import pytest
import math
import numpy as np
from simulation_tool.core import simulate_scheduling
from simulation_tool.models import SimulationResults

@pytest.fixture
def basic_schedule_params():
    return {"threads": 4, "queue_type": "fifo", "affinity": False}

@pytest.fixture
def complex_schedule_params():
    return {"threads": 8, "queue_type": "priority", "affinity": True}

def test_simulate_scheduling_returns_expected_type(basic_schedule_params):
    result = simulate_scheduling(basic_schedule_params)
    assert isinstance(result, SimulationResults)
    assert isinstance(result.time_distributions, list)
    assert isinstance(result.outlier_occurrences, int)

def test_simulate_scheduling_time_distributions_are_valid(basic_schedule_params):
    result = simulate_scheduling(basic_schedule_params)
    assert all(isinstance(v, float) for v in result.time_distributions)
    assert all(v >= 0.0 for v in result.time_distributions)

def test_simulate_scheduling_outliers_count_coherence(basic_schedule_params):
    result = simulate_scheduling(basic_schedule_params)
    mean_val = np.mean(result.time_distributions)
    std_val = np.std(result.time_distributions)
    threshold = mean_val + 3 * std_val
    counted_outliers = sum(1 for v in result.time_distributions if v > threshold)
    assert abs(counted_outliers - result.outlier_occurrences) <= 2  # tolerate small randomness

def test_simulate_scheduling_with_complex_params(complex_schedule_params):
    result = simulate_scheduling(complex_schedule_params)
    assert isinstance(result.time_distributions, list)
    assert len(result.time_distributions) > 0
    assert result.outlier_occurrences >= 0

def test_to_json_roundtrip(basic_schedule_params):
    result = simulate_scheduling(basic_schedule_params)
    json_obj = result.to_json()
    assert set(json_obj.keys()) == {"time_distributions", "outlier_occurrences"}
    assert isinstance(json_obj["time_distributions"], list)
    assert isinstance(json_obj["outlier_occurrences"], int)

def test_invalid_input_raises_error():
    with pytest.raises((TypeError, ValueError)):
        simulate_scheduling(None)
    with pytest.raises((TypeError, ValueError)):
        simulate_scheduling({"threads": "NaN"})