import { describe, expect, it } from 'vitest';
import {
    compareMetricValues,
    metricDuration,
    metricNumber,
    metricPercent,
    metricPeriodLabels
} from '../../src/lib/ui/metrics.js';

describe('metric presentation', () => {
    it('distinguishes unavailable evidence, zero, and tiny nonzero values', () => {
        expect(metricPercent(0, 0)).toBe('—');
        expect(metricPercent(0, 1)).toBe('0.0%');
        expect(metricPercent(0.0001, 1)).toBe('<0.1%');
        expect(metricDuration(0)).toBe('0 h');
        expect(metricDuration(0.1 / 3600)).toBe('<1 s');
        expect(metricDuration(45 / 3600)).toBe('45 s');
        expect(metricDuration(90 / 3600)).toBe('1.5 min');
        expect(metricNumber(0.0125)).toBe('<0.1');
    });

    it('sorts numerically while putting unavailable observations last in both directions', () => {
        const values = [2, null, 100, 0, 10];
        expect([...values].sort((a, b) => compareMetricValues(a, b, 'desc'))).toEqual([
            100,
            10,
            2,
            0,
            null
        ]);
        expect([...values].sort((a, b) => compareMetricValues(a, b, 'asc'))).toEqual([
            0,
            2,
            10,
            100,
            null
        ]);
    });

    it('labels daily buckets by their actual starting weekday in the report timezone', () => {
        const points = Array.from({ length: 8 }, (_, day) => ({
            startAt: Date.parse('2026-10-01T00:00:00Z') + day * 86_400_000
        }));
        expect(metricPeriodLabels(points, 7, 'America/New_York').map((item) => item.label)).toEqual(
            ['Wed', 'Thu', 'Fri', 'Sat', 'Sun', 'Mon', 'Tue', 'Wed']
        );
        expect(metricPeriodLabels(points, 7, 'UTC')[0].label).toBe('Thu');
        expect(metricPeriodLabels(points, 7, 'UTC')[0].position).toBe(6.25);
        expect(metricPeriodLabels([], 7, 'UTC')).toEqual([]);
    });

    it('keeps hourly and long-range labels sparse without relabelling UTC buckets as local days', () => {
        const points = Array.from({ length: 31 }, (_, day) => ({
            startAt: Date.parse('2026-10-01T00:00:00Z') + day * 86_400_000
        }));
        const labels = metricPeriodLabels(points, 30, 'UTC');
        expect(labels.length).toBeLessThanOrEqual(6);
        expect(labels[0]).toMatchObject({ label: 'Thu', date: '1' });
        const hourly = metricPeriodLabels(
            Array.from({ length: 25 }, (_, hour) => ({
                startAt: Date.parse('2026-11-01T04:00:00Z') + hour * 3_600_000
            })),
            1,
            'America/New_York'
        );
        expect(hourly[0].label).toBe('12 AM');
        expect(hourly[1].label).toBe('4 AM');
        expect(hourly).toHaveLength(5);
    });
});