/* Licensed 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.activiti.engine.impl.cmd;

import org.activiti.engine.ActivitiException;
import org.activiti.engine.impl.context.Context;
import org.activiti.engine.impl.form.DefaultFormHandler;
import org.activiti.engine.impl.interceptor.Command;
import org.activiti.engine.impl.interceptor.CommandContext;
import org.activiti.engine.impl.persistence.entity.ProcessDefinitionEntity;
import org.activiti.engine.impl.task.TaskDefinition;


/**
 * Command for retrieving start or task form keys.
 *
 * @author Falko Menge (camunda)
 */
public class GetFormKeyCmd implements Command<String> {

  protected String taskDefinitionKey;
  protected String processDefinitionId;

  /**
   * Retrieves a start form key.
   */
  public GetFormKeyCmd(String processDefinitionId) {
    setProcessDefinitionId(processDefinitionId);
  }

  /**
   * Retrieves a task form key.
   */
  public GetFormKeyCmd(String processDefinitionId, String taskDefinitionKey) {
    setProcessDefinitionId(processDefinitionId);
    if (taskDefinitionKey == null || taskDefinitionKey.length() < 1) {
      throw new ActivitiException("The task definition key is mandatory, but '" + taskDefinitionKey + "' has been provided.");
    }
    this.taskDefinitionKey = taskDefinitionKey;
  }

  protected void setProcessDefinitionId(String processDefinitionId) {
    if (processDefinitionId == null || processDefinitionId.length() < 1) {
      throw new ActivitiException("The process definition id is mandatory, but '" + processDefinitionId + "' has been provided.");
    }
    this.processDefinitionId = processDefinitionId;
  }

  public String execute(CommandContext commandContext) {
    ProcessDefinitionEntity processDefinition = Context
            .getProcessEngineConfiguration()
            .getDeploymentCache()
            .findDeployedProcessDefinitionById(processDefinitionId);
    DefaultFormHandler formHandler;
    if (taskDefinitionKey == null) {
      // TODO: Maybe add getFormKey() to FormHandler interface to avoid the following cast
      formHandler = (DefaultFormHandler) processDefinition.getStartFormHandler();
    } else {
      TaskDefinition taskDefinition = processDefinition.getTaskDefinitions().get(taskDefinitionKey);
      // TODO: Maybe add getFormKey() to FormHandler interface to avoid the following cast
      formHandler = (DefaultFormHandler) taskDefinition.getTaskFormHandler();
    }
    String formKey = null;
    if (formHandler.getFormKey() != null) {
      formKey = formHandler.getFormKey().getExpressionText();
    }
    return formKey;
  }

}