/**
 * @file tmux.js
 * @description Thin wrapper around the `tmux` CLI for the terminal-run
 * feature. Every dashboard-managed session is named `ccam-lane-<id>` (see
 * `pty-run.js`) so a real terminal can attach to the exact same session with
 * `tmux attach -t ccam-lane-<id>` (or `ccam lanes shell`). Never builds a
 * shell string — every call is `execFileSync("tmux", [...argv])` with an
 * explicit argument array (matches this repo's rule for git in worktree.js).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

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

// Test seam: swap the exec implementation so unit tests never invoke a real
// tmux binary. Mirrors run-spawner.js's __injectChildForTest/__reset style.
let execImpl = (args) => execFileSync("tmux", args, { encoding: "utf8" });

function __setExecImpl(fn) {
  execImpl = fn;
}
function __reset() {
  execImpl = (args) => execFileSync("tmux", args, { encoding: "utf8" });
}

function hasSession(name) {
  try {
    execImpl(["has-session", "-t", name]);
    return true;
  } catch {
    return false;
  }
}

/**
 * Create a detached tmux session running `argv` as the pane's command. Throws
 * if tmux itself fails to start (caller decides how to surface that).
 */
function newSession({ name, cwd, argv }) {
  execImpl(["new-session", "-d", "-s", name, "-c", cwd, "--", ...argv]);
}

/** Idempotent — a session that's already gone is not an error. */
function killSession(name) {
  try {
    execImpl(["kill-session", "-t", name]);
  } catch {
    /* already gone */
  }
}

/** Session names starting with `prefix`. Empty array if tmux has no server running at all. */
function listSessions(prefix) {
  let out;
  try {
    out = execImpl(["list-sessions", "-F", "#{session_name}"]);
  } catch {
    return [];
  }
  return out
    .split("\n")
    .map((s) => s.trim())
    .filter((s) => s && s.startsWith(prefix));
}

function isTmuxAvailable() {
  try {
    execImpl(["-V"]);
    return true;
  } catch {
    return false;
  }
}

module.exports = {
  hasSession,
  newSession,
  killSession,
  listSessions,
  isTmuxAvailable,
  __setExecImpl,
  __reset,
};
