/*
    * Copyright 2011 The Kuali Foundation.
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.ole.utility;
  
  import static org.apache.commons.lang.StringUtils.isBlank;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Logic for determining a base directory for Kuali applications by examining system properties and the environment the application is running in
   */
  public class ConfigUtil {
      private static final Logger logger = LoggerFactory.getLogger(ConfigUtil.class);
  
      public static final String KUALI_HOME_SYSTEM_PROPERTY = "kuali.home";
      public static final String KUALI_HOME_ENVIRONMENT_VAR = "KUALI_HOME";
      public static final String ENVIRONMENT = System.getProperty(Constants.ENVIRONMENT_PROPERTY, Constants.DEFAULT_ENVIRONMENT);
      public static final String KUALI_HOME_DEFAULT_VALUE = System.getProperty("user.home") + "/kuali/main/" + ENVIRONMENT;
  
      /**
       * Return the configured value for the <code>kuali.home</code> system property, the <code>KUALI_HOME</code> environment variable, or a default value for "kuali.home" based on
       * "user.home".
       * <p/>
       * When this method finishes the system property <code>kuali.home</code> is guaranteed to be set to the same value returned by this method.
       */
      public String getKualiHome() {
          String kualiHome = getValue(KUALI_HOME_SYSTEM_PROPERTY, KUALI_HOME_ENVIRONMENT_VAR, KUALI_HOME_DEFAULT_VALUE);
          String systemProperty = System.getProperty(KUALI_HOME_SYSTEM_PROPERTY);
          if (!kualiHome.equals(systemProperty)) {
              logger.info("Setting " + KUALI_HOME_SYSTEM_PROPERTY + "=" + kualiHome);
              System.setProperty(KUALI_HOME_SYSTEM_PROPERTY, kualiHome);
          }
          return kualiHome;
      }
  
      public String getGroupHome(String group) {
          return getKualiHome() + "/" + group;
      }
  
      public String getApplicationHome(String group, String application) {
          return getGroupHome(group) + "/" + application;
      }
  
      /**
       * Locate a value by examining system properties and environment variables. If a system property is found, the system property always wins. Otherwise the logic defers to the
       * environment variable before falling through to the default value.
       *
       * @param systemProperty
       * @param environmentVariable
       * @param defaultValue
       * @return
       */
      public String getValue(String systemProperty, String environmentVariable, String defaultValue) {
          if (!isBlank(systemProperty) && !isBlank(System.getProperty(systemProperty))) {
              return System.getProperty(systemProperty);
          } else if (!isBlank(environmentVariable) && !isBlank(System.getenv(environmentVariable))) {
              return System.getenv(environmentVariable);
          } else {
              return defaultValue;
          }
      }
  }