import { Buffer } from "node:buffer";

import { decodeInputrcKeySequence } from "./key-sequence.js";

export class InputrcMacroError extends Error {
  constructor(message: string) {
    super(message);
    this.name = "InputrcMacroError";
  }
}

export type MacroExpansionOptions = {
  maxBytes?: number;
};

/** Decode one inputrc macro while enforcing a bounded emitted-input budget. */
export function expandInputrcMacro(
  source: string,
  options: MacroExpansionOptions = {},
): string {
  const maxBytes = options.maxBytes ?? 4096;
  if (!Number.isInteger(maxBytes) || maxBytes < 1) {
    throw new RangeError("Inputrc macro maxBytes must be a positive integer");
  }

  const expanded = decodeInputrcKeySequence(source);
  if (Buffer.byteLength(expanded, "utf8") > maxBytes) {
    throw new InputrcMacroError(
      `Inputrc macro exceeds ${maxBytes} emitted bytes`,
    );
  }
  return expanded;
}