/*
    * 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.commons.scxml2.model;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.scxml2.ActionExecutionContext;
  import org.apache.commons.scxml2.Context;
  import org.apache.commons.scxml2.Evaluator;
  import org.apache.commons.scxml2.SCXMLExpressionException;
  import org.apache.commons.scxml2.TriggerEvent;
  import org.apache.commons.scxml2.semantics.ErrorConstants;
  
  /**
   * The class in this SCXML object model that corresponds to the
   * <if> SCXML element, which serves as a container for conditionally
   * executed elements. <else> and <elseif> can optionally
   * appear within an <if> as immediate children, and serve to partition
   * the elements within an <if>.
   *
   */
  public class If extends Action implements ActionsContainer {
  
      /**
       * Serial version UID.
       */
      private static final long serialVersionUID = 1L;
  
      /**
       * An conditional expression which can be evaluated to true or false.
       */
      private String cond;
  
      /**
       * The set of executable elements (those that inheriting from
       * Action) that are contained in this <if> element.
       */
      private List<Action> actions;
  
      /**
       * The boolean value that dictates whether the particular child action
       * should be executed.
       */
      private boolean execute;
  
      /**
       * Constructor.
       */
      public If() {
          super();
          this.actions = new ArrayList<Action>();
          this.execute = false;
      }
  
      @Override
      public final String getContainerElementName() {
          return ELEM_IF;
      }
  
      /**
       * Get the executable actions contained in this &lt;if&gt;.
       *
       * @return Returns the actions.
       */
      public final List<Action> getActions() {
          return actions;
      }
  
      /**
       * Add an Action to the list of executable actions contained in
       * this &lt;if&gt;.
       *
       * @param action The action to add.
       */
      public final void addAction(final Action action) {
          if (action != null) {
              this.actions.add(action);
          }
      }
  
      /**
       * Get the conditional expression.
       *
       * @return Returns the cond.
      */
     public final String getCond() {
         return cond;
     }
 
     /**
      * Set the conditional expression.
      *
      * @param cond The cond to set.
      */
     public final void setCond(final String cond) {
         this.cond = cond;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void execute(ActionExecutionContext exctx) throws ModelException, SCXMLExpressionException {
         EnterableState parentState = getParentEnterableState();
         Context ctx = exctx.getContext(parentState);
         Evaluator eval = exctx.getEvaluator();
         ctx.setLocal(getNamespacesKey(), getNamespaces());
         Boolean rslt;
         try {
             rslt = eval.evalCond(ctx, cond);
             if (rslt == null) {
                 if (exctx.getAppLog().isDebugEnabled()) {
                     exctx.getAppLog().debug("Treating as false because the cond expression was evaluated as null: '"
                             + cond + "'");
                 }
                 rslt = Boolean.FALSE;
             }
         } catch (SCXMLExpressionException e) {
             rslt = Boolean.FALSE;
             exctx.getInternalIOProcessor().addEvent(new TriggerEvent(TriggerEvent.ERROR_EXECUTION, TriggerEvent.ERROR_EVENT));
             exctx.getErrorReporter().onError(ErrorConstants.EXPRESSION_ERROR, "Treating as false due to error: "
                     + e.getMessage(), this);
         }
         execute = rslt;
         ctx.setLocal(getNamespacesKey(), null);
         // The "if" statement is a "container"
         for (Action aa : actions) {
             if (execute && !(aa instanceof ElseIf)) {
                 aa.execute(exctx);
             } else if (execute && aa instanceof ElseIf) {
                 break;
             } else if (aa instanceof Else) {
                 execute = true;
             } else if (aa instanceof ElseIf) {
                 ctx.setLocal(getNamespacesKey(), getNamespaces());
                 execute = eval.evalCond(ctx, ((ElseIf) aa).getCond());
                 ctx.setLocal(getNamespacesKey(), null);
             }
         }
     }
 
 }