/**
 * 이전 Pages 배포 세대의 자산 보존 — immutable preview URL(들)의 HTML/JS/CSS 의존
 * 그래프를 따라 내려받아, 새 빌드 dist 에 없는 파일만 추가한다(기존 파일은 덮어쓰지 않는다).
 * 사용: node preserve-assets.mjs
 */
import { mkdir, writeFile, readFile } from "node:fs/promises";
import { createHash } from "node:crypto";
import path from "node:path";

const ORIGINS = [
  "https://vignette.chanpaca.net",
  "https://5a525329.vignette-b1q.pages.dev",
  "https://e1c73735.vignette-b1q.pages.dev",
  "https://bbebb2d3.vignette-b1q.pages.dev",
  "https://44edecc8.vignette-b1q.pages.dev",
  "https://0ffdc694.vignette-b1q.pages.dev",
  "https://7bd59055.vignette-b1q.pages.dev",
];

const DIST = "dist";

async function exists(p) {
  try {
    await readFile(p);
    return true;
  } catch {
    return false;
  }
}

async function collect(origin) {
  const seen = new Map(); // path -> sha256 hex
  const html = await (await fetch(origin + "/")).text();
  // index.html 이 참조하는 엔트리 자산
  const refs = new Set();
  for (const m of html.matchAll(/(?:src|href)="(\/[^"]+\.(?:js|css))"/g)) refs.add(m[1]);
  for (const m of html.matchAll(/(?:src|href)="(\/[^"]+\.(?:png|svg|ico|webmanifest|json|woff2?))"/g))
    refs.add(m[1]);
  // JS 청크 의존 그래프 폐쇄
  const queue = [...refs];
  while (queue.length) {
    const ref = queue.pop();
    if (seen.has(ref)) continue;
    const res = await fetch(origin + ref);
    if (!res.ok) {
      seen.set(ref, "FETCH_FAILED_" + res.status);
      continue;
    }
    const buf = Buffer.from(await res.arrayBuffer());
    seen.set(ref, createHash("sha256").update(buf).digest("hex"));
    if (ref.endsWith(".js")) {
      const text = buf.toString("utf8");
      for (const m of text.matchAll(/["'`](\.\/[A-Za-z0-9_.-]+\.(?:js|css))["'`]/g)) {
        const p = path.posix.normalize(path.posix.join(path.posix.dirname(ref), m[1]));
        if (!seen.has(p)) queue.push(p);
      }
    }
  }
  return seen;
}

const perOrigin = [];
let added = 0;
const addedList = [];
for (const origin of ORIGINS) {
  const map = await collect(origin);
  let ok = 0;
  for (const [p, sha] of map) {
    if (sha.startsWith("FETCH_FAILED")) continue;
    const rel = p.replace(/^\//, "");
    const target = path.join(DIST, rel);
    if (await exists(target)) {
      ok += 1;
      continue;
    }
    await mkdir(path.dirname(target), { recursive: true });
    const res = await fetch(origin + p);
    await writeFile(target, Buffer.from(await res.arrayBuffer()));
    added += 1;
    addedList.push(rel);
  }
  perOrigin.push({ origin, assets: map.size, reused_in_new_build: ok });
  console.log(`origin ${origin}: ${map.size} assets, ${ok} already in new build`);
}
console.log(`assets_added: ${added}`);
await writeFile(
  "preserve-report.json",
  JSON.stringify({ origins: perOrigin, assets_added: added, added: addedList }, null, 1),
  "utf8",
);