// ═══════════════════════════════════════════════════════════
//  本機資料庫（SQLite，使用 Node 內建的 node:sqlite，免安裝套件）
//  存三種東西：
//   1. cache         — 整包 /api/macro 結果，重啟伺服器可即時載入
//   2. series        — 每個指標的完整歷史序列，供「走勢大圖」使用
//   3. score_history — 每天記一筆健康分數，累積成「分數走勢」
//  資料庫檔：data.db（已在 .gitignore 忽略）
// ═══════════════════════════════════════════════════════════

import { DatabaseSync } from 'node:sqlite';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const DB_PATH = path.join(__dirname, '..', 'data.db');

const db = new DatabaseSync(DB_PATH);
db.exec(`
  CREATE TABLE IF NOT EXISTS cache (
    key TEXT PRIMARY KEY,
    payload TEXT NOT NULL,
    updated_at INTEGER NOT NULL
  );
  CREATE TABLE IF NOT EXISTS series (
    series_key TEXT NOT NULL,
    date TEXT NOT NULL,
    val REAL NOT NULL,
    PRIMARY KEY (series_key, date)
  );
  CREATE TABLE IF NOT EXISTS score_history (
    date TEXT PRIMARY KEY,
    score INTEGER NOT NULL,
    regime TEXT
  );
`);

// ─── 整包結果的持久化快取 ───
export function savePayload(payload) {
  db.prepare('INSERT OR REPLACE INTO cache (key, payload, updated_at) VALUES (?, ?, ?)')
    .run('macro', JSON.stringify(payload), Date.now());
}
export function loadPayload() {
  const row = db.prepare('SELECT payload, updated_at FROM cache WHERE key = ?').get('macro');
  if (!row) return null;
  try {
    return { payload: JSON.parse(row.payload), updatedAt: row.updated_at };
  } catch {
    return null;
  }
}

// ─── 指標歷史序列 ───
const insertPoint = db.prepare('INSERT OR REPLACE INTO series (series_key, date, val) VALUES (?, ?, ?)');
export function saveSeries(key, points) {
  if (!points || points.length === 0) return;
  db.exec('BEGIN');
  try {
    for (const p of points) insertPoint.run(key, p.date, p.val);
    db.exec('COMMIT');
  } catch (e) {
    db.exec('ROLLBACK');
    throw e;
  }
}
export function getSeries(key, sinceISO) {
  if (sinceISO) {
    return db.prepare('SELECT date, val FROM series WHERE series_key = ? AND date >= ? ORDER BY date ASC')
      .all(key, sinceISO);
  }
  return db.prepare('SELECT date, val FROM series WHERE series_key = ? ORDER BY date ASC').all(key);
}

// ─── 每日健康分數快照（一天一筆，最新覆蓋）───
export function saveScoreSnapshot(score, regimeLabel) {
  const today = new Date().toISOString().slice(0, 10);
  db.prepare('INSERT OR REPLACE INTO score_history (date, score, regime) VALUES (?, ?, ?)')
    .run(today, score, regimeLabel || null);
}
export function getScoreHistory() {
  return db.prepare('SELECT date, score, regime FROM score_history ORDER BY date ASC').all();
}