// ═══════════════════════════════════════════════════════════
//  MacroScope 伺服器
//  - 對外提供 index.html（前端）
//  - GET /api/macro          整理好的總經資料（後端持金鑰呼叫 FRED）
//  - GET /api/series/:key     單一指標的歷史序列（給「走勢大圖」）
//  - GET /api/score-history   每日健康分數累積歷史
//  資料持久化於 SQLite（data.db）：重啟即時載入、每天累積分數快照
// ═══════════════════════════════════════════════════════════

import 'dotenv/config';
import express from 'express';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

import { GROUPS, INDICATOR_MAP } from './lib/indicators.js';
import { getIndicatorCards, getYieldCurve, MissingKeyError } from './lib/fred.js';
import { computeScore } from './lib/score.js';
import { EVENTS, EPISODES } from './lib/events.js';
import {
  savePayload, loadPayload, saveSeries, getSeries,
  saveScoreSnapshot, getScoreHistory,
  listTrades, getTrade, insertTrade, updateTrade, deleteTrade, tradeStats,
  getCachedJSON, putCachedJSON, getCachedEntry,
} from './lib/db.js';
import { getKnowledge, getNote, knowledgeReady } from './lib/knowledge.js';
import { getFundamentals, getLatestFilingInfo } from './lib/fundamentals.js';
import { buildReport } from './lib/fincheck.js';
import { getHistory, RANGES, INTERVALS } from './lib/marketdata.js';
import { runBacktest, STRATEGIES } from './lib/backtest.js';
import { getInvestMap } from './lib/investmap.js';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const app = express();
app.use(express.json());
const PORT = process.env.PORT || 3000;
const CACHE_TTL_MS = (Number(process.env.CACHE_TTL_SECONDS) || 3600) * 1000;
// 財報變動頻率低（季報），因此長期存資料庫、盡量沿用：
//  FUND_SOFT_MS 內直接用快取、完全不連網；超過才用輕量探針查 SEC 是否有新財報，
//  沒有新財報就續用快取（只更新檢查時間），有新財報或探針失敗且超過 FUND_HARD_MS 才重抓。
const FUND_SOFT_MS = (Number(process.env.FUND_SOFT_HOURS) || 12) * 3600 * 1000;
const FUND_HARD_MS = (Number(process.env.FUND_HARD_DAYS) || 3) * 24 * 3600 * 1000;
// 歷史股價快取：日線 6 小時內沿用、週/月線 1 天內沿用（節省 API）
const HIST_TTL_MS = (Number(process.env.HIST_SOFT_HOURS) || 6) * 3600 * 1000;
const SYMBOL_RE = /^[A-Z0-9.\-]{1,12}$/;
const hasKey = process.env.FRED_API_KEY && process.env.FRED_API_KEY !== 'your_fred_api_key_here';

// 記憶體快取（開機時會用 DB 內容預先填入）
let cache = { at: 0, payload: null };

async function buildPayload() {
  const [{ cards, seriesHistory, degraded }, yieldCurve] = await Promise.all([
    getIndicatorCards(),
    getYieldCurve(),
  ]);
  const { score, regime, breakdown, signals } = computeScore(cards);
  const groups = GROUPS.map((g) => ({
    key: g.key, title: g.title, titleEn: g.titleEn, icon: g.icon,
    colorKey: g.colorKey, intro: g.intro,
    cards: Object.values(cards).filter((c) => c.group === g.key),
  }));
  const payload = {
    updatedAt: new Date().toISOString(),
    score, regime, breakdown, signals, groups, yieldCurve, degraded,
  };
  return { payload, seriesHistory };
}

// 抓取 → 更新記憶體快取 → 寫入資料庫（序列 + 分數快照）
async function refreshAndCache() {
  const { payload, seriesHistory } = await buildPayload();
  cache = { at: Date.now(), payload };
  try {
    savePayload(payload);
    for (const [key, points] of Object.entries(seriesHistory)) saveSeries(key, points);
    saveScoreSnapshot(payload.score, payload.regime?.label);
  } catch (e) {
    console.warn('寫入資料庫失敗（不影響顯示）：', e.message);
  }
  return payload;
}

app.get('/api/macro', async (req, res) => {
  try {
    const fresh = req.query.fresh === '1';
    if (!fresh && cache.payload && Date.now() - cache.at < CACHE_TTL_MS) {
      return res.json({ ...cache.payload, cached: true });
    }
    const payload = await refreshAndCache();
    res.json({ ...payload, cached: false });
  } catch (err) {
    if (err instanceof MissingKeyError) {
      return res.status(503).json({
        error: 'missing_api_key',
        message: '尚未設定 FRED 金鑰。請複製 .env.example 為 .env 並填入免費的 FRED_API_KEY，再重新啟動伺服器。',
        hint: 'https://fred.stlouisfed.org/docs/api/api_key.html',
      });
    }
    // 若有舊快取，至少先給舊資料
    if (cache.payload) return res.json({ ...cache.payload, cached: true, stale: true });
    console.error('[api/macro] 失敗：', err);
    res.status(502).json({ error: 'fetch_failed', message: '取得資料失敗，請稍後再試。', detail: String(err?.message || err) });
  }
});

// 歷史事件標記 & 危機案例（靜態設定，給走勢標註與「歷史殷鑑」頁用）
app.get('/api/events', (req, res) => res.json({ events: EVENTS, episodes: EPISODES }));

// 單一指標歷史序列（給走勢大圖）
const RANGE_DAYS = { '1m': 30, '6m': 182, '1y': 365, '5y': 1825, '10y': 3650, max: null };
app.get('/api/series/:key', (req, res) => {
  const key = req.params.key;
  const ind = INDICATOR_MAP[key];
  if (!ind) return res.status(404).json({ error: 'unknown_series', message: `查無指標：${key}` });
  const range = RANGE_DAYS[req.query.range] !== undefined ? req.query.range : '1y';
  const days = RANGE_DAYS[range];
  const since = days ? new Date(Date.now() - days * 86400000).toISOString().slice(0, 10) : null;
  const points = getSeries(key, since);
  res.json({
    key, label: ind.label, labelEn: ind.labelEn,
    format: ind.format, decimals: ind.decimals ?? 2,
    inverted: !!ind.inverted, tip: ind.tip, substitute: ind.substitute || null,
    range, points,
  });
});

// 每日健康分數歷史
app.get('/api/score-history', (req, res) => {
  res.json({ points: getScoreHistory() });
});

// ─── 學習教材：知識庫 ───
app.get('/api/knowledge', (req, res) => {
  const k = getKnowledge();
  if (!k) return res.status(503).json({ error: 'knowledge_not_built', message: '知識庫尚未建立，請先執行 npm run build:knowledge。' });
  res.json(k);
});
app.get('/api/note/:kind/:id', (req, res) => {
  const note = getNote(req.params.kind, req.params.id);
  if (!note) return res.status(404).json({ error: 'note_not_found', message: '找不到這篇筆記。' });
  res.json(note);
});

// ─── 財報健檢 ───
app.get('/api/fundamentals/:symbol', async (req, res) => {
  const symbol = String(req.params.symbol || '').trim().toUpperCase();
  if (!/^[A-Z0-9.\-]{1,12}$/.test(symbol)) return res.status(400).json({ error: 'bad_symbol', message: '代號格式不正確。' });
  const cacheKey = 'fund:' + symbol;
  const fresh = req.query.fresh === '1';
  const entry = getCachedEntry(cacheKey); // { value, updatedAt } | null
  try {
    if (!fresh && entry) {
      const age = Date.now() - entry.updatedAt;
      // 1) 還很新 → 直接用快取，完全不連網
      if (age < FUND_SOFT_MS) return res.json({ ...entry.value, cached: true });
      // 2) 稍舊 → 用輕量探針確認 SEC 是否有新財報
      const probe = await getLatestFilingInfo(symbol).catch(() => null);
      const known = entry.value._latestFiling;
      const noUpdate = probe ? (known && probe.accn === known) : (age <= FUND_HARD_MS);
      if (noUpdate) {
        // 沒有新財報（或暫時無法判斷但還沒到硬上限）→ 續用快取，只更新「檢查時間」
        const v = { ...entry.value, _checkedAt: Date.now() };
        putCachedJSON(cacheKey, v); // 更新 updated_at，避免短時間內重複探針
        return res.json({ ...v, cached: true });
      }
    }
    // 3) 首次、或偵測到新財報、或使用者手動更新 → 真正抓取
    const fundamentals = await getFundamentals(symbol);
    const report = buildReport(fundamentals);
    const probe = await getLatestFilingInfo(symbol).catch(() => null);
    const now = Date.now();
    const payload = {
      symbol: fundamentals.symbol, name: fundamentals.name, source: fundamentals.source,
      currency: fundamentals.currency, asOf: fundamentals.asOf, price: fundamentals.price, report,
      _fetchedAt: now, _checkedAt: now,
      _latestFiling: probe ? probe.accn : null, _latestForm: probe ? probe.form : null,
    };
    putCachedJSON(cacheKey, payload);
    res.json({ ...payload, cached: false });
  } catch (err) {
    console.error('[api/fundamentals]', symbol, err?.message || err);
    // 抓取失敗但有舊資料 → 回舊資料（標記 stale），不讓使用者卡住、也避免一直重試燒 API
    if (entry) return res.json({ ...entry.value, cached: true, stale: true, fetchError: String(err?.message || err) });
    res.status(502).json({ error: 'fundamentals_failed', message: String(err?.message || err) });
  }
});

// ─── 歷史股價（價格走勢 + 回測共用，持久 DB 快取）───
async function getHistoryCached(symbol, range, interval, fresh) {
  const key = `hist:${symbol}:${range}:${interval}`;
  const ttl = interval === '1d' ? HIST_TTL_MS : 24 * 3600 * 1000;
  const entry = getCachedEntry(key);
  if (!fresh && entry && Date.now() - entry.updatedAt < ttl) return { ...entry.value, cached: true };
  try {
    const hist = await getHistory(symbol, range, interval);
    const payload = { ...hist, _fetchedAt: Date.now() };
    putCachedJSON(key, payload);
    return { ...payload, cached: false };
  } catch (err) {
    if (entry) return { ...entry.value, cached: true, stale: true, fetchError: String(err?.message || err) };
    throw err;
  }
}

app.get('/api/price/:symbol', async (req, res) => {
  const symbol = String(req.params.symbol || '').trim().toUpperCase();
  if (!SYMBOL_RE.test(symbol)) return res.status(400).json({ error: 'bad_symbol', message: '代號格式不正確。' });
  const range = RANGES.includes(req.query.range) ? req.query.range : '5y';
  const interval = INTERVALS.includes(req.query.interval) ? req.query.interval : '1d';
  try {
    const h = await getHistoryCached(symbol, range, interval, req.query.fresh === '1');
    res.json(h);
  } catch (err) {
    console.error('[api/price]', symbol, err?.message || err);
    res.status(502).json({ error: 'price_failed', message: String(err?.message || err) });
  }
});

app.get('/api/backtest/:symbol', async (req, res) => {
  const symbol = String(req.params.symbol || '').trim().toUpperCase();
  if (!SYMBOL_RE.test(symbol)) return res.status(400).json({ error: 'bad_symbol', message: '代號格式不正確。' });
  const strategy = STRATEGIES[req.query.strategy] ? req.query.strategy : 'buyhold';
  const range = RANGES.includes(req.query.range) ? req.query.range : '5y';
  const numQ = (k) => (req.query[k] != null && req.query[k] !== '') ? Number(req.query[k]) : undefined;
  try {
    const h = await getHistoryCached(symbol, range, '1d', false);
    const result = runBacktest(h.points, {
      strategy, monthly: numQ('monthly'), short: numQ('short'), long: numQ('long'), drop: numQ('drop'),
    });
    res.json({ symbol, name: h.name, currency: h.currency, range, cached: h.cached, ...result });
  } catch (err) {
    console.error('[api/backtest]', symbol, err?.message || err);
    res.status(502).json({ error: 'backtest_failed', message: String(err?.message || err) });
  }
});

app.get('/api/investmap', (req, res) => {
  try {
    const k = getKnowledge();
    const byNum = {};
    for (const p of (k?.principles || [])) byNum[p.num] = { title: p.title, id: p.id };
    res.json(getInvestMap(byNum));
  } catch (err) {
    res.status(500).json({ error: 'investmap_failed', message: String(err?.message || err) });
  }
});

// ─── 交易復盤 ───
app.get('/api/trades', (req, res) => res.json({ trades: listTrades() }));
app.get('/api/trades/stats', (req, res) => res.json(tradeStats()));
app.post('/api/trades', (req, res) => {
  try { res.json(insertTrade(req.body || {})); }
  catch (e) { res.status(400).json({ error: 'bad_trade', message: String(e?.message || e) }); }
});
app.put('/api/trades/:id', (req, res) => {
  const row = updateTrade(Number(req.params.id), req.body || {});
  if (!row) return res.status(404).json({ error: 'not_found', message: '查無此交易。' });
  res.json(row);
});
app.delete('/api/trades/:id', (req, res) => {
  deleteTrade(Number(req.params.id));
  res.json({ ok: true });
});

app.get('/api/health', (req, res) => res.json({ ok: true, knowledge: knowledgeReady() }));
app.use(express.static(__dirname));

app.listen(PORT, () => {
  console.log(`\nMacroScope 已啟動 → http://localhost:${PORT}\n`);
  if (!hasKey) {
    console.log('提醒：尚未設定 FRED_API_KEY，畫面會顯示設定教學。');
    console.log('申請免費金鑰：https://fred.stlouisfed.org/docs/api/api_key.html\n');
    return;
  }
  // 先用資料庫裡的舊資料填入快取（若有），讓頁面能即時開啟
  const saved = loadPayload();
  if (saved) {
    cache = { at: saved.updatedAt, payload: saved.payload };
    console.log('已從資料庫載入上次資料，頁面可即時開啟。');
  }
  // 背景刷新最新資料（首次或過期時較久，FRED 有流量限制）
  console.log('正在背景抓取最新資料（首次約需 20–40 秒）…');
  const t0 = Date.now();
  refreshAndCache()
    .then((payload) => {
      const ok = payload.groups.reduce((a, g) => a + g.cards.length, 0);
      console.log(`資料就緒：${ok} 個指標，健康分數 ${payload.score}（耗時 ${((Date.now() - t0) / 1000).toFixed(0)} 秒）\n`);
    })
    .catch((err) => console.log('背景抓取失敗（開啟頁面時會再試）：', String(err?.message || err), '\n'));
});
