#!/usr/bin/env node
// Copies module NN's tests for the learner's track into <workspace>/tests/.
import { cpSync, existsSync, mkdirSync, readFileSync } from "node:fs";
import { basename, join } from "node:path";
import { moduleDirs, courseRoot, testFiles, fail } from "./lib.mjs";

const [num, ws] = process.argv.slice(2);
if (!/^\d\d$/.test(num || "") || !ws) fail("usage: start-module.mjs <NN> <workspaceDir>");
if (num === "00") fail("Module 00 is not startable: M0 uses the naive-engine/ project, not a workspace.");

const cfg = JSON.parse(readFileSync(join(ws, ".course.json"), "utf8"));
const track = cfg.track;
if (track !== "rust" && track !== "ts") fail(`bad track in .course.json: ${track}`);

const mods = moduleDirs();
const mod = mods.find((m) => m.num === num);
if (!mod) fail(`no module ${num} in ${courseRoot()}`);

if (num !== "01") {
  const prevNum = String(Number(num) - 1).padStart(2, "0");
  const prev = mods.find((m) => m.num === prevNum);
  if (prev) {
    const missing = testFiles(prev.path, track).map((f) => basename(f))
      .filter((f) => !existsSync(join(ws, "tests", f)));
    if (missing.length) fail(`Cannot start module ${num}: finish module ${prevNum} first. Missing tests/${missing.join(", tests/")}`);
  }
}

const files = testFiles(mod.path, track);
if (!files.length) fail(`module ${num} has no ${track} tests`);
mkdirSync(join(ws, "tests"), { recursive: true });
for (const f of files) cpSync(f, join(ws, "tests", basename(f)));
console.log(`Copied ${files.length} test file(s) for module ${num} into ${join(ws, "tests")}`);

// Harness additions: module-local note, else the "- M<N>:" line of course/harness.md.
const note = join(mod.path, "harness-adds.md");
let adds = existsSync(note) ? readFileSync(note, "utf8").trim() : "";
if (!adds) {
  const h = join(courseRoot(), "harness.md");
  if (existsSync(h)) {
    const re = new RegExp(`^\\s*[-*]\\s*\\**M${Number(num)}\\b.*$`, "m");
    adds = (re.exec(readFileSync(h, "utf8")) || [""])[0].trim();
  }
}
console.log(adds ? `Harness functions added by module ${num}:\n${adds}` : `No harness additions recorded for module ${num} (see course/harness.md).`);