defineDescribe('Readme', [
	'./SequenceDiagram',
	'image/ImageRegion',
	'image/ImageSimilarity',
], (
	SequenceDiagram,
	ImageRegion,
	ImageSimilarity
) => {
	'use strict';

	const RESOLUTION = 4;

	const SAMPLE_REGEX = new RegExp(
		/(?:<img src="([^"]*)"[^>]*>[\s]*)?```(?!shell).*\n([^]+?)```/g
	);

	const SCREENSHOT_BLACKLIST = [
		// Renders differently but correctly in different browsers
		'screenshots/Themes.png',
	];

	function findSamples(content) {
		SAMPLE_REGEX.lastIndex = 0;
		const results = [];
		while(true) {
			const match = SAMPLE_REGEX.exec(content);
			if(!match) {
				break;
			}
			results.push({
				file: match[1],
				code: match[2],
			});
		}
		return results;
	}

	function makeSampleTests({file, code}, index) {
		describe('example #' + (index + 1), () => {
			if(file && !SCREENSHOT_BLACKLIST.includes(file)) {
				it('looks like ' + file + ' when rendered', (done) => {
					jasmine.addMatchers(ImageSimilarity.matchers);
					let actual = null;
					new SequenceDiagram(code)
						.getCanvas({resolution: RESOLUTION})
						.then((c) => {
							actual = ImageRegion
								.fromCanvas(c)
								.resize({width: 150});
						})
						.then(() => ImageRegion.loadURL(
							file,
							{width: actual.width, height: actual.height}
						))
						.then((expected) => {
							expect(actual).toLookLike(expected);
						})
						.catch(fail)
						.then(done);
				});
			} else {
				it('renders without error', () => {
					expect(() => new SequenceDiagram(code)).not.toThrow();
				});
			}
		});
	}

	return (fetch('README.md')
		.then((response) => response.text())
		.then(findSamples)
		.then((samples) => samples.forEach(makeSampleTests))
	);
});