import { access, readFile } from 'node:fs/promises';
import { join } from 'node:path';
import sharp from 'sharp';
import { fileTypeFromFile } from 'file-type';
import { createWorker, OEM } from 'tesseract.js';
import {
  BinaryBitmap,
  HybridBinarizer,
  MultiFormatReader,
  NotFoundException,
  RGBLuminanceSource,
} from '@zxing/library';

const normalize = (value) => value.normalize('NFKC').toLocaleLowerCase('en-US');
const fail = (rule, location = '') => { throw new Error(location ? `${rule}:${location}` : rule); };

export const loadDenylist = async (path) => {
  let text;
  try {
    text = await readFile(path, 'utf8');
  } catch {
    fail('PRIVACY-DENYLIST-001');
  }
  const terms = [...new Set(text.split(/\r?\n/u).map((line) => line.trim()).filter(Boolean).map(normalize))];
  if (terms.length === 0 || terms.some((term) => term.length < 3 || /[\u0000-\u001f\u007f]/u.test(term))) {
    fail('PRIVACY-DENYLIST-001');
  }
  return terms;
};

export const scanText = (bytesOrText, denylist, rule = 'PRIVACY-BYTES-001') => {
  const text = normalize(Buffer.isBuffer(bytesOrText) || bytesOrText instanceof Uint8Array
    ? Buffer.from(bytesOrText).toString('utf8')
    : String(bytesOrText));
  if (denylist.some((term) => text.includes(normalize(term)))) fail(rule);
};

const scanBarcode = async (path) => {
  let decoded;
  try {
    decoded = await sharp(path).removeAlpha().greyscale().raw().toBuffer({ resolveWithObject: true });
  } catch {
    fail('ASSET-DECODE-001');
  }
  const { data, info } = decoded;
  const luminance = new RGBLuminanceSource(new Uint8ClampedArray(data), info.width, info.height);
  const bitmap = new BinaryBitmap(new HybridBinarizer(luminance));
  try {
    new MultiFormatReader().decode(bitmap);
    fail('PRIVACY-BARCODE-001');
  } catch (error) {
    if (error instanceof NotFoundException || error?.name === 'NotFoundException') return;
    if (error instanceof Error && error.message === 'PRIVACY-BARCODE-001') throw error;
    fail('PRIVACY-BARCODE-002');
  }
};

const scanOcr = async (path, denylist) => {
  const candidates = ['/usr/share/tessdata', '/usr/share/tesseract-ocr/5/tessdata'];
  let langPath;
  for (const candidate of candidates) {
    try {
      await access(join(candidate, 'eng.traineddata'));
      langPath = candidate;
      break;
    } catch {}
  }
  if (!langPath) fail('PRIVACY-OCR-002');
  let worker;
  try {
    worker = await createWorker('eng', OEM.LSTM_ONLY, { langPath, gzip: false, cacheMethod: 'none' });
  } catch {
    fail('PRIVACY-OCR-002');
  }
  let timer;
  try {
    const result = await Promise.race([
      worker.recognize(path),
      new Promise((_, reject) => { timer = setTimeout(() => reject(new Error('timeout')), 25_000); }),
    ]);
    scanText(result.data.text, denylist, 'PRIVACY-OCR-001');
  } catch (error) {
    if (error instanceof Error && error.message === 'PRIVACY-OCR-001') throw error;
    fail('PRIVACY-OCR-002');
  } finally {
    if (timer !== undefined) clearTimeout(timer);
    await worker.terminate().catch(() => {});
  }
};

export const scanImage = async (path, denylist, options = {}) => {
  let type;
  try { type = await fileTypeFromFile(path); } catch { fail('PRIVACY-TYPE-001'); }
  if (!type || !['image/png', 'image/webp', 'image/jpeg'].includes(type.mime)) fail('PRIVACY-TYPE-001');
  let metadata;
  try {
    metadata = await sharp(path, { failOn: 'error', limitInputPixels: 50_000_000 }).metadata();
  } catch {
    fail('ASSET-DECODE-001');
  }
  if (metadata.exif || metadata.icc || metadata.iptc || metadata.xmp || metadata.orientation !== undefined) {
    fail('PRIVACY-METADATA-001');
  }
  scanText(await readFile(path), denylist);
  await scanBarcode(path);
  if (options.runOcr !== false) await scanOcr(path, denylist);
  return { width: metadata.width, height: metadata.height, mediaType: type.mime };
};

export const scanBinary = async (path, denylist) => {
  let bytes;
  try { bytes = await readFile(path); } catch { fail('PRIVACY-TYPE-001'); }
  scanText(bytes, denylist);
  let type;
  try { type = await fileTypeFromFile(path); } catch { fail('PRIVACY-TYPE-001'); }
  if (!type || !['video/webm', 'video/mp4'].includes(type.mime)) fail('PRIVACY-TYPE-001');
  return { mediaType: type.mime };
};