"""Tests for the unit conversion module."""

import numpy as np
import pytest

from disk_checker.core.converter import to_unit, UNIT_FACTORS, UNIT_LABELS


class TestToUnit:
    """Tests for to_unit function."""

    def test_nanoseconds_to_microseconds(self):
        """Test conversion from ns to us."""
        values = np.array([1000, 2000, 3000])
        result = to_unit(values, "us")
        expected = np.array([1.0, 2.0, 3.0])
        np.testing.assert_array_equal(result, expected)

    def test_nanoseconds_to_milliseconds(self):
        """Test conversion from ns to ms."""
        values = np.array([1000000, 2000000])
        result = to_unit(values, "ms")
        expected = np.array([1.0, 2.0])
        np.testing.assert_array_equal(result, expected)

    def test_nanoseconds_to_seconds(self):
        """Test conversion from ns to s."""
        values = np.array([1000000000, 2000000000])
        result = to_unit(values, "s")
        expected = np.array([1.0, 2.0])
        np.testing.assert_array_equal(result, expected)

    def test_same_unit_returns_same(self):
        """Test conversion to same unit."""
        values = np.array([100, 200, 300])
        result = to_unit(values, "ns")
        np.testing.assert_array_equal(result, values)

    def test_empty_array(self):
        """Test conversion with empty array."""
        values = np.array([])
        result = to_unit(values, "us")
        assert len(result) == 0

    def test_single_value(self):
        """Test conversion with single value."""
        result = to_unit(1000, "us")
        assert result == 1.0


class TestConstants:
    """Tests for module constants."""

    def test_unit_factors(self):
        """Test UNIT_FACTORS contains all expected units."""
        assert set(UNIT_FACTORS.keys()) == {"ns", "us", "ms", "s"}
        assert UNIT_FACTORS["ns"] == 1.0
        assert UNIT_FACTORS["us"] == 1e3
        assert UNIT_FACTORS["ms"] == 1e6
        assert UNIT_FACTORS["s"] == 1e9

    def test_unit_labels(self):
        """Test UNIT_LABELS contains all expected units."""
        assert set(UNIT_LABELS.keys()) == {"ns", "us", "ms", "s"}
        assert UNIT_LABELS["ns"] == "ns"
        assert UNIT_LABELS["us"] == "µs"
        assert UNIT_LABELS["ms"] == "ms"
        assert UNIT_LABELS["s"] == "s"