use HashMap;
use Utc;
use Regex;
/// Replaces placeholders in the response body with actual values.
///
/// - `body`: The response template with placeholders.
/// - `params`: A map containing request parameters (e.g., query or path params).
///
/// Supports:
/// - `{{timestamp}}` → Current UTC timestamp
/// - Other `{{var}}` → Replaced with values from `params`