// 改写 .atlas 里的贴图页名后缀（页名行是形如 `xilian.png` 的独立一行）。
// 逐行处理、只改匹配 `^\S+\.png$` 的行，保留原有行尾与其余内容，避免误伤区域名。
// 用法：node tools/atlas-pages.mjs <a.atlas> [后缀替换: .png=.webp] [--dry]

import { readFile, writeFile } from "node:fs/promises";

const args = process.argv.slice(2);
const file = args[0];
if (!file) {
  console.error("usage: node tools/atlas-pages.mjs <a.atlas> [.png=.webp] [--dry]");
  process.exit(2);
}
const pair = (args.find((a) => a.includes("=")) ?? ".png=.webp").split("=");
const dry = args.includes("--dry");

const text = await readFile(file, "utf8");
const lines = text.split("\n");
let changed = 0;
const out = lines.map((line) => {
  const m = line.match(/^(\S+\.png)(\r?)$/); // 注意保留 CRLF 行尾，实测这两个 .atlas 是 CRLF
  if (!m) return line;
  changed++;
  return line.replace(/\.png(\r?)$/, `${pair[1]}$1`);
});

if (!changed) {
  console.log(`${file}: 没有需要改写的页名行`);
  process.exit(0);
}
console.log(`${file}: ${changed} 个页名 → ${pair[1]}${dry ? "（试运行，未写入）" : ""}`);
if (!dry) await writeFile(file, out.join("\n"), "utf8");