import { spawn } from "node:child_process";
import { mkdirSync } from "node:fs";
import { withLock } from "./lock.mjs";

function run(cmd, args, opts = {}) {
  return new Promise((resolve, reject) => {
    const child = spawn(cmd, args, { stdio: "inherit", ...opts });
    child.on("error", reject);
    child.on("close", (code) =>
      code === 0 ? resolve() : reject(new Error(`${cmd} ${args.join(" ")} exited ${code}`))
    );
  });
}

/** Absolute path of the global build lock. Callers that build outside buildSite()
 *  (e.g. console preview builds) must take THIS same lock to serialize. */
export function buildLockPath(projectRoot) {
  return `${projectRoot}/agents/state/build.lock`;
}

/**
 * Build the Astro app and fix ownership so Apache can serve the output.
 * Serialized behind the global build lock so it never races the console's
 * preview/publish builds (concurrent astro builds would OOM this box).
 */
export async function buildSite({ projectRoot, appDir }) {
  const lockPath = buildLockPath(projectRoot);
  mkdirSync(`${projectRoot}/agents/state`, { recursive: true });
  await withLock(lockPath, async () => {
    await run("npm", ["run", "build"], { cwd: `${projectRoot}/${appDir}` });
    // Best-effort ownership fix (ignore failure if not running as root).
    try {
      await run("chown", ["-R", "www:www", `${projectRoot}/${appDir}`, `${projectRoot}/public`]);
    } catch (e) {
      console.warn(`[build] chown skipped: ${e.message}`);
    }
  });
}