import { Buffer } from 'buffer';
import iconv from 'iconv-lite';

export function detectBOM(buffer: Buffer): string | null {
  if (buffer[0] === 0xEF && buffer[1] === 0xBB && buffer[2] === 0xBF) return 'utf-8';
  if (buffer[0] === 0xFF && buffer[1] === 0xFE) return 'utf-16le';
  if (buffer[0] === 0xFE && buffer[1] === 0xFF) return 'utf-16be';
  return null;
}

export function stripBOM(content: string): string {
  return content.charCodeAt(0) === 0xFEFF ? content.slice(1) : content;
}

export function decodeBuffer(buffer: Buffer, encoding = 'utf-8'): string {
  const bom = detectBOM(buffer);
  if (bom) {
    return stripBOM(iconv.decode(buffer, bom));
  }
  return iconv.decode(buffer, encoding);
}

export function encodeString(content: string, encoding = 'utf-8', addBOM = false): Buffer {
  const encoded = iconv.encode(content, encoding);
  if (addBOM && encoding.toLowerCase() === 'utf-8') {
    return Buffer.concat([Buffer.from([0xEF, 0xBB, 0xBF]), encoded]);
  }
  return encoded;
}