package reproduction;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import javax.tools.DiagnosticCollector;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;
import javax.tools.StandardLocation;
import javax.tools.ToolProvider;

import org.junit.platform.engine.discovery.DiscoverySelectors;
import org.junit.platform.launcher.core.LauncherDiscoveryRequestBuilder;
import org.junit.platform.launcher.core.LauncherFactory;

public class Main {
	public static void main(String[] args) throws IOException {
		var className = "ExampleJUnit4Test";
		compileAndSelect(className);
		className = "ExampleJUnit5Test";
		compileAndSelect(className);
	}

	private static void compileAndSelect(String className) throws IOException {
		System.out.format("Testing class: %s\n", className);
		var compiler = ToolProvider.getSystemJavaCompiler();
		var diagnosticCollector = new DiagnosticCollector<>();
		StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnosticCollector, null, null);

		Path tempDirectory = Files.createTempDirectory(String.format("junit-reproduction-"));
		System.out.format("Compiling to %s\n", tempDirectory);
		fileManager.setLocation(StandardLocation.CLASS_OUTPUT, List.of(tempDirectory.toFile()));

		Iterable<? extends JavaFileObject> sources = fileManager
				.getJavaFileObjectsFromPaths(List.of(Path.of(className + ".java")));
		var task = compiler.getTask(null, fileManager, diagnosticCollector, null, null, sources);
		if (!task.call()) {
			System.out.println("Failed compilation!");
			return;
		}
		ClassLoader classLoader = fileManager.getClassLoader(StandardLocation.CLASS_OUTPUT);
		Iterable<? extends Path> classpathRootsIterable = fileManager.getLocationAsPaths(StandardLocation.CLASS_OUTPUT);
		Set<Path> classpathRoots = new HashSet<>();
		classpathRootsIterable.forEach(classpathRoots::add);

		var originalClassLoader = Thread.currentThread().getContextClassLoader();
		Thread.currentThread().setContextClassLoader(classLoader);
		var request = LauncherDiscoveryRequestBuilder.request()
				.selectors(DiscoverySelectors.selectClass(classLoader, className)).build();
		var launcher = LauncherFactory.create();
		var testPlan = launcher.discover(request);

		System.out.format("TestPlan contains tests: %s\n", testPlan.containsTests());

		Thread.currentThread().setContextClassLoader(originalClassLoader);
	}
}