package org.drools.workflow.instance.node;



import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.List;



import org.drools.definition.process.Node;

import org.drools.process.core.context.variable.VariableScope;

import org.drools.process.instance.context.variable.VariableScopeInstance;

import org.drools.workflow.core.node.ForEachNode;

import org.drools.workflow.core.node.ForEachNode.ForEachJoinNode;

import org.drools.workflow.core.node.ForEachNode.ForEachSplitNode;

import org.drools.workflow.instance.NodeInstance;

import org.drools.workflow.instance.NodeInstanceContainer;

import org.drools.workflow.instance.impl.NodeInstanceImpl;



/*

 * Copyright 2005 JBoss Inc

 * 

 * 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.

 */



/**

 * Runtime counterpart of a for each node.

 * 

 * @author <a href="mailto:kris_verlaenen@hotmail.com">Kris Verlaenen</a>

 */

public class ForEachNodeInstance extends CompositeNodeInstance {



    private static final long serialVersionUID = 4L;

    

    public ForEachNode getForEachNode() {

        return (ForEachNode) getNode();

    }



    public NodeInstance getNodeInstance(final Node node) {

        // TODO do this cleaner for split / join of for each?

        if (node instanceof ForEachSplitNode) {

            ForEachSplitNodeInstance nodeInstance = new ForEachSplitNodeInstance();

            nodeInstance.setNodeId(node.getId());

            nodeInstance.setNodeInstanceContainer(this);

            nodeInstance.setProcessInstance(getProcessInstance());

            return nodeInstance;

        } else if (node instanceof ForEachJoinNode) {

            ForEachJoinNodeInstance nodeInstance = (ForEachJoinNodeInstance)

                getFirstNodeInstance(node.getId());

            if (nodeInstance == null) {

                nodeInstance = new ForEachJoinNodeInstance();

                nodeInstance.setNodeId(node.getId());

                nodeInstance.setNodeInstanceContainer(this);

                nodeInstance.setProcessInstance(getProcessInstance());

            }

            return nodeInstance;

        }

        return super.getNodeInstance(node);

    }

    

    public class ForEachSplitNodeInstance extends NodeInstanceImpl {



        private static final long serialVersionUID = 4L;

        

        public ForEachSplitNode getForEachSplitNode() {

            return (ForEachSplitNode) getNode();

        }



        public void internalTrigger(org.drools.runtime.process.NodeInstance from, String type) {

            String collectionExpression = getForEachNode().getCollectionExpression();

            Collection<?> collection = evaluateCollectionExpression(collectionExpression);

            ((NodeInstanceContainer) getNodeInstanceContainer()).removeNodeInstance(this);

            List<NodeInstance> nodeInstances = new ArrayList<NodeInstance>();

            for (Object o: collection) {

                String variableName = getForEachNode().getVariableName();

                CompositeNodeInstance nodeInstance = (CompositeNodeInstance)

                    ((NodeInstanceContainer) getNodeInstanceContainer()).getNodeInstance(getForEachSplitNode().getTo().getTo());

                VariableScopeInstance variableScopeInstance = (VariableScopeInstance)

                    nodeInstance.resolveContextInstance(VariableScope.VARIABLE_SCOPE, variableName);

                variableScopeInstance.setVariable(variableName, o);

                nodeInstances.add(nodeInstance);

            }

            for (NodeInstance nodeInstance: nodeInstances) {

                ((org.drools.workflow.instance.NodeInstance) nodeInstance).trigger(this, getForEachSplitNode().getTo().getToType());

            }

            if (!getForEachNode().isWaitForCompletion()) {

            	ForEachNodeInstance.this.triggerCompleted(org.drools.workflow.core.Node.CONNECTION_DEFAULT_TYPE, false);

            }

        }

        

        private Collection<?> evaluateCollectionExpression(String collectionExpression) {

            // TODO: should evaluate this expression using MVEL

            VariableScopeInstance variableScopeInstance = (VariableScopeInstance)

                resolveContextInstance(VariableScope.VARIABLE_SCOPE, collectionExpression);

            if (variableScopeInstance == null) {

                throw new IllegalArgumentException(

                    "Could not find collection " + collectionExpression);

            }

            Object collection = variableScopeInstance.getVariable(collectionExpression);

            if (collection == null) {

            	return Collections.EMPTY_LIST;

            }

            if (collection instanceof Collection<?>) {

            	return (Collection<?>) collection;

            }

            if (collection.getClass().isArray() ) {

            	List<Object> list = new ArrayList<Object>();

            	for (Object o: (Object[]) collection) {

            		list.add(o);

            	}

                return list;

            }

            throw new IllegalArgumentException(

        		"Unexpected collection type: " + collection.getClass());

        }

        

    }

    

    public class ForEachJoinNodeInstance extends NodeInstanceImpl {



        private static final long serialVersionUID = 4L;

        

        public ForEachJoinNode getForEachJoinNode() {

            return (ForEachJoinNode) getNode();

        }



        public void internalTrigger(org.drools.runtime.process.NodeInstance from, String type) {

            if (getNodeInstanceContainer().getNodeInstances().size() == 1) {

            	((NodeInstanceContainer) getNodeInstanceContainer()).removeNodeInstance(this);

                if (getForEachNode().isWaitForCompletion()) {

                	triggerConnection(getForEachJoinNode().getTo());

                }

            }

        }

        

    }

    

}