learnLanguage/server.js

import express from 'express';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import {
  saveRecord,
  listRecords,
  getRecord,
  updateRecord,
  deleteRecord,
  getWord,
  listWords,
  upsertWordData,
  getRoot,
} from './db.js';
import { queryWords, queryWordsStream } from './llm.js';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const app = express();
app.use(express.json({ limit: '2mb' }));
app.use(express.static(path.join(__dirname, 'public')));

// 发起查询
app.post('/api/query', async (req, res) => {
  const sentence = (req.body.sentence || '').trim();
  const words = Array.isArray(req.body.words)
    ? req.body.words.map((w) => String(w).trim()).filter(Boolean)
    : [];

  if (!sentence) return res.status(400).json({ error: '请提供英语句子' });
  if (words.length === 0)
    return res.status(400).json({ error: '请提供至少一个要查询的单词' });
  if (words.length > 5)
    return res.status(400).json({ error: '一次最多查询 5 个单词' });

  try {
    const { raw, parsed } = await queryWords(sentence, words);
    const record = saveRecord({
      sentence,
      words,
      result: parsed,
      raw_result: raw,
    });
    res.json(record);
  } catch (err) {
    console.error('查询失败:', err.message);
    res.status(502).json({ error: `查询失败：${err.message}` });
  }
});


// 流式查询：SSE 增量推送 LLM 原始输出，完成后推送已保存的记录
app.post('/api/query/stream', async (req, res) => {
  const sentence = (req.body.sentence || '').trim();
  const words = Array.isArray(req.body.words)
    ? req.body.words.map((w) => String(w).trim()).filter(Boolean)
    : [];

  // 校验失败直接返回普通 JSON 错误
  if (!sentence) return res.status(400).json({ error: '请提供英语句子' });
  if (words.length === 0)
    return res.status(400).json({ error: '请提供至少一个要查询的单词' });
  if (words.length > 5)
    return res.status(400).json({ error: '一次最多查询 5 个单词' });

  res.set({
    'Content-Type': 'text/event-stream; charset=utf-8',
    'Cache-Control': 'no-cache',
    Connection: 'keep-alive',
    'X-Accel-Buffering': 'no',
  });
  res.flushHeaders();

  const send = (obj) => res.write(`data: ${JSON.stringify(obj)}\n\n`);

  try {
    // 查询已在词库中的单词：把已有释义带给 LLM，用于同义项合并
    const existingWords = words
      .map((w) => getWord(w))
      .filter(Boolean)
      .map((r) => ({ word: r.word, senses: r.senses.map((s) => s.sense), roots: r.roots }));

    const { raw, parsed } = await queryWordsStream(sentence, words, (delta) => {
      send({ type: 'delta', text: delta });
    }, existingWords);

    // 按单词维度并入词库（同义项合并、原句计入该单词记录）
    for (const w of parsed.words || []) {
      try {
        upsertWordData(w, sentence, parsed.sentence_translation || '');
      } catch (e) {
        console.error('词库更新失败:', e.message);
      }
    }

    const record = saveRecord({
      sentence,
      words,
      result: parsed,
      raw_result: raw,
    });
    send({ type: 'done', record });
  } catch (err) {
    console.error('流式查询失败:', err.message);
    send({ type: 'error', message: `查询失败：${err.message}` });
  } finally {
    res.end();
  }
});
// 词库列表
app.get('/api/words', (req, res) => {
  const { page, size } = pagerParams(req);
  res.json(listWords(page, size, req.query.q || ''));
});

// 单词详情（含全部释义与例句）
app.get('/api/words/:word', (req, res) => {
  const record = getWord(req.params.word.toLowerCase());
  if (!record) return res.status(404).json({ error: '词库中不存在该单词' });
  res.json(record);
});

// 词根详情（该词根下的所有学过的词，按含义变体并列）
app.get('/api/roots/:root', (req, res) => {
  const record = getRoot(req.params.root.toLowerCase());
  if (!record) return res.status(404).json({ error: '词根库中不存在' });
  res.json(record);
});

// 历史列表
app.get('/api/history', (req, res) => {
  const { page, size } = pagerParams(req);
  res.json(listRecords(page, size, req.query.q || ''));
});

// 历史详情
app.get('/api/history/:id', (req, res) => {
  const record = getRecord(req.params.id);
  if (!record) return res.status(404).json({ error: '记录不存在' });
  res.json(record);
});

// 编辑保存
app.put('/api/history/:id', (req, res) => {
  const { sentence, words, result } = req.body;
  if (!sentence || !Array.isArray(words) || !result) {
    return res.status(400).json({ error: '字段不完整' });
  }
  const record = updateRecord(req.params.id, { sentence, words, result });
  if (!record) return res.status(404).json({ error: '记录不存在' });
  res.json(record);
});

// 删除
app.delete('/api/history/:id', (req, res) => {
  const ok = deleteRecord(req.params.id);
  if (!ok) return res.status(404).json({ error: '记录不存在' });
  res.json({ ok: true });
});

// 分页参数解析（默认第 1 页、每页 10 条，上限 50）
function pagerParams(req) {
  const page = Math.max(1, parseInt(req.query.page) || 1);
  const size = Math.min(50, Math.max(1, parseInt(req.query.size) || 10));
  return { page, size };
}

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`✅ 服务已启动: http://localhost:${PORT}`);
});