/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005, JBoss Inc., and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jbpm.graph.exe;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jbpm.JbpmContext;
import org.jbpm.JbpmException;
import org.jbpm.db.JobSession;
import org.jbpm.graph.def.Event;
import org.jbpm.graph.def.Node;
import org.jbpm.graph.def.ProcessDefinition;
import org.jbpm.graph.def.Transition;
import org.jbpm.graph.log.SignalLog;
import org.jbpm.graph.log.TokenCreateLog;
import org.jbpm.graph.log.TokenEndLog;
import org.jbpm.jpdl.el.impl.JbpmExpressionEvaluator;
import org.jbpm.logging.exe.LoggingInstance;
import org.jbpm.logging.log.CompositeLog;
import org.jbpm.logging.log.ProcessLog;
import org.jbpm.svc.Services;
import org.jbpm.taskmgmt.exe.TaskMgmtInstance;
import org.jbpm.util.Clock;
import org.jbpm.util.EqualsUtil;

/**
 * represents one path of execution and maintains a pointer to a node 
 * in the {@link org.jbpm.graph.def.ProcessDefinition}.  Most common 
 * way to get a hold of the token objects is with {@link ProcessInstance#getRootToken()}
 * or {@link org.jbpm.graph.exe.ProcessInstance#findToken(String)}.
 */
public class Token implements Serializable {

  private static final long serialVersionUID = 1L;

  long id = 0;
  int version = 0;
  protected String name = null;
  protected Date start = null;
  protected Date end = null;
  protected Node node = null;
  protected Date nodeEnter = null;
  protected ProcessInstance processInstance = null;
  protected Token parent = null;
  protected Map children = null;
  protected List comments = null;
  protected ProcessInstance subProcessInstance = null;
  protected int nextLogIndex = 0;
  boolean isAbleToReactivateParent = true;
  boolean isTerminationImplicit = false;
  boolean isSuspended = false;
  String lock = null;

  // constructors
  /////////////////////////////////////////////////////////////////////////////
  
  public Token() {
  }

  /**
   * creates a root token.
   */
  public Token(ProcessInstance processInstance) {
    this.start = Clock.getCurrentTime();
    this.processInstance = processInstance;
    this.node = processInstance.getProcessDefinition().getStartState();
    this.isTerminationImplicit = processInstance.getProcessDefinition().isTerminationImplicit();
    
    // optimization:  assigning an id is not necessary since the process instance will be saved shortly.
    // Services.assignId(this);
  }

  /**
   * creates a child token.
   */
  public Token(Token parent, String name) {
    this.start = Clock.getCurrentTime();
    this.processInstance = parent.getProcessInstance();
    this.name = name;
    this.node = parent.getNode();
    this.parent = parent;
    parent.addChild(this);
    this.isTerminationImplicit = parent.isTerminationImplicit();
    parent.addLog(new TokenCreateLog(this));
    
    // assign an id to this token before events get fired
    Services.assignId(this);
  }

  // operations
  /////////////////////////////////////////////////////////////////////////////

  void addChild(Token token) {
    if (children==null) {
      children = new HashMap();
    }
    children.put(token.getName(), token);
  }

  /**
   * provides a signal to the token. this method activates this token and leaves
   * the current state over the default transition.
   */
  public void signal() {
    if (node==null) {
      throw new JbpmException("token '" + this + "' can't be signalled cause it is currently not positioned in a node");
    }
    if (node.getDefaultLeavingTransition() == null) {
      throw new JbpmException("couldn't signal token '" + this + "' : node '" + node + "' doesn't have a default transition");
    }
    signal(node.getDefaultLeavingTransition(), new ExecutionContext(this));
  }

  /**
   * provides a signal to the token. this leave the current state over the given
   * transition name.
   */
  public void signal(String transitionName) {
    if (node==null) {
      throw new JbpmException("token '" + this + "' can't be signalled cause it is currently not positioned in a node");
    }
    if (node.getDefaultLeavingTransition() == null) {
      throw new JbpmException("couldn't signal token '" + this + "' : node '" + node + "' doesn't have a default transition");
    }
    Transition leavingTransition = node.getLeavingTransition(transitionName);
    if (leavingTransition==null) {
      throw new JbpmException("transition '"+transitionName+"' does not exist on "+node);
    }
    signal(leavingTransition, new ExecutionContext(this));
  }
  
  /**
   * provides a signal to the token. this leave the current state over the given
   * transition name.
   */
  public void signal(Transition transition) {
    signal(transition, new ExecutionContext(this));
  }
  

  void signal(ExecutionContext executionContext) {
    signal(node.getDefaultLeavingTransition(), executionContext);
  }

  void signal(Transition transition, ExecutionContext executionContext) {
    if (transition == null) {
      throw new JbpmException("couldn't signal without specifying  a leaving transition : transition is null");
    }
    if (executionContext == null) {
      throw new JbpmException("couldn't signal without an execution context: executionContext is null");
    }
    if (isSuspended) {
      throw new JbpmException("can't signal token '"+name+"' ("+id+"): it is suspended");
    }
    if (isLocked()) {
      throw new JbpmException("this token is locked by "+lock);
    }

    startCompositeLog(new SignalLog(transition));
    try {
      // fire the event before-signal
      Node signalNode = node;
      signalNode.fireEvent(Event.EVENTTYPE_BEFORE_SIGNAL, executionContext);
      
      // start calculating the next state
      node.leave(executionContext, transition);
      
      // if required, check if this token is implicitly terminated
      checkImplicitTermination();
      
      // fire the event after-signal
      signalNode.fireEvent(Event.EVENTTYPE_AFTER_SIGNAL, executionContext);
      
    } finally {
      endCompositeLog();
    }
  }
  
  /**
   * a set of all the leaving transitions on the current node for which the condition expression resolves to true. 
   */
  public Set getAvailableTransitions() {
    Set availableTransitions = new HashSet();
    if (node!=null) {
    	addAvailableTransitionsOfNode(node, availableTransitions);
    }
    return availableTransitions;
  }
  
  /**
   * adds available transitions of that node to the Set
   * and after that calls itself recursivly for the SuperSate of the Node
   * if it has a super state
   */
  private void addAvailableTransitionsOfNode(Node currentNode, Set availableTransitions) {
      List leavingTransitions = currentNode.getLeavingTransitions();
      if (leavingTransitions!=null) {
        Iterator iter = leavingTransitions.iterator();
        while (iter.hasNext()) {
          Transition transition = (Transition) iter.next();
          String conditionExpression = transition.getCondition();
          if (conditionExpression!=null) {
            Object result = JbpmExpressionEvaluator.evaluate(conditionExpression, new ExecutionContext(this));
            if ( (result instanceof Boolean)
                 && (((Boolean)result).booleanValue())
               ) {
              availableTransitions.add(transition);
            }
          } else {
            availableTransitions.add(transition);
          }
        }
      }	  
      if (currentNode.getSuperState() != null) {
    	  addAvailableTransitionsOfNode(currentNode.getSuperState(), availableTransitions);
      }
  }

  /**
   * ends this token and all of its children (if any). this is the last active (=not-ended) child of a parent token, 
   * the parent token will be ended as well and that verification will continue to 
   * propagate.
   */
  public void end() {
    end(true);
  }
  
  /**
   * ends this token with optional parent ending verification.
   * @param verifyParentTermination specifies if the parent token should be checked for termination.
   * if verifyParentTermination is set to true and this is the last non-ended child of a parent token, 
   * the parent token will be ended as well and the verification will continue to propagate.
   */
  public void end(boolean verifyParentTermination) {
    // if not already ended
    if (end==null) {

      // ended tokens cannot reactivate parents
      isAbleToReactivateParent = false;
      
      // set the end date
      // the end date is also the flag that indicates that this token has ended.
      this.end = Clock.getCurrentTime();
      
      // end all this token's children
      if (children != null) {
        Iterator iter = children.values().iterator();
        while (iter.hasNext()) {
          Token child = (Token) iter.next();
          if (!child.hasEnded()) {
            child.end();
          }
        }
      }
      
      if (subProcessInstance!=null) {
        subProcessInstance.end();
      }

      // only log the end of child-tokens.  the process instance logs replace the root token logs.
      if (parent!=null) {
        // add a log
        parent.addLog(new TokenEndLog(this));
      }

      // if there are tasks associated to this token, remove signalling capabilities
      TaskMgmtInstance taskMgmtInstance = (processInstance!=null ? processInstance.getTaskMgmtInstance() : null);
      if (taskMgmtInstance!=null) {
        taskMgmtInstance.removeSignalling(this);
      }

      if (verifyParentTermination) {
        // if this is the last active token of the parent, 
        // the parent needs to be ended as well
        notifyParentOfTokenEnd();
      }
    }
  }
  
  // comments /////////////////////////////////////////////////////////////////

  public void addComment(String message) {
    addComment(new Comment(message));
  }

  public void addComment(Comment comment) {
    if (comments==null) comments = new ArrayList();
    comments.add(comment);
    comment.setToken(this);
  }
  
  public List getComments() {
    return comments;
  }
 
  // operations helper methods ////////////////////////////////////////////////

  /**
   * notifies a parent that one of its nodeMap has ended.
   */
  void notifyParentOfTokenEnd() {
    if (isRoot()) {
      processInstance.end();
    } else {
      
      if (!parent.hasActiveChildren()) {
        parent.end();
      }
    }
  }

  /**
   * tells if this token has child tokens that have not yet ended.
   */
  public boolean hasActiveChildren() {
    boolean foundActiveChildToken = false;
    // try and find at least one child token that is
    // still active (= not ended)
    if (children!=null) {
      Iterator iter = children.values().iterator();
      while ((iter.hasNext()) && (!foundActiveChildToken)) {
        Token child = (Token) iter.next();
        if (!child.hasEnded()) {
          foundActiveChildToken = true;
        }
      }
    }
    return foundActiveChildToken;
  }

  // log convenience methods //////////////////////////////////////////////////

  /**
   * convenience method for adding a process log.
   */
  public void addLog(ProcessLog processLog) {
    LoggingInstance li = (LoggingInstance) processInstance.getInstance(LoggingInstance.class);
    if (li != null) {
      processLog.setToken(this);