import { MeiliSearch } from 'meilisearch';
import type { SearchParams } from 'meilisearch';

export class MeiliService {
  private client: MeiliSearch;
  private indexes: string[];

  constructor() {
    const runtimeConfig = useRuntimeConfig();

    const host = runtimeConfig.public?.meili?.host;
    const apiKey = runtimeConfig.public?.meili?.searchKey;

    if (!host) throw new Error('Meilisearch host not configured');
    if (!apiKey) throw new Error('Meilisearch server key missing');

    this.client = new MeiliSearch({ host, apiKey });
    this.indexes = runtimeConfig.public.meili.indexes || [];
  }

  /** 构建索引名: products_zh-CN */
  private buildIndexNames(locale?: string) {
    if (!locale) return this.indexes;
    return this.indexes.map((i) => `${i.trim()}_${locale}`);
  }

  /** Server 封装的搜索方法 */
  async search<
    K extends keyof MeiliIndexMap = keyof MeiliIndexMap,
    T extends MeiliIndexMap[K] = MeiliIndexMap[K],
  >(query: string, params: SearchParams = {}, locale?: string) {
    const trimmedQuery = query.trim();
    if (!trimmedQuery) return [];

    const activeIndexes = this.buildIndexNames(locale);
    if (!activeIndexes.length) {
      logger.warn('No Meilisearch indexes configured.');
      return [];
    }

    const requests = activeIndexes.map(async (indexUID) => {
      const response = await this.client
        .index(indexUID)
        .search<T>(trimmedQuery, {
          limit: params.limit ?? 10,
          ...params,
        });

      return {
        indexUid: indexUID,
        rawIndex: indexUID.replace(`_${locale}`, ''),
        hits: response.hits,
        estimatedTotalHits: response.estimatedTotalHits ?? response.hits.length,
        processingTimeMs: response.processingTimeMs ?? 0,
      } as SearchSection<T>;
    });

    // 并行安全执行
    const results = await Promise.allSettled(requests);

    results
      .filter(
        (result): result is PromiseRejectedResult =>
          result.status === 'rejected'
      )
      .forEach((result) => {
        logger.error('Meilisearch query failed', result.reason);
      });

    const fulfilled = results.filter(
      (r): r is PromiseFulfilledResult<SearchSection<T>> =>
        r.status === 'fulfilled'
    );

    return fulfilled.map((r) => r.value).filter((s) => s.hits.length > 0);
  }
}

/** 单例 */
let instance: MeiliService | null = null;

export const getMeiliService = () => {
  if (!instance) instance = new MeiliService();
  return instance;
};