/**
 * @file desktop-env.js
 * @description The graphical session's own environment variables, for panes
 * the dashboard spawns. The server usually runs as a systemd *user* service,
 * which has no `DISPLAY`/`WAYLAND_DISPLAY` of its own — so neither does any
 * tmux pane it starts, and a `claude` running in one cannot reach the X or
 * Wayland clipboard: pasting an image answers "no image found in clipboard"
 * while the same CLI in a normal terminal pastes fine. `systemctl --user
 * show-environment` is the canonical local source for those values (the
 * desktop session imports them there at login), with this process's own
 * environment preferred when it already has them — a checkout started from a
 * terminal inherits the real ones.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const { execFileSync } = require("node:child_process");

/** The only names forwarded. A pane gets a clipboard, not the whole session. */
const FORWARDED = ["DISPLAY", "WAYLAND_DISPLAY", "XAUTHORITY", "XDG_RUNTIME_DIR"];

let execImpl = (args) =>
  execFileSync("systemctl", args, {
    encoding: "utf8",
    timeout: 2000,
    stdio: ["ignore", "pipe", "ignore"],
  });

/** Test seam — same pattern as tmux.js. */
function __setExecImpl(fn) {
  execImpl = fn;
}

/** `KEY=value` lines from `systemctl --user show-environment`, as a map. */
function systemdUserEnv() {
  let out;
  try {
    out = execImpl(["--user", "show-environment"]);
  } catch {
    // No systemd user manager (macOS, a container, a plain login shell) — the
    // process environment below is the only source then.
    return {};
  }
  const env = {};
  for (const line of String(out).split("\n")) {
    const eq = line.indexOf("=");
    if (eq > 0) env[line.slice(0, eq)] = line.slice(eq + 1);
  }
  return env;
}

/**
 * The forwarded variables that actually have a usable value right now.
 * A value carrying a newline is dropped rather than passed on: these end up in
 * a `tmux -e NAME=value` argv, and a line break there is not a value tmux can
 * represent.
 */
function desktopEnv() {
  const fromSystemd = systemdUserEnv();
  const out = {};
  for (const name of FORWARDED) {
    const value = process.env[name] || fromSystemd[name];
    if (typeof value === "string" && value && !/[\r\n\0]/.test(value)) out[name] = value;
  }
  return out;
}

module.exports = { desktopEnv, FORWARDED, __setExecImpl };