const fs = require('fs');
const path = require('path');
const pool = require('./db');
const {
  savePaintingImages,
  downloadImageToFile,
  generateThumbnailFromFull,
  pickExt,
} = require('../scripts/image-fetcher');

const IMAGE_DIR = path.resolve(process.env.IMAGE_DIR || './data/images');
const FETCH_TIMEOUT_MS = 15000;
const inflight = new Map();

function safePaintingBase(artistName, title) {
  return `${artistName}_${title}`.replace(/[^a-zA-Z0-9_-]/g, '_');
}

function unlinkIfExists(absPath) {
  if (absPath && fs.existsSync(absPath)) {
    try {
      fs.unlinkSync(absPath);
    } catch {
      // ignore
    }
  }
}

function withTimeout(promise, ms) {
  return Promise.race([
    promise,
    new Promise((_, reject) => setTimeout(() => reject(new Error('Image fetch timeout')), ms)),
  ]);
}

function localFileExists(relPath) {
  if (!relPath) return false;
  return fs.existsSync(path.join(IMAGE_DIR, relPath));
}

function syncPaintingFromDisk(row) {
  const safeBase = `${row.artist_name}_${row.title}`.replace(/[^a-zA-Z0-9_-]/g, '_');
  let imagePath = row.image_path;
  let thumbPath = row.thumbnail_path;

  for (const ext of ['.jpg', '.jpeg', '.png', '.webp', '.JPG']) {
    const full = path.join(IMAGE_DIR, 'paintings', safeBase + ext);
    if (!imagePath && fs.existsSync(full)) {
      imagePath = `paintings/${safeBase}${ext}`;
    }
    const thumb = path.join(IMAGE_DIR, 'paintings', 'thumbs', safeBase + '_thumb' + ext);
    if (!thumbPath && fs.existsSync(thumb)) {
      thumbPath = `paintings/thumbs/${safeBase}_thumb${ext}`;
    }
  }
  if (!thumbPath && imagePath) thumbPath = imagePath;
  return { imagePath, thumbPath };
}

/** Fast preload: link local files only, no external API calls */
async function preloadArtistImagesLocal(artistId) {
  const rows = await pool.query(
    `SELECT p.id, p.title, p.image_path, p.thumbnail_path, a.name AS artist_name
     FROM paintings p
     JOIN artists a ON a.id = p.artist_id
     WHERE p.artist_id = $1`,
    [artistId]
  );

  let linked = 0;
  for (const row of rows.rows) {
    const hasLocal =
      localFileExists(row.thumbnail_path) || localFileExists(row.image_path);
    if (hasLocal) {
      linked++;
      continue;
    }

    const synced = syncPaintingFromDisk(row);
    if (synced.imagePath || synced.thumbPath) {
      await pool.query(
        `UPDATE paintings SET image_path = COALESCE($1, image_path), thumbnail_path = COALESCE($2, thumbnail_path) WHERE id = $3`,
        [synced.imagePath, synced.thumbPath, row.id]
      );
      linked++;
    }
  }

  return { fetched: linked, total: rows.rows.length };
}

async function ensurePaintingImages(paintingId, size = 'thumb') {
  const key = `${paintingId}:${size}`;
  if (inflight.has(key)) return inflight.get(key);

  const promise = (async () => {
    const result = await pool.query(
      `SELECT p.id, p.title, p.wikipedia_title, p.image_path, p.thumbnail_path, a.name AS artist_name
       FROM paintings p
       JOIN artists a ON a.id = p.artist_id
       WHERE p.id = $1`,
      [paintingId]
    );
    if (result.rows.length === 0) return null;

    const row = result.rows[0];
    const wantThumb = size !== 'full';

    if (wantThumb && localFileExists(row.thumbnail_path)) return row.thumbnail_path;
    if (!wantThumb && localFileExists(row.image_path)) return row.image_path;
    if (wantThumb && localFileExists(row.image_path)) return row.image_path;

    const synced = syncPaintingFromDisk(row);
    if (synced.imagePath || synced.thumbPath) {
      await pool.query(
        `UPDATE paintings
         SET image_path = COALESCE($1, image_path),
             thumbnail_path = COALESCE($2, thumbnail_path)
         WHERE id = $3`,
        [synced.imagePath, synced.thumbPath, paintingId]
      );
      if (wantThumb && localFileExists(synced.thumbPath)) return synced.thumbPath;
      if (wantThumb && localFileExists(synced.imagePath)) return synced.imagePath;
      if (!wantThumb && localFileExists(synced.imagePath)) return synced.imagePath;
    }

    if (!row.wikipedia_title) return null;

    const saved = await withTimeout(
      savePaintingImages(
        row.wikipedia_title,
        `${row.artist_name}_${row.title}`,
        IMAGE_DIR,
        { artistName: row.artist_name, paintingTitle: row.title, type: 'painting' }
      ),
      FETCH_TIMEOUT_MS
    ).catch(() => ({ imagePath: null, thumbnailPath: null }));

    if (saved.imagePath || saved.thumbnailPath) {
      await pool.query(
        `UPDATE paintings
         SET image_path = COALESCE($1, image_path),
             thumbnail_path = COALESCE($2, thumbnail_path)
         WHERE id = $3`,
        [saved.imagePath, saved.thumbnailPath, paintingId]
      );
    }

    if (wantThumb) return saved.thumbnailPath || saved.imagePath;
    return saved.imagePath || saved.thumbnailPath;
  })().finally(() => inflight.delete(key));

  inflight.set(key, promise);
  return promise;
}

async function replacePaintingImageFromUrl(paintingId, imageUrl) {
  const result = await pool.query(
    `SELECT p.id, p.title, p.image_path, p.thumbnail_path, a.name AS artist_name
     FROM paintings p
     JOIN artists a ON a.id = p.artist_id
     WHERE p.id = $1`,
    [paintingId]
  );
  if (result.rows.length === 0) {
    throw new Error('Painting not found');
  }

  const row = result.rows[0];
  const safeBase = safePaintingBase(row.artist_name, row.title);
  const paintingsDir = path.join(IMAGE_DIR, 'paintings');
  const thumbsDir = path.join(IMAGE_DIR, 'paintings', 'thumbs');
  if (!fs.existsSync(paintingsDir)) fs.mkdirSync(paintingsDir, { recursive: true });
  if (!fs.existsSync(thumbsDir)) fs.mkdirSync(thumbsDir, { recursive: true });

  const fullExt = pickExt(imageUrl);
  const fullDest = path.join(paintingsDir, safeBase + fullExt);
  const thumbDest = path.join(thumbsDir, safeBase + '_thumb.jpg');

  unlinkIfExists(row.image_path ? path.join(IMAGE_DIR, row.image_path) : null);
  unlinkIfExists(row.thumbnail_path ? path.join(IMAGE_DIR, row.thumbnail_path) : null);
  unlinkIfExists(fullDest);
  unlinkIfExists(thumbDest);

  await downloadImageToFile(imageUrl, fullDest, { force: true });

  let thumbnailPath = null;
  try {
    await generateThumbnailFromFull(fullDest, thumbDest);
    thumbnailPath = path.join('paintings', 'thumbs', safeBase + '_thumb.jpg').replace(/\\/g, '/');
  } catch {
    thumbnailPath = path.join('paintings', safeBase + fullExt).replace(/\\/g, '/');
  }

  const imagePath = path.join('paintings', safeBase + fullExt).replace(/\\/g, '/');

  await pool.query(
    `UPDATE paintings SET image_path = $1, thumbnail_path = $2 WHERE id = $3`,
    [imagePath, thumbnailPath, paintingId]
  );

  return { imagePath, thumbnailPath };
}

module.exports = {
  ensurePaintingImages,
  preloadArtistImagesLocal,
  replacePaintingImageFromUrl,
  IMAGE_DIR,
};