/*

  * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH

  *

  * 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 de.smartics.properties.spi.config.definition;

 import static de.smartics.properties.api.config.domain.key.ApplicationId.ANY_APP;

 import static de.smartics.properties.api.config.domain.key.EnvironmentId.ANY_ENV;

 import java.io.Serializable;

 import java.util.StringTokenizer;

 import javax.annotation.concurrent.ThreadSafe;

 import de.smartics.properties.api.config.domain.key.ApplicationId;

 import de.smartics.properties.api.config.domain.key.ConfigurationKey;

 import de.smartics.properties.api.config.domain.key.EnvironmentId;

 import de.smartics.util.lang.Arguments;

 /**

  * Derives a {@link ConfigurationKey} from a path found in a definition file.

  */

 @ThreadSafe

 public final class DefinitionKeyHelper implements Serializable

 {

   // ********************************* Fields *********************************

   // --- constants ------------------------------------------------------------

   /**

    * The class version identifier.

    */

   private static final long serialVersionUID = 1L;

   // --- members --------------------------------------------------------------

   /**

    * The context to evaluate the configuration keys from properties file paths.

    *

    * @serial

    */

   private final PropertiesDefinitionContext context;

   // ****************************** Initializer *******************************

   // ****************************** Constructors ******************************

   /**

    * Convenience constructor using the default TLDs and not registering any

    * environments, nodes or groups.

    */

   public DefinitionKeyHelper()

   {

     this(new PropertiesDefinitionContext());

   }

   /**

    * Default constructor.

    *

    * @param context the context to evaluate the configuration keys from

    *          properties file paths.

    * @throws NullPointerException if {@code context} is <code>null</code>.

    */

   public DefinitionKeyHelper(final PropertiesDefinitionContext context)

     throws NullPointerException

   {

     Arguments.checkNotNull("context", context);

     this.context = context;

   }

   // ****************************** Inner Classes *****************************

   // ********************************* Methods ********************************

   // --- init -----------------------------------------------------------------

   // --- get&set --------------------------------------------------------------

   // --- business -------------------------------------------------------------

   /**

    * Parses the given path to create a configuration key.

    * <p>

    * The expected syntax is as follows:

    * </p>

    * <ol>

    * <li><code>/environment</code></li>

    * <li><code>/environment/node</code></li>

    * <li><code>/environment/node/group</code></li>

    * <li><code>/environment/node/group/application</code></li>

    * <li><code>/environment/node/group/application/version</code></li>

    * <li><code>/environment/group</code></li>

    * <li><code>/environment/group/application</code></li>

    * <li><code>/environment/group/application/version</code></li>

    * <li><code>/group</code></li>

    * <li><code>/group/application</code></li>

    * <li><code>/group/application/version</code></li>

    * </ol>

    * <p>

    * A file ending with properties following the path will be chopped.

    * </p>

    * <p>

    * The parser has to determine whether a part of the path is a

    * <code>environment</code>, a <code>node</code> or a <code>group</code>.

    * Since a <code>node</code> is always prefixed by an <code>environment</code>

    * only the following two cases have to be dealt with:

    * </p>

    * <ol>

    * <li><code>environment</code> vs. <code>group</code></li>

    * <li><code>node</code> vs. <code>group</code></li>

    * </ol>

    * <p>

    * <code>group</code>s start with

    * </p>

    * <ol>

    * <li>A TLD as registered by default by

    * {@link PropertiesDefinitionContext#DEFAULT_TLDS} or explicitly

    * registered with {@link PropertiesDefinitionContext}</li>

    * <li>Two letters followed by a dot (<code>.</code>)</li>

    * <li>Any sequence of characters that is explicitly registered as a group in

    * the <code>definition.xml</code> file</li>

    * </ol>

    * <p>

    * <code>environment</code>s and <code>node</code>s do not start as

    * <code>groups</code> except they are explicitly registered in the

    * <code>definition.xml</code> file.

    * </p>

    *

    * @param pathWithFile the path to parse.

    * @return the configuration key.

    * @throws IllegalArgumentException if the given {@code path} is not valid

    *           according to the rules given above.

    */

   public ConfigurationKey parse(final String pathWithFile)

     throws IllegalArgumentException

   {

     final ConfigurationKey explicitKey = fetchExplicitKey(pathWithFile);

     if (explicitKey != null)

     {

       return explicitKey;

     }

     final String path = chopFile(pathWithFile);

     final StringTokenizer tokenizer = new StringTokenizer(path, "/");

     if (tokenizer.hasMoreTokens())

     {

       final ConfigurationKey key;

       final String token = tokenizer.nextToken();

       if (isGroup(token))

       {

         key = parseApplicationKey(token, tokenizer);

       }

       else

       {

         key = parseEnvironmentKey(token, tokenizer);

       }

       return key;

     }

     return new ConfigurationKey(EnvironmentId.ANY_ENV, ApplicationId.ANY_APP);

     // throw new IllegalArgumentException(

     // "Path '" + path + "' does not contain an environment or group.");

   }

   private static String chopFile(final String pathWithFile)

   {

     if (pathWithFile.endsWith(".properties"))

     {

       final int lastSlash = pathWithFile.lastIndexOf('/');

       if (lastSlash != -1)

       {

         final String path = pathWithFile.substring(0, lastSlash);

         return path;

       }

       return "";

     }

     return pathWithFile;

   }

   private ConfigurationKey fetchExplicitKey(final String path)

   {

     ConfigurationKey key = context.getKey(path);

     if (key == null)

     {

       key = context.getKey(null);

     }

     return key;

   }

   private boolean isGroup(final String token)

   {

     if (context.isRegisteredEnvironment(token)

         || context.isRegisteredNode(token))

     {

       return false;

     }

     return context.isGroup(token);

   }

   private ConfigurationKey parseEnvironmentKey(final String environment,

       final StringTokenizer tokenizer)

   {

     final EnvironmentId envId;

     final ApplicationId appId;

     if (tokenizer.hasMoreTokens())

     {

       final String token = tokenizer.nextToken();

       if (isGroup(token))

       {

         envId = new EnvironmentId(environment);

         appId = parseAppId(token, tokenizer);

       }

       else

       {

         envId = new EnvironmentId(environment, token);

         if (tokenizer.hasMoreTokens())

         {

           appId = parseAppId(tokenizer.nextToken(), tokenizer);

         }

         else

         {

           appId = ANY_APP;

         }

       }

     }

     else

     {

       envId = new EnvironmentId(environment);

       appId = ANY_APP;

     }

     final ConfigurationKey key = new ConfigurationKey(envId, appId);

     return key;

   }

   private ApplicationId parseAppId(final String group,

       final StringTokenizer tokenizer)

   {

     String artifact = null;

     String version = null;

     if (tokenizer.hasMoreTokens())

     {

       artifact = tokenizer.nextToken();

       if (tokenizer.hasMoreTokens())

       {

         version = tokenizer.nextToken();

       }

     }

     return new ApplicationId(group, artifact, version);

   }

   private ConfigurationKey parseApplicationKey(final String group,

       final StringTokenizer tokenizer)

   {

     final EnvironmentId envId = ANY_ENV;

     final ApplicationId appId = parseAppId(group, tokenizer);

     return new ConfigurationKey(envId, appId);

   }

   // --- object basics --------------------------------------------------------

 }