/*
 * 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.jackrabbit.oak.plugins.migration.version;

import org.apache.jackrabbit.oak.api.CommitFailedException;
import org.apache.jackrabbit.oak.api.Type;
import org.apache.jackrabbit.oak.commons.PathUtils;
import org.apache.jackrabbit.oak.plugins.nodetype.TypePredicate;
import org.apache.jackrabbit.oak.plugins.version.ReadWriteVersionManager;
import org.apache.jackrabbit.oak.spi.commit.CommitInfo;
import org.apache.jackrabbit.oak.spi.commit.DefaultEditor;
import org.apache.jackrabbit.oak.spi.commit.Editor;
import org.apache.jackrabbit.oak.spi.commit.EditorProvider;
import org.apache.jackrabbit.oak.spi.state.NodeBuilder;
import org.apache.jackrabbit.oak.spi.state.NodeState;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Collections;
import java.util.Set;

import static com.google.common.collect.ImmutableSet.of;
import static org.apache.jackrabbit.JcrConstants.JCR_UUID;
import static org.apache.jackrabbit.JcrConstants.MIX_REFERENCEABLE;
import static org.apache.jackrabbit.JcrConstants.MIX_VERSIONABLE;
import static org.apache.jackrabbit.oak.spi.version.VersionConstants.MIX_REP_VERSIONABLE_PATHS;
import static org.apache.jackrabbit.oak.plugins.migration.version.VersionHistoryUtil.addMixin;
import static org.apache.jackrabbit.oak.plugins.migration.version.VersionHistoryUtil.getVersionHistoryBuilder;
import static org.apache.jackrabbit.oak.plugins.migration.version.VersionHistoryUtil.getVersionStorage;
import static org.apache.jackrabbit.oak.plugins.migration.version.VersionHistoryUtil.removeVersionProperties;

/**
 * The VersionableEditor provides two possible ways to handle
 * versionable nodes:
 * <ul>
 *     <li>it can copy the version histories of versionable nodes, or</li>
 *     <li>
 *         it can skip copying version histories and remove the
 *         {@code mix:versionable} mixin together with any related
 *         properties (see {@link VersionHistoryUtil#removeVersionProperties(NodeBuilder, TypePredicate)}).
 *     </li>
 * </ul>
 */
public class VersionableEditor extends DefaultEditor {

    private static final Logger logger = LoggerFactory.getLogger(VersionableEditor.class);

    private static final Set<String> SKIPPED_PATHS = of("/oak:index", "/jcr:system/jcr:versionStorage");

    private final Provider provider;

    private final NodeBuilder rootBuilder;

    private final NodeBuilder versionStorage;

    private final TypePredicate isReferenceable;

    private final TypePredicate isVersionable;

    private final VersionCopier versionCopier;

    private final ReadWriteVersionManager vMgr;

    private String path;

    private VersionableEditor(Provider provider, NodeBuilder rootBuilder) {
        this.rootBuilder = rootBuilder;
        this.versionStorage = getVersionStorage(rootBuilder);
        this.vMgr = new ReadWriteVersionManager(versionStorage, rootBuilder);

        this.provider = provider;
        this.isVersionable = new TypePredicate(rootBuilder.getNodeState(), MIX_VERSIONABLE);
        this.isReferenceable = new TypePredicate(rootBuilder.getNodeState(), MIX_REFERENCEABLE);
        this.versionCopier = new VersionCopier(rootBuilder, getVersionStorage(provider.sourceRoot), versionStorage);
        this.path = "/";

    }

    public static class Provider implements EditorProvider {

        private final NodeState sourceRoot;

        private final String workspaceName;

        private final VersionCopyConfiguration config;

        public Provider(NodeState sourceRoot, String workspaceName, VersionCopyConfiguration config) {
            this.sourceRoot = sourceRoot;
            this.workspaceName = workspaceName;
            this.config = config;
        }

        @Override
        public Editor getRootEditor(NodeState before, NodeState after, NodeBuilder rootBuilder, CommitInfo info) throws CommitFailedException {
            return new VersionableEditor(this, rootBuilder);
        }
    }

    @Override
    public Editor childNodeAdded(String name, NodeState after) throws CommitFailedException {
        final String path = PathUtils.concat(this.path, name);
        // skip deleted nodes and well known paths that may not contain versionable nodes
        if (after == null || SKIPPED_PATHS.contains(path)) {
            return null;
        }

        // assign path field only after checking that we don't skip this subtree
        this.path = path;

        final VersionCopyConfiguration c = provider.config;
        if (isVersionable.test(after)) {
            final String versionableUuid = getProperty(after, JCR_UUID, Type.STRING);
            if (c.isCopyVersions() && c.skipOrphanedVersionsCopy()) {
                copyVersionHistory(after);
            } else if (c.isCopyVersions() && !c.skipOrphanedVersionsCopy()) {
                // all version histories have been copied, but maybe the date
                // range for orphaned entries is narrower
                if (c.getOrphanedMinDate().after(c.getVersionsMinDate())) {
                    copyVersionHistory(after);
                }
            }

            if (isVersionHistoryExists(versionableUuid)) {
                setVersionablePath(versionableUuid);
            } else {
                NodeBuilder versionableBuilder = getNodeBuilder(rootBuilder, this.path);
                removeVersionProperties(versionableBuilder, isReferenceable);
                if (isVersionable.test(versionableBuilder.getNodeState())) {
                    logger.warn("Node {} is still versionable. Creating empty version history.", path);
                    createEmptyHistory(versionableBuilder);
                }
            }
        }

        return this;
    }

    private boolean copyVersionHistory(NodeState versionable) {
        assert versionable.exists();

        final String versionableUuid = versionable.getProperty(JCR_UUID).getValue(Type.STRING);
        return versionCopier.copyVersionHistory(versionableUuid, provider.config.getVersionsMinDate(),
            provider.config.preserveOnTarget());
    }

    private void setVersionablePath(String versionableUuid) {
        final NodeBuilder versionHistory = VersionHistoryUtil.getVersionHistoryBuilder(versionStorage, versionableUuid);
        if (!versionHistory.hasProperty(provider.workspaceName)) {
            versionHistory.setProperty(provider.workspaceName, path, Type.PATH);
        }
        addMixin(versionHistory, MIX_REP_VERSIONABLE_PATHS);
    }

    private boolean isVersionHistoryExists(String versionableUuid) {
        return getVersionHistoryBuilder(versionStorage, versionableUuid).exists();
    }

    private void createEmptyHistory(NodeBuilder versionable) throws CommitFailedException {
        vMgr.getOrCreateVersionHistory(versionable, Collections.<String,Object>emptyMap());
    }

    @Override
    public Editor childNodeChanged(String name, NodeState before, NodeState after) throws CommitFailedException {
        return childNodeAdded(name, after);
    }

    @Override
    public Editor childNodeDeleted(String name, NodeState before) throws CommitFailedException {
        return childNodeAdded(name, null);
    }

    @Override
    public void leave(NodeState before, NodeState after) throws CommitFailedException {
        this.path = PathUtils.getParentPath(this.path);
    }

    private static <T> T getProperty(NodeState state, String name, Type<T> type) {
        if (state.hasProperty(name)) {
            return state.getProperty(name).getValue(type);
        }
        return null;
    }

    private static NodeBuilder getNodeBuilder(NodeBuilder root, String path) {
        NodeBuilder builder = root;
        for (String name : PathUtils.elements(path)) {
            builder = builder.getChildNode(name);
        }
        return builder;
    }


}
