/**
 * @file shared-tools.js
 * @description Server mode with one Linux user per account (S3/S4): the AI
 * tools every account runs, installed once under `/opt/agenthub/tools`
 * (owned by the dashboard's account, `r-x` for everyone). A member's pane has
 * `/opt/agenthub/tools/bin` first on its PATH (`run-as.memberPaneEnv`) and
 * cannot enter the host's home, where the AI Tools page installs them — so
 * every installed tool is PUBLISHED there: after an install or update, at
 * server start, and by `agenthub server tools publish`.
 *
 * What a publish copies, from the tool's real (symlink-resolved) path:
 *  - a native executable (ELF): that one file;
 *  - a file inside an npm package (`…/node_modules/<pkg>/…`): the package
 *    folder (its dependencies live inside it for a global install);
 *  - a script in a folder of its own (`…/versions/<v>/cursor-agent`): that
 *    folder — never a shared `bin` folder, nor a dot-folder right under the
 *    home (`~/.tool/tool`: its login usually sits beside it), both refused.
 * A file whose name says it holds a login (`CONFIG_SECRET_RE`) is never
 * copied: the copy is readable by every account.
 * Each copy lands in `<root>/<id>/<size>-<mtime>/` (so an unchanged tool is not
 * copied twice) and `<root>/bin/<command>` is pointed at it. Old copies are
 * kept (a running pane may still execute one). Self-updates in a member's
 * pane cannot touch them: the files are not the member's.
 *
 * The dashboard's own scripts members need (hook handler, `agenthub` CLI,
 * MCP server, statusline) are published to `/opt/agenthub/app` the same way,
 * with an `agenthub` launcher in `<root>/bin`.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

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

const toolsRoot = () => process.env.AGENTHUB_TOOLS_ROOT || "/opt/agenthub/tools";
const appRoot = () => process.env.AGENTHUB_APP_ROOT || "/opt/agenthub/app";

const err = (code, message) => Object.assign(new Error(message), { code });

/** `<root>/bin/<command>` when it exists and runs, else null. */
function sharedPath(command) {
  if (typeof command !== "string" || !/^[A-Za-z0-9._-]+$/.test(command)) return null;
  const p = path.join(toolsRoot(), "bin", command);
  try {
    fs.accessSync(p, fs.constants.X_OK);
    return p;
  } catch {
    return null;
  }
}

function isElf(file) {
  const fd = fs.openSync(file, "r");
  try {
    const buf = Buffer.alloc(4);
    fs.readSync(fd, buf, 0, 4, 0);
    return buf.equals(Buffer.from([0x7f, 0x45, 0x4c, 0x46]));
  } finally {
    fs.closeSync(fd);
  }
}

/**
 * What to copy for an executable at `real`: `{src, entry}` — `src` a file or
 * a folder, `entry` the executable's path relative to the copy ("" = src).
 */
function planFor(real) {
  const parts = real.split(path.sep);
  const nm = parts.lastIndexOf("node_modules");
  if (nm !== -1 && nm + 1 < parts.length - 1) {
    const end = parts[nm + 1].startsWith("@") ? nm + 3 : nm + 2;
    const src = parts.slice(0, end).join(path.sep);
    return { src, entry: path.relative(src, real) };
  }
  if (isElf(real)) return { src: real, entry: "" };
  const dir = path.dirname(real);
  const home = require("node:os").homedir();
  if (path.basename(dir) === "bin" || dir === path.dirname(dir) || path.dirname(dir) === home) {
    throw err(
      "ESHAREDLAYOUT",
      `${real} is a script in a shared folder — install this tool under ${toolsRoot()} by hand`
    );
  }
  return { src: dir, entry: path.basename(real) };
}

const secretName = (f) => require("./ai-tools").CONFIG_SECRET_RE.test(path.basename(f));

/** Point `link` at `target` (relative), replacing what was there in one rename. */
function relink(link, target) {
  const tmp = `${link}.agenthub-tmp`;
  fs.rmSync(tmp, { force: true });
  fs.symlinkSync(path.relative(path.dirname(link), target), tmp);
  fs.renameSync(tmp, link);
}

/**
 * Publish one installed catalog tool. Resolves `{id, command, path, copied}`.
 * @throws ENOTINSTALLED, ESHAREDLAYOUT
 */
async function publish(id) {
  const aiTools = require("./ai-tools");
  const entry = aiTools.get(id);
  const found = entry && aiTools.detect(id, { fresh: true });
  if (!found?.installed || !found.path) throw err("ENOTINSTALLED", `${id} is not installed`);
  const command = entry.detect[0];
  const real = fs.realpathSync(found.path);
  if (real.startsWith(toolsRoot() + path.sep)) {
    return { id, command, path: real, copied: false }; // already a shared copy
  }
  const plan = planFor(real);
  const stat = fs.statSync(real);
  const dest = path.join(toolsRoot(), id, `${stat.size}-${Math.floor(stat.mtimeMs)}`);
  const copy = plan.entry ? path.join(dest, path.basename(plan.src)) : path.join(dest, command);
  let copied = false;
  if (!fs.existsSync(dest)) {
    const tmp = `${dest}.agenthub-tmp`;
    await fs.promises.rm(tmp, { recursive: true, force: true });
    await fs.promises.mkdir(tmp, { recursive: true });
    const into = plan.entry ? path.join(tmp, path.basename(plan.src)) : path.join(tmp, command);
    await fs.promises.cp(plan.src, into, {
      recursive: true,
      verbatimSymlinks: true,
      filter: (f) => !secretName(f),
    });
    await chmodReadable(tmp);
    await fs.promises.rename(tmp, dest);
    copied = true;
  }
  fs.mkdirSync(path.join(toolsRoot(), "bin"), { recursive: true, mode: 0o755 });
  const exe = plan.entry ? path.join(copy, plan.entry) : copy;
  relink(path.join(toolsRoot(), "bin", command), exe);
  return { id, command, path: exe, copied };
}

/** `a+rX` over a tree: every account may read and run it, nobody but us write. */
async function chmodReadable(p) {
  const st = await fs.promises.lstat(p);
  if (st.isSymbolicLink()) return;
  const mode = st.isDirectory() || st.mode & 0o111 ? 0o755 : 0o644;
  await fs.promises.chmod(p, mode);
  if (st.isDirectory()) {
    for (const name of await fs.promises.readdir(p)) await chmodReadable(path.join(p, name));
  }
}

/** Every installed catalog tool; one that cannot be published is reported, not thrown. */
async function publishAll() {
  const aiTools = require("./ai-tools");
  const out = [];
  for (const t of aiTools.list()) {
    if (!aiTools.detect(t.id, { fresh: true }).installed) continue;
    try {
      out.push(await publish(t.id));
    } catch (e) {
      out.push({ id: t.id, error: e.message });
    }
  }
  return out;
}

const APP_DIRS = ["scripts", "server/lib", "bin", "mcp", "statusline"];

/**
 * The dashboard's own scripts a member's pane runs (hook handler, CLI, MCP
 * server, statusline), from this install, plus the `agenthub` launcher.
 */
async function publishApp(root = path.join(__dirname, "..", "..")) {
  for (const dir of APP_DIRS) {
    const src = path.join(root, dir);
    if (!fs.existsSync(src)) continue;
    const dest = path.join(appRoot(), dir);
    await fs.promises.mkdir(dest, { recursive: true });
    await fs.promises.cp(src, dest, { recursive: true, force: true });
    await chmodReadable(dest);
  }
  // The CLI reads its version from here.
  if (fs.existsSync(path.join(root, "package.json"))) {
    await fs.promises.copyFile(
      path.join(root, "package.json"),
      path.join(appRoot(), "package.json")
    );
    await fs.promises.chmod(path.join(appRoot(), "package.json"), 0o644);
  }
  const launcher = path.join(toolsRoot(), "bin", "agenthub");
  const body =
    "#!/bin/sh\n# AgentHub CLI for members' panes (published by the dashboard).\n" +
    `exec ${path.join(toolsRoot(), "bin", "node")} ${path.join(appRoot(), "bin", "agenthub.js")} "$@"\n`;
  fs.mkdirSync(path.dirname(launcher), { recursive: true });
  fs.writeFileSync(`${launcher}.tmp`, body, { mode: 0o755 });
  fs.renameSync(`${launcher}.tmp`, launcher);
}

module.exports = { sharedPath, planFor, publish, publishAll, publishApp, toolsRoot };