// Pure decision logic for the daemon version-check flow. Kept in its own
// module so it can be unit-tested without mocking Electron, execFile, or
// the HTTP health probe.

export interface VersionCheckHealth {
  status?: string;
  cli_version?: string;
  active_task_count?: number;
}

export type VersionAction = "restart" | "defer" | "ok" | "not_running";

/**
 * Decides what the daemon-manager should do given the currently-resolved
 * bundled CLI version and the latest /health payload.
 *
 *   not_running: no daemon is up, nothing to do
 *   ok:          versions match, OR either side is unknown (fail safe)
 *   defer:       versions differ but the daemon is busy — wait for drain
 *   restart:     versions differ and the daemon is idle — safe to restart
 *
 * Pure function: no I/O, no side effects, no module state.
 */
export function decideVersionAction(
  bundled: string | null,
  running: VersionCheckHealth | null,
): VersionAction {
  if (!running || running.status !== "running") return "not_running";

  const runningVersion = running.cli_version;
  if (!bundled || !runningVersion) return "ok";
  if (runningVersion === bundled) return "ok";

  const activeTasks = running.active_task_count ?? 0;
  if (activeTasks > 0) return "defer";
  return "restart";
}