/**
    * This file Copyright (c) 2017-2018 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.ui.api.app.AppContext;
  import info.magnolia.ui.api.app.SubAppContext;
  
  import java.io.Serializable;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  import java.util.Objects;
  
  import com.google.common.collect.ImmutableList;
  import com.vaadin.ui.UI;
  
  /**
   * A simple abstraction for the UI context identification. Useful in the two following scenarios:
   * <p>
   * Used by {@link SessionStore} as the key of a {@link BeanStore} containing
   * scoped objects (see {@link UiContextReference#asString() method}).
   * </p>
   * <p>
   * Helps to resolve the {@link com.google.inject.BindingAnnotation Guice Binding Annotation} corresponding
   * to the UI context, which provides access to context-specific type bindings
   * (orchestrated by e.g. {@link UiContextApplyingProvider}).
   * </p>
   * <p>
   * Also provides a list of the keys that are more 'general' than the current.  
   * </p>
   *
   * @see UiContextApplyingProvider
   * @see CurrentUiContextReference
   * @see SessionStore
   * @see UiScopes
   */
  public interface UiContextReference extends Serializable {
  
      /**
       * Get String representation of UI context ref; useful
       * when the reference needs to be used as a key in a hash map
       * (e.g. in {@link BeanStore}).
       */
      String asString();
  
      /**
       * Get {@link UiContextAnnotation} which corresponds to
       * this UI context reference. Such annotation is also a
       * {@link com.google.inject.BindingAnnotation} used by Guice.
       */
      UiContextAnnotation getAnnotation();
  
      /**
       * Get all the ('broader') references that can be resolved from
       * the current one.
       */
      default List<UiContextReference> getParentReferences() {
          return Collections.emptyList();
      }
  
      // UI context reference factory methods
  
      static UiContextReference ofUi(UI ui) {
          return new UiContextReferenceImpl(ui) {
              @Override
              public UiContextAnnotation getAnnotation() {
                  return UiAnnotations.forAdmincentral();
              }
         };
     }
 
     static UiContextReference ofCurrentUi() {
         return new UiContextReferenceImpl() {
             @Override
             public UiContextAnnotation getAnnotation() {
                 return UiAnnotations.forAdmincentral();
             }
         };
     }
 
     /**
      * Creates a UI context reference bound to a concrete instance of an app.
      * All the app scoped objects relevant to that app will be resolvable through
      * this reference.
      *
      * @param appContext concrete instance of a app context
      * @return ui context reference bound to the app instance
      */
     static UiContextReference ofApp(AppContext appContext) {
         return new AppContextReference(appContext);
     }
 
     /**
      * Creates a UI context reference bound to a concrete instance of a sub-app.
      * All the scoped objects relevant to that sub-app will be resolvable through
      * this reference.
      *
      * @param subAppContext concrete instance of a sub-app context
      * @return ui context reference bound to sub-app instance
      */
     static UiContextReference ofSubApp(SubAppContext subAppContext) {
         return new SubAppContextReference(subAppContext);
     }
 
     static UiContextReference ofView(String viewId, UiContextReference parentKey) {
         return new ViewContextReference(viewId, parentKey);
     }
 
     static UiContextReference genericSubAppContextReference() {
         return new UiContextReferenceImpl() {
 
             @Override
             public UiContextAnnotation getAnnotation() {
                 return UiAnnotations.forSubApps();
             }
 
             @Override
             public List<UiContextReference> getParentReferences() {
                 final UiContextReference genericAppContextKey = genericAppContextReference();
                 return ImmutableList.<UiContextReference>builder().add(genericAppContextKey).addAll(genericAppContextKey.getParentReferences()).build();
             }
         };
     }
 
     static UiContextReference genericAppContextReference() {
         return new UiContextReferenceImpl() {
             @Override
             public UiContextAnnotation getAnnotation() {
                 return UiAnnotations.forApps();
             }
 
             @Override
             public List<UiContextReference> getParentReferences() {
                 return Arrays.asList(UiContextReference.ofCurrentUi());
             }
         };
     }
 
     static UiContextReference genericViewContextRefence() {
         return new UiContextReferenceImpl() {
             @Override
             public UiContextAnnotation getAnnotation() {
                 return UiAnnotations.forViews();
             }
 
             @Override
             public List<UiContextReference> getParentReferences() {
                 return Collections.emptyList();
             }
         };
     }
 
     // Implementations of the UI context keys
 
     /**
      * App specific UI context reference.
      */
     class AppContextReference extends UiContextReferenceImpl {
         private final AppContext appContext;
 
         AppContextReference(AppContext appContext) {
             this.appContext = appContext;
         }
 
         @Override
         String getScopeId() {
             return String.format("%s:%s", appName(), this.appContext.hashCode());
         }
 
         private String appName() {
             return this.appContext.getName();
         }
 
         @Override
         public UiContextAnnotation getAnnotation() {
             return UiAnnotations.forApp(appName());
         }
 
         @Override
         public List<UiContextReference> getParentReferences() {
             return Arrays.asList(genericAppContextReference(), UiContextReference.ofCurrentUi());
         }
     }
 
     /**
      * Sub-app specific UI context reference.
      */
     class SubAppContextReference extends UiContextReferenceImpl {
 
         private final SubAppContext subAppContext;
 
         SubAppContextReference(SubAppContext subAppContext) {
             this.subAppContext = subAppContext;
         }
 
         @Override
         protected String getScopeId() {
             return String.format("%s:%s:%s", appName(), subAppName(), subAppContext.hashCode());
         }
 
         private String subAppName() {
             return subAppContext.getSubAppDescriptor().getName();
         }
 
         private String appName() {
             return subAppContext.getAppContext().getName();
         }
 
         @Override
         public UiContextAnnotation getAnnotation() {
             return UiAnnotations.forSubApp(appName(), subAppName());
         }
 
         @Override
         public List<UiContextReference> getParentReferences() {
             final UiContextReference appContextKey = UiContextReference.ofApp(this.subAppContext.getAppContext());
             return ImmutableList.<UiContextReference>builder().add(genericSubAppContextReference()).add(appContextKey).addAll(appContextKey.getParentReferences()).build();
         }
     }
 
     /**
      * View-specific UI context reference implementation.
      */
     class ViewContextReference extends UiContextReferenceImpl {
 
         private final String viewId;
         private final UiContextReference parentKey;
 
         ViewContextReference(String viewId, UiContextReference parentKey) {
             this.viewId = viewId;
             this.parentKey = parentKey;
         }
 
         @Override
         String getScopeId() {
             return viewId;
         }
 
         @Override
         public UiContextAnnotation getAnnotation() {
             return new ViewImpl(viewId);
         }
 
         @Override
         public List<UiContextReference> getParentReferences() {
             return ImmutableList.<UiContextReference>builder().add(genericViewContextRefence()).add(parentKey).addAll(parentKey.getParentReferences()).build();
         }
     }
 
     /**
      * Base {@link UiContextReference} implementation.
      */
     abstract class UiContextReferenceImpl implements UiContextReference {
 
         private final String uiId;
 
         UiContextReferenceImpl(UI ui) {
             this.uiId = ui.getEmbedId();
         }
 
         UiContextReferenceImpl() {
             this(UI.getCurrent());
         }
 
         @Override
         public String asString() {
             return String.format("%s:%s", getUiInstancePrefix(), getScopeId());
         }
 
         String getUiInstancePrefix() {
             return String.format("%s", uiId);
         }
 
         String getScopeId() {
             return "";
         }
 
         @Override
         public boolean equals(Object o) {
             if (this == o) return true;
             if (!(o instanceof UiContextReference)) return false;
             return Objects.equals(this.asString(), ((UiContextReference) o).asString());
         }
 
         @Override
         public int hashCode() {
             return Objects.hashCode(this.asString());
         }
 
         @Override
         public String toString() {
             return asString();
         }
     }
 }