src/main/java/org/apache/sling/resourceresolver/impl/observation/ResourceChangeListenerInfo.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.sling.resourceresolver.impl.observation;

import static org.apache.sling.api.resource.observation.ResourceChangeListener.CHANGES;
import static org.apache.sling.api.resource.observation.ResourceChangeListener.PATHS;
import static org.apache.sling.commons.osgi.PropertiesUtil.toStringArray;

import java.util.Collections;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;

import org.apache.sling.api.resource.ResourceUtil;
import org.apache.sling.api.resource.observation.ExternalResourceChangeListener;
import org.apache.sling.api.resource.observation.ResourceChange.ChangeType;
import org.apache.sling.api.resource.observation.ResourceChangeListener;
import org.apache.sling.api.resource.path.Path;
import org.apache.sling.api.resource.path.PathSet;
import org.apache.sling.commons.osgi.PropertiesUtil;
import org.osgi.framework.ServiceReference;

/**
 * Information about a resource change listener.
 */
public class ResourceChangeListenerInfo implements Comparable<ResourceChangeListenerInfo> {

    private static final Set<ChangeType> DEFAULT_CHANGE_RESOURCE_TYPES = EnumSet.of(ChangeType.ADDED, ChangeType.REMOVED, ChangeType.CHANGED);

    private static final Set<ChangeType> DEFAULT_CHANGE_PROVIDER_TYPES = EnumSet.of(ChangeType.PROVIDER_ADDED, ChangeType.PROVIDER_REMOVED);

    private final PathSet paths;

    private final Set<ChangeType> resourceChangeTypes;

    private final Set<ChangeType> providerChangeTypes;

    private final Set<String> propertyNamesHint;

    private final boolean valid;

    private volatile boolean external = false;

    private volatile ResourceChangeListener listener;

    public ResourceChangeListenerInfo(final ServiceReference<ResourceChangeListener> ref, final List<String> searchPaths) {
        boolean configValid = true;
        final Set<String> pathsSet = new HashSet<>();
        final String paths[] = toStringArray(ref.getProperty(PATHS), null);
        if ( paths != null ) {
            for(final String p : paths) {
                boolean isGlobPattern = false;
                String normalisedPath = ResourceUtil.normalize(p);
                if (p.startsWith(Path.GLOB_PREFIX)) {
                    isGlobPattern = true;
                    normalisedPath =  ResourceUtil.normalize(p.substring(Path.GLOB_PREFIX.length()));
                }
                if (!".".equals(p) && normalisedPath.isEmpty()) {
                    configValid = false;
                } else if ( normalisedPath.startsWith("/") && !isGlobPattern ) {
                    pathsSet.add(normalisedPath);
                } else if (normalisedPath.startsWith("/") && isGlobPattern) {
                    pathsSet.add(Path.GLOB_PREFIX + normalisedPath);
                } else {
                    for(final String sp : searchPaths) {
                        if ( p.equals(".") ) {
                            pathsSet.add(sp);
                        } else {
                            if (isGlobPattern) {
                                pathsSet.add(Path.GLOB_PREFIX + ResourceUtil.normalize(sp + normalisedPath));
                            } else {
                                pathsSet.add(ResourceUtil.normalize(sp + normalisedPath));
                            }
                        }
                    }
                }
            }
        }
        if ( pathsSet.isEmpty() ) {
            configValid = false;
        } else {
            // check for sub paths
            final Iterator<String> iter = pathsSet.iterator();
            while ( iter.hasNext() ) {
                final String path = iter.next();
                boolean remove = false;
                for(final String p : pathsSet) {
                    if ( p.length() > path.length() && path.startsWith(p + "/") ) {
                        remove = true;
                        break;
                    }
                }
                if ( remove ) {
                    iter.remove();
                }
            }
        }
        this.paths = PathSet.fromStringCollection(pathsSet);
        if (ref.getProperty(CHANGES) != null ) {
            final Set<ChangeType> rts = new HashSet<>();
            final Set<ChangeType> pts = new HashSet<>();
            try {
                for (final String changeName : toStringArray(ref.getProperty(CHANGES))) {
                    final ChangeType ct = ChangeType.valueOf(changeName);
                    if (ct.ordinal() < ChangeType.PROVIDER_ADDED.ordinal()) {
                        rts.add(ct);
                    } else {
                        pts.add(ct);
                    }
                }
            } catch (final Exception e) {
                configValid = false;
            }
            if ( rts.isEmpty() ) {
                this.resourceChangeTypes = Collections.emptySet();
            } else if ( rts.size() == 3 ) {
                this.resourceChangeTypes = DEFAULT_CHANGE_RESOURCE_TYPES;
            } else {
                this.resourceChangeTypes = Collections.unmodifiableSet(rts);
            }
            if ( pts.isEmpty() ) {
                this.providerChangeTypes = Collections.emptySet();
            } else if ( pts.size() == 2 ) {
                this.providerChangeTypes = DEFAULT_CHANGE_PROVIDER_TYPES;
            } else {
                this.providerChangeTypes = Collections.unmodifiableSet(pts);
            }
        } else {
            // default is added, changed, removed for resources and
            // added and removed for providers
            this.resourceChangeTypes = DEFAULT_CHANGE_RESOURCE_TYPES;
            this.providerChangeTypes = DEFAULT_CHANGE_PROVIDER_TYPES;
        }

        if ( ref.getProperty(ResourceChangeListener.PROPERTY_NAMES_HINT) != null ) {
            this.propertyNamesHint = new HashSet<>();
            for(final String val : PropertiesUtil.toStringArray(ref.getProperty(ResourceChangeListener.PROPERTY_NAMES_HINT)) ) {
                this.propertyNamesHint.add(val);
            }
        } else {
            this.propertyNamesHint = null;
        }
        this.valid = configValid;
    }

    public boolean isValid() {
        return this.valid;
    }

    public Set<ChangeType> getResourceChangeTypes() {
        return this.resourceChangeTypes;
    }

    public Set<ChangeType> getProviderChangeTypes() {
        return this.providerChangeTypes;
    }

    public PathSet getPaths() {
        return this.paths;
    }

    /**
     * Return a set of property name hints
     * @return The set of names or {@code null}.
     */
    public Set<String> getPropertyNamesHint() {
        return this.propertyNamesHint;
    }

    public boolean isExternal() {
        return this.external;
    }

    public ResourceChangeListener getListener() {
        return listener;
    }

    public void setListener(final ResourceChangeListener listener) {
        this.listener = listener;
        this.external = listener instanceof ExternalResourceChangeListener;
    }

    private int compareSet(final Set<String> t, final Set<String> o) {
        if ( t == null && o == null ) {
            return 0;
        }
        if ( t == null ) {
            return -1;
        }
        if ( o == null ) {
            return 1;
        }
        final Set<String> tPaths = new TreeSet<>(t);
        final Set<String> oPaths = new TreeSet<>(o);

        int result = tPaths.size() - oPaths.size();
        if ( result == 0 ) {
            final Iterator<String> tPathsIter = tPaths.iterator();
            final Iterator<String> oPathsIter = oPaths.iterator();
            while ( result == 0 && tPathsIter.hasNext() ) {
                result = tPathsIter.next().compareTo(oPathsIter.next());
            }
        }
        return result;
    }

    private int compareChangeTypes(final Set<ChangeType> t, final Set<ChangeType> o) {
        int result = t.size() - o.size();
        if ( result == 0 ) {
            final Iterator<ChangeType> tIter = t.iterator();
            final Iterator<ChangeType> oIter = o.iterator();
            while ( result == 0 && tIter.hasNext() ) {
                result = tIter.next().compareTo(oIter.next());
            }
        }
        return result;
    }

    @Override
    public int compareTo(final ResourceChangeListenerInfo o) {
        // paths first
        int result = compareSet(this.paths.toStringSet(), o.paths.toStringSet());
        if ( result == 0 ) {
            // hints
            result = compareSet(this.propertyNamesHint, o.propertyNamesHint);
            if ( result == 0 ) {
                // external next
                result = Boolean.valueOf(this.external).compareTo(o.external);
                if ( result == 0 ) {
                    result = compareChangeTypes(this.resourceChangeTypes, o.resourceChangeTypes);
                    if ( result == 0 ) {
                        result = compareChangeTypes(this.providerChangeTypes, o.providerChangeTypes);
                    }
                }
            }
        }
        return result;
    }

    @Override
    public String toString() {
        return "ResourceChangeListenerInfo [paths=" + paths + ", resourceChangeTypes=" + resourceChangeTypes
                + ", providerChangeTypes=" + providerChangeTypes + ", propertyNamesHint=" + propertyNamesHint
                + ", valid=" + valid + ", external=" + external + ", listener=" + listener + "]";
    }
}