// Triplet 統計 action — 知識圖譜規模統計
// 零 SQL / 零 D1：取全部 triplet record（走基本盤 API），在記憶體 reduce 出統計。
// GET /triplets/stats

import type { KbdbClient } from '../lib/kbdb-client';
import { queryTriplets } from './triplet-crud';

export interface TripletStats {
  total: number;
  // 保留 by_owner_id（原 by_user_id 改名，對齊基本盤 owner_id 欄位）。
  // 注：基本盤 record 不回傳 owner_id / 時間戳，故 by_owner_id/recent 在純插件層無法填，
  //     待 [→arcrun] base 於 record 回應帶上 owner_id + created_at 後補。
  by_owner_id: Record<string, number>;
  recent: { today: number; this_week: number };
  top_subjects: { subject: string; count: number }[];
  top_predicates: { predicate: string; count: number }[];
}

export async function getTripletStats(client: KbdbClient): Promise<TripletStats> {
  const { triplets } = await queryTriplets(client, { limit: 2000 });

  const subjectCounts = new Map<string, number>();
  const predicateCounts = new Map<string, number>();
  const ownerCounts: Record<string, number> = {};

  for (const t of triplets) {
    subjectCounts.set(t.subject, (subjectCounts.get(t.subject) ?? 0) + 1);
    predicateCounts.set(t.predicate, (predicateCounts.get(t.predicate) ?? 0) + 1);
  }

  const top = (m: Map<string, number>) =>
    [...m.entries()].sort((a, b) => b[1] - a[1]).slice(0, 10);

  return {
    total: triplets.length,
    by_owner_id: ownerCounts, // base record 暫無 owner_id，待上游補
    recent: { today: 0, this_week: 0 }, // base record 暫無 created_at，待上游補
    top_subjects: top(subjectCounts).map(([subject, count]) => ({ subject, count })),
    top_predicates: top(predicateCounts).map(([predicate, count]) => ({ predicate, count })),
  };
}