/**
 * @file Daily copy of the AI Tools catalog from the newest AgentHub release,
 * so a new tool or a fixed flag reaches a user without a plugin update. Only a
 * release NEWER than the running build is copied (a dev checkout ahead of the
 * newest release is never rolled back), each file is validated at release
 * trust by ai-tools.js, and the set is replaced whole or not at all. Stored
 * in `<data dir>/runtime/ai-tools-remote/`. Off with AGENTHUB_AI_TOOLS_SYNC=0.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const fs = require("node:fs");
const path = require("node:path");
const { getDataDir } = require("./claude-home");
const {
  compareVersions,
  releaseApiUrl,
  fetchReleaseFromUrl,
  repoUrlFor,
  DEFAULT_ROOT,
} = require("./update-check");

const DAY_MS = 24 * 60 * 60 * 1000;
const FIRST_MS = 60 * 1000;
const MAX_FILES = 200;
const MAX_BYTES = 64 * 1024;
const NAME_RE = /^[a-z0-9][a-z0-9-]{0,39}\.json$/;

let versionOverride = null;

const disabled = () => /^(0|false|off)$/i.test(process.env.AGENTHUB_AI_TOOLS_SYNC || "");
const remoteDir = () => path.join(getDataDir(), "runtime", "ai-tools-remote");

function runningVersion() {
  if (versionOverride) return versionOverride;
  try {
    return JSON.parse(fs.readFileSync(path.join(DEFAULT_ROOT, "package.json"), "utf8")).version;
  } catch {
    return null;
  }
}

function readMeta() {
  try {
    const m = JSON.parse(fs.readFileSync(path.join(remoteDir(), "meta.json"), "utf8"));
    return typeof m.tag === "string" ? m : null;
  } catch {
    return null;
  }
}

/** The synced dir when it holds a release newer than this build; else null. */
function activeRemoteDir() {
  if (disabled()) return null;
  const meta = readMeta();
  const running = runningVersion();
  if (!meta || !running || compareVersions(meta.tag, running) <= 0) return null;
  return remoteDir();
}

function catalogMeta() {
  if (!activeRemoteDir()) return { source: "builtin", tag: null, fetchedAt: null };
  const { tag, fetchedAt } = readMeta();
  return { source: "remote", tag, fetchedAt: fetchedAt || null };
}

async function getText(url) {
  const res = await fetch(url, {
    signal: AbortSignal.timeout(15_000),
    headers: { accept: "application/json" },
    redirect: "follow",
  });
  if (!res.ok) throw new Error(`http_${res.status}`);
  // ponytail: reads the body before checking its size; stream with a byte cap
  // if a forge ever answers with something large enough to matter.
  return res.text();
}

/** One pass. Never throws; `{ok:false, reason}` on every miss. */
async function syncOnce({ repoUrl, root = DEFAULT_ROOT } = {}) {
  if (disabled()) return { ok: false, reason: "disabled" };
  const repo = repoUrl || (await repoUrlFor(root));
  const api = repo && releaseApiUrl(repo);
  if (!api) return { ok: false, reason: "no_remote" };
  const rel = await fetchReleaseFromUrl(repo);
  if (!rel.ok) return { ok: false, reason: rel.reason };
  const running = runningVersion();
  if (!running || compareVersions(rel.tag, running) <= 0) return { ok: false, reason: "not_newer" };

  const { validate, refresh } = require("./ai-tools");
  const origin = new URL(api).origin;
  const tmp = `${remoteDir()}.tmp-${process.pid}`;
  try {
    const listUrl = api.replace(
      /\/releases\/latest$/,
      `/contents/server/data/ai-tools?ref=${encodeURIComponent(rel.tag)}`
    );
    const entries = JSON.parse(await getText(listUrl));
    if (!Array.isArray(entries) || entries.length > MAX_FILES) {
      return { ok: false, reason: "bad_listing" };
    }
    fs.rmSync(tmp, { recursive: true, force: true });
    fs.mkdirSync(tmp, { recursive: true });
    for (const e of entries) {
      if (e?.type !== "file" || !NAME_RE.test(e.name || "")) continue;
      let url;
      try {
        url = new URL(e.download_url);
      } catch {
        continue;
      }
      if (url.origin !== origin) continue; // only the forge the release came from
      const text = await getText(url.href); // a failed download aborts the pass
      if (Buffer.byteLength(text) > MAX_BYTES) continue;
      let doc;
      try {
        doc = JSON.parse(text);
      } catch {
        continue;
      }
      if (validate(doc, "remote")) fs.writeFileSync(path.join(tmp, e.name), text);
    }
    fs.writeFileSync(
      path.join(tmp, "meta.json"),
      JSON.stringify({ tag: rel.tag, fetchedAt: new Date().toISOString() }) + "\n"
    );
    const old = `${remoteDir()}.old-${process.pid}`;
    if (fs.existsSync(remoteDir())) fs.renameSync(remoteDir(), old);
    fs.renameSync(tmp, remoteDir());
    fs.rmSync(old, { recursive: true, force: true });
    refresh();
    return { ok: true, tag: rel.tag };
  } catch (err) {
    fs.rmSync(tmp, { recursive: true, force: true });
    return { ok: false, reason: "unreachable", error: err.message };
  }
}

function startAiToolsSync() {
  if (disabled()) return;
  setTimeout(() => {
    void syncOnce();
    setInterval(() => void syncOnce(), DAY_MS).unref();
  }, FIRST_MS).unref();
}

/** Test seam: pin the running version, or null for package.json. */
function __setVersion(v) {
  versionOverride = v;
}

module.exports = {
  syncOnce,
  startAiToolsSync,
  activeRemoteDir,
  catalogMeta,
  remoteDir,
  __setVersion,
};