/**
    * This file Copyright (c) 2016-2018 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.ui.framework.ioc;
  
  import info.magnolia.objectfactory.CandidateParameterResolver;
  import info.magnolia.objectfactory.ComponentProvider;
  import info.magnolia.objectfactory.ParameterResolver;
  import info.magnolia.objectfactory.guice.GuiceComponentProvider;
  
  import java.io.Serializable;
  import java.util.function.Supplier;
  
  import com.google.inject.Key;
  import com.vaadin.server.VaadinServlet;
  
  /**
   * Lightweight {@link ComponentProvider} implementation for UI components which conducts provisioning
   * by delegating it to the only UI Guice instance via a {@link GuiceComponentProvider} associated with it.
   * <p>
   * The only significant function of such {@link ComponentProvider component provider} is that it
   * is bound to a certain UI context via {@link UiContextReference} which is pushed into {@link CurrentUiContextReference}
   * before any Guice invocation. By doing this Guice knows (when uncertain) what flavour of components to inject.
   * </p>
   *
   * @see UiAnnotations
   * @see UiContextApplyingProvider
   */
  public class UiContextBoundComponentProvider implements ComponentProvider, Serializable {
  
      private final transient GuiceComponentProvider parentComponentProvider;
  
      private final CurrentUiContextReference currentUiContextReference;
  
      private final UiContextReference uiContextReference;
  
      public UiContextBoundComponentProvider(UiContextReference uiContextReference) {
          this(uiContextReference, (GuiceComponentProvider) VaadinServlet.getCurrent().getServletContext().getAttribute("componentProvider"), CurrentUiContextReference.get());
      }
  
      public UiContextBoundComponentProvider(UiContextReference uiContextReference, GuiceComponentProvider parentComponentProvider, CurrentUiContextReference currentUiContextReference) {
          this.uiContextReference = uiContextReference;
          this.parentComponentProvider = parentComponentProvider;
          this.currentUiContextReference = currentUiContextReference;
      }
  
      public UiContextReference getUiContextReference() {
          return this.uiContextReference;
      }
  
      @Override
      public <T> Class<? extends T> getImplementation(Class<T> type) {
          return getParent().getImplementation(getClosestMappedType(type));
      }
  
      private <T> Key<T> getClosestMappedType(Class<T> type) {
          return this.currentUiContextReference.getAvailableContextReferences().stream()
                  .map(key -> Key.get(type, key.getAnnotation()))
                  // first check if there is a matching annotated type mapping
                  .filter(key -> getParent().getTypeMappings().containsKey(key))
                  .findFirst()
                  // otherwise just fetch the un-annotated type mapping
                  .orElseGet(() -> Key.get(type));
      }
  
      @Override
      public <T> T getSingleton(Class<T> type) {
          return getParent().getSingleton(type);
      }
 
     @Override
     public <T> T getComponent(Class<T> type) {
         return provideInCurrentScope(() -> getParent().getComponent(type));
     }
 
     @Override
     public <T> T newInstance(Class<T> type, Object... parameters) {
         return newInstanceWithParameterResolvers(type, new CandidateParameterResolver(parameters));
     }
 
     @Override
     public <T> T newInstanceWithParameterResolvers(Class<T> type, ParameterResolver... parameters) {
         return provideInCurrentScope(() -> getParent().newInstanceWithParameterResolvers(getClosestMappedType(type), parameters));
     }
 
     @Override
     public GuiceComponentProvider getParent() {
         return this.parentComponentProvider;
     }
 
     private <T> T provideInCurrentScope(Supplier<T> provider) {
         final UiContextReference previousUiContextReference = currentUiContextReference.getUiContextReference();
         currentUiContextReference.setUiContextReference(this.uiContextReference);
         try {
             return provider.get();
         } finally {
             currentUiContextReference.setUiContextReference(previousUiContextReference);
         }
     }
 }