from __future__ import annotations

import json
import socket
import time

import pytest

from server_core import PROTOCOL_VERSION, FalloutTogetherServer, states_share_interest


def recv_packet(sock: socket.socket, timeout: float = 2.0) -> dict:
    sock.settimeout(timeout)
    data = b""
    while b"\n" not in data:
        data += sock.recv(4096)
    line, _ = data.split(b"\n", 1)
    return json.loads(line.decode("utf-8"))


def send_packet(sock: socket.socket, packet: dict) -> None:
    sock.sendall(json.dumps(packet, separators=(",", ":")).encode() + b"\n")


def connect(server: FalloutTogetherServer) -> tuple[socket.socket, dict]:
    sock = socket.create_connection(("127.0.0.1", server.port), timeout=2.0)
    return sock, recv_packet(sock)


def hello(sock: socket.socket) -> dict:
    send_packet(sock, {"type": "hello", "protocolVersion": PROTOCOL_VERSION})
    return recv_packet(sock)


def transform(cell: str, x: float, y: float, world: str = "0000003C") -> dict:
    return {
        "type": "transform",
        "x": x,
        "y": y,
        "z": 0.0,
        "angleZ": 0.0,
        "cellId": cell,
        "worldspaceId": world,
    }


def start_server(max_players: int = 16) -> FalloutTogetherServer:
    server = FalloutTogetherServer(host="127.0.0.1", port=0, max_players=max_players)
    server.start()
    deadline = time.time() + 2
    while not server.is_running() and time.time() < deadline:
        time.sleep(0.01)
    return server


def test_interest_exact_cell_and_exterior_radius():
    a = transform("00000001", 0, 0)
    same = transform("00000001", 50000, 50000)
    near = transform("00000002", 1000, 1000)
    far = transform("00000002", 20000, 20000)
    other_world = transform("00000002", 1000, 1000, world="0000003D")
    assert states_share_interest(a, same)
    assert states_share_interest(a, near)
    assert not states_share_interest(a, far)
    assert not states_share_interest(a, other_world)


def test_idle_transport_does_not_take_world_authority():
    server = start_server()
    idle, _ = connect(server)
    active, active_welcome = connect(server)
    ready = hello(active)
    assert ready["playerId"] == active_welcome["playerId"]
    stats = server.get_stats()
    assert stats["connectedClients"] == 1
    assert stats["pendingConnections"] == 1
    assert server._world_state_host_player_id == active_welcome["playerId"]
    idle.close()
    active.close()
    server.stop()


def test_max_players_applies_to_activated_sessions_not_probes():
    server = start_server(max_players=1)
    first, _ = connect(server)
    hello(first)
    second, _ = connect(server)
    send_packet(second, {"type": "hello", "protocolVersion": PROTOCOL_VERSION})
    ended = recv_packet(second)
    assert ended["type"] == "sessionEnded"
    assert ended["code"] == "server_full"
    first.close()
    second.close()
    server.stop()


def test_protocol_mismatch_is_rejected():
    server = start_server()
    sock, _ = connect(server)
    send_packet(sock, {"type": "hello", "protocolVersion": PROTOCOL_VERSION + 1})
    ended = recv_packet(sock)
    assert ended["type"] == "sessionEnded"
    assert ended["code"] == "protocol_mismatch"
    sock.close()
    server.stop()


def test_nan_transform_is_rejected_and_not_cached():
    server = start_server()
    sock, welcome = connect(server)
    hello(sock)
    sock.sendall(
        b'{"type":"transform","x":NaN,"y":0,"z":0,"angleZ":0,"cellId":"00000001"}\n'
    )
    time.sleep(0.05)
    client = server._find_client_by_player_id(welcome["playerId"])
    assert client is not None
    assert client.last_transform is None
    assert server.get_stats()["packetsRejected"] >= 1
    sock.close()
    server.stop()


def test_transform_interest_filters_distant_peer():
    server = start_server()
    a, _ = connect(server)
    hello(a)
    b, _ = connect(server)
    hello(b)
    send_packet(b, transform("00000020", 25000, 25000))
    time.sleep(0.05)
    send_packet(a, transform("00000010", 0, 0))
    b.settimeout(0.2)
    with pytest.raises(socket.timeout):
        b.recv(4096)
    assert server.get_stats()["transformPacketsInterestFiltered"] >= 1
    a.close()
    b.close()
    server.stop()


def test_oversized_unterminated_packet_closes_session():
    server = start_server()
    sock, _ = connect(server)
    sock.sendall(b"x" * (64 * 1024 + 1))
    ended = recv_packet(sock)
    assert ended["type"] == "sessionEnded"
    assert ended["code"] == "packet_too_large"
    sock.close()
    server.stop()