'use strict';
const fs = require('fs');
const path = require('path');
const yaml = require('js-yaml');

const LINK_FILE = path.join(__dirname, '..', 'source', '_data', 'link.yml');
const FRIEND_API = process.env.FRIEND_API || 'https://fc.weiguang.eu.org/friend';

function norm(url) { return String(url || '').replace(/\/+$/, ''); }

async function fetchFriendErrors() {
  const res = await fetch(FRIEND_API, {
    headers: { 'User-Agent': 'friend-check/1.0' },
    timeout: 15000,
  });
  if (!res.ok) throw new Error(`friend API -> HTTP ${res.status}`);
  const list = await res.json();
  if (!Array.isArray(list)) throw new Error('friend API returned a non-array payload');
  const map = new Map();
  for (const f of list) if (f && f.link) map.set(norm(f.link), Boolean(f.error));
  return map;
}

async function main() {
  const data = yaml.load(fs.readFileSync(LINK_FILE, 'utf8'));
  if (!Array.isArray(data)) { console.error('ERROR: link.yml is not a list'); process.exit(1); }

  let errMap;
  try {
    errMap = await fetchFriendErrors();
  } catch (e) {
    console.error(`WARN: cannot reach friend API (${e.message}); leaving link.yml untouched`);
    return;   // 后端不可达时绝不乱动 link.yml
  }

  const normalGroups = data.filter((g) => !g.lost_contact && Array.isArray(g.link_list));
  const lostGroup = data.find((g) => g.lost_contact) || null;

  const entries = [];
  for (const g of normalGroups) for (const it of g.link_list) entries.push({ it, from: 'normal' });
  if (lostGroup) for (const it of lostGroup.link_list) entries.push({ it, from: 'lost' });

  if (entries.length === 0) { console.log('No friends to check.'); return; }

  const classified = entries.map((e) => {
    const key = norm(e.it.link);
    const known = errMap.has(key);
    return { ...e, error: known ? errMap.get(key) : false, known };
  });

  const normalList = classified.filter((c) => !c.error).map((c) => c.it);
  const lostList = classified.filter((c) => c.error).map((c) => c.it);

  // 写回 link.yml：正常组放第一组，失联组单独
  if (normalGroups.length === 0) {
    data.unshift({ class_name: '友谊长存', class_desc: '那些人，那些事',
      flink_style: 'anzhiyu', hundredSuffix: '', link_list: normalList });
  } else {
    for (const g of normalGroups) g.link_list = [];
    normalGroups[0].link_list = normalList;
  }
  if (!lostGroup) {
    data.push({ class_name: '失联友链', class_desc: '已失联的友链',
      lost_contact: true, flink_style: 'anzhiyu', hundredSuffix: '', link_list: lostList });
  } else {
    lostGroup.link_list = lostList;
  }

  fs.writeFileSync(LINK_FILE, yaml.dump(data, { lineWidth: 200, noRefs: true }));

  const unknown = classified.filter((c) => !c.known).map((c) => c.it.name);
  console.log(`classified: ${entries.length}, normal: ${normalList.length}, lost: ${lostList.length}`);
  for (const c of classified)
    console.log(`  [${c.error ? 'lost' : 'ok'}]${c.known ? '' : ' (untracked)'} ${c.it.name} ${c.it.link}`);
  if (unknown.length) console.log(`WARN: not yet tracked by backend (kept in normal group): ${unknown.join(', ')}`);
}

main().catch((e) => { console.error(e); process.exit(1); });