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

const candidates = [
  "node_modules/@indiekit/indiekit/config/express.js",
];

const marker = "SESSION_MAX_AGE_DAYS";
const from = "maxAge: 7 * 24 * 60 * 60 * 1000, // 7 days,";
const to   = "maxAge: Number.parseInt(process.env.SESSION_MAX_AGE_DAYS || '30', 10) * 24 * 60 * 60 * 1000, // SESSION_MAX_AGE_DAYS days";

async function exists(filePath) {
  try { await access(filePath); return true; } catch { return false; }
}

let checked = 0;
let patched = 0;

for (const filePath of candidates) {
  if (!(await exists(filePath))) continue;
  checked += 1;

  const source = await readFile(filePath, "utf8");
  if (source.includes(marker)) {
    console.log("[postinstall] Session maxAge patch already applied");
    continue;
  }

  if (!source.includes(from)) {
    console.warn("[postinstall] Skipping session maxAge patch: upstream format changed");
    continue;
  }

  await writeFile(filePath, source.replace(from, to), "utf8");
  patched += 1;
}

if (checked === 0) {
  console.log("[postinstall] No indiekit express config found");
} else if (patched > 0) {
  console.log("[postinstall] Patched session maxAge to use SESSION_MAX_AGE_DAYS env var (default 30)");
}