import { homedir } from "node:os";
import { join } from "node:path";

/**
 * Expand a leading `~` (or `~/…`, `~\…`) in a user-supplied path to the
 * current user's home directory. Spawned processes don't get shell
 * expansion, so env vars like `CODEX_HOME=~/.codex-work` would be passed
 * verbatim and treated as relative paths by the receiver.
 *
 * Matches the behavior of the other `expandHomePath` helpers in the
 * workspace layers and CLI bootstrap: `~` alone and both `~/` and `~\`
 * separators are handled. Returns the input unchanged if it doesn't
 * start with `~` or is empty. Does not handle `~user` (other-user)
 * expansion.
 */
export function expandHomePath(value: string): string {
  if (!value) return value;
  if (value === "~") return homedir();
  if (value.startsWith("~/") || value.startsWith("~\\")) {
    return join(homedir(), value.slice(2));
  }
  return value;
}