/**
 * Canonical JSON serialization.
 * Order keys, normalize encoding, handle arrays consistently.
 */
export function canonicalizeJson(obj: Record<string, unknown>): string {
  return JSON.stringify(obj, Object.keys(obj).sort());
}

/**
 * Calculate canonical hash of a message.
 * Excludes: hash, signatures, cles_de_chiffrement.
 */
export function calculateCanonicalHash(
  message: Record<string, unknown>,
  algo: string = 'sha256',
): string {
  const { hash, signatures, cles_de_chiffrement, ...canonical } = message;
  const canonicalJson = canonicalizeJson(canonical);
  return hashString(canonicalJson, algo);
}

/**
 * Hash a string with specified algorithm.
 */
export function hashString(input: string, algo: string): string {
  if (algo === 'sha256') {
    const encoder = new TextEncoder();
    const data = encoder.encode(input);
    return crypto.subtle.digest('SHA-256', data).then((hashBuffer) => {
      const hashArray = Array.from(new Uint8Array(hashBuffer));
      return hashArray.map((b) => b.toString(16).padStart(2, '0')).join('');
    }) as unknown as string;
  }
  throw new Error(`Unsupported hash algorithm: ${algo}`);
}

/**
 * Async version of hashString.
 */
export async function hashStringAsync(input: string, algo: string): Promise<string> {
  if (algo === 'sha256') {
    const encoder = new TextEncoder();
    const data = encoder.encode(input);
    const hashBuffer = await crypto.subtle.digest('SHA-256', data);
    const hashArray = Array.from(new Uint8Array(hashBuffer));
    return hashArray.map((b) => b.toString(16).padStart(2, '0')).join('');
  }
  throw new Error(`Unsupported hash algorithm: ${algo}`);
}