/* 스프레드시트 D 시험 번들 도우미 — TS 를 그 자리에서 CommonJS 로 풀어 모음.
 * 남의 몫 파일이 아직 빈 몸(「아직 없음」)이면 spreadsheet_d_fakes.cjs 의 가짜로 바꿔 끼움.
 *   load(entry)            Node 안에서 모듈을 돌려 exports 를 줌(pytest 도우미가 씀)
 *   node 이 파일 harness   브라우저 시험 틀 번들 → tmp/spreadsheet_d/harness.js (git 밖)
 * `.cjs` = 루트 package.json 의 "type":"module" 과 무관하게 CommonJS. */

const fs = require("fs");
const path = require("path");

const ROOT = path.join(__dirname, "..", "..", "..");
const ts = require(path.join(ROOT, "config", "node_modules", "typescript"));
const SS = path.join(ROOT, "A00_Common", "spreadsheet");
const FAKES = path.join(__dirname, "spreadsheet_d_fakes.cjs");

const isStub = (file) => fs.readFileSync(file, "utf8").includes("아직 없음(");

/** 가져오기 글 → 모듈 id(파일 경로 · `fake:<이름>` · `css:<경로>`) */
function resolve(spec, from) {
  if (spec === "@ui/ui_template_elements") return "fake:el";
  let abs;
  if (spec.startsWith("@ui/")) abs = path.join(ROOT, "ui_template", spec.slice(4));
  else if (spec.startsWith(".")) abs = path.resolve(path.dirname(from), spec);
  else throw new Error(`모르는 가져오기: ${spec} (${from})`);
  if (/\.(css|json|cjs)$/.test(abs)) return (abs.endsWith(".css") ? "css:" : "") + abs;
  if (!abs.endsWith(".ts")) abs += ".ts";
  if (path.dirname(abs) === SS && isStub(abs))
    return "fake:" + path.basename(abs, ".ts").replace(/^spreadsheet_/, "");
  return abs;
}

/** 입구부터 딸린 모듈 전부 → id → {code, deps} */
function collect(entry, stubs = []) {
  const mods = new Map();
  const walk = (id) => {
    if (mods.has(id)) return;
    let code;
    if (id.startsWith("fake:")) {
      const name = id.slice(5);
      if (name !== "el") stubs.push(name);
      code = `module.exports = require("${FAKES.replace(/\\/g, "/")}")[${JSON.stringify(name)}];`;
      mods.set(id, { code, deps: { [FAKES.replace(/\\/g, "/")]: FAKES } });
      walk(FAKES);
      return;
    }
    if (id.startsWith("css:")) {
      const css = fs.readFileSync(id.slice(4), "utf8");
      code = `if (typeof document !== "undefined") { const s = document.createElement("style"); s.textContent = ${JSON.stringify(css)}; document.head.append(s); }`;
      mods.set(id, { code, deps: {} });
      return;
    }
    const src = fs.readFileSync(id, "utf8");
    if (id.endsWith(".json")) code = `module.exports = ${src};`;
    else if (id.endsWith(".ts"))
      code = ts.transpileModule(src, {
        fileName: id,
        compilerOptions: { module: ts.ModuleKind.CommonJS, target: ts.ScriptTarget.ES2022 },
      }).outputText;
    else code = src;
    const deps = {};
    mods.set(id, { code, deps });
    for (const m of code.matchAll(/require\("([^"]+)"\)/g)) {
      const dep = m[1] === FAKES.replace(/\\/g, "/") ? FAKES : resolve(m[1], id);
      deps[m[1]] = dep;
      walk(dep);
    }
  };
  walk(entry);
  return mods;
}

/** Node 안에서 돌림 */
function load(entry) {
  const abs = path.resolve(entry);
  const id = resolve("./" + path.basename(abs).replace(/\.ts$/, ""), abs); // 빈 몸이면 가짜
  const mods = collect(id);
  const cache = new Map();
  const req = (id) => {
    if (cache.has(id)) return cache.get(id).exports;
    const m = mods.get(id);
    const module = { exports: {} };
    cache.set(id, module);
    new Function("exports", "module", "require", m.code)(module.exports, module, (s) =>
      req(m.deps[s]),
    );
    return module.exports;
  };
  return req(id);
}

/** 브라우저 한 파일 */
function bundle(entry, out) {
  const stubs = [];
  const mods = collect(path.resolve(entry), stubs);
  const ids = [...mods.keys()];
  const defs = ids
    .map((id, i) => {
      const m = mods.get(id);
      const map = Object.fromEntries(Object.entries(m.deps).map(([s, d]) => [s, ids.indexOf(d)]));
      return `[${JSON.stringify(map)}, function (exports, module, require) {\n${m.code}\n}]`;
    })
    .join(",\n");
  const text = `(function () {
const defs = [${defs}];
const cache = [];
function req(i) {
  if (cache[i]) return cache[i].exports;
  const module = (cache[i] = { exports: {} });
  defs[i][1](module.exports, module, (s) => req(defs[i][0][s]));
  return module.exports;
}
window.__ssFakes = ${JSON.stringify([...new Set(stubs)])};
req(${ids.indexOf(path.resolve(entry))});
})();\n`;
  fs.mkdirSync(path.dirname(out), { recursive: true });
  fs.writeFileSync(out, text);
  return { out, modules: ids.length, fakes: [...new Set(stubs)] };
}

module.exports = { load, bundle, ROOT, SS };

if (require.main === module && process.argv[2] === "harness") {
  const r = bundle(
    path.join(__dirname, "harness_spreadsheet_d.cjs"),
    path.join(ROOT, "tmp", "spreadsheet_d", "harness.js"),
  );
  console.log(JSON.stringify(r));
}