientState } = usePatientServiceContext();
    const { extractReferenceId } = useFhirServiceContext();

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

        const handleEncounterEvent = (cloudEvent: any) => {
            const encounter: Encounter = cloudEvent.data;
            const eventType = cloudEvent.type;
            const patientId = extractReferenceId(encounter.subject);

            if (patientState.id === patientId) {
                switch (eventType) {
                    case 'com.akashichealthrecords.fhir.encounter.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.
                        setEncountersList(prev =>
                            prev.some(p => p.id === encounter.id)
                                ? prev.map(p => p.id === encounter.id ? encounter : p)
                                : [...prev, encounter]
                        );
                        break;
                    case 'com.akashichealthrecords.fhir.encounter.updated':
                        setEncountersList(prev =>
                            isArchived(encounter)
                                ? prev.filter(p => p.id !== encounter.id)
                                : prev.map(p => p.id === encounter.id ? encounter : p)
                        );
                        break;
                    case 'com.akashichealthrecords.fhir.encounter.deleted':
                        setEncountersList(prev => prev.filter(p => p.id !== encounter.id));
                        break;
                }
            }
        };

        subscribe('com.akashichealthrecords.fhir.encounter.created', handleEncounterEvent);
        subscribe('com.akashichealthrecords.fhir.encounter.updated', handleEncounterEvent);
        subscribe('com.akashichealthrecords.fhir.encounter.deleted', handleEncounterEvent);

        return () => {
            unsubscribe('com.akashichealthrecords.fhir.encounter.created', handleEncounterEvent);
            unsubscribe('com.akashichealthrecords.fhir.encounter.updated', handleEncounterEvent);
            unsubscribe('com.akashichealthrecords.fhir.encounter.deleted', handleEncounterEvent);
        };
    }, [patientState, subscribe, unsubscribe, extractReferenceId, encountersList]);
};