// @ts-expect-error -- bun:test is a runtime built-in with no types installed
import { describe, expect, test } from 'bun:test';
import { getImageDiskUsageTotalSize } from '../src/lib/server/docker-disk-usage-core';

describe('getImageDiskUsageTotalSize', () => {
	test('uses Docker aggregate size instead of summing virtual image sizes', () => {
		const diskUsage = {
			LayersSize: 70_326_328_267,
			Images: [
				{ Size: 189_295_958_800 },
				{ Size: 82_498_083_216 }
			]
		};

		expect(getImageDiskUsageTotalSize(diskUsage)).toBe(70_326_328_267);
	});

	test('prefers the current ImageUsage.TotalSize response field', () => {
		expect(getImageDiskUsageTotalSize({
			ImageUsage: { TotalSize: 42 },
			LayersSize: 99
		})).toBe(42);
	});

	test('supports the legacy LayersSize response field', () => {
		expect(getImageDiskUsageTotalSize({ LayersSize: 42 })).toBe(42);
	});

	test('preserves zero as a valid aggregate size', () => {
		expect(getImageDiskUsageTotalSize({
			ImageUsage: { TotalSize: 0 },
			LayersSize: 99
		})).toBe(0);
		expect(getImageDiskUsageTotalSize({ LayersSize: 0 })).toBe(0);
	});

	test('falls back from an invalid current value to a valid legacy value', () => {
		expect(getImageDiskUsageTotalSize({
			ImageUsage: { TotalSize: Number.NaN },
			LayersSize: 42
		})).toBe(42);
	});

	test('returns null when no trustworthy aggregate is available', () => {
		expect(getImageDiskUsageTotalSize(undefined)).toBeNull();
		expect(getImageDiskUsageTotalSize({})).toBeNull();
		expect(getImageDiskUsageTotalSize({ LayersSize: -1 })).toBeNull();
		expect(getImageDiskUsageTotalSize({
			ImageUsage: { TotalSize: '42' },
			LayersSize: null
		})).toBeNull();
	});

	// Reproduces the reporter's case: many images sharing one large base layer, so
	// summing each image's virtual Size over-counts the shared data many times over.
	// The aggregate (what `docker system df` shows as the Images SIZE) is the truth.
	test('shared layers: aggregate is used, not the inflated per-image sum', () => {
		const BASE = 9_000_000_000; // a ~9 GB base layer shared by every image
		const images = Array.from({ length: 8 }, (_, i) => ({ Size: BASE + i * 100_000_000 }));
		const summed = images.reduce((s, img) => s + img.Size, 0); // ~74 GB - the bug
		const aggregate = BASE + 8 * 100_000_000;                   // ~9.8 GB - the truth

		expect(getImageDiskUsageTotalSize({ LayersSize: aggregate, Images: images })).toBe(aggregate);
		expect(summed).toBeGreaterThan(aggregate * 5); // the old sum was several times larger
	});
});