export interface TemplateVars {
  [key: string]: string;
}

/**
 * Replaces {{PLACEHOLDER}} tokens with provided values.
 * Does NOT expand ${ENV_VAR} syntax — those pass through for shell resolution.
 */
export function renderTemplate(
  template: string,
  vars: TemplateVars,
  options: { strict?: boolean } = {},
): string {
  return template.replace(
    /\{\{([A-Z_][A-Z0-9_]*)\}\}/g,
    (match, varName: string) => {
      if (varName in vars) {
        return vars[varName];
      }
      if (options.strict) {
        throw new Error(`Template variable not provided: {{${varName}}}`);
      }
      return '';
    },
  );
}