/**
 * @file Where a setting saved from the dashboard (CLAUDE_HOME, CODEX_HOME, the
 * pinned DASHBOARD_DATA_DIR) persists, and the startup env load order.
 *
 * The file is `$XDG_CONFIG_HOME/agenthub/settings.env` (default
 * `~/.config/agenthub/`, or `AGENTHUB_SETTINGS_FILE`) — outside the repo,
 * because a plugin install runs from the plugin cache Claude Code replaces on
 * every update, and outside CLAUDE_HOME, because the data dir is derived from
 * CLAUDE_HOME and the setting that moves it cannot live under it.
 *
 * Load order: the real environment wins, then a checkout's own `<repo>/.env`
 * (per checkout, so more specific than a per-user file: a dev checkout whose
 * `.env` names its own DASHBOARD_DATA_DIR never opens the live database), then
 * this file; a key is only ever set while still unset, and a key the real
 * environment or `.env` set is `env_owned` — a value saved from the dashboard
 * would be overridden again at the next start, and the UI says so. The keys
 * that came from a file are listed in `AGENTHUB_FILE_KEYS`, so a server that
 * inherits this process's env (a self-restart spawns its successor with it)
 * does not mistake them for the real environment's and re-reads them. Deliberately dependency-free —
 * `server/index.js` runs it before anything else is required.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

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

/** Keys the real environment supplied at startup; filled by `loadEnvFiles`. */
const envOwned = new Set();

function settingsFilePath(env = process.env) {
  if (env.AGENTHUB_SETTINGS_FILE) return env.AGENTHUB_SETTINGS_FILE;
  const base = env.XDG_CONFIG_HOME || path.join(os.homedir(), ".config");
  return path.join(base, "agenthub", "settings.env");
}

function expandHome(value) {
  return value.replace(/^~(?=\/|$)/, os.homedir());
}

function parseEnv(text) {
  const out = [];
  for (const line of text.split("\n")) {
    const trimmed = line.trim();
    if (!trimmed || trimmed.startsWith("#")) continue;
    const eq = trimmed.indexOf("=");
    if (eq === -1) continue;
    const key = trimmed.slice(0, eq).trim();
    let val = trimmed.slice(eq + 1).trim();
    if ((val.startsWith('"') && val.endsWith('"')) || (val.startsWith("'") && val.endsWith("'"))) {
      val = val.slice(1, -1);
    }
    out.push([key, val]);
  }
  return out;
}

/**
 * Fill `env` from `owned` then `files`, in order, never overwriting a key
 * already set. A key from an `owned` file (the checkout's `.env`) counts as
 * the environment's, like one the real environment held. `files` defaults to
 * the settings file, located AFTER the owned files load, so an
 * `AGENTHUB_SETTINGS_FILE` set in `.env` is the file read and written.
 * @returns {Set<string>} the owned keys (inherited file-loaded keys, named in
 *   `AGENTHUB_FILE_KEYS`, excluded).
 */
function loadEnvFiles({ env = process.env, owned = [], files } = {}) {
  for (const k of (env.AGENTHUB_FILE_KEYS || "").split(",")) if (k) delete env[k];
  delete env.AGENTHUB_FILE_KEYS;
  const before = new Set(Object.keys(env).filter((k) => env[k]));
  const loaded = new Set();
  const load = (file, into) => {
    let text;
    try {
      text = fs.readFileSync(file, "utf8");
    } catch {
      return;
    }
    for (const [key, val] of parseEnv(text)) {
      if (!env[key]) {
        env[key] = expandHome(val);
        into.add(key);
      }
    }
  };
  for (const file of owned) load(file, before);
  for (const file of files ?? [settingsFilePath(env)]) load(file, loaded);
  if (loaded.size) env.AGENTHUB_FILE_KEYS = [...loaded].join(",");
  if (env === process.env) for (const k of before) envOwned.add(k);
  return before;
}

/**
 * Persist a setting and apply it to this process. A key the real environment
 * does not own joins `AGENTHUB_FILE_KEYS`, like one loaded from the file.
 */
function applySetting(key, value) {
  writeSetting(key, value);
  process.env[key] = value;
  if (envOwned.has(key)) return;
  const keys = new Set((process.env.AGENTHUB_FILE_KEYS || "").split(",").filter(Boolean));
  keys.add(key);
  process.env.AGENTHUB_FILE_KEYS = [...keys].join(",");
}

/**
 * Set or replace one `KEY=value` line — every earlier line for that key,
 * `KEY = value` included, is dropped, or the first one would still win at the
 * next load. Atomic, dir 0700, file 0600, through a symlink to its target.
 */
// ponytail: read-modify-write without a lock — two servers saving at the same
// instant can drop one key; add a lock file if that ever happens for real.
function writeSetting(key, value, file = settingsFilePath()) {
  if (/[\r\n]/.test(value)) throw new Error(`${key} may not contain a line break`);
  fs.mkdirSync(path.dirname(file), { recursive: true, mode: 0o700 });
  let lines = [];
  try {
    lines = fs
      .readFileSync(file, "utf8")
      .split("\n")
      .filter((l) => l.trim() !== "");
  } catch {
    /* first write */
  }
  const isKey = (l) => {
    const t = l.trim();
    return !t.startsWith("#") && t.includes("=") && t.slice(0, t.indexOf("=")).trim() === key;
  };
  let done = false;
  lines = lines.flatMap((l) =>
    !isKey(l) ? [l] : done ? [] : ((done = true), [`${key}=${value}`])
  );
  if (!done) lines.push(`${key}=${value}`);
  let target = file;
  try {
    target = fs.realpathSync(file);
  } catch {
    /* first write */
  }
  const tmp = `${target}.${process.pid}.tmp`;
  fs.writeFileSync(tmp, `${lines.join("\n")}\n`, { mode: 0o600 });
  fs.renameSync(tmp, target);
}

/**
 * The one check an editable home directory passes. A directory that IS, or
 * CONTAINS, the OS user's home — `/`, `/home`, `~` itself, or a symlink, a
 * bind mount or (on a case-insensitive disk) a differently-cased path to any of
 * them — is refused (`EBADHOME`): everything under such a home becomes
 * readable, and partly writable, through its config panel. Compared by device
 * and inode against the home and each of its ancestors.
 * @returns {string} the normalized absolute path (not symlink-resolved).
 */
function validateHomeDir(label, input) {
  const invalid = (message) => Object.assign(new Error(message), { code: "INVALID_PATH" });
  const trimmed = String(input).trim();
  if (/[\x00-\x1f]/.test(trimmed)) throw invalid(`${label} may not contain control characters`);
  const expanded = expandHome(trimmed);
  if (!path.isAbsolute(expanded)) throw invalid(`${label} must be an absolute path`);
  const resolved = path.resolve(expanded);
  const tooBroad = () =>
    Object.assign(new Error(`Too broad for ${label}: ${resolved} contains your home directory`), {
      code: "EBADHOME",
    });
  const contains = (dir, home) =>
    home === dir || home.startsWith(dir.endsWith(path.sep) ? dir : dir + path.sep);
  if (contains(resolved, path.resolve(os.homedir()))) throw tooBroad();
  if (!fs.existsSync(resolved)) throw invalid(`Directory does not exist: ${resolved}`);
  if (!fs.statSync(resolved).isDirectory()) throw invalid(`Not a directory: ${resolved}`);
  let realHome;
  try {
    realHome = fs.realpathSync(os.homedir());
  } catch {
    realHome = path.resolve(os.homedir());
  }
  const idOf = (p) => {
    try {
      const st = fs.statSync(p);
      return `${st.dev}:${st.ino}`;
    } catch {
      return null;
    }
  };
  const target = idOf(resolved);
  for (let dir = realHome; ; dir = path.dirname(dir)) {
    if (idOf(dir) === target) throw tooBroad();
    if (dir === path.dirname(dir)) break;
  }
  return resolved;
}

module.exports = {
  settingsFilePath,
  loadEnvFiles,
  writeSetting,
  applySetting,
  validateHomeDir,
  envOwned,
};