package com.atlassian.plugin.util;
   
   import io.atlassian.util.concurrent.LazyReference;
   import org.apache.commons.io.IOUtils;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import java.io.IOException;
   import java.io.InputStream;
  import java.util.Properties;
  
  /**
   * General utility functions for plugin framework.
   *
   * @since 2.7.0
   */
  public final class PluginFrameworkUtils {
      private static final Logger LOG = LoggerFactory.getLogger(PluginFrameworkUtils.class);
      private static final String BUILD_PROPERTY_PATH = "META-INF/maven/com.atlassian.plugins/atlassian-plugins-core/pom.properties";
  
      /**
       * Not for instantiation.
       */
      private PluginFrameworkUtils() {
      }
  
      /**
       * Get the current plugin framework version.
       * This is not necessarily in OSGi format as it is generated by maven during build process.
       *
       * @return current plugin framework version.
       */
      public static String getPluginFrameworkVersion() {
          return pluginFrameworkVersionRef.get();
      }
  
      private static final LazyReference<String> pluginFrameworkVersionRef = new LazyReference<String>() {
          @Override
          protected String create() {
              return getPluginFrameworkVersionInternal();
          }
      };
  
      private static String getPluginFrameworkVersionInternal() {
          Properties props = new Properties();
          InputStream in = null;
  
          try {
              in = ClassLoaderUtils.getResourceAsStream(BUILD_PROPERTY_PATH, PluginFrameworkUtils.class);
              if (in != null) {
                  // this should automatically get rid of comment lines.
                  props.load(in);
                  return props.getProperty("version");
              } else {
                  // probably ran via IDEA where pom.properties won't exist
                  return "2.7.0";
              }
  
          } catch (IOException e) {
              LOG.error("cannot determine the plugin framework version", e);
              throw new IllegalStateException("cannot determine the plugin framework version", e);
          } finally {
              IOUtils.closeQuietly(in);
          }
      }
  }