/**
 * 批量取图脚本（在有网络的本机运行）：
 *   按 Wikidata P18 → Commons 同名分类 → Commons 关键词搜索 的顺序，
 *   为每个车型下载若干张真实照片到「本地共享图库」（uploads + photos 表），
 *   并记录署名（作者/许可证/来源）。下载后应用即从本地提供图片，运行时不再访问 Commons。
 *
 * 用法（在 apps/api 目录）：
 *   node scripts/fetch-images.mjs                 # 全部缺图车型，每个 1 张
 *   node scripts/fetch-images.mjs --per 3         # 每个车型最多 3 张
 *   node scripts/fetch-images.mjs --limit 20      # 仅处理前 20 个缺图车型
 *   node scripts/fetch-images.mjs --category 电力机车
 *   node scripts/fetch-images.mjs --dry           # 只检索不下载不入库
 *
 * 所有下载图片一律入库为「候选(candidate)」，进入管理员「候选审图」队列，
 * 由人工确认后才会作为封面/图册展示（候选 + 人工确认 双闸门，保证准确与合规）。
 *
 * 注意：需联网访问 wikidata.org / commons.wikimedia.org（自由授权，已记录署名）。
 *       下载完成后图片保存在本地 app/data/uploads/，库表记录在 app/data/app.db。
 */
import Database from 'better-sqlite3';
import { mkdirSync } from 'fs';
import { writeFile } from 'fs/promises';
import { join, resolve, dirname } from 'path';
import { fileURLToPath } from 'url';
import { randomBytes } from 'crypto';

const __dirname = dirname(fileURLToPath(import.meta.url));
const ROOT = resolve(__dirname, '..', '..', '..'); // Train/
const MACHINES_DB = join(ROOT, 'app', 'data', 'machines.db');
const APP_DB = process.env.APP_DB_PATH || join(ROOT, 'app', 'data', 'app.db');
const UPLOAD_DIR = process.env.UPLOAD_DIR || join(ROOT, 'app', 'data', 'uploads');
const UA = 'ChinaLocoAtlas/0.1 (image fetcher; contact admin)';

const args = process.argv.slice(2);
const opt = (k) => {
  const i = args.indexOf(k);
  return i >= 0 ? args[i + 1] : undefined;
};
const LIMIT = opt('--limit') ? Number(opt('--limit')) : Infinity;
const PER = opt('--per') ? Math.max(1, Number(opt('--per'))) : 1;
const CATEGORY = opt('--category');
const DRY = args.includes('--dry');
const STATUS = 'candidate'; // 一律入候选，交管理员「候选审图」确认

const CAT_HINT = {
  蒸汽机车: 'steam locomotive',
  电力机车: 'electric locomotive',
  内燃机车: 'diesel locomotive',
  动车组: 'EMU',
  客车: 'passenger car',
  货车: 'freight car',
  检测车: 'inspection car',
  旅游列车: 'tourist train',
};

const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
const latin = (s) => (s.match(/[A-Za-z0-9-]+/g) || []).join('');
const strip = (h) => (h || '').replace(/<[^>]*>/g, '').replace(/\s+/g, ' ').trim();
const isImg = (s) => /\.(jpe?g|png)$/i.test(s || '');

async function api(url) {
  const res = await fetch(url, { headers: { 'User-Agent': UA } });
  if (!res.ok) throw new Error('HTTP ' + res.status);
  return res.json();
}

/** 从 Commons File:xxx 取缩略图 url + 署名。*/
async function commonsFileInfo(title) {
  const u =
    'https://commons.wikimedia.org/w/api.php?action=query&format=json&origin=*' +
    `&titles=${encodeURIComponent(title)}&prop=imageinfo&iiprop=url|extmetadata&iiurlwidth=1280`;
  const d = await api(u);
  const pages = d?.query?.pages || {};
  const p = Object.values(pages)[0];
  const ii = p?.imageinfo?.[0];
  if (!ii?.thumburl) return null;
  const em = ii.extmetadata || {};
  return {
    url: ii.thumburl,
    descriptionUrl: ii.descriptionurl || '',
    author: strip(em.Artist?.value) || '未署名',
    license: strip(em.LicenseShortName?.value) || '见来源',
  };
}

/** 1) Wikidata P18 主图（最多 1 张，最准）。*/
async function viaWikidata(model) {
  const q = `${latin(model.model_code) || model.model_code} ${CAT_HINT[model.category] || 'train'}`;
  const s = await api(
    'https://www.wikidata.org/w/api.php?action=wbsearchentities&format=json&origin=*' +
      `&language=en&type=item&limit=3&search=${encodeURIComponent(q)}`,
  );
  for (const hit of s?.search || []) {
    const e = await api(
      'https://www.wikidata.org/w/api.php?action=wbgetentities&format=json&origin=*' +
        `&props=claims&ids=${hit.id}`,
    );
    const p18 = e?.entities?.[hit.id]?.claims?.P18?.[0]?.mainsnak?.datavalue?.value;
    if (p18) {
      const info = await commonsFileInfo('File:' + p18);
      if (info) return [{ ...info, via: 'wikidata' }];
    }
  }
  return [];
}

/** 2) Commons 同名分类（可多张）。*/
async function viaCategory(model, want) {
  const code = latin(model.model_code) || model.model_code;
  const out = [];
  for (const cat of [`Category:China Railways ${code}`, `Category:${code}`]) {
    const d = await api(
      'https://commons.wikimedia.org/w/api.php?action=query&format=json&origin=*' +
        `&list=categorymembers&cmtype=file&cmlimit=20&cmtitle=${encodeURIComponent(cat)}`,
    );
    for (const f of d?.query?.categorymembers || []) {
      if (!isImg(f.title)) continue;
      const info = await commonsFileInfo(f.title);
      if (info) out.push({ ...info, via: 'category' });
      if (out.length >= want) return out;
    }
  }
  return out;
}

/** 3) Commons 关键词搜索（最不准，兜底，可多张）。*/
async function viaSearch(model, want) {
  const q = `${latin(model.model_code) || model.model_code} ${CAT_HINT[model.category] || 'train'} China Railway`;
  const d = await api(
    'https://commons.wikimedia.org/w/api.php?action=query&format=json&origin=*' +
      `&generator=search&gsrnamespace=6&gsrlimit=${Math.max(3, want)}&gsrsearch=${encodeURIComponent(q)}` +
      '&prop=imageinfo&iiprop=url|extmetadata&iiurlwidth=1280',
  );
  const pages = d?.query?.pages || {};
  const out = [];
  for (const p of Object.values(pages)) {
    const ii = p?.imageinfo?.[0];
    if (!ii?.thumburl || !isImg(ii.thumburl)) continue;
    const em = ii.extmetadata || {};
    out.push({
      url: ii.thumburl,
      descriptionUrl: ii.descriptionurl || '',
      author: strip(em.Artist?.value) || '未署名',
      license: strip(em.LicenseShortName?.value) || '见来源',
      via: 'search',
    });
    if (out.length >= want) break;
  }
  return out;
}

/** 聚合各来源，按 url 去重，返回最多 want 张。*/
async function collectImages(model, want) {
  const seen = new Set();
  const out = [];
  const push = (arr) => {
    for (const it of arr) {
      if (out.length >= want) break;
      if (seen.has(it.url)) continue;
      seen.add(it.url);
      out.push(it);
    }
  };
  push(await viaWikidata(model));
  if (out.length < want) push(await viaCategory(model, want - out.length));
  if (out.length < want) push(await viaSearch(model, want - out.length));
  return out;
}

async function main() {
  mkdirSync(UPLOAD_DIR, { recursive: true });
  const mdb = new Database(MACHINES_DB, { readonly: true });
  const adb = new Database(APP_DB);

  const admin =
    adb.prepare("SELECT id FROM users WHERE role='admin' ORDER BY id LIMIT 1").get() ||
    adb.prepare('SELECT id FROM users ORDER BY id LIMIT 1').get();
  if (!admin) {
    console.error('找不到用户：请先启动后端注册一个管理员（或设 ADMIN_EMAIL）。');
    process.exit(1);
  }

  const where = CATEGORY ? 'WHERE c.name = ?' : '';
  const models = mdb
    .prepare(
      `SELECT m.id, m.model_code, c.name AS category
       FROM model m JOIN category c ON c.id = m.category_id ${where}
       ORDER BY m.id`,
    )
    .all(...(CATEGORY ? [CATEGORY] : []));

  const hasPhoto = adb.prepare('SELECT 1 FROM photos WHERE model_id = ? LIMIT 1');
  const insert = adb.prepare(
    `INSERT INTO photos (model_id, uploader_id, filename, caption, status, source_url, author, license)
     VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
  );

  console.log(
    `取图：每车型最多 ${PER} 张，入库状态=候选(candidate)${DRY ? '（dry-run）' : ''}；保存到 ${UPLOAD_DIR}`,
  );

  const report = [];
  let done = 0;
  let saved = 0;
  for (const m of models) {
    if (done >= LIMIT) break;
    if (hasPhoto.get(m.id)) continue;
    done++;
    let hits = [];
    try {
      hits = await collectImages(m, PER);
    } catch (e) {
      report.push(`✗ ${m.model_code}：检索出错 ${e.message}`);
      await sleep(300);
      continue;
    }
    if (hits.length === 0) {
      report.push(`— ${m.model_code}：未找到`);
      await sleep(200);
      continue;
    }
    if (DRY) {
      report.push(`✓ ${m.model_code}：[dry] ${hits.map((h) => h.via).join(',')} (${hits.length} 张)`);
      await sleep(200);
      continue;
    }
    let n = 0;
    for (const hit of hits) {
      try {
        const buf = Buffer.from(
          await (await fetch(hit.url, { headers: { 'User-Agent': UA } })).arrayBuffer(),
        );
        const ext = (hit.url.match(/\.(jpe?g|png)/i) || ['.jpg'])[0].toLowerCase();
        const fn = `${Date.now()}-${randomBytes(6).toString('hex')}${ext}`;
        await writeFile(join(UPLOAD_DIR, fn), buf);
        insert.run(m.id, admin.id, fn, `${m.model_code}（${hit.via}）`, STATUS, hit.descriptionUrl, hit.author, hit.license);
        n++;
        saved++;
      } catch (e) {
        report.push(`✗ ${m.model_code}：下载失败 ${e.message}`);
      }
      await sleep(300); // 礼貌限速
    }
    if (n > 0) report.push(`✓ ${m.model_code}：入库 ${n} 张（${STATUS}）`);
  }

  const ok = report.filter((r) => r.startsWith('✓')).length;
  const miss = report.filter((r) => r.startsWith('—')).length;
  const err = report.filter((r) => r.startsWith('✗')).length;
  console.log(report.join('\n'));
  console.log(`\n命中 ${ok} · 未找到 ${miss} · 出错 ${err}（处理 ${done} 个车型，保存 ${saved} 张）`);
  console.log('候选图已入库，请用管理员在网页"候选审图 / 图册"逐个确认后作为封面展示。');
}

main();