/*

 * Copyright (c) 2005, 2018, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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 com.sun.tools.javac.processing;

import java.lang.annotation.Annotation;

import javax.annotation.processing.*;

import javax.lang.model.element.*;

import javax.lang.model.util.*;

import java.util.*;

import com.sun.tools.javac.code.Source.Feature;

import com.sun.tools.javac.util.DefinedBy;

import com.sun.tools.javac.util.DefinedBy.Api;

/**

 * Object providing state about a prior round of annotation processing.

 *

 * <p>The methods in this class do not take type annotations into account,

 * as target types, not java elements.

 *

 * <p><b>This is NOT part of any supported API.

 * If you write code that depends on this, you do so at your own risk.

 * This code and its internal interfaces are subject to change or

 * deletion without notice.</b>

 */

public class JavacRoundEnvironment implements RoundEnvironment {

    // Default equals and hashCode methods are okay.

    private final boolean processingOver;

    private final boolean errorRaised;

    private final ProcessingEnvironment processingEnv;

    private final Elements eltUtils;

    private final boolean allowModules;

    // Caller must pass in an immutable set

    private final Set<? extends Element> rootElements;

    JavacRoundEnvironment(boolean processingOver,

                          boolean errorRaised,

                          Set<? extends Element> rootElements,

                          JavacProcessingEnvironment processingEnv) {

        this.processingOver = processingOver;

        this.errorRaised = errorRaised;

        this.rootElements = rootElements;

        this.processingEnv = processingEnv;

        this.allowModules = Feature.MODULES.allowedInSource(processingEnv.source);

        this.eltUtils = processingEnv.getElementUtils();

    }

    public String toString() {

        return String.format("[errorRaised=%b, rootElements=%s, processingOver=%b]",

                             errorRaised,

                             rootElements,

                             processingOver);

    }

    @DefinedBy(Api.ANNOTATION_PROCESSING)

    public boolean processingOver() {

        return processingOver;

    }

    /**

     * Returns {@code true} if an error was raised in the prior round

     * of processing; returns {@code false} otherwise.

     *

     * @return {@code true} if an error was raised in the prior round

     * of processing; returns {@code false} otherwise.

     */

    @DefinedBy(Api.ANNOTATION_PROCESSING)

    public boolean errorRaised() {

        return errorRaised;

    }

    /**

     * Returns the type elements specified by the prior round.

     *

     * @return the types elements specified by the prior round, or an

     * empty set if there were none

     */

    @DefinedBy(Api.ANNOTATION_PROCESSING)

    public Set<? extends Element> getRootElements() {

        return rootElements;

    }

    /**

     * Returns the elements annotated with the given annotation type.

     * Only type elements <i>included</i> in this round of annotation

     * processing, or declarations of members, parameters, or type

     * parameters declared within those, are returned.  Included type

     * elements are {@linkplain #getRootElements specified

     * types} and any types nested within them.

     *

     * @param a  annotation type being requested

     * @return the elements annotated with the given annotation type,

     * or an empty set if there are none

     */

    @DefinedBy(Api.ANNOTATION_PROCESSING)

    public Set<? extends Element> getElementsAnnotatedWith(TypeElement a) {

        throwIfNotAnnotation(a);

        Set<Element> result = Collections.emptySet();

        ElementScanner9<Set<Element>, TypeElement> scanner =

            new AnnotationSetScanner(result);

        for (Element element : rootElements)

            result = scanner.scan(element, a);

        return result;

    }

    @DefinedBy(Api.ANNOTATION_PROCESSING)

    public Set<? extends Element> getElementsAnnotatedWithAny(TypeElement... annotations) {

        // Don't bother to special-case annotations.length == 1 as

        // return getElementsAnnotatedWith(annotations[0]);

        Set<TypeElement> annotationSet = new LinkedHashSet<>(annotations.length);

        for (TypeElement annotation : annotations) {

            throwIfNotAnnotation(annotation);

            annotationSet.add(annotation);

        }

        Set<Element> result = Collections.emptySet();

        ElementScanner9<Set<Element>, Set<TypeElement>> scanner =

            new AnnotationSetMultiScanner(result);

        for (Element element : rootElements)

            result = scanner.scan(element, annotationSet);

        return result;

    }

    // Could be written as a local class inside getElementsAnnotatedWith

    private class AnnotationSetScanner extends

        ElementScanningIncludingTypeParameters<Set<Element>, TypeElement> {

        // Insertion-order preserving set

        private Set<Element> annotatedElements = new LinkedHashSet<>();

        AnnotationSetScanner(Set<Element> defaultSet) {

            super(defaultSet);

        }

        @Override @DefinedBy(Api.LANGUAGE_MODEL)

        public Set<Element> scan(Element e, TypeElement annotation) {

            for (AnnotationMirror annotMirror :  eltUtils.getAllAnnotationMirrors(e)) {

                if (annotation.equals(mirrorAsElement(annotMirror))) {

                    annotatedElements.add(e);

                    break;

                }

            }

            e.accept(this, annotation);

            return annotatedElements;

        }

        @Override @DefinedBy(Api.LANGUAGE_MODEL)

        public Set<Element> visitModule(ModuleElement e, TypeElement annotation) {

            // Do not scan a module

            return annotatedElements;

        }

        @Override @DefinedBy(Api.LANGUAGE_MODEL)

        public Set<Element> visitPackage(PackageElement e, TypeElement annotation) {

            // Do not scan a package

            return annotatedElements;

        }

    }

    // Could be written as a local class inside getElementsAnnotatedWithAny

    private class AnnotationSetMultiScanner extends

        ElementScanningIncludingTypeParameters<Set<Element>, Set<TypeElement>> {

        // Insertion-order preserving set

        private Set<Element> annotatedElements = new LinkedHashSet<>();

        AnnotationSetMultiScanner(Set<Element> defaultSet) {

            super(defaultSet);

        }

        @Override @DefinedBy(Api.LANGUAGE_MODEL)

        public Set<Element> scan(Element e, Set<TypeElement> annotations) {

            for (AnnotationMirror annotMirror : eltUtils.getAllAnnotationMirrors(e)) {

                if (annotations.contains(mirrorAsElement(annotMirror))) {

                    annotatedElements.add(e);

                    break;

                }

            }

            e.accept(this, annotations);

            return annotatedElements;

        }

        @Override @DefinedBy(Api.LANGUAGE_MODEL)

        public Set<Element> visitModule(ModuleElement e, Set<TypeElement> annotations) {

            // Do not scan a module

            return annotatedElements;

        }

        @Override @DefinedBy(Api.LANGUAGE_MODEL)

        public Set<Element> visitPackage(PackageElement e, Set<TypeElement> annotations) {

            // Do not scan a package

            return annotatedElements;

        }

    }

    private static abstract class ElementScanningIncludingTypeParameters<R, P>

        extends ElementScanner9<R, P> {

        protected ElementScanningIncludingTypeParameters(R defaultValue) {

            super(defaultValue);

        }

        @Override @DefinedBy(Api.LANGUAGE_MODEL)

        public R visitType(TypeElement e, P p) {

            // Type parameters are not considered to be enclosed by a type

            scan(e.getTypeParameters(), p);

            return super.visitType(e, p);

        }

        @Override @DefinedBy(Api.LANGUAGE_MODEL)

        public R visitExecutable(ExecutableElement e, P p) {

            // Type parameters are not considered to be enclosed by an executable

            scan(e.getTypeParameters(), p);

            return super.visitExecutable(e, p);

        }

    }

    /**

     * {@inheritDoc}

     */

    @DefinedBy(Api.ANNOTATION_PROCESSING)

    public Set<? extends Element> getElementsAnnotatedWith(Class<? extends Annotation> a) {

        throwIfNotAnnotation(a);

        String name = a.getCanonicalName();

        if (name == null)

            return Collections.emptySet();

        else {

            TypeElement annotationType = annotationToElement(a);

            if (annotationType == null)

                return Collections.emptySet();

            else

                return getElementsAnnotatedWith(annotationType);

        }

    }

    @DefinedBy(Api.ANNOTATION_PROCESSING)

    public Set<? extends Element> getElementsAnnotatedWithAny(Set<Class<? extends Annotation>> annotations) {

        List<TypeElement> annotationsAsElements = new ArrayList<>(annotations.size());

        for (Class<? extends Annotation> annotation : annotations) {

            throwIfNotAnnotation(annotation);

            String name = annotation.getCanonicalName();

            if (name == null)

                continue;

            annotationsAsElements.add(annotationToElement(annotation));

        }

        return getElementsAnnotatedWithAny(annotationsAsElements.toArray(new TypeElement[0]));

    }

    private TypeElement annotationToElement(Class<? extends Annotation> annotation) {

        // First, try an element lookup based on the annotation's

        // canonical name. If that fails or is ambiguous, try a lookup

        // using a particular module, perhaps an unnamed one. This

        // offers more compatibility for compiling in single-module

        // mode where the runtime module of an annotation type may

        // differ from the single module being compiled.

        String name = annotation.getCanonicalName();

        TypeElement annotationElement = eltUtils.getTypeElement(name);

        if (annotationElement != null)

            return annotationElement;

        else if (allowModules) {

            String moduleName = Objects.requireNonNullElse(annotation.getModule().getName(), "");

            return eltUtils.getTypeElement(eltUtils.getModuleElement(moduleName), name);

        } else {

            return null;

        }

    }

    private Element mirrorAsElement(AnnotationMirror annotationMirror) {

        return annotationMirror.getAnnotationType().asElement();

    }

    private static final String NOT_AN_ANNOTATION_TYPE =

        "The argument does not represent an annotation type: ";

    private void throwIfNotAnnotation(Class<? extends Annotation> a) {

        if (!a.isAnnotation())

            throw new IllegalArgumentException(NOT_AN_ANNOTATION_TYPE + a);

    }

    private void throwIfNotAnnotation(TypeElement a) {

        if (a.getKind() != ElementKind.ANNOTATION_TYPE)

            throw new IllegalArgumentException(NOT_AN_ANNOTATION_TYPE + a);

    }

}