import type { FieldTimeline, FieldTimelineEntry } from './buildFieldTimeline';
import { PROFILE_HISTORY, readFieldValue } from './profileHistoryFields';

/**
 * One verified demographic edit from `GET Patient/{id}/demographic-history`: the field this practice
 * changed, its new value (absent when cleared), when, and who. Never a previous value.
 */
export interface DemographicHistoryRow {
    field: string;
    value?: unknown;
    recorded: string;
    author: { reference: string; display?: string };
}

/** The Patient field a history binding reads, or undefined for one the route never covers. */
const fieldOf = (path: string): string | undefined => {
    if (path === PROFILE_HISTORY.name) return 'name';
    if (path === PROFILE_HISTORY.phone || path === PROFILE_HISTORY.email) return 'telecom';
    if (path.startsWith('profile:address:')) return 'address';
    if (path.startsWith('profile:')) return undefined;
    return path.split(/[.[]/)[0];
};

const sameValue = (a: unknown, b: unknown): boolean => JSON.stringify(a) === JSON.stringify(b);

/**
 * A field's timeline from verified edits alone. `rows` newest-first. The oldest entry stands without
 * a "before": what preceded this practice's first edit is not ours to show.
 */
export function demographicTimeline(rows: DemographicHistoryRow[], path: string, label: string): FieldTimeline {
    const field = fieldOf(path);
    const values = rows
        .filter((row) => row.field === field)
        .map((row) => ({ row, value: readFieldValue({ resourceType: 'Patient', [row.field]: row.value }, path) }));

    const entries: FieldTimelineEntry[] = values
        .filter((current, index) => index === values.length - 1 || !sameValue(current.value, values[index + 1].value))
        .map(({ row, value }) => ({
            value,
            whenIso: row.recorded,
            ...(row.author.display ? { who: row.author.display } : { whoConfidence: 'unknown' as const }),
        }));

    return { path, label, changed: entries.length > 0, entries };
}