// scripts/encrypt_pdf.ts
import * as fs from 'fs'
import * as path from 'path'
import pako from 'pako'

import { fileURLToPath } from 'url'

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const PDF_DIR = path.resolve(__dirname, '../../public/pdf')

// 工具：ArrayBuffer / Uint8Array 转 Base64
function ab2b64(buffer: ArrayBuffer) {
  let binary = '';
  const bytes = new Uint8Array(buffer);
  bytes.forEach(b => binary += String.fromCharCode(b));
  return btoa(binary);
}

// 简单混淆：Base64 -> URL安全 + 去掉 '='
function obfuscate(base64str: string) {
  return base64str.replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
}

// 主函数：压缩 + 混淆
function compressAndObfuscate(inputPath: string, outputPath: string) {
  const input = fs.readFileSync(inputPath)

  // 压缩成 Uint8Array
  const compressed = pako.deflate(new Uint8Array(input));
  // 转 Base64 字符串
  const b64 = ab2b64(compressed.buffer);
  // 混淆返回
  const output = obfuscate(b64);

  fs.writeFileSync(outputPath, output)

  console.log(`✔ Compress: ${path.basename(inputPath)}`)
}

function encryptAllPDFs(): void {
  const files = fs.readdirSync(PDF_DIR)
  for (const file of files) {
    const fullPath = path.join(PDF_DIR, file)
    if (!fs.statSync(fullPath).isFile() || !file.endsWith('.pdf')) continue

    const encPath = fullPath + '.enc'
    if (fs.existsSync(encPath)) {
      console.log(`⏭ Skipped (already Compress): ${file}`)
      continue
    }

    compressAndObfuscate(fullPath, encPath)
  }
}

encryptAllPDFs()