package org.apache.onami.configuration;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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.

  */

 import static com.google.inject.name.Names.named;

 import static java.lang.String.format;

 import static org.apache.onami.configuration.PropertiesIterator.newPropertiesIterator;

 import java.io.File;

 import java.net.MalformedURLException;

 import java.net.URI;

 import java.net.URL;

 import java.util.Iterator;

 import java.util.LinkedList;

 import java.util.List;

 import java.util.Map;

 import java.util.Map.Entry;

 import java.util.Properties;

 import org.apache.onami.configuration.binder.PropertyValueBindingBuilder;

 import org.apache.onami.configuration.binder.XMLPropertiesFormatBindingBuilder;

 import com.google.inject.AbstractModule;

 import com.google.inject.ProvisionException;

 /**

  * The ConfigurationModule simplifies the task of loading configurations in Google Guice.

  */

 public abstract class ConfigurationModule

     extends AbstractModule

 {

     /**

      * The environment variable prefix, {@code env.}

      */

     private static final String ENV_PREFIX = "env.";

     /**

      * The {@code classpath} URL scheme constant

      */

     private static final String CLASSPATH_SCHEME = "classpath";

     private List<PropertiesURLReader> readers;

     @Override

     protected final void configure()

     {

         if ( readers != null )

         {

             throw new IllegalStateException( "Re-entry not allowed" );

         }

         readers = new LinkedList<PropertiesURLReader>();

         bindConfigurations();

         try

         {

             for ( PropertiesURLReader reader : readers )

             {

                 try

                 {

                     bindProperties( reader.readConfiguration() );

                 }

                 catch ( Exception e )

                 {

                     addError( "An error occurred while reading properties from '%s': %s", reader.getUrl(),

                               e.getMessage() );

                 }

             }

         }

         finally

         {

             readers = null;

         }

     }

     /**

      *

      */

     protected abstract void bindConfigurations();

     /**

      * Binds to a property with the given name.

      *

      * @param name The property name

      * @return The property value binder

      */

     protected PropertyValueBindingBuilder bindProperty( final String name )

     {

         checkNotNull( name, "Property name cannot be null." );

         return new PropertyValueBindingBuilder()

         {

             public void toValue( final String value )

             {

                 checkNotNull( value, "Null value not admitted for property '%s's", name );

                 bindConstant().annotatedWith( named( name ) ).to( value );

             }

         };

     }

     /**

      *

      * @param properties

      * @return

      */

     protected void bindProperties( Properties properties )

     {

         checkNotNull( properties, "Parameter 'properties' must be not null" );

         bindProperties( newPropertiesIterator( properties ) );

     }

     /**

      *

      * @param properties

      */

     protected void bindProperties( Iterable<Entry<String, String>> properties )

     {

         checkNotNull( properties, "Parameter 'properties' must be not null" );

         bindProperties( properties.iterator() );

     }

     /**

      *

      * @param properties

      */

     protected void bindProperties( Iterator<Entry<String, String>> properties )

     {

         checkNotNull( properties, "Parameter 'properties' must be not null" );

         while ( properties.hasNext() )

         {

             Entry<String, String> property = properties.next();

             bindProperty( property.getKey() ).toValue( property.getValue() );

         }

     }

     /**

      * Add the Environment Variables properties, prefixed by {@code env.}.

      */

     protected void bindSystemProperties()

     {

         bindProperties( System.getProperties() );

     }

     /**

      *

      * @param properties

      * @return

      */

     protected void bindProperties( Map<String, String> properties )

     {

         checkNotNull( properties, "Parameter 'properties' must be not null" );

         bindProperties( newPropertiesIterator( properties ) );

     }

     /**

      * Add the System Variables properties.

      */

     protected void bindEnvironmentVariables()

     {

         bindProperties( newPropertiesIterator( ENV_PREFIX, System.getenv() ) );

     }

     /**

      *

      *

      * @param propertiesResource

      * @return

      */

     protected XMLPropertiesFormatBindingBuilder bindProperties( final File propertiesResource )

     {

         checkNotNull( propertiesResource, "Parameter 'propertiesResource' must be not null" );

         return bindProperties( propertiesResource.toURI() );

     }

     /**

      *

      *

      * @param propertiesResource

      * @return

      */

     protected XMLPropertiesFormatBindingBuilder bindProperties( final URI propertiesResource )

     {

         checkNotNull( propertiesResource, "Parameter 'propertiesResource' must be not null" );

         if ( CLASSPATH_SCHEME.equals( propertiesResource.getScheme() ) )

         {

             String path = propertiesResource.getPath();

             if ( propertiesResource.getHost() != null )

             {

                 path = propertiesResource.getHost() + path;

             }

             return bindProperties( path );

         }

         try

         {

             return bindProperties( propertiesResource.toURL() );

         }

         catch ( MalformedURLException e )

         {

             throw new ProvisionException( format( "URI '%s' not supported: %s", propertiesResource, e.getMessage() ) );

         }

     }

     /**

      *

      * @param classPathResource

      * @return

      */

     protected XMLPropertiesFormatBindingBuilder bindProperties( final String classPathResource )

     {

         return bindProperties( classPathResource, getClass().getClassLoader() );

     }

     /**

      *

      * @param classPathResource

      * @param classLoader

      * @return

      */

     protected XMLPropertiesFormatBindingBuilder bindProperties( final String classPathResource,

                                                                 final ClassLoader classLoader )

     {

         checkNotNull( classPathResource, "Parameter 'classPathResource' must be not null" );

         checkNotNull( classLoader, "Parameter 'classLoader' must be not null" );

         String resourceURL = classPathResource;

         if ( '/' == classPathResource.charAt( 0 ) )

         {

             resourceURL = classPathResource.substring( 1 );

         }

         URL url = classLoader.getResource( resourceURL );

         checkNotNull( url,

                       "ClassPath resource '%s' not found, make sure it is in the ClassPath or you're using the right ClassLoader",

                       classPathResource );

         return bindProperties( url );

     }

     /**

      *

      * @param propertiesResource

      * @return

      */

     protected XMLPropertiesFormatBindingBuilder bindProperties( final URL propertiesResource )

     {

         checkNotNull( propertiesResource, "parameter 'propertiesResource' must not be null" );

         PropertiesURLReader reader = new PropertiesURLReader( propertiesResource );

         readers.add( reader );

         return reader;

     }

     private static void checkNotNull( Object object, String messageFormat, Object...args )

     {

         if ( object == null )

         {

             throw new IllegalArgumentException( format( messageFormat, args ) );

         }

     }

 }