/**
    * Copyright (C) 2014-2015 Philip Helger (www.helger.com)
    * philip[at]helger[dot]com
    *
    * 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 com.helger.schematron.pure.binding;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.locks.ReadWriteLock;
  import java.util.concurrent.locks.ReentrantReadWriteLock;
  
  import javax.annotation.Nonnull;
  import javax.annotation.Nullable;
  import javax.annotation.concurrent.ThreadSafe;
  
  import com.helger.commons.ValueEnforcer;
  import com.helger.commons.annotation.Nonempty;
  import com.helger.commons.annotation.PresentForCodeCoverage;
  import com.helger.commons.annotation.ReturnsMutableCopy;
  import com.helger.commons.collection.CollectionHelper;
  import com.helger.commons.exception.InitializationException;
  import com.helger.schematron.pure.binding.xpath.PSXPathQueryBinding;
  
  /**
   * The registry class for all available query bindings. To register your own
   * query binding, call {@link #registerQueryBinding(String, IPSQueryBinding)}.
   *
   * @author Philip Helger
   */
  @ThreadSafe
  public final class PSQueryBindingRegistry
  {
    /**
     * Name of the query binding for which the default binding is registered.
     */
    public static final String QUERY_BINDING_XSLT = "xslt";
  
    /**
     * Name of the query binding for which the default binding is registered.
     */
    public static final String QUERY_BINDING_XSLT2 = "xslt2";
  
    /**
     * The default XPath binding object to be used
     */
    public static final IPSQueryBinding DEFAULT_QUERY_BINDING = PSXPathQueryBinding.getInstance ();
  
    private static final ReadWriteLock s_aRWLock = new ReentrantReadWriteLock ();
    private static final Map <String, IPSQueryBinding> s_aMap = new HashMap <String, IPSQueryBinding> ();
  
    static
    {
      try
      {
        registerQueryBinding (QUERY_BINDING_XSLT, DEFAULT_QUERY_BINDING);
        registerQueryBinding (QUERY_BINDING_XSLT2, DEFAULT_QUERY_BINDING);
      }
      catch (final SchematronBindException ex)
      {
        throw new InitializationException (ex);
      }
    }
  
    @PresentForCodeCoverage
    private static final PSQueryBindingRegistry s_aInstance = new PSQueryBindingRegistry ();
  
    private PSQueryBindingRegistry ()
    {}
  
    public static void registerQueryBinding (@Nonnull @Nonempty final String sName,
                                             @Nonnull final IPSQueryBinding aQueryBinding) throws SchematronBindException
    {
      ValueEnforcer.notEmpty (sName, "Name");
      ValueEnforcer.notNull (aQueryBinding, "QueryBinding");
  
      s_aRWLock.writeLock ().lock ();
      try
      {
        if (s_aMap.containsKey (sName))
          throw new SchematronBindException ("A queryBinding with the name '" + sName + "' is already registered!");
        s_aMap.put (sName, aQueryBinding);
      }
      finally
      {
        s_aRWLock.writeLock ().unlock ();
      }
    }
 
   /**
    * Get the query binding with the specified name.
    *
    * @param sName
    *        The name to the query binding to retrieve. May be <code>null</code>.
    *        If it is <code>null</code> than the {@link #DEFAULT_QUERY_BINDING}
    *        object is returned.
    * @return <code>null</code> if no such query binding was found.
    */
   @Nullable
   public static IPSQueryBinding getQueryBindingOfName (@Nullable final String sName)
   {
     if (sName == null)
       return DEFAULT_QUERY_BINDING;
 
     s_aRWLock.readLock ().lock ();
     try
     {
       return s_aMap.get (sName);
     }
     finally
     {
       s_aRWLock.readLock ().unlock ();
     }
   }
 
   /**
    * Get the query binding with the specified name
    *
    * @param sName
    *        The name of the query binding to look up. May be <code>null</code>.
    * @return Never <code>null</code>.
    * @throws SchematronBindException
    *         In case the query binding could not be resolved!
    */
   @Nonnull
   public static IPSQueryBinding getQueryBindingOfNameOrThrow (@Nullable final String sName) throws SchematronBindException
   {
     final IPSQueryBinding aQB = getQueryBindingOfName (sName);
     if (aQB == null)
       throw new SchematronBindException ("No query binding implementation present for query binding '" + sName + "'");
     return aQB;
   }
 
   /**
    * @return A non-<code>null</code> map with all contained query bindings from
    *         name to object.
    */
   @Nonnull
   @ReturnsMutableCopy
   public static Map <String, IPSQueryBinding> getAllRegisteredQueryBindings ()
   {
     s_aRWLock.readLock ().lock ();
     try
     {
       return CollectionHelper.newMap (s_aMap);
     }
     finally
     {
       s_aRWLock.readLock ().unlock ();
     }
   }
 }