/**
 * ETag generation utilities
 */

import type * as plugins from '../plugins.js';

/**
 * Generate ETag from file stats
 * Uses weak ETag format: W/"size-mtime"
 */
export function generateETag(stat: { size: number; mtime: Date }): string {
  const mtime = stat.mtime.getTime().toString(16);
  const size = stat.size.toString(16);
  return `W/"${size}-${mtime}"`;
}

/**
 * Generate strong ETag from content
 * Uses hash of content
 */
export async function generateStrongETag(content: Uint8Array): Promise<string> {
  const hashBuffer = await crypto.subtle.digest('SHA-256', content as unknown as ArrayBuffer);
  const hashArray = Array.from(new Uint8Array(hashBuffer));
  const hashHex = hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
  return `"${hashHex.slice(0, 32)}"`;
}

/**
 * Check if ETag matches
 */
export function matchesETag(etag: string, ifNoneMatch: string | null): boolean {
  if (!ifNoneMatch) return false;

  // Handle multiple ETags
  const etags = ifNoneMatch.split(',').map(e => e.trim());

  // Wildcard match
  if (etags.includes('*')) return true;

  // Weak comparison (ignore W/ prefix)
  const normalizeETag = (e: string) => e.replace(/^W\//, '');
  const normalizedETag = normalizeETag(etag);

  return etags.some(e => normalizeETag(e) === normalizedETag);
}