'use strict';

const { Pool } = require('pg');

const cache = new Map();
const CACHE_MAX = 200;

function createEmbeddingClient(cfg, opts = {}) {
  const pool = new Pool({ connectionString: opts.pgUrl || cfg.ragPgUrl, max: 2, connectionTimeoutMillis: 5000 });
  const model = cfg.embModel || 'text-embedding-v4';
  const dim = cfg.embDim || 1024;
  const baseUrl = String(cfg.embBaseUrl || '').replace(/\/+$/, '');
  const apiKey = cfg.embApiKey;
  const translateModel = cfg.embTranslateModel || 'qwen-turbo';

  async function embedQuery(text) {
    const key = String(text || '').slice(0, 200);
    if (cache.has(key)) return cache.get(key);
    if (!baseUrl || !apiKey) throw new Error('Embedding provider is not configured');
    const res = await fetch(`${baseUrl}/embeddings`, {
      method: 'POST',
      headers: { Authorization: `Bearer ${apiKey}`, 'Content-Type': 'application/json' },
      body: JSON.stringify({ model, input: text, encoding_format: 'float', dimensions: dim }),
      signal: AbortSignal.timeout(15000),
    });
    const json = await res.json();
    if (!res.ok || !json.data || !json.data[0] || !json.data[0].embedding) {
      throw new Error('embedQuery failed: ' + JSON.stringify(json).slice(0, 200));
    }
    const vec = json.data[0].embedding;
    if (cache.size >= CACHE_MAX) cache.delete(cache.keys().next().value);
    cache.set(key, vec);
    return vec;
  }

  function vecStr(v) {
    return '[' + v.join(',') + ']';
  }

  async function translateQueryToEnglish(query) {
    try {
      const res = await fetch(`${baseUrl}/chat/completions`, {
        method: 'POST',
        headers: { Authorization: `Bearer ${apiKey}`, 'Content-Type': 'application/json' },
        body: JSON.stringify({
          model: translateModel,
          max_tokens: 80,
          messages: [
            { role: 'system', content: 'Translate the user message into a concise English search query for a B2B jewelry wholesaler FAQ. Output ONLY the English translation, no explanation, no quotes.' },
            { role: 'user', content: query },
          ],
        }),
        signal: AbortSignal.timeout(15000),
      });
      const json = await res.json();
      const out = (((json.choices || [])[0] || {}).message || {}).content || '';
      return String(out).trim().replace(/^["']|["']$/g, '');
    } catch (err) {
      console.error(JSON.stringify({ ts: new Date().toISOString(), warn: `kb translate failed: ${err.message}` }));
      return null;
    }
  }

  return { pool, embedQuery, vecStr, translateQueryToEnglish, model, dim };
}

module.exports = { createEmbeddingClient };