"""Regressions for three bugs that only a real aircraft exposed.

Each of these passed every simulator test while being wrong against the drone,
which is why they have their own file: the simulator was written from the same
assumptions as the code, so it agreed with it.
"""

from mcbebop.arsdk.types import BufferId, DataType, Frame
from mcbebop.protocol import codec, xml_index
from mcbebop.protocol.types import Direction


def test_argument_less_events_are_recorded():
    """Eight events carry no arguments; their arrival IS the message.

    AllStatesChanged and AllSettingsChanged are how the drone says a state dump
    is finished. Keying only by argument meant they decoded to an empty dict and
    disappeared, so nothing could wait for the end of a burst.
    """
    for name in ("common.CommonState.AllStatesChanged", "common.SettingsState.AllSettingsChanged"):
        spec = xml_index.get(name)
        assert spec.args == (), "this test is about events that have no arguments"
        _, values = codec.decode_event(codec.encode_command(spec, {}))
        assert values == {spec.name: True}

    bare = [c for c in xml_index.all_commands() if c.direction is Direction.FROM_DRONE and not c.args]
    assert len(bare) == 8


def test_every_bare_event_decodes_to_something():
    for spec in xml_index.all_commands():
        if spec.direction is Direction.FROM_DRONE and not spec.args:
            _, values = codec.decode_event(codec.encode_command(spec, {}))
            assert values, f"{spec.full_name} decoded to nothing"


def test_acknowledgement_is_decided_by_data_type_not_buffer():
    """A live Bebop 2 sends DATA_WITH_ACK on buffer 126, not 127.

    The naming says 127 is the drone's acknowledged buffer, and requiring both
    the type and the buffer to agree meant no frame was ever acknowledged. The
    drone then resent its state rather than continuing, and most of it never
    arrived: 35 keys instead of 192.
    """
    import inspect

    from mcbebop.arsdk import connection as conn_mod

    source = inspect.getsource(conn_mod.Connection._handle)
    ack_line = next(line for line in source.splitlines() if "DataType.DATA_WITH_ACK" in line)
    assert "buffer_id" not in ack_line, "the ack decision must not depend on which buffer it arrived on"

    # Both buffers must round-trip to a valid ack target.
    for buffer_id in (BufferId.D2C_NON_ACK, BufferId.D2C_ACK):
        frame = Frame(DataType.DATA_WITH_ACK, buffer_id, 9, b"\x00\x05\x00\x00")
        assert Frame.decode_all(frame.encode())[0].buffer_id == buffer_id
        assert 0 <= BufferId.ack_for(buffer_id) <= 255