/*
 * Copyright 2017 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.bpmn2.xml;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;

import org.drools.core.xml.BaseAbstractHandler;
import org.drools.core.xml.ExtensibleXmlParser;
import org.drools.core.xml.Handler;
import org.jbpm.bpmn2.core.Association;
import org.jbpm.bpmn2.core.IntermediateLink;
import org.jbpm.bpmn2.core.Lane;
import org.jbpm.bpmn2.core.SequenceFlow;
import org.jbpm.process.core.context.variable.Variable;
import org.jbpm.ruleflow.core.RuleFlowProcess;
import org.jbpm.workflow.core.Node;
import org.jbpm.workflow.core.NodeContainer;
import org.jbpm.workflow.core.node.CompositeNode;
import org.w3c.dom.Element;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;

public class SequenceFlowHandler extends BaseAbstractHandler implements Handler {

    public SequenceFlowHandler() {
        initValidParents();
        initValidPeers();
        this.allowNesting = false;
    }

    protected void initValidParents() {
        this.validParents = new HashSet<>();
        this.validParents.add(NodeContainer.class);
    }

    protected void initValidPeers() {
        this.validPeers = new HashSet<>();
        this.validPeers.add(null);
        this.validPeers.add(Lane.class);
        this.validPeers.add(Variable.class);
        this.validPeers.add(Node.class);
        this.validPeers.add(SequenceFlow.class);
        this.validPeers.add(Lane.class);
        this.validPeers.add(Association.class);
        // TODO: this is right?
        this.validPeers.add(IntermediateLink.class);
    }

    @SuppressWarnings("unchecked")
    public Object start(final String uri, final String localName,
                        final Attributes attrs, final ExtensibleXmlParser parser)
            throws SAXException {
        parser.startElementBuilder(localName, attrs);

        final String id = attrs.getValue("id");
        final String sourceRef = attrs.getValue("sourceRef");
        final String targetRef = attrs.getValue("targetRef");
        final String bendpoints = attrs.getValue("g:bendpoints");
        final String name = attrs.getValue("name");
        final String priority = attrs.getValue("http://www.jboss.org/drools",
                                               "priority");

        NodeContainer nodeContainer = (NodeContainer) parser.getParent();

        List<SequenceFlow> connections = null;
        if (nodeContainer instanceof RuleFlowProcess) {
            RuleFlowProcess process = (RuleFlowProcess) nodeContainer;
            connections = (List<SequenceFlow>) process
                    .getMetaData(ProcessHandler.CONNECTIONS);
            if (connections == null) {
                connections = new ArrayList<>();
                process.setMetaData(ProcessHandler.CONNECTIONS, connections);
            }
        } else if (nodeContainer instanceof CompositeNode) {

            CompositeNode compositeNode = (CompositeNode) nodeContainer;
            connections = (List<SequenceFlow>) compositeNode
                    .getMetaData(ProcessHandler.CONNECTIONS);
            if (connections == null) {
                connections = new ArrayList<>();
                compositeNode.setMetaData(ProcessHandler.CONNECTIONS,
                                          connections);
            }
        }

        SequenceFlow connection = new SequenceFlow(id, sourceRef, targetRef);
        connection.setBendpoints(bendpoints);
        connection.setName(name);
        if (priority != null) {
            connection.setPriority(Integer.parseInt(priority));
        }

        if (connections != null) {
            connections.add(connection);
        }

        return connection;
    }

    public Object end(final String uri, final String localName,
                      final ExtensibleXmlParser parser) throws SAXException {
        final Element element = parser.endElementBuilder();
        SequenceFlow sequenceFlow = (SequenceFlow) parser.getCurrent();

        org.w3c.dom.Node xmlNode = element.getFirstChild();
        while (xmlNode != null) {
            String nodeName = xmlNode.getNodeName();
            if ("conditionExpression".equals(nodeName)) {
                String expression = xmlNode.getTextContent();
                org.w3c.dom.Node languageNode = xmlNode.getAttributes()
                        .getNamedItem("language");
                if (languageNode != null) {
                    String language = languageNode.getNodeValue();
                    if (XmlBPMNProcessDumper.JAVA_LANGUAGE.equals(language)) {
                        sequenceFlow.setLanguage("java");
                    } else if (XmlBPMNProcessDumper.MVEL_LANGUAGE.equals(language)) {
                        sequenceFlow.setLanguage("mvel");
                    } else if (XmlBPMNProcessDumper.RULE_LANGUAGE.equals(language)) {
                        sequenceFlow.setType("rule");
                    } else if (XmlBPMNProcessDumper.XPATH_LANGUAGE.equals(language)) {
                        sequenceFlow.setLanguage("XPath");
                    } else if (XmlBPMNProcessDumper.JAVASCRIPT_LANGUAGE.equals(language)) {
                        sequenceFlow.setLanguage("JavaScript");
                    } else if (XmlBPMNProcessDumper.FEEL_LANGUAGE.equals(language)) {
                        sequenceFlow.setLanguage("FEEL");
                    } else {
                        throw new IllegalArgumentException("Unknown language " + language);
                    }
                }
                sequenceFlow.setExpression(expression);
            }
            xmlNode = xmlNode.getNextSibling();
        }
        return sequenceFlow;
    }

    public Class<?> generateNodeFor() {
        return SequenceFlow.class;
    }
}
