/**
 * 今彩539 增量更新腳本 (Incremental Update)
 * 只抓取比現有資料更新的期號，速度快、省流量
 * 用法: node update.js
 */

const https = require('https');
const fs = require('fs');

const DATA_FILE = 'lottery_539_data.json';
const API_URL = 'https://www.pilio.idv.tw/Json_ltonew.asp';

// ── Load existing data ────────────────────────────────────────────────────────
const existing = JSON.parse(fs.readFileSync(DATA_FILE, 'utf8'));
const lastDex = Math.max(...existing.draws.map(d => parseInt(d.dex)));
console.log(`📂 現有資料：${existing.draws.length} 期 (最新 dex=${lastDex})`);

// ── Fetch helper ──────────────────────────────────────────────────────────────
function fetchJson(lindex, ldesc) {
  return new Promise((resolve, reject) => {
    const postData = `Lkind=lto539&Lindex=${lindex}&Ldesc=${ldesc}`;
    const opts = {
      hostname: 'www.pilio.idv.tw',
      port: 443,
      path: '/Json_ltonew.asp',
      method: 'POST',
      headers: {
        'User-Agent': 'Mozilla/5.0',
        'Content-Type': 'application/x-www-form-urlencoded',
        'Content-Length': Buffer.byteLength(postData)
      }
    };
    const req = https.request(opts, res => {
      let raw = '';
      res.on('data', c => raw += c);
      res.on('end', () => {
        try { resolve(JSON.parse(raw)); }
        catch { reject(new Error('JSON parse failed: ' + raw.slice(0, 100))); }
      });
    });
    req.on('error', reject);
    req.write(postData);
    req.end();
  });
}

function pad(n) { return String(parseInt(n)).padStart(2, '0'); }

function parseDate(raw) {
  const clean = raw.replace(/<[^>]+>/g, ' ').trim();
  const m = clean.match(/^(\d{2})[\/-](\d{2})\s+(\d{2})\((.)\)/);
  if (!m) return clean;
  const yr = parseInt(m[3]) < 50 ? `20${m[3]}` : `19${m[3]}`;
  return `${yr}/${m[1]}/${m[2]} (${m[4]})`;
}

// ── Fetch only new draws ──────────────────────────────────────────────────────
async function fetchNewDraws() {
  const newDraws = [];
  console.log('🔍 檢查是否有新期數...');

  let currentIndex = lastDex;
  while (true) {
    let batch;
    try { batch = await fetchJson(currentIndex, 0); } // 0 is ascending (old to new)
    catch (e) {
      console.log('⚠️ API Error:', e.message);
      break; 
    }

    const arr = batch.lotto || [];
    if (!arr.length) break;

    for (const item of arr) {
      const idx = parseInt(item.dex);
      if (idx <= lastDex) {
        continue;
      }
      const numText = item.num.replace(/<[^>]+>/gi, '').replace(/&nbsp;/gi, ' ');
      const nums = numText.match(/\d{1,2}/g).map(n => pad(n));
      if (nums.length < 5) continue;
      
      newDraws.push({
        date: parseDate(item.date),
        dateSort: (() => {
          const clean = item.date.replace(/<[^>]+>/g, ' ').trim();
          const m = clean.match(/^(\d{2})[\/-](\d{2})\s+(\d{2})\(/);
          if (m) {
             const y = parseInt(m[3]);
             const fullYr = y < 50 ? `20${String(y).padStart(2,'0')}` : `19${String(y).padStart(2,'0')}`;
             return `${fullYr}${m[1]}${m[2]}`;
          }
          return '';
        })(),
        numbers: nums.slice(0,5),
        dex: item.dex,
      });
    }

    currentIndex = arr[arr.length - 1].dex;
  }

  // API fetches descending, but our newDraws needs to be appended in ascending order later
  // wait, we just return it, the main function sorts it: .sort((a,b)=>parseInt(a.dex)-parseInt(b.dex))
  return newDraws;
}

// ── Prediction (M3 SpreadOverdue) ─────────────────────────────────────────────
const BUCKETS = [
  [1,2,3,4,5,6,7,8],
  [9,10,11,12,13,14,15],
  [16,17,18,19,20,21,22],
  [23,24,25,26,27,28,29,30],
  [31,32,33,34,35,36,37,38,39],
];

function predict(draws) {
  const gaps = {};
  for (let i = 1; i <= 39; i++) gaps[pad(i)] = draws.length;
  for (let i = draws.length - 1; i >= Math.max(0, draws.length - 600); i--)
    for (const n of draws[i].numbers)
      if (gaps[pad(n)] === draws.length) gaps[pad(n)] = draws.length - 1 - i;
  return BUCKETS.map(b =>
    b.map(n => ({ n: pad(n), s: gaps[pad(n)] || 0 })).sort((a,b)=>b.s-a.s)[0].n
  ).sort((a,b) => parseInt(a)-parseInt(b));
}

// ── Main ──────────────────────────────────────────────────────────────────────
(async () => {
  const newDraws = await fetchNewDraws();

  if (newDraws.length === 0) {
    console.log('✅ 已是最新資料，無需更新');
    return;
  }

  console.log(`✨ 新增 ${newDraws.length} 期：`);
  for (const d of newDraws) console.log(`   期 ${d.dex}  ${d.date}  ${d.numbers.join(', ')}`);

  // Merge & sort
  const merged = [...existing.draws, ...newDraws]
    .sort((a, b) => parseInt(a.dex) - parseInt(b.dex));

  // Deduplicate by dex
  const seen = new Set();
  const deduped = merged.filter(d => {
    if (seen.has(d.dex)) return false;
    seen.add(d.dex);
    return true;
  });

  // Update prediction
  const prediction = predict(deduped);
  console.log(`🎯 新預測號碼：${prediction.join(', ')}`);

  const out = {
    ...existing,
    draws: deduped,
    prediction,
    generatedAt: new Date().toISOString(),
    modelVersion: 'M3_SpreadOverdue',
    modelNote: '回測≥1命中率 51.3%',
  };

  fs.writeFileSync(DATA_FILE, JSON.stringify(out, null, 2), 'utf8');
  console.log(`✅ lottery_539_data.json 已更新 (共 ${deduped.length} 期)`);
  console.log('\n▶  接著請執行: node backtest.js');
})();