// Ported from FilesPage.html lines 3478 (formatBytes), 3811-3857, 3979.

/** Escape a string for safe insertion into XML attribute values / text content. (3811) */
export function xmlEscape(str) {
  return str.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;');
}

/** (3815) */
export function escapeRegex(str) { return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'); }

/**
 * Decode a URI-encoded href (e.g., "my%20image.jpg" -> "my image.jpg").
 * Handles double-encoding gracefully. (3821)
 */
export function decodeHref(href) {
  try { return decodeURIComponent(href); }
  catch (e) { return href; }
}

/**
 * Safely read a text file from the zip, handling BOM and encoding.
 * Strips UTF-8 BOM. Detects encoding from XML declaration or meta tag. (3830)
 * `fileObj` is a JSZip file object.
 */
export async function safeReadText(fileObj) {
  const raw = await fileObj.async('uint8array');

  // Detect and strip UTF-8 BOM (EF BB BF)
  let offset = 0;
  if (raw.length >= 3 && raw[0] === 0xEF && raw[1] === 0xBB && raw[2] === 0xBF) {
    offset = 3;
  }

  // Try UTF-8 first (vast majority of EPUBs)
  const utf8 = new TextDecoder('utf-8', { fatal: true });
  try {
    return utf8.decode(raw.subarray(offset));
  } catch (e) { /* not valid UTF-8 */ }

  // Peek at XML declaration or meta charset for encoding hint
  const ascii = new TextDecoder('ascii', { fatal: false }).decode(raw.subarray(offset, offset + 512));
  const encodingMatch = ascii.match(/encoding=["']([^"']+)["']/i) ||
                        ascii.match(/charset=["']?([^"'\s;]+)/i);
  const encoding = encodingMatch ? encodingMatch[1].toLowerCase() : 'windows-1252';

  try {
    return new TextDecoder(encoding, { fatal: false }).decode(raw.subarray(offset));
  } catch (e) {
    // Last resort: lossy latin1
    return new TextDecoder('iso-8859-1', { fatal: false }).decode(raw.subarray(offset));
  }
}

/**
 * Resolve a relative href against a base file path.
 * Handles multiple ../, ./, absolute /, and bare relative paths. (3979)
 */
export function resolvePath(basePath, href) {
  if (href.startsWith('/')) return href.substring(1);
  href = href.replace(/^\.\//, '');
  const baseDir = basePath.includes('/') ? basePath.substring(0, basePath.lastIndexOf('/')) : '';
  const baseParts = baseDir ? baseDir.split('/') : [];
  const hrefParts = href.split('/');
  while (hrefParts.length > 0 && hrefParts[0] === '..') {
    hrefParts.shift();
    if (baseParts.length > 0) baseParts.pop();
  }
  const resolved = [...baseParts, ...hrefParts].join('/');
  return resolved.replace(/\/+/g, '/');
}

/** (3478) */
export function formatBytes(b) {
  if (!b) return '0 B';
  const k = 1024;
  const s = ['B', 'KB', 'MB', 'GB'];
  const i = Math.floor(Math.log(b) / Math.log(k));
  return (b / Math.pow(k, i)).toFixed(1) + ' ' + s[i];
}