/**
 * @file Centralized Codex home directory path management. Resolves the Codex
 * home directory, project-level Codex surfaces, and project roots. Supports a
 * custom root via the CODEX_HOME environment variable so the dashboard can
 * track non-standard Codex installations, and changes it at runtime
 * (`setCodexHome`, persisted to the settings file).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

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

/**
 * The Codex home directory. Resolves to $CODEX_HOME if set, else
 * ~/.codex. Always reads process.env at call time so tests can inject.
 *
 * @returns {string} Absolute path to the Codex home directory.
 */
function getCodexHome() {
  return process.env.CODEX_HOME || path.join(os.homedir(), ".codex");
}

/**
 * CODEX_HOME as given and, when a symlink makes it differ, as resolved — so a
 * path Codex reports (it may canonicalize) matches either.
 *
 * @returns {string[]} one or two absolute paths.
 */
function codexHomes() {
  const raw = path.resolve(getCodexHome());
  try {
    const real = fs.realpathSync(raw);
    return real === raw ? [raw] : [raw, real];
  } catch {
    return [raw];
  }
}

/**
 * The directory where Codex stores per-project surfaces (rollout journals,
 * SQLite mirrors, etc.) for a project at the given working directory.
 *
 * @param {string} cwd Absolute path to a project root.
 * @returns {string} Absolute path to <cwd>/.codex.
 */
function getProjectCodexDir(cwd) {
  return path.join(cwd, ".codex");
}

/**
 * The project root. For now, this is just an identity function — cwd is
 * the project root. Exists as a contract for consistency with claude-home.js
 * and to anchor the path-resolution hierarchy.
 *
 * @param {string} cwd Absolute path to a project root (where AGENTS.md lives).
 * @returns {string} The same cwd.
 */
function getProjectRoot(cwd) {
  return cwd;
}

/**
 * Update CODEX_HOME at runtime: `process.env` changes at once and the value
 * persists to the settings file (see `settings-env.js`). The path passes the
 * shared guard that refuses anything that is or contains the user's home
 * (`EBADHOME`). A codex pane gets this value through tmux `-e` at its next
 * start; one already running keeps the home it started with.
 *
 * @param {string} newPath absolute path, `~/` expanded.
 * @returns {string} the resolved absolute path.
 */
function setCodexHome(newPath) {
  const { validateHomeDir, applySetting } = require("./settings-env");
  const resolved = validateHomeDir("CODEX_HOME", newPath);
  applySetting("CODEX_HOME", resolved);
  return resolved;
}

module.exports = {
  codexHomes,
  getCodexHome,
  setCodexHome,
  getProjectCodexDir,
  getProjectRoot,
};