import json

import pytest

from packet_codec import MAX_MESSAGE_BYTES, PacketCodecError, decode_packet, encode_packet
from transport_policy import Delivery


def test_encoded_packet_has_no_tcp_line_framing():
    encoded = encode_packet({"type": "transform", "x": 1.0})
    assert encoded.packet_type == "transform"
    assert encoded.delivery is Delivery.UNRELIABLE_SEQUENCED
    assert encoded.payload == b'{"type":"transform","x":1.0}'
    assert not encoded.payload.endswith(b"\n")


def test_reliable_packet_carries_delivery_policy_separately_from_json():
    encoded = encode_packet({"type": "playerState", "characterName": "Nomad"})
    assert encoded.delivery is Delivery.RELIABLE_ORDERED
    assert json.loads(encoded.payload) == {"type": "playerState", "characterName": "Nomad"}


def test_decode_packet_accepts_one_complete_message_without_delimiter():
    assert decode_packet(b'{"type":"sessionReady","playerId":7}') == {
        "type": "sessionReady",
        "playerId": 7,
    }


def test_codec_rejects_nonfinite_invalid_utf8_nonobject_and_missing_type():
    with pytest.raises(PacketCodecError):
        encode_packet({"type": "transform", "x": float("nan")})
    with pytest.raises(PacketCodecError):
        decode_packet(b'{"type":"transform","x":NaN}')
    with pytest.raises(PacketCodecError):
        decode_packet(b"\xff")
    with pytest.raises(PacketCodecError):
        decode_packet(b"[]")
    with pytest.raises(PacketCodecError):
        decode_packet(b"{}")


def test_codec_enforces_64k_message_limit_before_transport():
    payload = "x" * MAX_MESSAGE_BYTES
    with pytest.raises(PacketCodecError):
        encode_packet({"type": "playerState", "characterName": payload})
    with pytest.raises(PacketCodecError):
        decode_packet(b"x" * (MAX_MESSAGE_BYTES + 1))