import { describe, test, expect } from 'vitest';

import { mergeV8CoverageByUrl, type V8CoverageEntry } from './coverage-options';

const fn = (functionName: string, ranges: Array<[number, number, number]>) => ({
	functionName,
	isBlockCoverage: true,
	ranges: ranges.map(([startOffset, endOffset, count]) => ({ startOffset, endOffset, count })),
});

describe('mergeV8CoverageByUrl', () => {
	test('keeps distinct URLs separate', () => {
		const entries: V8CoverageEntry[] = [
			{ url: 'a.js', source: 'a', functions: [fn('', [[0, 10, 1]])] },
			{ url: 'b.js', source: 'b', functions: [fn('', [[0, 10, 1]])] },
		];
		expect(mergeV8CoverageByUrl(entries)).toHaveLength(2);
	});

	test('collapses re-loaded same-URL scripts into one, summing range counts', () => {
		const merged = mergeV8CoverageByUrl([
			{
				url: 'a.js',
				source: 'src',
				functions: [
					fn('f', [
						[0, 10, 1],
						[4, 8, 1],
					]),
				],
			},
			{
				url: 'a.js',
				source: 'src',
				functions: [
					fn('f', [
						[0, 10, 2],
						[4, 8, 0],
					]),
				],
			},
		]);

		expect(merged).toHaveLength(1);
		expect(merged[0].source).toBe('src'); // one source copy, not two
		const ranges = merged[0].functions[0].ranges;
		expect(ranges.find((r) => r.startOffset === 0)?.count).toBe(3); // 1 + 2
		expect(ranges.find((r) => r.startOffset === 4)?.count).toBe(1); // 1 + 0
	});

	test('unions ranges and functions present in only one copy', () => {
		const merged = mergeV8CoverageByUrl([
			{ url: 'a.js', source: 'src', functions: [fn('f', [[0, 10, 1]])] },
			{
				url: 'a.js',
				source: 'src',
				functions: [
					fn('f', [
						[0, 10, 1],
						[20, 30, 5],
					]),
					fn('g', [[40, 50, 2]]),
				],
			},
		]);

		expect(merged).toHaveLength(1);
		const fns = merged[0].functions;
		expect(fns.map((f) => f.functionName).sort()).toEqual(['f', 'g']);
		expect(
			fns.find((f) => f.functionName === 'f')?.ranges.find((r) => r.startOffset === 20)?.count,
		).toBe(5);
	});
});