"""``--query-file``: the single-query transport that never passes through a shell.

Split out of ``hermes_cli/main.py``.
"""

import sys


def _read_query_file(args) -> None:
    """--query-file: read the single query from a file (or stdin via '-').

    Callers never have to shell-quote message bodies — this is the transport
    the Bot Mode DM protocol uses; interpolating arbitrary text into a
    double-quoted shell argument truncates on quotes and executes $(...)
    (see tools/bot_mode_probe.py).
    """
    _qfile = getattr(args, "query_file", None)
    if not _qfile:
        return
    if args.query:
        # argparse's mutually-exclusive group catches the normal CLI path;
        # this guards programmatic callers that fill the namespace directly.
        print("Error: -q/--query and --query-file are mutually exclusive", file=sys.stderr)
        sys.exit(2)
    try:
        if _qfile == "-":
            args.query = sys.stdin.read()
        else:
            with open(_qfile, "r", encoding="utf-8-sig", errors="replace") as _fh:
                args.query = _fh.read()
    except OSError as _e:
        print(f"Error: cannot read --query-file {_qfile}: {_e}", file=sys.stderr)
        sys.exit(2)
    if not (args.query or "").strip():
        print(f"Error: --query-file {_qfile} is empty", file=sys.stderr)
        sys.exit(2)