/*
 * 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.maven.plugin;

import javax.inject.Named;
import javax.inject.Singleton;

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.maven.artifact.Artifact;
import org.apache.maven.project.ExtensionDescriptor;
import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
import org.codehaus.plexus.personality.plexus.lifecycle.phase.Disposable;

/**
 * Default extension realm cache implementation. Assumes cached data does not change.
 */
@Named
@Singleton
public class DefaultExtensionRealmCache implements ExtensionRealmCache, Disposable {
    /**
     * CacheKey
     */
    protected static class CacheKey implements Key {

        private final List<File> files;

        private final List<Long> timestamps;

        private final List<Long> sizes;

        private final List<String> ids;

        private final int hashCode;

        public CacheKey(List<Artifact> extensionArtifacts) {
            this.files = new ArrayList<>(extensionArtifacts.size());
            this.timestamps = new ArrayList<>(extensionArtifacts.size());
            this.sizes = new ArrayList<>(extensionArtifacts.size());
            this.ids = new ArrayList<>(extensionArtifacts.size());

            for (Artifact artifact : extensionArtifacts) {
                File file = artifact.getFile();
                files.add(file);
                timestamps.add((file != null) ? Long.valueOf(file.lastModified()) : Long.valueOf(0));
                sizes.add((file != null) ? Long.valueOf(file.length()) : Long.valueOf(0));
                ids.add(artifact.getVersion());
            }

            this.hashCode =
                    31 * files.hashCode() + 31 * ids.hashCode() + 31 * timestamps.hashCode() + 31 * sizes.hashCode();
        }

        @Override
        public int hashCode() {
            return hashCode;
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) {
                return true;
            }

            if (!(o instanceof CacheKey)) {
                return false;
            }

            CacheKey other = (CacheKey) o;

            return ids.equals(other.ids)
                    && files.equals(other.files)
                    && timestamps.equals(other.timestamps)
                    && sizes.equals(other.sizes);
        }

        @Override
        public String toString() {
            return files.toString();
        }
    }

    protected final Map<Key, CacheRecord> cache = new ConcurrentHashMap<>();

    @Override
    public Key createKey(List<Artifact> extensionArtifacts) {
        return new CacheKey(extensionArtifacts);
    }

    public CacheRecord get(Key key) {
        return cache.get(key);
    }

    public CacheRecord put(
            Key key, ClassRealm extensionRealm, ExtensionDescriptor extensionDescriptor, List<Artifact> artifacts) {
        Objects.requireNonNull(extensionRealm, "extensionRealm cannot be null");

        if (cache.containsKey(key)) {
            throw new IllegalStateException("Duplicate extension realm for extension " + key);
        }

        CacheRecord record = new CacheRecord(extensionRealm, extensionDescriptor, artifacts);

        cache.put(key, record);

        return record;
    }

    public void flush() {
        for (CacheRecord record : cache.values()) {
            ClassRealm realm = record.getRealm();
            try {
                realm.getWorld().disposeRealm(realm.getId());
            } catch (NoSuchRealmException e) {
                // ignore
            }
        }
        cache.clear();
    }

    public void register(MavenProject project, Key key, CacheRecord record) {
        // default cache does not track extension usage
    }

    public void dispose() {
        flush();
    }
}
