/**
 * Copyright 2010 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.jbpm.workflow.core.impl;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicLong;

import org.jbpm.process.core.Context;
import org.jbpm.process.core.ContextResolver;
import org.jbpm.workflow.core.Constraint;
import org.jbpm.workflow.core.Node;
import org.jbpm.workflow.core.node.CompositeNode;
import org.kie.api.definition.process.Connection;
import org.kie.api.definition.process.NodeContainer;

/**
 * Default implementation of a node.
 * 
 */
public abstract class NodeImpl implements Node, Serializable, ContextResolver {

    private static final long serialVersionUID = 510l;

	protected static final NodeImpl[] EMPTY_NODE_ARRAY = new NodeImpl[0];

    private long id;
    private static final AtomicLong uniqueIdGen = new AtomicLong(0);

    private String name;
    private Map<String, List<Connection>> incomingConnections;
    private Map<String, List<Connection>> outgoingConnections;
    private NodeContainer parentNodeContainer;
    private Map<String, Context> contexts = new HashMap<String, Context>();
    private Map<String, Object> metaData = new HashMap<String, Object>();
    
    protected Map<ConnectionRef, Constraint> constraints = new HashMap<ConnectionRef, Constraint>();

    public NodeImpl() {
        this.id = -1;
        this.incomingConnections = new HashMap<String, List<Connection>>();
        this.outgoingConnections = new HashMap<String, List<Connection>>();
    }

    public long getId() {
        return this.id;
    }
    
    public String getUniqueId() {
    	String result = id + "";
    	NodeContainer nodeContainer = getNodeContainer();
    	while (nodeContainer instanceof CompositeNode) {
    		CompositeNode composite = (CompositeNode) nodeContainer;
    		result = composite.getId() + ":" + result;
    		nodeContainer = composite.getNodeContainer();
    	}
    	return result;
    }

    public void setId(final long id) {
        this.id = id;
        String uniqueId = (String) getMetaData("UniqueId");
        if( uniqueId == null ) { 
            setMetaData("UniqueId", "_jbpm-unique-" + uniqueIdGen.getAndIncrement() );
        }
    }

    public String getName() {
        return this.name;
    }

    public void setName(final String name) {
        this.name = name;
    }

    public Map<String, List<Connection>> getIncomingConnections() {
        // TODO: users can still modify the lists inside this Map
        return Collections.unmodifiableMap(this.incomingConnections);
    }

    public Map<String, List<Connection>> getOutgoingConnections() {
        // TODO: users can still modify the lists inside this Map
        return Collections.unmodifiableMap(this.outgoingConnections);
    }

    public void addIncomingConnection(final String type, final Connection connection) {
        validateAddIncomingConnection(type, connection);
        List<Connection> connections = this.incomingConnections.get(type);
        if (connections == null) {
            connections = new ArrayList<Connection>();
            this.incomingConnections.put(type, connections);
        }
        connections.add(connection);
    }

    public void validateAddIncomingConnection(final String type, final Connection connection) {
        if (type == null) {
            throw new IllegalArgumentException("Connection type cannot be null");
        }
        if (connection == null) {
            throw new IllegalArgumentException("Connection cannot be null");
        }
    }
    
    public List<Connection> getIncomingConnections(String type) {
        List<Connection> result = incomingConnections.get(type);
        if (result == null) {
            return new ArrayList<Connection>();
        }
        return result;
    }

    public void addOutgoingConnection(final String type, final Connection connection) {
        validateAddOutgoingConnection(type, connection);
        List<Connection> connections = this.outgoingConnections.get(type);
        if (connections == null) {
            connections = new ArrayList<Connection>();
            this.outgoingConnections.put(type, connections);
        }
        connections.add(connection);
    }

    public void validateAddOutgoingConnection(final String type, final Connection connection) {
        if (type == null) {
            throw new IllegalArgumentException("Connection type cannot be null");
        }
        if (connection == null) {
            throw new IllegalArgumentException("Connection cannot be null");
        }
    }

    public List<Connection> getOutgoingConnections(String type) {
        List<Connection> result = outgoingConnections.get(type);
        if (result == null) {
            return new ArrayList<Connection>();
        }
        return result;
    }

    public void removeIncomingConnection(final String type, final Connection connection) {
        validateRemoveIncomingConnection(type, connection);
        this.incomingConnections.get(type).remove(connection);
    }
    
    public void clearIncomingConnection() {
        this.incomingConnections.clear();
    }
    
    public void clearOutgoingConnection() {
        this.outgoingConnections.clear();
    }

    public void validateRemoveIncomingConnection(final String type, final Connection connection) {
        if (type == null) {
            throw new IllegalArgumentException("Connection type cannot be null");
        }
        if (connection == null) {
            throw new IllegalArgumentException("Connection is null");
        }
        if (!incomingConnections.get(type).contains(connection)) {
            throw new IllegalArgumentException("Given connection <"
                    + connection + "> is not part of the incoming connections");
        }
    }

    public void removeOutgoingConnection(final String type, final Connection connection) {
        validateRemoveOutgoingConnection(type, connection);
        this.outgoingConnections.get(type).remove(connection);
    }

    public void validateRemoveOutgoingConnection(final String type, final Connection connection) {
        if (type == null) {
            throw new IllegalArgumentException("Connection type cannot be null");
        }
        if (connection == null) {
            throw new IllegalArgumentException("Connection is null");
        }
        if (!this.outgoingConnections.get(type).contains(connection)) {
            throw new IllegalArgumentException("Given connection <"
                    + connection + "> is not part of the outgoing connections");
        }
    }
    
    /** Helper method for nodes that have at most one default incoming connection */
	public Connection getFrom() {
        final List<Connection> list =
            getIncomingConnections(org.jbpm.workflow.core.Node.CONNECTION_DEFAULT_TYPE);
        if (list.size() == 0) {
            return null;
        }
        if (list.size() == 1) {
        	return list.get(0);
        }
        if ("true".equals(System.getProperty("jbpm.enable.multi.con"))) { 
        	return list.get(0);
        } else {
        	throw new IllegalArgumentException(
    		"Trying to retrieve the from connection but multiple connections are present");
        }
    }

    /** Helper method for nodes that have at most one default outgoing connection */
    public Connection getTo() {
        final List<Connection> list =
            getOutgoingConnections(org.jbpm.workflow.core.Node.CONNECTION_DEFAULT_TYPE);
        if (list.size() == 0) {
            return null;
        }
        if (list.size() == 1) {
        	return list.get(0);
        }
        if ("true".equals(System.getProperty("jbpm.enable.multi.con"))) { 
        	return list.get(0);
        } else {
        	throw new IllegalArgumentException(
    		"Trying to retrieve the to connection but multiple connections are present");
        }
    }

    /** Helper method for nodes that have multiple default incoming connections */
    public List<Connection> getDefaultIncomingConnections() {
        return getIncomingConnections(org.jbpm.workflow.core.Node.CONNECTION_DEFAULT_TYPE);
    }

    /** Helper method for nodes that have multiple default outgoing connections */
    public List<Connection> getDefaultOutgoingConnections() {
        return getOutgoingConnections(org.jbpm.workflow.core.Node.CONNECTION_DEFAULT_TYPE);
    }

    public NodeContainer getNodeContainer() {
        return parentNodeContainer;
    }
    
    public void setNodeContainer(NodeContainer nodeContainer) {
        this.parentNodeContainer = nodeContainer;
    }
    
    public void setContext(String contextId, Context context) {
        this.contexts.put(contextId, context);
    }
    
    public Context getContext(String contextId) {
        return this.contexts.get(contextId);
    }
    
    public Context resolveContext(String contextId, Object param) {
        Context context = getContext(contextId);
        if (context != null) {
            context = context.resolveContext(param);
            if (context != null) {
                return context;
            }
        }
        return ((org.jbpm.workflow.core.NodeContainer) parentNodeContainer).resolveContext(contextId, param);
    }
    
    public void setMetaData(String name, Object value) {
        this.metaData.put(name, value);
    }
    
    public Object getMetaData(String name) {
        return this.metaData.get(name);
    }
    
    public Map<String, Object> getMetaData() {
    	return this.metaData;
    }
    
    public void setMetaData(Map<String, Object> metaData) {
    	this.metaData = metaData;
    }
    
    public Constraint getConstraint(final Connection connection) {
        if ( connection == null ) {
            throw new IllegalArgumentException( "connection is null" );
        }

        
       ConnectionRef ref = new ConnectionRef(connection.getTo().getId(), connection.getToType());
       return this.constraints.get(ref);
       
    }

    public Constraint internalGetConstraint(final ConnectionRef ref) {
        return this.constraints.get(ref);
    }

    public void setConstraint(final Connection connection,
                              final Constraint constraint) {
    	if ( connection == null ) {
            throw new IllegalArgumentException( "connection is null" );
        }
        if (!getDefaultOutgoingConnections().contains(connection)) {
            throw new IllegalArgumentException("connection is unknown:" + connection);
        }
        addConstraint(
            new ConnectionRef(connection.getTo().getId(), connection.getToType()),
            constraint);

    }

    public void addConstraint(ConnectionRef connectionRef, Constraint constraint) {
    	if (connectionRef == null) {
    		throw new IllegalArgumentException(
				"A " + this.getName() + " node only accepts constraints linked to a connection");
    	}
        this.constraints.put(connectionRef, constraint);
    }

    public Map<ConnectionRef, Constraint> getConstraints() {
        return Collections.unmodifiableMap( this.constraints );
    }
    
}
