type CompletionMetric =
  'claimed' | 'not_claimed' | 'recovered' | 'fence_rejected' | 'event_committed' | 'retry_wait' | 'needs_review';
const counts = new Map<CompletionMetric, number>();
let snapshot: Array<{ state: string; count: number; age: number }> = [];
const states = ['pending', 'processing', 'retry_wait', 'needs_review'];
export function countCompletion(event: CompletionMetric) {
  counts.set(event, (counts.get(event) ?? 0) + 1);
}
export function observeCompletion(rows: typeof snapshot) {
  snapshot = rows;
}
export function renderCompletionMetrics() {
  return [
    '# TYPE cmpp_completion_events_total counter',
    ...[...counts].map(([event, value]) => `cmpp_completion_events_total{event="${event}"} ${value}`),
    '# TYPE cmpp_completion_work gauge',
    '# TYPE cmpp_completion_oldest_seconds gauge',
    ...states.flatMap((state) => {
      const row = snapshot.find((item) => item.state === state);
      return [
        `cmpp_completion_work{state="${state}"} ${Number(row?.count ?? 0)}`,
        `cmpp_completion_oldest_seconds{state="${state}"} ${Math.max(0, Number(row?.age ?? 0))}`,
      ];
    }),
  ];
}