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/*
 * Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
 * under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright
 * ownership. Camunda licenses this file to you under the Apache License,
 * Version 2.0; 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.camunda.bpm.engine.impl.scripting.engine;

import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.script.Bindings;
import javax.script.ScriptEngine;

import org.camunda.bpm.engine.delegate.VariableScope;
import org.camunda.bpm.engine.impl.cfg.ProcessEngineConfigurationImpl;
import org.camunda.bpm.engine.impl.context.Context;


/**
 * A {@link Bindings} implementation which wraps an existing binding and enhances the key / value map with
 * read-only access to:
 * 

 * variables provided in a {@link VariableScope},
 * additional bindings provided through a set of {@link Resolver Resolvers}.
 * 
 *
 * Note on backwards compatibility: before 7.2 the Script
 * bindings behaved in a way that all script variables were automatically exposed
 * as process variables. You can enable this behavior by setting {@link #autoStoreScriptVariables}.
 * 
 *
 *
 * @author Tom Baeyens
 * @author Daniel Meyer
 */
public class ScriptBindings implements Bindings {

  /**
   * The script engine implementations put some key/value pairs into the binding.
   * This list contains those keys, such that they wouldn't be stored as process variable.
   *
   * This list contains the keywords for JUEL, Javascript and Groovy.
   */
  protected static final Set UNSTORED_KEYS =
    new HashSet(Arrays.asList(
      "out",
      "out:print",
      "lang:import",
      "context",
      "elcontext",
      "print",
      "println",
      "S", // Spin Internal Variable
      "XML", // Spin Internal Variable
      "JSON", // Spin Internal Variable
      ScriptEngine.ARGV, // jRuby is only setting this variable and execution instead of exporting any other variables
      "execution",
      "__doc__" // do not export python doc string
      ));

  protected List scriptResolvers;
  protected VariableScope variableScope;

  protected Bindings wrappedBindings;

  /** if true, all script variables will be set in the variable scope. */
  protected boolean autoStoreScriptVariables;

  public ScriptBindings(List scriptResolvers, VariableScope variableScope, Bindings wrappedBindings) {
    this.scriptResolvers = scriptResolvers;
    this.variableScope = variableScope;
    this.wrappedBindings = wrappedBindings;
    autoStoreScriptVariables = isAutoStoreScriptVariablesEnabled();
  }

  protected boolean isAutoStoreScriptVariablesEnabled() {
    ProcessEngineConfigurationImpl processEngineConfiguration = Context.getProcessEngineConfiguration();
    if(processEngineConfiguration != null) {
      return processEngineConfiguration.isAutoStoreScriptVariables();
    }
    return false;
  }

  public boolean containsKey(Object key) {
    for (Resolver scriptResolver: scriptResolvers) {
      if (scriptResolver.containsKey(key)) {
        return true;
      }
    }
    return wrappedBindings.containsKey(key);
  }

  public Object get(Object key) {
    Object result = null;

    if(wrappedBindings.containsKey(key)) {
      result = wrappedBindings.get(key);

    } else {
      for (Resolver scriptResolver: scriptResolvers) {
        if (scriptResolver.containsKey(key)) {
          result = scriptResolver.get(key);
        }
      }
    }

    return result;
  }

  public Object put(String name, Object value) {

    if(autoStoreScriptVariables) {
      if (!UNSTORED_KEYS.contains(name)) {
        Object oldValue = variableScope.getVariable(name);
        variableScope.setVariable(name, value);
        return oldValue;
      }
    }

    return wrappedBindings.put(name, value);
  }

  public Set> entrySet() {
    return calculateBindingMap().entrySet();
  }

  public Set keySet() {
    return calculateBindingMap().keySet();
  }

  public int size() {
    return calculateBindingMap().size();
  }

  public Collection