import type { Bundle, Communication } from 'fhir/r4';

/**
 * The server adds a just-sent message to the FIRST page of a thread read until the search indexes it, and
 * leaves later pages as searched, so a paged read can carry one message twice. The later copy is the
 * searched one and wins, in its own position.
 */
export const oneCopyPerThreadMessage = (bundle: Bundle<Communication>): Bundle<Communication> => {
    const entries = bundle.entry ?? [];
    const lastIndex = new Map<string, number>();
    entries.forEach((entry, index) => {
        const id = entry.resource?.id;
        if (id) lastIndex.set(id, index);
    });
    const kept = entries.filter((entry, index) => {
        const id = entry.resource?.id;
        return !id || lastIndex.get(id) === index;
    });
    return kept.length === entries.length ? bundle : { ...bundle, entry: kept };
};