/**
 *
 */
package de.intevation.gnv.artifacts;

import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.xml.xpath.XPathConstants;

import net.sf.ehcache.Cache;

import org.apache.log4j.Logger;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import de.intevation.artifactdatabase.Config;
import de.intevation.artifactdatabase.ProxyArtifact;
import de.intevation.artifactdatabase.XMLUtils;
import de.intevation.artifacts.Artifact;
import de.intevation.artifacts.ArtifactDatabase;
import de.intevation.artifacts.ArtifactFactory;
import de.intevation.artifacts.ArtifactNamespaceContext;
import de.intevation.artifacts.CallContext;
import de.intevation.artifacts.CallMeta;
import de.intevation.gnv.artifacts.cache.CacheFactory;
import de.intevation.gnv.artifacts.context.GNVArtifactContext;
import de.intevation.gnv.artifacts.fis.product.Product;
import de.intevation.gnv.artifacts.ressource.RessourceFactory;
import de.intevation.gnv.state.DefaultInputData;
import de.intevation.gnv.state.InputData;
import de.intevation.gnv.state.InputValue;
import de.intevation.gnv.state.OutputMode;
import de.intevation.gnv.state.OutputState;
import de.intevation.gnv.state.State;
import de.intevation.gnv.state.StateBase;
import de.intevation.gnv.state.StateFactory;
import de.intevation.gnv.state.exception.StateException;
import de.intevation.gnv.transition.Transition;
import de.intevation.gnv.transition.TransitionFactory;
import de.intevation.gnv.utils.ArtifactXMLUtilities;

/**
 * @author Tim Englich         (tim.englich@intevation.de)
 * @author Ingo Weinzierl      (ingo.weinzierl@intevation.de)
 * @author Sascha L. Teichmann (sascha.teichmann@intevation.de)
 */
public abstract class GNVArtifactBase extends GNVDefaultArtifact 
                                      implements PreSettingArtifact {

    /**
     * the logger, used to log exceptions and additonaly information
     */
    private static Logger log = Logger.getLogger(GNVArtifactBase.class);
    /**
     * The UID of this Class
     */
    private static final long serialVersionUID = -8907096744400741458L;

    /**
     * The Identifier for the Replacement of the Artifactname
     */
    public static final String XPATH_IDENTIFIER_REPLACE = "IDENTIFIER";

    /**
     * The XPATH to the XML-Fragment that should be used for the Configuration
     */
    public static final String XPATH_ARTIFACT_CONFIGURATION = "/artifact-database/artifacts/artifact[@name='"
                                                              + XPATH_IDENTIFIER_REPLACE
                                                              + "']";

    public static final String XPATH_STATIC_NODE = "/art:result/art:ui/art:static";

    public static final String XPATH_INPUT_DATA = "/art:action/art:data/art:input";

    public static final String XPATH_INCLUDE_UI = "/art:action/art:include-ui";

    public static final String XPATH_TARGET_NAME = "/art:action/art:target/@name";

    public static final String XPATH_OUTPUT_NAME = "/art:action/art:out/@name"; 

    public static final String XPATH_OUTPUT_PARAMS = "/art:action/art:out/art:params/art:input"; 

    public static final String INITIAL_STATE = "product";

    /**
     * The current State
     */
    protected State current = null;

    /**
     * The States that can be used
     */
    protected Map<String, State> states = null;
    
    /**
     * The Transitions which can switch between the different States.
     */
    protected Collection<Transition> transitions = null;

    /**
     * The current product
     */
    protected Product product;

    /**
     * The Name of the Artifact
     */
    protected String name = null;

    /**
     * The Presettings of InputData which can be used to
     * travel through the States in different Ways or
     * manipulate the InputData
     */
    private Map<String, InputData> preSettings = null;

    /**
     * Constructor
     */
    public GNVArtifactBase() {
        super();
    }


    @Override
    public Document advance(Document target, CallContext context) {
        log.debug("GNVArtifactBase.advance()");

        Document result      = XMLUtils.newDocument();
        String   targetState = XMLUtils.xpathString(
            target, XPATH_TARGET_NAME, ArtifactNamespaceContext.INSTANCE
        );

        // no current state...
        if (current == null) {
            log.debug("No current state. Advance not possible.");

            result = createReport(
                result,
                "exceptionreport",
                "exception",
                "No State activated."
            );

            return result;
        }

        State next = null;

        try {

            // step forward
            if (isStateCurrentlyReachable(targetState)) {
                next = states.get(targetState);

                // 2. Transfer Results
                next.putInputData(current.getInputData(), identifier);
                next.setParent(current);
                next.setPreSettings(this.preSettings);

                if (current != null) {
                    current.endOfLife(context.globalContext());
                }

                // 3. Switch to next State
                current = next;

                // 4. Initialize next Step
                current.initialize(identifier, context);

                result = createReport(
                    result, "result", "success", "Advance success"
                );
            }

            // step backward
            else if((next = getPreviousState(current, targetState)) != null) {

                // reset input data
                resetFutureStates(current, targetState);

                // remove data from future states from cache
                resetDescribeData(current, identifier, targetState);

                if (current != null) {
                    current.endOfLife(context.globalContext());
                }

                current = next;

                result = createReport(
                    result, "result", "success", "Advance success"
                );
            }

            // goto initial step
            else if(targetState.equals(INITIAL_STATE)) {

                String fis                    = product.getArtifactFactory();
                ArtifactDatabase db           = context.getDatabase();
                GNVProductArtifactFactory fac = (GNVProductArtifactFactory)
                    db.getInternalArtifactFactory(fis);

                Artifact select = fac.createArtifact(identifier, context, null);
                context.putContextValue(ProxyArtifact.REPLACE_PROXY, select);

                resetDescribeData(current, identifier, INITIAL_STATE);

                result = createReport(
                    result, "result", "success", "Advance success"
                );
            }

            // advance not possible
            else {
                log.warn("advance not possible for target: " + targetState);
                result = createReport(
                    result,
                    "exceptionreport",
                    "exception",
                    "Statetransition not supported"
                );
            }
        }
        catch (StateException se) {
            log.error(se, se);
            result = createReport(
                result,
                "exceptionreport",
                "exception",
                se.getLocalizedMessage()
            );
        }

        return result;
    }


    protected Document createReport(
        Document document,
        String   nodeName,
        String   state,
        String   msg
    ) {
        XMLUtils.ElementCreator creator = new XMLUtils.ElementCreator(
            document,
            ArtifactNamespaceContext.NAMESPACE_URI,
            ArtifactNamespaceContext.NAMESPACE_PREFIX
        );

        Element reportNode = creator.create(nodeName);
        Element stateNode  = creator.create(state);

        stateNode.setTextContent(msg);
        reportNode.appendChild(stateNode);
        document.appendChild(reportNode);

        return document;

    }


    protected State getPreviousState(State current, String name) {
        if (current == null) {
            return null;
        }

        if (current.getID().equals(name)) {
            return current;
        }
        else {
            return getPreviousState(current.getParent(), name);
        }
    }

    public void resetDescribeData(State state, String uuid, String target) {
        CacheFactory factory = CacheFactory.getInstance();
        
        if (factory.isInitialized()) {
            Cache  cache = factory.getCache();
            String key   = uuid + StateBase.DESCRIBEDATAKEY;

            net.sf.ehcache.Element value = cache.get(key);
            if (value == null)
                return;

            List data = (List) value.getObjectValue();
            while(!target.equals(state.getID())) {
                data.remove(data.size()-1);
                state = state.getParent();

                if (state == null)
                    break;
            }

            cache.put(new net.sf.ehcache.Element(key, data));
        }
    }


    protected void resetFutureStates(State current, String name) {
        if (current == null) {
            return;
        }

        if (current.getID().equals(name)) {
            return;
        }
        else {
            current.reset(identifier);
            resetFutureStates(current.getParent(), name);
        }
    }


    private boolean isStateCurrentlyReachable(String stateid){
        Iterator<Transition> it = this.transitions.iterator();
        String from = this.current.getID();
        while (it.hasNext()){
            Transition transition = it.next();
            if (transition.getFrom().equals(from)){
                if (transition.getTo().equals(stateid) && transition.isValid(this.current)){
                    return true;
                }
            }
        }
        return false;
    }
    
    public Document initialize (CallContext context) {
        Document result = XMLUtils.newDocument();
        try {
            this.current.initialize(super.identifier, context);
            result = new ArtifactXMLUtilities()
            .createSuccessReport("Initialize success",
                    XMLUtils.newDocument());
        } catch (StateException e) {
            log.error(e,e);
            result = new ArtifactXMLUtilities().createExceptionReport(e
                    .getLocalizedMessage(), XMLUtils.newDocument());
        }
        return result;
    }

    protected String readStateName(Document document) {
        String returnValue = XMLUtils.xpathString(
            document, XPATH_TARGET_NAME, ArtifactNamespaceContext.INSTANCE);
        return returnValue;
    }

    protected Node getConfigurationFragment(Document document) {
        log.debug("GNVArtifactBase.getConfigurationFragment");
        String xpathQuery = XPATH_ARTIFACT_CONFIGURATION.replaceAll(
                XPATH_IDENTIFIER_REPLACE, this.name);
        
        Element configurationNode = (Element)Config.getNodeXPath(document, xpathQuery);
        
        String link = configurationNode.getAttribute("xlink:href");
        if (link != null ){
            String absolutFileName = Config.replaceConfigDir(link);
            configurationNode = (Element)new ArtifactXMLUtilities().readConfiguration(absolutFileName);
        }
        
        return configurationNode;
    }

    /**
     * @see de.intevation.artifactdatabase.DefaultArtifact#feed(org.w3c.dom.Document,
     *      de.intevation.artifacts.CallContext)
     */
    @Override
    public Document feed(Document target, CallContext context) {
        log.debug("GNVArtifactBase.feed");
        Document result = XMLUtils.newDocument();
        try {
            if (this.current != null) {
                Collection<InputData> inputData = this.parseInputData(
                    target,
                    XPATH_INPUT_DATA);

                if (!inputData.isEmpty()){
                    this.current.putInputData(inputData, super.identifier);
                    result = new ArtifactXMLUtilities().createSuccessReport(
                            "Feed success", XMLUtils.newDocument());
                }else{
                    String msg = "No Inputdata given. Please select at least one Entry.";
                    log.warn(msg);
                    result = new ArtifactXMLUtilities().createExceptionReport(msg,
                            XMLUtils.newDocument());
                }
            } else {
                String msg = "No State instantiated";
                log.warn(msg);
                result = new ArtifactXMLUtilities().createExceptionReport(msg,
                        XMLUtils.newDocument());
            }
        } catch (StateException e) {
            log.error(e, e);
            result = new ArtifactXMLUtilities().createExceptionReport(e
                    .getLocalizedMessage(), XMLUtils.newDocument());
        }
        return result;
    }


    /**
     * @see de.intevation.artifactdatabase.DefaultArtifact#describe(org.w3c.dom.Document, de.intevation.artifacts.CallContext)
     */
    @Override
    public Document describe(Document data, CallContext context) {
        log.debug("GNVArtifactBase.describe");

        Document document = createDescibeOutput(
            context,
            identifier,
            getIncludeUIFromDocument(data)
        );

        // insert node for rendering product field
        Element staticNode = (Element) XMLUtils.xpath(
            document,
            XPATH_STATIC_NODE,
            XPathConstants.NODE,
            ArtifactNamespaceContext.INSTANCE
        );

        XMLUtils.ElementCreator creator = new XMLUtils.ElementCreator(
            document,
            XMLUtils.XFORM_URL,
            XMLUtils.XFORM_PREFIX
        );

        XMLUtils.ElementCreator artCreator = new XMLUtils.ElementCreator(
            document,
            ArtifactNamespaceContext.NAMESPACE_URI,
            ArtifactNamespaceContext.NAMESPACE_PREFIX
        );

        return document;
    }

    /**
     * @see de.intevation.artifactdatabase.DefaultArtifact#setup(java.lang.String, de.intevation.artifacts.ArtifactFactory, java.lang.Object, org.w3c.dom.Document)
     */
    @Override
    public void setup(String identifier, ArtifactFactory factory, 
                      Object context,Document data) {
        log.debug("GNVArtifactBase.setup");
        super.setup(identifier, factory, context, data);

        Object localContext = context;
        if (context instanceof CallContext) {
            localContext = ((CallContext) context).globalContext();

        }

        if (localContext instanceof GNVArtifactContext) {
            GNVArtifactContext gnvContext = (GNVArtifactContext) localContext;
            Document doc = gnvContext.getConfig();
            Node artifactNode = this.getConfigurationFragment(doc);
                        
            NodeList stateList = Config.getNodeSetXPath(artifactNode,
                    "states/state");
            this.states = new HashMap<String, State>(stateList
                    .getLength());
            for (int i = 0; i < stateList.getLength(); i++) {
                State tmpState = StateFactory.getInstance()
                        .createState(stateList.item(i));
                if (tmpState != null) {
                    log.debug("Initiate new state: " + tmpState.getID());
                    this.states.put(tmpState.getID(), tmpState);
                    if (this.current == null) {
                        this.current = tmpState;
                    }
                }
            }
            
            NodeList transitionList = Config.getNodeSetXPath(artifactNode,
            "states/transition");
            this.transitions = new ArrayList<Transition>(transitionList.getLength());
            for (int i = 0; i < transitionList.getLength(); i++) {
                Transition tmpTransition = TransitionFactory.getInstance()
                        .createTransition(transitionList.item(i));
                if (tmpTransition != null) {
                    this.transitions.add(tmpTransition);
                }
            }

        }
    }


    protected Document createDescibeOutput(
        CallContext context,
        String      uuid,
        boolean     incudeUI
    ) {
        log.debug("GNVArtifactBase.createDescibeOutput");
        Document document = XMLUtils.newDocument();

        XMLUtils.ElementCreator creator = new XMLUtils.ElementCreator(
            document,
            ArtifactNamespaceContext.NAMESPACE_URI,
            ArtifactNamespaceContext.NAMESPACE_PREFIX
        );
        Element rootNode = this.createRootNode(creator, document);
        this.createHeader(creator, rootNode, document, "describe");
        this.createOutputs(creator, rootNode, document);
        this.createCurrentState(creator, rootNode, document);
        this.createReachableStates(creator, rootNode, document);
        this.createModel(creator, rootNode, document);
        if (incudeUI){
            this.createUserInterface(creator, rootNode, document, context, uuid);
        }

        return document;
    }
    
    protected boolean getIncludeUIFromDocument(Document document){
        String value = XMLUtils.xpathString(
            document, XPATH_INCLUDE_UI, ArtifactNamespaceContext.INSTANCE);

        boolean includeUI = false;
        if (value != null){
            includeUI = Boolean.parseBoolean(value);
        }
        return includeUI;
    }

    protected Element createRootNode(
        XMLUtils.ElementCreator creator,
        Document                document
    ) {
        Element rootNode = creator.create("result");
        document.appendChild(rootNode);
        return rootNode;
    }

    protected void createHeader(
        XMLUtils.ElementCreator creator,
        Element                 parent,
        Document                document,
        String                  documentType
    ) {
        Element typeNode = creator.create("type");
        creator.addAttr(typeNode, "name", documentType);
        parent.appendChild(typeNode);

        Element uuidNode = creator.create("uuid");
        creator.addAttr(uuidNode, "value", super.identifier);
        parent.appendChild(uuidNode);

        Element hashNode = creator.create("hash");
        creator.addAttr(hashNode, "value", this.hash());
        parent.appendChild(hashNode);
    }

    protected Element createSelectBox(
        XMLUtils.ElementCreator artCreator,
        XMLUtils.ElementCreator creator,
        Document                document,
        CallContext             context
    ) {
        RessourceFactory resource = RessourceFactory.getInstance();
        CallMeta callMeta         = (CallMeta) context.getMeta();
        String productName        = product.getName();

        Element selectNode = creator.create("select1");
        creator.addAttr(selectNode, "ref", "product");
        artCreator.addAttr(selectNode, "state", INITIAL_STATE, true);


        Element labelNode = creator.create("label");
        labelNode.setTextContent(
            resource.getRessource(callMeta.getLanguages(), "product", "product")
        );

        Element choicesNode = creator.create("choices");

        Element itemNode = creator.create("item");
        creator.addAttr(itemNode, "selected", "true");

        Element choiceLabel = creator.create("label");
        choiceLabel.setTextContent(resource.getRessource(
            callMeta.getLanguages(),
            productName,
            productName
        ));

        Element choiceValue = creator.create("value");
        choiceValue.setTextContent(productName);

        itemNode.appendChild(choiceLabel);
        itemNode.appendChild(choiceValue);
        choicesNode.appendChild(itemNode);

        selectNode.appendChild(labelNode);
        selectNode.appendChild(choicesNode);

        return selectNode;
    }


    protected void createReachableStates(
        XMLUtils.ElementCreator creator,
        Element                 parent,
        Document                document
    ) {
        Element stateNode = creator.create("reachable-states");
        if (this.current != null) {

            // add future states
            Iterator<Transition> transitions = this.transitions.iterator();
            while (transitions.hasNext()) {
                Transition tmpTransition = transitions.next();
                if (tmpTransition.getFrom().equals(current.getID()) && 
                    tmpTransition.isValid(this.current)){
                    Element currentNode = creator.create("state");
                    creator.addAttr(currentNode, "name", tmpTransition.getTo());
                    creator.addAttr(
                        currentNode,
                        "description",
                        this.states.get(tmpTransition.getTo()).getDescription());
                    stateNode.appendChild(currentNode);
                }
            }


            // add old states
            appendOldReachableStates(creator, stateNode, current);
        }
        parent.appendChild(stateNode);
    }


    protected void appendOldReachableStates(
        XMLUtils.ElementCreator creator,
        Element                 parent,
        State                   state
    ) {
        if (state == null)
            return;

        while (state != null) {
            Element currentNode = creator.create("state");
            creator.addAttr(currentNode, "name", state.getID());
            creator.addAttr(currentNode, "description", state.getDescription());
            parent.appendChild(currentNode);

            state = state.getParent();
        }
    }


    protected void createCurrentState(
        XMLUtils.ElementCreator creator,
        Element                 parent,
        Document                document
    ) {
        Element stateNode = creator.create("state");
        creator.addAttr(stateNode, "name", this.current.getID());
        creator.addAttr(stateNode, "description", this.current.getDescription());
        parent.appendChild(stateNode);
    }

    protected void createModel(
        XMLUtils.ElementCreator creator,
        Element                 parent,
        Document                document
    ) {
        Element modelNode = creator.create("model");
        if (this.current != null) {
            Collection<InputValue> inputValues = this.current
                    .getRequiredInputValues();
            if (inputValues != null) {
                Iterator<InputValue> it = inputValues.iterator();
                while (it.hasNext()) {
                    InputValue inputValue = it.next();
                    Element inputNode = creator.create("input");
                    creator.addAttr(inputNode, "name", inputValue.getName());
                    creator.addAttr(inputNode, "type", inputValue.getType());
                    modelNode.appendChild(inputNode);
                }
            }
        }
        parent.appendChild(modelNode);
    }

    protected void createUserInterface(
        XMLUtils.ElementCreator creator,
        Element                 parent,
        Document                document,
        CallContext             context,
        String                  uuid
    ) {
        XMLUtils.ElementCreator xCreator = new XMLUtils.ElementCreator(
            document,
            XMLUtils.XFORM_URL,
            XMLUtils.XFORM_PREFIX
        );

        Element uiNode     = creator.create("ui");
        Element staticNode = creator.create("static");
        Element dynamic    = creator.create("dynamic");

        uiNode.appendChild(staticNode);
        uiNode.appendChild(dynamic);

        parent.appendChild(uiNode);

        // append fis to dynamic part
        appendFis(document, staticNode, context, product.getArtifactFactory());

        if (this.current != null) {
            Element staticUI = createSelectBox(
                creator, xCreator, document, context
            );
            staticNode.appendChild(staticUI);

            this.current.describe(
                document, uiNode, context, uuid
            );
        }
    }


    protected void createOutputs(
        XMLUtils.ElementCreator creator,
        Element                 parent,
        Document                document
    ) {
        log.debug("GNVArtifactBase.createOutputs");
        Element outputsNode = creator.create("outputs");
        if (this.current instanceof OutputState) {
            Collection<OutputMode> outputModes = ((OutputState) this.current)
                    .getOutputModes();
            if (outputModes != null) {
                Iterator<OutputMode> it = outputModes.iterator();
                while (it.hasNext()) {
                    OutputMode outputMode = it.next();
                    log.debug("Write Outputnode for " + outputMode.toString());
                    Element outputModeNode = creator.create("output");
                    creator.addAttr(
                        outputModeNode, "name", outputMode.getName());
                    creator.addAttr(
                        outputModeNode, "description", outputMode.getDescription());
                    creator.addAttr(
                        outputModeNode, "mime-type", outputMode.getMimeType());
                    outputsNode.appendChild(outputModeNode);

                    Collection<InputValue> inputParameters = outputMode
                            .getInputParameters();
                    if (inputParameters != null) {
                        Element inputParametersNode = creator.create("parameter");
                        outputModeNode.appendChild(inputParametersNode);
                        Iterator<InputValue> it2 = inputParameters.iterator();
                        while (it2.hasNext()) {
                            InputValue inputValue = it2.next();
                            Element inputParameterNode =
                                creator.create("parameter");
                            creator.addAttr(
                                inputParameterNode, "name", inputValue.getName());
                            creator.addAttr(
                                inputParameterNode, "type", inputValue.getType());
                            creator.addAttr(
                                inputParameterNode, "value", inputValue.getDefaultValue());
                            inputParametersNode.appendChild(inputParameterNode);
                        }
                    }
                }
            } else {
                log.warn("No Outputmodes given.");
            }
        }
        parent.appendChild(outputsNode);
    }

    protected Collection<InputData> parseInputData(Document document,
                                                   String xPath) {
        HashMap<String, InputData> returnValue = null;

        NodeList inputElemets = (NodeList) XMLUtils.xpath(document, xPath,
                XPathConstants.NODESET, ArtifactNamespaceContext.INSTANCE);
        if (inputElemets != null) {
            returnValue = new HashMap<String, InputData>();

            for (int i = 0; i < inputElemets.getLength(); i++) {
                Element inputDataNode = (Element)inputElemets.item(i);
                String name = inputDataNode.getAttribute("name");
                String value = inputDataNode.getAttribute("value");

                if (returnValue.containsKey(name)) {
                    InputData inputData = returnValue.get(name);
                    inputData.concartValue(value);
                    log.debug(inputData.toString());
                    returnValue.put(name, inputData);
                } else {
                    InputData inputData = new DefaultInputData(name, value);

                    returnValue.put(name, inputData);
                }
            }
        }
        return returnValue.values();
    }

    /**
     * @see de.intevation.artifactdatabase.DefaultArtifact#out(org.w3c.dom.Document,
     *      java.io.OutputStream, de.intevation.artifacts.CallContext)
     */
    @Override
    public void out(Document format, OutputStream outputStream,
                    CallContext context) throws IOException {
        log.debug("TGNVArtifactBase.out");
        try {

            if (current != null && current instanceof OutputState) {
                ((OutputState) current)
                        .out(format, this.parseInputData(
                                format, XPATH_OUTPUT_PARAMS),
                                outputStream, super.identifier, context);
            }
        } catch (StateException e) {
            log.error(e, e);
            throw new IOException(e.getMessage());
        }
    }

    protected static String readOutputType(Document document) {
        String value = XMLUtils.xpathString(
            document, XPATH_OUTPUT_NAME, ArtifactNamespaceContext.INSTANCE);
        return value;
    }


    public void setProduct(Product product) {
        this.product = product;
    }

    public void endOfLife(Object globalContext) {
        super.endOfLife(globalContext);

        if (current != null) {
            current.endOfLife(globalContext);
        }
    }
    
    /**
     * @see de.intevation.gnv.artifacts.PreSettingArtifact#getPreSettings()
     */
    public Map<String, InputData> getPreSettings() {
        return this.preSettings;
    }
    
    /**
     * @see de.intevation.gnv.artifacts.PreSettingArtifact#setPreSettings(java.util.Map)
     */
    public void setPreSettings(Map<String, InputData> preSettings) {
        this.preSettings = preSettings;
        if (this.current != null){
            this.current.setPreSettings(preSettings);
        }
    }
}
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