ClearGraphCommand.java

/*
 * Copyright 2016 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed 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.kie.workbench.common.stunner.core.graph.command.impl;

import java.util.Iterator;

import org.jboss.errai.common.client.api.annotations.MapsTo;
import org.jboss.errai.common.client.api.annotations.Portable;
import org.kie.workbench.common.stunner.core.command.CommandResult;
import org.kie.workbench.common.stunner.core.graph.Edge;
import org.kie.workbench.common.stunner.core.graph.Graph;
import org.kie.workbench.common.stunner.core.graph.Node;
import org.kie.workbench.common.stunner.core.graph.command.GraphCommandExecutionContext;
import org.kie.workbench.common.stunner.core.graph.command.GraphCommandResultBuilder;
import org.kie.workbench.common.stunner.core.rule.RuleViolation;

/**
 * A Command to clear all elements in the graph structure
 * TODO: Undo not supported yet.
 */
@Portable
public final class ClearGraphCommand extends AbstractGraphCommand {

    private final String rootUUID;

    public ClearGraphCommand(final @MapsTo("rootUUID") String rootUUID) {
        this.rootUUID = rootUUID;
    }

    @Override
    @SuppressWarnings("unchecked")
    public CommandResult<RuleViolation> execute(final GraphCommandExecutionContext context) {
        final CommandResult<RuleViolation> results = allow(context);
        if (!results.getType().equals(CommandResult.Type.ERROR)) {
            final Graph<?, Node> graph = getGraph(context);
            if (hasRootUUID()) {
                Iterator<Node> nodes = graph.nodes().iterator();
                if (null != nodes) {
                    nodes.forEachRemaining(node -> {
                        if (!node.getUUID().equals(rootUUID)) {
                            getMutableIndex(context).removeNode(node);
                            nodes.remove();
                        } else {
                            // Clear outgoing edges for canvas root element.
                            node.getOutEdges().stream().forEach(edge -> getMutableIndex(context).removeEdge((Edge) edge));
                            node.getOutEdges().clear();
                        }
                    });
                }
            } else {
                graph.clear();
                getMutableIndex(context).clear();
            }
        }
        return results;
    }

    protected CommandResult<RuleViolation> check(final GraphCommandExecutionContext context) {
        if (hasRootUUID()) {
            checkNodeNotNull(context,
                             rootUUID);
        }
        return GraphCommandResultBuilder.SUCCESS;
    }

    @Override
    public CommandResult<RuleViolation> undo(final GraphCommandExecutionContext context) {
        throw new UnsupportedOperationException("Undo operation for Clear Graph Command is still not supported. ");
    }

    public String getRootUUID() {
        return rootUUID;
    }

    private boolean hasRootUUID() {
        return null != this.rootUUID && rootUUID.trim().length() > 0;
    }

    @Override
    public String toString() {
        return "ClearGraphCommand [rootUUID=" + rootUUID + "]";
    }
}