#!/usr/bin/env node
// Expansion Drop must touch only content: fail if any changed path is under an engine dir.
import { readFileSync } from "node:fs";
import { execFileSync } from "node:child_process";
import { join, posix } from "node:path";
import { fail } from "./lib.mjs";

const [ws, baseRef] = process.argv.slice(2);
if (!ws || !baseRef) fail("usage: expansion-check.mjs <workspaceDir> <baseRef>");

const git = (...a) => execFileSync("git", a, { cwd: ws, encoding: "utf8" }).split("\n").filter(Boolean);
const cfg = JSON.parse(readFileSync(join(ws, ".course.json"), "utf8"));
const changed = new Set([
  ...git("diff", "--name-only", "--relative", baseRef),
  ...git("ls-files", "--others", "--exclude-standard"),
]);
const engine = (cfg.engineDirs || []).map((d) => posix.normalize(d).replace(/\/$/, ""));
const bad = [...changed].filter((p) => engine.some((d) => p === d || p.startsWith(d + "/")));
if (bad.length) fail("expansion-check: engine changed during Expansion Drop\n" + bad.map((p) => "  " + p).join("\n"));
console.log(`expansion-check: ok (${changed.size} changed, none in engine)`);