// hotupdate.js —— 热更新：拉取 manifest、下载、校验、解压应用（复用 lib/zip.js）。
"use strict";
const fs = require("fs");
const path = require("path");
const crypto = require("crypto");
const { extractZip } = require("./zip");
const hotstate = require("./hotstate");

const UA = "codex-market";
const OWNER = "mhgmh";
const REPO = "codex-market-app";
const API = `https://up.tokendun.cc/api/v1/repos/${OWNER}/${REPO}`;
const HOT_TAG = "hot";
// 可选 ed25519 公钥（SPKI PEM）。留空则只做 sha256 校验；填入后强制校验签名。
const HOT_PUBKEY_PEM = "";

// 语义版本比较：a>b→1, a<b→-1, 相等→0
function cmp(a, b) {
  const pa = String(a || "0").replace(/^v/, "").split(".").map((n) => parseInt(n, 10) || 0);
  const pb = String(b || "0").replace(/^v/, "").split(".").map((n) => parseInt(n, 10) || 0);
  for (let i = 0; i < Math.max(pa.length, pb.length); i++) {
    if ((pa[i] || 0) > (pb[i] || 0)) return 1;
    if ((pa[i] || 0) < (pb[i] || 0)) return -1;
  }
  return 0;
}

async function fetchJson(url, ms = 8000) {
  const ctrl = new AbortController();
  const t = setTimeout(() => ctrl.abort(), ms);
  try {
    const res = await fetch(url, { headers: { "User-Agent": UA }, signal: ctrl.signal });
    if (!res.ok) throw new Error(`HTTP ${res.status}`);
    return await res.json();
  } finally { clearTimeout(t); }
}

// 拉取 hot release 里的 hotupdate.json；失败返回 null（断网/无 release 时静默）
async function fetchManifest() {
  let rel;
  try {
    rel = await fetchJson(`${API}/releases/tags/${HOT_TAG}`);
  } catch { return null; }
  const assets = (rel && rel.assets) || [];
  const mAsset = assets.find((a) => a.name === "hotupdate.json");
  if (!mAsset) return null;
  try {
    const m = await fetchJson(mAsset.browser_download_url || `${API.replace("/api/v1/repos", "")}/`);
    // 若 bundleUrl 缺失，尝试从同 release 的 asset 里按 contentVersion 找 bundle
    if (m && !m.bundleUrl && m.contentVersion) {
      const b = assets.find((a) => a.name === `bundle-${m.contentVersion}.zip`);
      if (b) m.bundleUrl = b.browser_download_url;
    }
    return m;
  } catch { return null; }
}

// 评估是否有可用热更 / 是否需完整包。
// bundledHotVersion：随包内置的内容版本；appVersion：当前原生版本。
function evaluate(manifest, appVersion, bundledHotVersion, hotBase) {
  if (!manifest || !manifest.contentVersion) return { hasHot: false };
  const confirmed = hotstate.effectiveVersion(hotBase); // 已确认的热更版本
  const effective = cmp(confirmed || "0", bundledHotVersion || "0") > 0 ? confirmed : (bundledHotVersion || "0");
  const newer = cmp(manifest.contentVersion, effective) > 0;
  const minOk = cmp(appVersion, manifest.minAppVersion || "0") >= 0;
  const needFull = !!manifest.requiresFull || !minOk;
  return {
    hasHot: newer,
    needFull: newer && needFull,       // 有新内容但当前原生版本不够 → 必须下完整包
    canHot: newer && minOk && !manifest.requiresFull,
    contentVersion: manifest.contentVersion,
    minAppVersion: manifest.minAppVersion || null,
    notes: manifest.notes || "",
    mandatory: !!manifest.mandatory,
  };
}

// 下载 + 校验 + 解压 + 置 target。onProgress(percent 0..100)
async function applyManifest(manifest, hotBase, onProgress) {
  if (!manifest || !manifest.bundleUrl || !manifest.sha256) {
    throw new Error("热更清单不完整");
  }
  const ver = manifest.contentVersion;
  onProgress && onProgress(1);
  const res = await fetch(manifest.bundleUrl, { headers: { "User-Agent": UA } });
  if (!res.ok) throw new Error(`下载失败（${res.status}）`);
  // 带进度读取
  const total = Number(res.headers.get("content-length")) || 0;
  const reader = res.body.getReader();
  const chunks = [];
  let got = 0;
  for (;;) {
    const { done, value } = await reader.read();
    if (done) break;
    chunks.push(value);
    got += value.length;
    if (total && onProgress) onProgress(Math.min(99, Math.round((got / total) * 100)));
  }
  const buf = Buffer.concat(chunks.map((c) => Buffer.from(c)));

  // sha256（必做）
  const sum = crypto.createHash("sha256").update(buf).digest("hex");
  if (sum.toLowerCase() !== String(manifest.sha256).toLowerCase()) {
    throw new Error("SHA256 校验失败，已丢弃");
  }
  // ed25519 签名（可选：仅当内嵌公钥非空）
  if (HOT_PUBKEY_PEM) {
    if (!manifest.signature) throw new Error("缺少签名");
    const ok = crypto.verify(
      null,
      Buffer.from(`${manifest.sha256}:${ver}`),
      HOT_PUBKEY_PEM,
      Buffer.from(manifest.signature, "base64")
    );
    if (!ok) throw new Error("签名校验失败");
  }

  // 解压到中转目录 → 校验结构 → 原子 rename
  fs.mkdirSync(hotBase, { recursive: true });
  const tmp = path.join(hotBase, `.tmp-${ver}`);
  fs.rmSync(tmp, { recursive: true, force: true });
  fs.mkdirSync(tmp, { recursive: true });
  extractZip(buf, tmp);
  if (!fs.existsSync(path.join(tmp, "electron", "main.js")) ||
      !fs.existsSync(path.join(tmp, "renderer", "index.html"))) {
    fs.rmSync(tmp, { recursive: true, force: true });
    throw new Error("热更包结构不完整");
  }
  const dst = path.join(hotBase, ver);
  fs.rmSync(dst, { recursive: true, force: true });
  fs.renameSync(tmp, dst);
  hotstate.setTarget(hotBase, ver); // 下次启动生效
  onProgress && onProgress(100);
  return { ok: true, version: ver };
}

module.exports = { fetchManifest, evaluate, applyManifest, cmp };