"""
Tests for sim/queue.py — queue position model.
"""
from sim.queue import QueueModel, QueuePosition, fill_probability


class TestQueueModel:
    def test_place_bid(self):
        qm = QueueModel()
        oid = qm.place_order("bid", 50000.0, 0.01, sim_time=100.0)
        tob = qm.top_of_book()
        assert tob["best_bid"] == 50000.0
        assert tob["best_ask"] == 0  # no asks placed

    def test_queue_position_is_front(self):
        qm = QueueModel()
        oid = qm.place_order("ask", 50002.0, 0.01, sim_time=100.0)
        qp = qm.queue_position("ask", 50002.0, oid)
        assert qp is not None
        assert qp.position == 0
        assert qp.is_front

    def test_queue_position_behind_others(self):
        qm = QueueModel()
        qm.place_order("bid", 50000.0, 0.01, sim_time=99.0)
        oid2 = qm.place_order("bid", 50000.0, 0.01, sim_time=100.0)
        qp = qm.queue_position("bid", 50000.0, oid2)
        assert qp is not None
        assert qp.position == 1  # behind first order

    def test_cancel_order(self):
        qm = QueueModel()
        oid = qm.place_order("bid", 50000.0, 0.01, sim_time=100.0)
        filled = qm.cancel_order(oid, sim_time=105.0)
        assert filled == 0.0
        assert qm.order_status(oid)["status"] == "cancelled"
        assert len(qm.active_orders()) == 0

    def test_trade_eats_ask(self):
        qm = QueueModel()
        oid = qm.place_order("ask", 50002.0, 0.01, sim_time=100.0)
        fills = qm.process_trade("buy", 50002.0, 0.01, sim_time=101.0)
        assert len(fills) == 1
        assert fills[0]["size"] == 0.01

    def test_trade_eats_bid(self):
        qm = QueueModel()
        oid = qm.place_order("bid", 50000.0, 0.02, sim_time=100.0)
        fills = qm.process_trade("sell", 50000.0, 0.01, sim_time=101.0)
        assert fills[0]["size"] == 0.01
        assert qm.order_status(oid)["filled"] == 0.01

    def test_partial_fill_remaining(self):
        qm = QueueModel()
        oid = qm.place_order("bid", 50000.0, 0.03, sim_time=100.0)
        qm.process_trade("sell", 50000.0, 0.01, sim_time=101.0)
        status = qm.order_status(oid)
        assert status["filled"] == 0.01
        assert status["status"] == "active"

    def test_fully_filled_status(self):
        qm = QueueModel()
        oid = qm.place_order("bid", 50000.0, 0.01, sim_time=100.0)
        qm.process_trade("sell", 50000.0, 0.01, sim_time=101.0)
        assert qm.order_status(oid)["status"] == "filled"

    def test_trade_crosses_spread(self):
        qm = QueueModel()
        qm.place_order("ask", 50002.0, 0.01, sim_time=100.0)
        qm.place_order("ask", 50003.0, 0.01, sim_time=100.0)
        fills = qm.process_trade("buy", 50003.0, 0.02, sim_time=101.0)
        assert len(fills) == 2

    def test_top_of_book(self):
        qm = QueueModel()
        qm.place_order("bid", 50000.0, 0.01, sim_time=100.0)
        qm.place_order("ask", 50002.0, 0.02, sim_time=100.0)
        tob = qm.top_of_book()
        assert tob["best_bid"] == 50000.0
        assert tob["best_ask"] == 50002.0
        assert tob["spread"] == 2.0


class TestFillProbability:
    def test_front_of_queue(self):
        result = fill_probability(queue_pos=0, total_queue_depth=1.0, order_size=0.01, arrival_rate=1.0, time_horizon=1.0)
        assert result["fill_probability"] > 0.5

    def test_deep_in_queue(self):
        result = fill_probability(queue_pos=5, total_queue_depth=10.0, order_size=0.01, arrival_rate=1.0, time_horizon=1.0)
        assert result["fill_probability"] < 0.5

    def test_no_arrivals_zero_prob(self):
        result = fill_probability(queue_pos=0, total_queue_depth=1.0, order_size=0.01, arrival_rate=0.0, time_horizon=1.0)
        assert result["fill_probability"] == 0.0