"""Tests for helper functions."""

import pandas as pd
import pytest

from disk_checker.core.helpers import human_count, percentile_table


class TestHumanCount:
    """Tests for human_count function."""

    def test_small_number(self):
        """Test formatting of small numbers."""
        assert human_count(100) == "100"
        assert human_count(50) == "50"

    def test_thousands(self):
        """Test formatting of thousands."""
        assert human_count(1500) == "2k"
        assert human_count(2500) == "3k"
        assert human_count(1000) == "1k"
        assert human_count(999) == "999"

    def test_millions(self):
        """Test formatting of millions."""
        assert human_count(1500000) == "1.5M"
        assert human_count(2750000) == "2.8M"

    def test_billions(self):
        """Test formatting of billions."""
        assert human_count(1500000000) == "1.5G"
        assert human_count(2750000000) == "2.8G"

    def test_zero(self):
        """Test formatting of zero."""
        assert human_count(0) == "0"

    def test_position_argument_ignored(self):
        """Test that _pos argument is ignored."""
        assert human_count(1000, 0) == "1k"


class TestPercentileTable:
    """Tests for percentile_table function."""

    def test_basic_percentiles(self):
        """Test basic percentile table generation."""
        df = pd.DataFrame({
            "metric": ["read_clat"] * 3,
            "latency_ns": [1000, 2000, 3000],
            "count": [1, 2, 1],
        })
        result = percentile_table(df, "read_clat", "us", [50, 90])
        assert "Metric: read_clat" in result
        assert "total I/Os: 4" in result
        assert "percentile" in result
        assert "latency" in result

    def test_missing_metric(self):
        """Test percentile table with missing metric."""
        df = pd.DataFrame({
            "metric": ["read_clat"],
            "latency_ns": [1000],
            "count": [1],
        })
        result = percentile_table(df, "write_clat", "us", [50])
        assert "(no data for metric write_clat)" in result

    def test_unit_display(self):
        """Test that correct unit is displayed."""
        df = pd.DataFrame({
            "metric": ["read_clat"],
            "latency_ns": [1000000],  # 1ms in ns
            "count": [1],
        })
        result = percentile_table(df, "read_clat", "ms", [50])
        assert "ms" in result