/**
    * Copyright 2009-2012 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.codehaus.mojo.properties;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Properties;
  import java.util.Set;
  
  import org.apache.commons.io.IOUtils;
  import org.apache.commons.lang.StringUtils;
  import org.apache.maven.plugin.AbstractMojo;
  import org.apache.maven.plugin.MojoExecutionException;
  import org.apache.maven.project.MavenProject;
  import org.codehaus.plexus.util.cli.CommandLineUtils;
  import org.springframework.core.io.DefaultResourceLoader;
  import org.springframework.core.io.Resource;
  import org.springframework.core.io.ResourceLoader;
  
  /**
   * The read-project-properties goal reads property files and stores the properties as project properties. It serves as
   * an alternate to specifying properties in pom.xml.
   *
   * @author <a href="mailto:zarars@gmail.com">Zarar Siddiqi</a>
   * @author <a href="mailto:Krystian.Nowak@gmail.com">Krystian Nowak</a>
   * @version $Id: ReadPropertiesMojo.java 8861 2009-01-21 15:35:38Z pgier $
   * @goal read-project-properties
   */
  public class ReadPropertiesMojo extends AbstractMojo {
  
      /**
       * @parameter default-value="${project}"
       * @required
       * @readonly
       */
      private MavenProject project;
  
      /**
       * Locations where properties files can be found. Any url Spring resource loading can understand is valid. eg
       * <code>classpath:myprops.properties</code>. Both, .properties and .xml style properties are supported.
       *
       * @parameter
       * @required
       */
      private String[] locations;
  
      /**
       * If true, the plugin will silently ignore any non-existent properties files, and the build will continue
       *
       * @parameter expression="${properties.quiet}" default-value="false"
       */
      private boolean quiet;
  
      /**
       * Comma separated list of property values to ignore
       *
       * @parameter expression="${properties.ignore}"
       */
      private String ignore;
  
      @Override
      public void execute() throws MojoExecutionException {
          List<String> ignoreList = getListFromCSV(ignore);
          Properties projectProperties = project.getProperties();
          if (!StringUtils.isBlank(ignore)) {
              getLog().info("Ignoring " + ignore);
          }
          for (int i = 0; i < locations.length; i++) {
              String location = locations[i];
              if (!validate(location)) {
                  continue;
              }
              getLog().info("Loading " + location);
              Properties p = getProperties(location);
              updateProperties(projectProperties, p, ignoreList);
          }
  
          Properties env = getEnvironment();
          for (String name : projectProperties.stringPropertyNames()) {
              String value = getPropertyValue(name, projectProperties, env);
              projectProperties.setProperty(name, value);
          }
     }
 
     protected Properties getEnvironment() throws MojoExecutionException {
         try {
             return CommandLineUtils.getSystemEnvVars();
         } catch (IOException e) {
             throw new MojoExecutionException("Error get environment variables", e);
         }
     }
 
     protected void updateProperties(Properties p1, Properties p2, List<String> ignore) {
         Set<String> names = p2.stringPropertyNames();
         for (String name : names) {
             if (!ignore.contains(name)) {
                 String value = p2.getProperty(name);
                 p1.setProperty(name, value);
             }
         }
     }
 
     protected static final List<String> getListFromCSV(String csv) {
         if (StringUtils.isBlank(csv)) {
             return new ArrayList<String>();
         }
         List<String> list = new ArrayList<String>();
         String[] tokens = StringUtils.split(csv, ",");
         for (String token : tokens) {
             list.add(token.trim());
         }
         return list;
     }
 
     /**
      * Retrieves a property value, replacing values like ${token} using the Properties to look them up. Shamelessly
      * adapted from:
      * http://maven.apache.org/plugins/maven-war-plugin/xref/org/apache/maven/plugin/war/PropertyUtils.html
      *
      * It will leave unresolved properties alone, trying for System properties, and environment variables and implements
      * reparsing (in the case that the value of a property contains a key), and will not loop endlessly on a pair like
      * test = ${test}
      *
      * @param k
      *            property key
      * @param p
      *            project properties
      * @param environment
      *            environment variables
      * @return resolved property value
      */
     protected String getPropertyValue(String k, Properties p, Properties environment) {
         String v = p.getProperty(k);
         String ret = "";
         int idx, idx2;
 
         while ((idx = v.indexOf("${")) >= 0) {
             // append prefix to result
             ret += v.substring(0, idx);
 
             // strip prefix from original
             v = v.substring(idx + 2);
 
             idx2 = v.indexOf("}");
 
             // if no matching } then bail
             if (idx2 < 0) {
                 break;
             }
 
             // strip out the key and resolve it
             // resolve the key/value for the ${statement}
             String nk = v.substring(0, idx2);
             v = v.substring(idx2 + 1);
             String nv = p.getProperty(nk);
 
             // try global environment
             if (nv == null) {
                 nv = System.getProperty(nk);
             }
 
             // try environment variable
             if (nv == null && nk.startsWith("env.") && environment != null) {
                 nv = environment.getProperty(nk.substring(4));
             }
 
             // if the key cannot be resolved,
             // leave it alone ( and don't parse again )
             // else prefix the original string with the
             // resolved property ( so it can be parsed further )
             // taking recursion into account.
             if (nv == null || nv.equals(nk)) {
                 ret += "${" + nk + "}";
             } else {
                 v = nv + v;
             }
         }
         return ret + v;
     }
 
     protected boolean exists(String location) {
         if (StringUtils.isBlank(location)) {
             return false;
         }
         File file = new File(location);
         if (file.exists()) {
             return true;
         }
         ResourceLoader loader = new DefaultResourceLoader();
         Resource resource = loader.getResource(location);
         return resource.exists();
     }
 
     protected boolean validate(String location) throws MojoExecutionException {
         boolean exists = exists(location);
         if (exists) {
             return true;
         }
         if (quiet) {
             getLog().info("Ignoring non-existent properties file '" + location + "'");
             return false;
         } else {
             throw new MojoExecutionException("Non-existent properties file '" + location + "'");
         }
     }
 
     protected InputStream getInputStream(String location) throws IOException {
         File file = new File(location);
         if (file.exists()) {
             return new FileInputStream(location);
         }
         ResourceLoader loader = new DefaultResourceLoader();
         Resource resource = loader.getResource(location);
         return resource.getInputStream();
     }
 
     protected Properties getProperties(String location) throws MojoExecutionException {
         InputStream in = null;
         try {
             Properties properties = new Properties();
             in = getInputStream(location);
             if (location.toLowerCase().endsWith(".xml")) {
                 properties.loadFromXML(in);
             } else {
                 properties.load(in);
             }
             return properties;
         } catch (IOException e) {
             throw new MojoExecutionException("Error reading properties file " + location, e);
         } finally {
             IOUtils.closeQuietly(in);
         }
     }
 
     public boolean isQuiet() {
         return quiet;
     }
 
     public void setQuiet(boolean quiet) {
         this.quiet = quiet;
     }
 
     public String getIgnore() {
         return ignore;
     }
 
     public void setIgnore(String ignoreProperties) {
         this.ignore = ignoreProperties;
     }
 
     public MavenProject getProject() {
         return project;
     }
 
     public String[] getLocations() {
         return locations;
     }
 
     public void setLocations(String[] locations) {
         this.locations = locations;
     }
 
 }