/*

 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.graalvm.compiler.serviceprovider.processor;

import java.io.IOException;

import java.io.OutputStreamWriter;

import java.io.PrintWriter;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Set;

import javax.annotation.processing.AbstractProcessor;

import javax.annotation.processing.FilerException;

import javax.annotation.processing.RoundEnvironment;

import javax.annotation.processing.SupportedAnnotationTypes;

import javax.lang.model.SourceVersion;

import javax.lang.model.element.Element;

import javax.lang.model.element.TypeElement;

import javax.lang.model.type.MirroredTypeException;

import javax.lang.model.type.TypeMirror;

import javax.tools.Diagnostic.Kind;

import javax.tools.FileObject;

import javax.tools.StandardLocation;

import org.graalvm.compiler.serviceprovider.ServiceProvider;

/**

 * Processes classes annotated with {@link ServiceProvider}. For a service defined by {@code S} and

 * a class {@code P} implementing the service, this processor generates the file

 * {@code META-INF/providers/P} whose contents are a single line containing the fully qualified name

 * of {@code S}.

 */

@SupportedAnnotationTypes("org.graalvm.compiler.serviceprovider.ServiceProvider")

public class ServiceProviderProcessor extends AbstractProcessor {

    private final Set<TypeElement> processed = new HashSet<>();

    private final Map<TypeElement, String> serviceProviders = new HashMap<>();

    @Override

    public SourceVersion getSupportedSourceVersion() {

        return SourceVersion.latest();

    }

    private boolean verifyAnnotation(TypeMirror serviceInterface, TypeElement serviceProvider) {

        if (!processingEnv.getTypeUtils().isSubtype(serviceProvider.asType(), serviceInterface)) {

            String msg = String.format("Service provider class %s must implement service interface %s", serviceProvider.getSimpleName(), serviceInterface);

            processingEnv.getMessager().printMessage(Kind.ERROR, msg, serviceProvider);

            return false;

        }

        return true;

    }

    private void processElement(TypeElement serviceProvider) {

        if (processed.contains(serviceProvider)) {

            return;

        }

        processed.add(serviceProvider);

        ServiceProvider annotation = serviceProvider.getAnnotation(ServiceProvider.class);

        if (annotation != null) {

            try {

                annotation.value();

            } catch (MirroredTypeException ex) {

                    if (serviceProvider.getNestingKind().isNested()) {

                        /*

                         * This is a simplifying constraint that means we don't have to process the

                         * qualified name to insert '$' characters at the relevant positions.

                         */

                        String msg = String.format("Service provider class %s must be a top level class", serviceProvider.getSimpleName());

                        processingEnv.getMessager().printMessage(Kind.ERROR, msg, serviceProvider);

                    } else {

                    }

                }

            }

        }

    }

    private void writeProviderFile(TypeElement serviceProvider, String interfaceName) {

        String filename = "META-INF/providers/" + serviceProvider.getQualifiedName();

        try {

            FileObject file = processingEnv.getFiler().createResource(StandardLocation.CLASS_OUTPUT, "", filename, serviceProvider);

            PrintWriter writer = new PrintWriter(new OutputStreamWriter(file.openOutputStream(), "UTF-8"));

            writer.println(interfaceName);

            writer.close();

        } catch (IOException e) {

            processingEnv.getMessager().printMessage(isBug367599(e) ? Kind.NOTE : Kind.ERROR, e.getMessage(), serviceProvider);

        }

    }

    /**

     * Determines if a given exception is (most likely) caused by

     * <a href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=367599">Bug 367599</a>.

     */

    private static boolean isBug367599(Throwable t) {

        if (t instanceof FilerException) {

            for (StackTraceElement ste : t.getStackTrace()) {

                if (ste.toString().contains("org.eclipse.jdt.internal.apt.pluggable.core.filer.IdeFilerImpl.create")) {

                    // See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=367599

                    return true;

                }

            }

        }

        return t.getCause() != null && isBug367599(t.getCause());

    }

    @Override

    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {

        if (roundEnv.processingOver()) {

            for (Entry<TypeElement, String> e : serviceProviders.entrySet()) {

                writeProviderFile(e.getKey(), e.getValue());

            }

            serviceProviders.clear();

            return true;

        }

        for (Element element : roundEnv.getElementsAnnotatedWith(ServiceProvider.class)) {

            assert element.getKind().isClass();

            processElement((TypeElement) element);

        }

        return true;

    }

}