/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.oodt.cas.workflow.repository;

//OODT imports
import org.apache.oodt.cas.metadata.Metadata;
import org.apache.oodt.cas.workflow.util.XmlStructFactory;
import org.apache.oodt.cas.workflow.examples.NoOpTask;
import org.apache.oodt.cas.workflow.structs.Workflow;
import org.apache.oodt.cas.workflow.structs.WorkflowTask;
import org.apache.oodt.cas.workflow.structs.WorkflowCondition;
import org.apache.oodt.cas.workflow.structs.WorkflowTaskConfiguration;
import org.apache.oodt.cas.workflow.structs.WorkflowTaskInstance;
import org.apache.oodt.cas.workflow.structs.exceptions.RepositoryException;
import org.apache.oodt.cas.workflow.structs.exceptions.WorkflowTaskInstanceException;

//JDK imports
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Set;
import java.util.UUID;
import java.util.Vector;
import java.util.Iterator;
import java.util.Arrays;
import java.net.URI;
import java.net.URISyntaxException;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.FileFilter;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.Element;
import org.xml.sax.InputSource;

/**
 * @author mattmann
 * @version $Revsion$
 * 
 * <p>
 * A {@link WorkflowRepository} that loads events, {@link Workflow}s,
 * {@link WorkflowTask}s and {@link WorkflowCondition}s from specialized xml
 * files. The WorkflowRepository is given an initial set of seed directory uris,
 * where it looks for the following files:
 * 
 * <ul>
 * <li>conditions.xml - defines workflow pre conditions</li>
 * <li>tasks.xml - defines workflow tasks</li>
 * <li>*.workflow.xml - individual workflow xml files specifying a single
 * workflow</li>
 * <li>events.xml - maps available workflows to event names</li>
 * </ul>
 * 
 * All of the WorkflowTasks, WorkflowConditions and Workflows themselves are
 * cached in memory by their ids (which are typically URNs).
 * </p>
 */
public class XMLWorkflowRepository implements WorkflowRepository {

    /* the list of directory URIs where workflow xml files live */
    private List workflowHomeUris = null;

    /* our log stream */
    private static Logger LOG = Logger.getLogger(XMLWorkflowRepository.class
            .getName());

    /* our task map */
    private static HashMap taskMap = new HashMap();

    /* our condition map */
    private static HashMap conditionMap = new HashMap();

    /* our workflow map */
    private static HashMap workflowMap = new HashMap();

    /* our event map */
    private static HashMap eventMap = new HashMap();

    private static FileFilter workflowXmlFilter = new FileFilter() {
        public boolean accept(File pathname) {
            return pathname.isFile()
                    && pathname.toString().endsWith(".workflow.xml");
        }
    };

    /**
     * <p>
     * Constructs a new XMLWorkflowRepository with the given parameter
     * <code>uris</code>.
     * </p>
     * 
     * @param uris
     *            URIs pointing to directories that follow the XML workflow
     *            repository convention documented at the top of this class.
     */
    public XMLWorkflowRepository(List uris) {
        workflowHomeUris = uris;

        // load the tasks and conditions
        loadConditions(workflowHomeUris);
        loadTasks(workflowHomeUris);
        loadWorkflows(workflowHomeUris);
        loadEvents(workflowHomeUris);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getRegisteredEvents()
     */
    public List getRegisteredEvents() throws RepositoryException {
        return Arrays.asList(eventMap.keySet().toArray());
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getWorkflowTaskById(java.lang.String)
     */
    public WorkflowTask getWorkflowTaskById(String taskId)
            throws RepositoryException {
        return (WorkflowTask) taskMap.get(taskId);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getWorkflowConditionById(java.lang.String)
     */
    public WorkflowCondition getWorkflowConditionById(String conditionId)
            throws RepositoryException {
        return (WorkflowCondition) conditionMap.get(conditionId);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getWorkflowByName(java.lang.String)
     */
    public Workflow getWorkflowByName(String workflowName)
            throws RepositoryException {
        for (Iterator i = workflowMap.keySet().iterator(); i.hasNext();) {
            String workflowId = (String) i.next();
            Workflow w = (Workflow) workflowMap.get(workflowId);

            if (w.getName().equals(workflowName)) {
                return w;
            }
        }

        return null;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getWorkflowById(java.lang.String)
     */
    public Workflow getWorkflowById(String workflowId)
            throws RepositoryException {
        return (Workflow) workflowMap.get(workflowId);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getWorkflows()
     */
    public List getWorkflows() throws RepositoryException {
        return Arrays.asList(workflowMap.values().toArray());
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getTasksByWorkflowId(java.lang.String)
     */
    public List getTasksByWorkflowId(String workflowId)
            throws RepositoryException {
        Workflow w = getWorkflowById(workflowId);
        return w.getTasks();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getTasksByWorkflowName(java.lang.String)
     */
    public List getTasksByWorkflowName(String workflowName)
            throws RepositoryException {
        Workflow w = getWorkflowByName(workflowName);
        return w.getTasks();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getWorkflowsForEvent(java.lang.String)
     */
    public List getWorkflowsForEvent(String eventName)
            throws RepositoryException {
        return (List) eventMap.get(eventName);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getConditionsByTaskName(java.lang.String)
     */
    public List getConditionsByTaskName(String taskName)
            throws RepositoryException {
        for (Iterator i = taskMap.values().iterator(); i.hasNext();) {
            WorkflowTask t = (WorkflowTask) i.next();
            if (t.getTaskName().equals(taskName)) {
                return t.getConditions();
            }
        }

        return null;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getConditionsByTaskId(java.lang.String)
     */
    public List getConditionsByTaskId(String taskId) throws RepositoryException {
        WorkflowTask t = (WorkflowTask) taskMap.get(taskId);
        if (t != null) {
            return t.getConditions();
        } else
            return null;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getConfigurationByTaskId(java.lang.String)
     */
    public WorkflowTaskConfiguration getConfigurationByTaskId(String taskId)
            throws RepositoryException {
        WorkflowTask task = (WorkflowTask) taskMap.get(taskId);
        return task.getTaskConfig();
    }
    

    /* (non-Javadoc)
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#addTask(org.apache.oodt.cas.workflow.structs.WorkflowTask)
     */
    @Override
    public String addTask(WorkflowTask task) throws RepositoryException {
      // check its conditions
      if(task.getPreConditions() != null && task.getPreConditions().size() > 0){
        for(WorkflowCondition cond: task.getPreConditions()){
          if(!this.conditionMap.containsKey(cond.getConditionId())){
            throw new RepositoryException("Reference in new task: ["+task.getTaskName()+"] to undefined pre condition ith id: ["+cond.getConditionId()+"]");            
          }          
        }
        
        for(WorkflowCondition cond: task.getPostConditions()){
          if(!this.conditionMap.containsKey(cond.getConditionId())){
            throw new RepositoryException("Reference in new task: ["+task.getTaskName()+"] to undefined post condition ith id: ["+cond.getConditionId()+"]");            
          }              
        }
      }
      
        String taskId = task.getTaskId() != null ? 
             task.getTaskId():UUID.randomUUID().toString();
        this.taskMap.put(taskId, task);
        return taskId;
    }
    

    /* (non-Javadoc)
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#addWorkflow(org.apache.oodt.cas.workflow.structs.Workflow)
     */
    @Override
    public String addWorkflow(Workflow workflow) throws RepositoryException {
       // first check to see that its tasks are all present
      if(workflow.getTasks() == null || (workflow.getTasks() != null && workflow.getTasks().size() == 0)){
        throw new RepositoryException("Attempt to define a new worklfow: ["+workflow.getName()+"] with no tasks.");
      }
      
      for(WorkflowTask task: (List<WorkflowTask>)workflow.getTasks()){
        if(!this.taskMap.containsKey(task.getTaskId())){
          throw new RepositoryException("Reference in new workflow: ["+workflow.getName()+"] to undefined task with id: ["+task.getTaskId()+"]");
        }
        
        // check its conditions
        if(task.getConditions() != null && task.getConditions().size() > 0){
          for(WorkflowCondition cond: (List<WorkflowCondition>)task.getConditions()){
            if(!this.conditionMap.containsKey(cond.getConditionId())){
              throw new RepositoryException("Reference in new workflow: ["+workflow.getName()+"] to undefined condition ith id: ["+cond.getConditionId()+"]");
            }
          }
        }
      }
      
      // generate its ID
      String workflowId = UUID.randomUUID().toString();
      workflow.setId(workflowId);
      this.workflowMap.put(workflowId, workflow);
      this.eventMap.put(workflowId, Collections.singletonList(workflow));
      return workflowId;
    }    
    
    /* (non-Javadoc)
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getConditionsByWorkflowId(java.lang.String)
     */
    @Override
    public List<WorkflowCondition> getConditionsByWorkflowId(String workflowId)
        throws RepositoryException {
      if(!this.workflowMap.containsKey(workflowId)) throw new 
         RepositoryException("Attempt to obtain conditions for a workflow: " +
         		"["+workflowId+"] that does not exist!");
      
      return ((Workflow)this.workflowMap.get(workflowId)).getConditions();
    }    
    

    /* (non-Javadoc)
     * @see org.apache.oodt.cas.workflow.repository.WorkflowRepository#getTaskById(java.lang.String)
     */
    @Override
    public WorkflowTask getTaskById(String taskId) throws RepositoryException {
      return (WorkflowTask)this.taskMap.get(taskId);
    }    

    /**
     * @param args
     */
    public static void main(String[] args) throws RepositoryException {
        String usage = "XmlWorkflowRepository <uri 1>...<uri n>\n";
        List uris = null;

        if (args.length == 0) {
            System.err.println(usage);
            System.exit(1);
        }

        uris = new Vector(args.length);

        for (int i = 0; i < args.length; i++) {
            if (args[i] != null) {
                uris.add(args[i]);
            }
        }

        XMLWorkflowRepository repo = new XMLWorkflowRepository(uris);

        List workflows = repo.getWorkflows();

        if (workflows != null) {
            for (Iterator i = workflows.iterator(); i.hasNext();) {
                Workflow w = (Workflow) i.next();
                System.out.println("Workflow: [id=" + w.getId() + ", name="
                        + w.getName() + "]");

                System.out.println("Tasks: ");

                for (Iterator j = w.getTasks().iterator(); j.hasNext();) {
                    WorkflowTask task = (WorkflowTask) j.next();

                    System.out.println("Task: [class="
                            + task.getTaskInstanceClassName() + ", id="
                            + task.getTaskId() + ", name=" + task.getTaskName()
                            + ", order=" + task.getOrder() + ",reqMetFields="
                            + task.getRequiredMetFields() + "]");
                    System.out.println("Configuration: ");

                    for (Iterator k = task.getTaskConfig().getProperties()
                            .keySet().iterator(); k.hasNext();) {
                        String key = (String) k.next();
                        String value = (String) task.getTaskConfig()
                                .getProperties().get(key);

                        System.out.println("[name=" + key + ", value=" + value
                                + "]");
                    }

                    System.out.println("Conditions: ");

                    for (Iterator k = task.getConditions().iterator(); k
                            .hasNext();) {
                        WorkflowCondition condition = (WorkflowCondition) k
                                .next();
                        System.out.println("Condition: ["
                                + condition.getClass().getName() + ", id="
                                + condition.getConditionId() + ", name="
                                + condition.getConditionName() + ", timeout="
                                + condition.getTimeoutSeconds()+ ", optional="
                                + condition.isOptional()+", order="
                                + condition.getOrder() + "]");
                        
                        System.out.println("Configuration: ");
                        for (String cKeyName : (Set<String>) (Set<?>) condition
                          .getCondConfig().getProperties().keySet()) {
                         System.out.println("[name=" + cKeyName + ", value="
                         + condition.getCondConfig().getProperty(cKeyName) + "]");
                        }
                    }

                }

            }
        } else {
            System.out.println("No workflows defined!");
        }

    }

    private void loadTasks(List dirUris) {
        if (dirUris != null && dirUris.size() > 0) {
            for (Iterator i = dirUris.iterator(); i.hasNext();) {
                String dirUri = (String) i.next();

                try {
                    File workflowDir = new File(new URI(dirUri));
                    if (workflowDir.isDirectory()) {
                        String workflowDirStr = workflowDir.getAbsolutePath();

                        if (!workflowDirStr.endsWith("/")) {
                            workflowDirStr += "/";
                        }

                        Document taskRoot = getDocumentRoot(workflowDirStr
                                + "tasks.xml");

                        Element taskElement = taskRoot.getDocumentElement();

                        NodeList taskElemList = taskElement
                                .getElementsByTagName("task");

                        if (taskElemList != null
                                && taskElemList.getLength() > 0) {
                            for (int j = 0; j < taskElemList.getLength(); j++) {
                                Element taskElem = (Element) taskElemList
                                        .item(j);
                                WorkflowTask task = XmlStructFactory
                                        .getWorkflowTask(taskElem, conditionMap);
                                if (task != null) {
                                    taskMap.put(task.getTaskId(), task);
                                }
                            }

                        }
                    }
                } catch (URISyntaxException e) {
                    LOG
                            .log(
                                    Level.WARNING,
                                    "DirUri: "
                                            + dirUri
                                            + " is not a directory: skipping task loading for it.");
                }

            }
        }
    }

    private void loadConditions(List dirUris) {
        if (dirUris != null && dirUris.size() > 0) {
            for (Iterator i = dirUris.iterator(); i.hasNext();) {
                String dirUri = (String) i.next();

                try {
                    File workflowDir = new File(new URI(dirUri));
                    if (workflowDir.isDirectory()) {
                        String workflowDirStr = workflowDir.getAbsolutePath();

                        if (!workflowDirStr.endsWith("/")) {
                            workflowDirStr += "/";
                        }

                        Document conditionRoot = getDocumentRoot(workflowDirStr
                                + "conditions.xml");

                        Element conditionElement = conditionRoot
                                .getDocumentElement();

                        NodeList conditionElemList = conditionElement
                                .getElementsByTagName("condition");

                        if (conditionElemList != null
                                && conditionElemList.getLength() > 0) {
                            for (int j = 0; j < conditionElemList.getLength(); j++) {
                                Element conditionElem = (Element) conditionElemList
                                        .item(j);
                                WorkflowCondition condition = XmlStructFactory
                                        .getWorkflowCondition(conditionElem);
                                if (condition != null) {
                                    conditionMap.put(
                                            condition.getConditionId(),
                                            condition);
                                }
                            }

                        }
                    }
                } catch (URISyntaxException e) {
                    LOG
                            .log(
                                    Level.WARNING,
                                    "DirUri: "
                                            + dirUri
                                            + " is not a directory: skipping condition loading for it.");
                }

            }
        }
    }

    private void loadWorkflows(List dirUris) {
        if (dirUris != null && dirUris.size() > 0) {
            for (Iterator i = dirUris.iterator(); i.hasNext();) {
                String dirUri = (String) i.next();

                try {
                    File workflowDir = new File(new URI(dirUri));
                    if (workflowDir.isDirectory()) {
                        String workflowDirStr = workflowDir.getAbsolutePath();

                        if (!workflowDirStr.endsWith("/")) {
                            workflowDirStr += "/";
                        }

                        // get all the workflow xml files
                        File[] workflowFiles = workflowDir
                                .listFiles(workflowXmlFilter);

                        for (int j = 0; j < workflowFiles.length; j++) {
                            String workflowXmlFile = workflowFiles[j]
                                    .getAbsolutePath();
                            Document workflowRoot = getDocumentRoot(workflowXmlFile);

                            String workflowId = workflowRoot
                                    .getDocumentElement().getAttribute("id");
                            if (workflowMap.get(workflowId) == null) {
                                Workflow w = XmlStructFactory.getWorkflow(
                                        workflowRoot.getDocumentElement(),
                                        taskMap, conditionMap);
                                
                                if(w.getConditions() != null && w.getConditions().size() > 0){
                                  // add a virtual first task, with the conditions 
                                  w.getTasks().add(0, getGlobalWorkflowConditionsTask(w.getName(), w.getId(), w.getConditions()));
                                }
                                workflowMap.put(workflowId, w);
                            } else {
                                LOG
                                        .log(
                                                Level.FINE,
                                                "Ignoring workflow file: "
                                                        + workflowXmlFile
                                                        + " when loading workflows, workflow id: "
                                                        + workflowId
                                                        + " already loaded");
                            }

                        }
                    }
                } catch (URISyntaxException e) {
                    LOG
                            .log(
                                    Level.WARNING,
                                    "DirUri: "
                                            + dirUri
                                            + " is not a directory: skipping workflow loading for it.");
                }

            }
        }
    }

    private void loadEvents(List dirUris) {
        if (dirUris != null && dirUris.size() > 0) {
            for (Iterator i = dirUris.iterator(); i.hasNext();) {
                String dirUri = (String) i.next();

                try {
                    File workflowDir = new File(new URI(dirUri));
                    if (workflowDir.isDirectory()) {
                        String workflowDirStr = workflowDir.getAbsolutePath();

                        if (!workflowDirStr.endsWith("/")) {
                            workflowDirStr += "/";
                        }

                        Document eventRoot = getDocumentRoot(workflowDirStr
                                + "events.xml");

                        Element eventElement = eventRoot.getDocumentElement();

                        NodeList eventElemList = eventElement
                                .getElementsByTagName("event");

                        if (eventElemList != null
                                && eventElemList.getLength() > 0) {
                            for (int j = 0; j < eventElemList.getLength(); j++) {
                                Element eventElem = (Element) eventElemList
                                        .item(j);

                                String eventName = eventElem
                                        .getAttribute("name");
                                Workflow w = null;

                                NodeList workflowNodeList = eventElem
                                        .getElementsByTagName("workflow");

                                if (workflowNodeList != null
                                        && workflowNodeList.getLength() > 0) {
                                    List workflowList = new Vector();

                                    for (int k = 0; k < workflowNodeList
                                            .getLength(); k++) {
                                        Element workflowElement = (Element) workflowNodeList
                                                .item(k);
                                        w = (Workflow) workflowMap
                                                .get(workflowElement
                                                        .getAttribute("id"));

                                        if (w != null) {
                                            workflowList.add(w);
                                        }
                                    }

                                    eventMap.put(eventName, workflowList);
                                }
                            }
                        }
                    }
                } catch (URISyntaxException e) {
                    LOG
                            .log(
                                    Level.WARNING,
                                    "DirUri: "
                                            + dirUri
                                            + " is not a directory: skipping event loading for it.");
                }

            }
        }
    }

    private Document getDocumentRoot(String xmlFile) {
        // open up the XML file
        DocumentBuilderFactory factory = null;
        DocumentBuilder parser = null;
        Document document = null;
        InputSource inputSource = null;

        InputStream xmlInputStream = null;

        try {
            xmlInputStream = new File(xmlFile).toURL().openStream();
        } catch (IOException e) {
            LOG.log(Level.WARNING,
                    "IOException when getting input stream from [" + xmlFile
                            + "]: returning null document root");
            return null;
        }

        inputSource = new InputSource(xmlInputStream);

        try {
            factory = DocumentBuilderFactory.newInstance();
            parser = factory.newDocumentBuilder();
            document = parser.parse(inputSource);
        } catch (Exception e) {
            LOG.warning("Unable to parse xml file [" + xmlFile + "]."
                    + "Reason is [" + e + "]");
            return null;
        }

        return document;
    }
    
    private WorkflowTask getGlobalWorkflowConditionsTask(String workflowName, String workflowId, List<WorkflowCondition> conditions){
      WorkflowTask task = new WorkflowTask();
      task.setConditions(conditions);
      task.setTaskConfig(new WorkflowTaskConfiguration());
      task.setTaskId(workflowId+"-global-conditions-eval");
      task.setTaskName(workflowName+"-global-conditions-eval");
      task.setTaskInstanceClassName(NoOpTask.class.getName());
      this.taskMap.put(task.getTaskId(), task);
      return task;
    }

}