/**
 * Cryptographic Utilities
 * 
 * Hash functions for content deduplication and verification.
 */

import { createHash } from 'crypto';

/**
 * Generate SHA-256 hash of content
 */
export function sha256(content) {
  if (typeof content !== 'string') {
    content = JSON.stringify(content);
  }
  return createHash('sha256').update(content).digest('hex');
}

/**
 * Generate content hash for metadata comparison
 * Excludes volatile fields like server_time
 */
export function hashMetadata(metadata) {
  if (!metadata) return null;

  // Extract stable fields only
  const stableFields = {
    name: metadata.name,
    pubkey: metadata.pubkey,
    version: metadata.version,
    description: metadata.description,
    description_long: metadata.description_long,
    contact: metadata.contact,
    motd: metadata.motd,
    icon_url: metadata.icon_url,
    nuts: metadata.nuts,
    tos_url: metadata.tos_url,
  };

  // Sort keys for consistent hashing
  const sorted = JSON.stringify(stableFields, Object.keys(stableFields).sort());
  return sha256(sorted);
}

/**
 * Generate a short hash for display
 */
export function shortHash(content, length = 8) {
  return sha256(content).substring(0, length);
}