import java.io.IOException;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.lang.instrument.UnmodifiableClassException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.ProtectionDomain;
import java.util.Arrays;

import com.oracle.java.testlibrary.ExitCode;
import com.oracle.java.testlibrary.OutputAnalyzer;
import com.oracle.java.testlibrary.ProcessTools;

/**
 * @test
 * @library /testlibrary
 * @build TestLambdaFormRetransformation
 * @run main TestLambdaFormRetransformation
 */
public class TestLambdaFormRetransformation {
    private static String MANIFEST = String.format("Manifest-Version: 1.0\n" +
            "Premain-Class: %s\nCan-Retransform-Classes: true\n",
            Agent.class.getName());

    private static String CP = System.getProperty("test.classes");;

    public static void main(String args[]) throws Throwable {
        Path agent = TestLambdaFormRetransformation.buildAgent();
        OutputAnalyzer oa = ProcessTools.executeTestJvm(
                "-javaagent:" + agent.toAbsolutePath().toString(), "-version");
        oa.shouldHaveExitValue(ExitCode.OK.value);
    }

    private static Path buildAgent() throws IOException {
        Path manifest = TestLambdaFormRetransformation.createManifest();
        Path jar = Files.createTempFile(Paths.get("."), null, ".jar");

        String[] args = new String[] {
                "-cfm",
                jar.toAbsolutePath().toString(),
                manifest.toAbsolutePath().toString(),
                "-C",
                TestLambdaFormRetransformation.CP,
                Agent.class.getName() + ".class"
        };

        sun.tools.jar.Main jarTool
                = new sun.tools.jar.Main(System.out, System.err, "jar");

        if (!jarTool.run(args)) {
            throw new Error("jar failed: args=" + Arrays.toString(args));
        }

        return jar;
    }

    private static Path createManifest() throws IOException {
        Path manifest = Files.createTempFile(Paths.get("."), null, ".mf");
        byte[] manifestBytes
                = TestLambdaFormRetransformation.MANIFEST.getBytes();
        Files.write(manifest, manifestBytes);
        return manifest;
    }
}

class Agent implements ClassFileTransformer {
    private static Runnable lambda = () -> {
        System.out.println("I'll crash you!");
    };

    public static void premain(String args, Instrumentation instrumentation) {
        if (!instrumentation.isRetransformClassesSupported()) {
            System.out.println("Class retransformation is not supported.");
            return;
        }

        System.out.println("Calling lambda to ensure that lambda forms "
                + "were created");
        Agent.lambda.run();
        System.out.println("Registering class file transformer");
        instrumentation.addTransformer(new Agent());

        for (Class c : instrumentation.getAllLoadedClasses()) {
            if (c.getName().contains("LambdaForm")
                    && instrumentation.isModifiableClass(c)) {
                System.out.format("We've found a modifiable lambda form: %s%n",
                        c.getName());
                try {
                    instrumentation.retransformClasses(c);
                } catch (UnmodifiableClassException e) {
                    throw new AssertionError("Modification of modifiable class "
                            + "caused UnmodifiableClassException", e);
                }
            }
        }
    }

    public static void main(String args[]) {
    }

    @Override
    public byte[] transform(ClassLoader loader, String className,
            Class<?> classBeingRedefined, ProtectionDomain protectionDomain,
            byte[] classfileBuffer) throws IllegalClassFormatException {
        System.out.println("Transforming " + className);
        return classfileBuffer.clone();
    }
}