// 列出所有唯一實體（subject ∪ object）— 零 SQL / 零 D1
// 取全部 triplet record（走基本盤 API），在記憶體統計 as_subject/as_object/total。
// GET /entities

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

export interface EntityStat {
  name: string;
  as_subject: number;
  as_object: number;
  total: number;
}

export interface EntityListResult {
  entities: EntityStat[];
  total: number;
  limit: number;
  offset: number;
}

export async function listTripletEntities(
  client: KbdbClient,
  { limit = 200, offset = 0, q }: { limit?: number; offset?: number; q?: string },
): Promise<EntityListResult> {
  const safeLimit = Math.min(limit, 500);
  const { triplets } = await queryTriplets(client, { limit: 2000 });

  const stats = new Map<string, EntityStat>();
  const bump = (name: string, role: 'as_subject' | 'as_object') => {
    if (!name) return;
    let s = stats.get(name);
    if (!s) {
      s = { name, as_subject: 0, as_object: 0, total: 0 };
      stats.set(name, s);
    }
    s[role] += 1;
    s.total += 1;
  };

  for (const t of triplets) {
    bump(t.subject, 'as_subject');
    bump(t.object, 'as_object');
  }

  let entities = [...stats.values()];
  if (q) {
    const needle = q.toLowerCase();
    entities = entities.filter((e) => e.name.toLowerCase().includes(needle));
  }
  entities.sort((a, b) => b.total - a.total);

  const total = entities.length;
  const page = entities.slice(offset, offset + safeLimit);

  return { entities: page, total, limit: safeLimit, offset };
}