import socket

import pytest

from packet_codec import MAX_MESSAGE_BYTES, encode_packet
from tcp_transport import LineMessageBuffer, TcpFramingError, frame_message, send_message


def test_tcp_framing_adds_delimiter_only_at_transport_boundary():
    encoded = encode_packet({"type": "playerState", "characterName": "Nomad"})
    assert not encoded.payload.endswith(b"\n")
    framed = frame_message(encoded.payload)
    assert framed == encoded.payload + b"\n"


def test_line_buffer_preserves_fragmented_and_coalesced_messages():
    buffer = LineMessageBuffer()
    assert buffer.feed(b'{"type":"first"') == []
    messages = buffer.feed(b'}\n{"type":"second"}\n{"type":"third"')
    assert messages == [b'{"type":"first"}', b'{"type":"second"}']
    assert buffer.buffered_bytes > 0
    assert buffer.feed(b'}\r\n') == [b'{"type":"third"}']
    assert buffer.buffered_bytes == 0


def test_line_buffer_rejects_oversize_unterminated_and_terminated_messages():
    with pytest.raises(TcpFramingError):
        LineMessageBuffer().feed(b"x" * (MAX_MESSAGE_BYTES + 1))
    with pytest.raises(TcpFramingError):
        LineMessageBuffer().feed((b"x" * (MAX_MESSAGE_BYTES + 1)) + b"\n")


def test_frame_rejects_raw_delimiters_and_oversize_payloads():
    with pytest.raises(TcpFramingError):
        frame_message(b"bad\nmessage")
    with pytest.raises(TcpFramingError):
        frame_message(b"bad\rmessage")
    with pytest.raises(TcpFramingError):
        frame_message(b"x" * (MAX_MESSAGE_BYTES + 1))


def test_send_message_preserves_existing_tcp_wire_format():
    reader, writer = socket.socketpair()
    try:
        payload = encode_packet({"type": "keepAlive"}).payload
        send_message(writer, payload)
        assert reader.recv(4096) == payload + b"\n"
    finally:
        reader.close()
        writer.close()