/*
 * Copyright The WildFly Authors
 * SPDX-License-Identifier: Apache-2.0
 */

package org.jboss.as.server.deployment.annotation;

import org.jboss.jandex.AnnotationInstance;
import org.jboss.jandex.ClassInfo;
import org.jboss.jandex.DotName;
import org.jboss.jandex.Index;

import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

/**
 * Composite annotation index.  Represents an annotation index for an entire deployment.
 *
 * @author John Bailey
 */
public class CompositeIndex {
    final Collection<Index> indexes;

    public CompositeIndex(final Collection<Index> indexes) {
        this.indexes = indexes;
    }

    public CompositeIndex(final CompositeIndex... indexes) {
        this.indexes = new ArrayList<Index>();
        for(CompositeIndex index : indexes) {
            this.indexes.addAll(index.indexes);
        }
    }

    /**
     * @see {@link Index#getAnnotations(org.jboss.jandex.DotName)}
     */
    public List<AnnotationInstance> getAnnotations(final DotName annotationName) {
        final List<AnnotationInstance> allInstances = new ArrayList<AnnotationInstance>();
        for (Index index : indexes) {
            final List<AnnotationInstance> list = index.getAnnotations(annotationName);
            if (list != null) {
                allInstances.addAll(list);
            }
        }
        return Collections.unmodifiableList(allInstances);
    }

    /**
     * @see {@link Index#getKnownDirectSubclasses(org.jboss.jandex.DotName)}
     */
    public Set<ClassInfo> getKnownDirectSubclasses(final DotName className) {
        final Set<ClassInfo> allKnown = new HashSet<ClassInfo>();
        for (Index index : indexes) {
            final List<ClassInfo> list = index.getKnownDirectSubclasses(className);
            if (list != null) {
                allKnown.addAll(list);
            }
        }
        return Collections.unmodifiableSet(allKnown);
    }

    /**
     * Returns all known subclasses of the given class, even non-direct sub classes. (i.e. it returns all known classes that are
     * assignable to the given class);
     *
     * @param className The class
     * @return All known subclasses
     */
    public Set<ClassInfo> getAllKnownSubclasses(final DotName className) {
        final Set<ClassInfo> allKnown = new HashSet<ClassInfo>();
        final Set<DotName> processedClasses = new HashSet<DotName>();
        getAllKnownSubClasses(className, allKnown, processedClasses);
        return allKnown;
    }

    private void getAllKnownSubClasses(DotName className, Set<ClassInfo> allKnown, Set<DotName> processedClasses) {
        final Set<DotName> subClassesToProcess = new HashSet<DotName>();
        subClassesToProcess.add(className);
        while (!subClassesToProcess.isEmpty()) {
            final Iterator<DotName> toProcess = subClassesToProcess.iterator();
            DotName name = toProcess.next();
            toProcess.remove();
            processedClasses.add(name);
            getAllKnownSubClasses(name, allKnown, subClassesToProcess, processedClasses);
        }
    }

    private void getAllKnownSubClasses(DotName name, Set<ClassInfo> allKnown, Set<DotName> subClassesToProcess,
            Set<DotName> processedClasses) {
        for (Index index : indexes) {
            final List<ClassInfo> list = index.getKnownDirectSubclasses(name);
            if (list != null) {
                for (final ClassInfo clazz : list) {
                    final DotName className = clazz.name();
                    if (!processedClasses.contains(className)) {
                        allKnown.add(clazz);
                        subClassesToProcess.add(className);
                    }
                }
            }
        }
    }

    /**
     * @see {@link Index#getKnownDirectImplementors(DotName)}
     */
    public Set<ClassInfo> getKnownDirectImplementors(final DotName className) {
        final Set<ClassInfo> allKnown = new HashSet<ClassInfo>();
        for (Index index : indexes) {
            final List<ClassInfo> list = index.getKnownDirectImplementors(className);
            if (list != null) {
                allKnown.addAll(list);
            }
        }
        return Collections.unmodifiableSet(allKnown);
    }

    /**
     * Returns all known classes that implement the given interface, directly and indirectly. This will all return classes that
     * implement sub interfaces of the interface, and sub classes of classes that implement the interface. (In short, it will
     * return every class that is assignable to the interface that is found in the index)
     * <p/>
     * This will only return classes, not interfaces.
     *
     * @param interfaceName The interface
     * @return All known implementors of the interface
     */
    public Set<ClassInfo> getAllKnownImplementors(final DotName interfaceName) {
        final Set<ClassInfo> allKnown = new HashSet<ClassInfo>();
        final Set<DotName> subInterfacesToProcess = new HashSet<DotName>();
        final Set<DotName> processedClasses = new HashSet<DotName>();
        subInterfacesToProcess.add(interfaceName);
        while (!subInterfacesToProcess.isEmpty()) {
            final Iterator<DotName> toProcess = subInterfacesToProcess.iterator();
            DotName name = toProcess.next();
            toProcess.remove();
            processedClasses.add(name);
            getKnownImplementors(name, allKnown, subInterfacesToProcess, processedClasses);
        }
        return allKnown;
    }

    private void getKnownImplementors(DotName name, Set<ClassInfo> allKnown, Set<DotName> subInterfacesToProcess,
            Set<DotName> processedClasses) {
        for (Index index : indexes) {
            final List<ClassInfo> list = index.getKnownDirectImplementors(name);
            if (list != null) {
                for (final ClassInfo clazz : list) {
                    final DotName className = clazz.name();
                    if (!processedClasses.contains(className)) {
                        if (Modifier.isInterface(clazz.flags())) {
                            subInterfacesToProcess.add(className);
                        } else {
                            if (!allKnown.contains(clazz)) {
                                allKnown.add(clazz);
                                processedClasses.add(className);
                                getAllKnownSubClasses(className, allKnown, processedClasses);
                            }
                        }
                    }
                }
            }
        }
    }

    /**
     * @see {@link Index#getClassByName(org.jboss.jandex.DotName)}
     */
    public ClassInfo getClassByName(final DotName className) {
        for (Index index : indexes) {
            final ClassInfo info = index.getClassByName(className);
            if (info != null) {
                return info;
            }
        }
        return null;
    }

    /**
     * @see {@link org.jboss.jandex.Index#getKnownClasses()}
     */
    public Collection<ClassInfo> getKnownClasses() {
        final List<ClassInfo> allKnown = new ArrayList<ClassInfo>();
        for (Index index : indexes) {
            final Collection<ClassInfo> list = index.getKnownClasses();
            if (list != null) {
                allKnown.addAll(list);
            }
        }
        return Collections.unmodifiableCollection(allKnown);
    }

    public Collection<Index> getIndexes() {
        return Collections.unmodifiableCollection(indexes);
    }
}
