import type { Provenance } from 'fhir/r4';
import type { MyHistoryEvent } from '../history/collapseHistory';
import type { ResourceHistoryFetchResult } from './useFieldHistoryFetch';

export interface RecordCreation {
    who?: string;
    whenIso?: string;
    /** The attribution could not be read, so who created the record is not known here. */
    unreadable: boolean;
}

const isCreate = (provenance: Provenance): boolean =>
    provenance.activity?.text === 'CREATE'
    || (provenance.activity?.coding ?? []).some((coding) => coding.code === 'CREATE');

/**
 * Who created a resource, from its stored CREATE Provenance, or from the caller's own activity feed
 * when they may not read Provenance. Never the current user and never a field on the resource, and
 * never from a read that did not cover the whole attribution.
 */
export function readRecordCreation(
    result: ResourceHistoryFetchResult,
    activity: MyHistoryEvent[],
    resourceType: string,
    resourceId: string,
): RecordCreation {
    if (result.provenanceRefused) {
        const event = activity.find((row) =>
            row.action === 'C'
            && row.resourceType === resourceType
            && row.resourceId === resourceId
            && Boolean(row.actorName));
        if (event) return { who: event.actorName, whenIso: event.recorded, unreadable: false };
        return { unreadable: true };
    }
    if (result.provenanceUnreadable || result.attribution !== 'complete') {
        return { unreadable: true };
    }

    const created = result.provenances.find(isCreate);
    const agent = created?.agent?.[0]?.who;
    const who = agent?.display ?? agent?.reference;
    return who ? { who, whenIso: created?.recorded, unreadable: false } : { unreadable: false };
}