/**
    * This file Copyright (c) 2012-2018 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.api.app.launcherlayout;
  
  import info.magnolia.cms.security.User;
  import info.magnolia.cms.security.operations.AccessDefinition;
  import info.magnolia.config.registry.DefinitionMetadata;
  import info.magnolia.config.registry.DefinitionProvider;
  import info.magnolia.config.registry.Registry;
  import info.magnolia.context.MgnlContext;
  import info.magnolia.event.EventBus;
  import info.magnolia.event.SystemEventBus;
  import info.magnolia.i18nsystem.I18nizer;
  import info.magnolia.ui.api.app.AppDescriptor;
  import info.magnolia.ui.api.app.registry.AppDescriptorRegistry;
  import info.magnolia.ui.api.app.registry.AppRegistryEvent;
  import info.magnolia.ui.api.app.registry.AppRegistryEventHandler;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import java.util.Optional;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.atomic.AtomicReference;
  import java.util.stream.Collectors;
  
  import javax.inject.Inject;
  import javax.inject.Named;
  import javax.inject.Provider;
  import javax.inject.Singleton;
  
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.google.common.cache.CacheBuilder;
  import com.google.common.cache.CacheLoader;
  import com.google.common.cache.LoadingCache;
  
  /**
   * Default {@link AppLauncherLayoutManager} implementation.
   */
  @Singleton
  public class AppLauncherLayoutManagerImpl implements AppLauncherLayoutManager {
  
      private final Logger log = LoggerFactory.getLogger(AppLauncherLayoutManagerImpl.class);
  
      private final AppDescriptorRegistry appDescriptorRegistry;
  
      private final EventBus systemEventBus;
  
      private final AtomicReference<AppLauncherLayoutDefinition> layoutDefinitionReference = new AtomicReference<AppLauncherLayoutDefinition>();
  
      private final Provider<I18nizer> i18nizerProvider;
  
      private final LoadingCache<User, AppLauncherLayout> appPermissionsCache = CacheBuilder.newBuilder()
              .initialCapacity(1)
              .maximumSize(50)
              .build(new CacheLoader<User, AppLauncherLayout>() {
                  public AppLauncherLayout load(User user) {
                      log.debug("Computing app-launcher layout permissions for user " + user.getName());
                      return doGetLayoutForUser(user);
                  }
              });
  
      @Inject
      public AppLauncherLayoutManagerImpl(AppDescriptorRegistry appDescriptorRegistry, @Named(SystemEventBus.NAME) EventBus systemEventBus, Provider<I18nizer> i18nizerProvider) {
          this.appDescriptorRegistry = appDescriptorRegistry;
         this.systemEventBus = systemEventBus;
         this.i18nizerProvider = i18nizerProvider;
 
         /**
          * Propagate events from {@link info.magnolia.ui.api.app.registry.AppDescriptorRegistry} to notify listeners
          * that the layout has changed.
          */
         systemEventBus.addHandler(AppRegistryEvent.class, new AppRegistryEventHandler() {
 
             @Override
             public void onAppRegistered(AppRegistryEvent event) {
                 logAndSendChangedEvent(event);
             }
 
             @Override
             public void onAppReregistered(AppRegistryEvent event) {
                 logAndSendChangedEvent(event);
             }
 
             @Override
             public void onAppUnregistered(AppRegistryEvent event) {
                 logAndSendChangedEvent(event);
             }
 
             /**
              * Sends an event on the system event bus.
              */
             private void logAndSendChangedEvent(AppRegistryEvent event) {
                 String name = event.getAppDescriptorMetadata().getName();
                 log.debug("Got AppRegistryEvent." + event.getEventType() + " for app: " + name);
                 appPermissionsCache.invalidateAll();
                 systemEventBus.fireEvent(new AppLauncherLayoutChangedEvent());
                 log.debug("Sending AppLauncherLayoutChangedEvent on the system bus");
             }
         });
     }
 
     @Deprecated
     @Override
     public AppLauncherLayout getLayoutForCurrentUser() {
         return getLayoutForUser(MgnlContext.getUser());
     }
 
     @Override
     public AppLauncherLayout getLayoutForUser(User user) {
         try {
             return appPermissionsCache.get(user);
         } catch (ExecutionException e) {
             log.error("Could not resolve app permissions for user {}", user, e);
         }
         return new AppLauncherLayout();
     }
 
     private AppLauncherLayout doGetLayoutForUser(User user) {
         AppLauncherLayoutDefinition layoutDefinition = layoutDefinitionReference.get();
         if (layoutDefinition == null) {
             return new AppLauncherLayout();
         }
 
         Optional<AppLauncherGroup> defaultGroup = Optional.empty();
         Collection<String> processedApps = new ArrayList<>();
 
         AppLauncherLayoutlayout/AppLauncherLayout.html#AppLauncherLayout">AppLauncherLayout layout = new AppLauncherLayout();
         for (AppLauncherGroupDefinition groupDefinition : layoutDefinition.getGroups()) {
             if (!isGroupVisibleForUser(groupDefinition, user)) {
                 processedApps.addAll(groupDefinition.getApps().stream().map(AppLauncherGroupEntryDefinition::getName).collect(Collectors.toList()));
                 continue;
             }
 
             List<AppLauncherGroupEntry> entries = new ArrayList<>();
             for (AppLauncherGroupEntryDefinition entryDefinition : groupDefinition.getApps()) {
                 processedApps.add(entryDefinition.getName());
                 final Optional<AppDescriptor> appDescriptor = getAppDescriptor(entryDefinition.getName());
                 if (!appDescriptor.isPresent() || layoutDefinition.getHiddenApps().contains(appDescriptor.get().getName()) || !isAppVisibleForUser(entryDefinition,  appDescriptor.get(), user)) {
                     continue;
                 }
                 entries.add(createAppEntry(entryDefinition, appDescriptor.get()));
             }
 
             if (!entries.isEmpty() || groupDefinition.getName().equals(layoutDefinition.getDefaultGroup())) {
                 AppLauncherGrouperlayout/AppLauncherGroup.html#AppLauncherGroup">AppLauncherGroup group = new AppLauncherGroup();
                 group.setName(groupDefinition.getName());
                 group.setLabel(groupDefinition.getLabel());
                 group.setColor(groupDefinition.getColor());
                 group.setPermanent(groupDefinition.isPermanent());
                 group.setClientGroup(groupDefinition.isClientGroup());
                 group.setApps(entries);
                 layout.addGroup(group);
 
                 if (groupDefinition.getName().equals(layoutDefinition.getDefaultGroup())) {
                     defaultGroup = Optional.of(group);
                 }
             }
         }
 
         final List<String> unprocessedApps = appDescriptorRegistry.getAllMetadata().stream()
                 .map(DefinitionMetadata::getName)
                 .filter(entry -> !processedApps.contains(entry) && !layoutDefinition.getHiddenApps().contains(entry))
                 .collect(Collectors.toList());
 
         if (layoutDefinition.getDefaultGroup() != null && !defaultGroup.isPresent()) {
             log.debug("Configured default group ({}={}) doesn't exist or user doesn't have permission for it.", "config:/modules/ui-admincentral/config/appLauncherLayout@defaultGroup", layoutDefinition.getDefaultGroup());
         }
 
         if (defaultGroup.isPresent()) {
             for (String appName : unprocessedApps) {
                 final Optional<AppDescriptor> appDescriptor = getAppDescriptor(appName);
                 if (appDescriptor.isPresent()) {
                     final ConfiguredAppLauncherGroupEntryDefinitionhtml#ConfiguredAppLauncherGroupEntryDefinition">ConfiguredAppLauncherGroupEntryDefinition appLauncherGroupEntryDefinition = new ConfiguredAppLauncherGroupEntryDefinition();
                     appLauncherGroupEntryDefinition.setName(appName);
                     if (isAppVisibleForUser(appLauncherGroupEntryDefinition,  appDescriptor.get(), user)) {
                         defaultGroup.get().getApps().add( createAppEntry(appLauncherGroupEntryDefinition, appDescriptor.get()));
                         log.debug("App {{}} is not registered in the applauncher. Adding it to the default applauncher group {{}}", appName, defaultGroup.get().getName());
                     }
                 }
             }
         } else if (!unprocessedApps.isEmpty()) {
             log.debug("Apps {} are not registered in the applauncher. Configure a default group (at {}) where to add unregistered apps automatically.", unprocessedApps, "config:/modules/ui-admincentral/config/appLauncherLayout@defaultGroup");
         }
         return layout;
     }
 
     @Override
     public void setLayout(AppLauncherLayoutDefinition layout) {
         this.layoutDefinitionReference.set(i18nizerProvider.get().decorate(layout));
         log.debug("Sending AppLauncherLayoutChangedEvent on the system bus");
         appPermissionsCache.invalidateAll();
         systemEventBus.fireEvent(new AppLauncherLayoutChangedEvent());
     }
 
     private AppLauncherGroupEntry createAppEntry(AppLauncherGroupEntryDefinition entryDefinition, AppDescriptor appDescriptor) {
         AppLauncherGroupEntryout/AppLauncherGroupEntry.html#AppLauncherGroupEntry">AppLauncherGroupEntry entry = new AppLauncherGroupEntry();
         entry.setName(entryDefinition.getName());
         entry.setEnabled(entryDefinition.isEnabled());
         entry.setAppDescriptor(appDescriptor);
         return entry;
     }
 
     private Optional<AppDescriptor> getAppDescriptor(String appName) {
         try {
             final DefinitionProvider<AppDescriptor> definitionProvider = appDescriptorRegistry.getProvider(appName);
             if (definitionProvider.isValid()) {
                 AppDescriptor appDescriptor = i18nizerProvider.get().decorate(definitionProvider.get());
                 if (StringUtils.isBlank(appDescriptor.getLabel()) || StringUtils.isBlank(appDescriptor.getIcon())) {
                     log.warn("Label and/or icon for app [{}] are blank. App won't be displayed in the app launcher. Please either define them in the configuration tree or in the app's i18n properties file.", appName);
                 } else {
                     return Optional.of(appDescriptor);
                 }
             }
         } catch (Registry.NoSuchDefinitionException e) {
             log.warn("Definition not found: {}", e.getMessage());
         } catch (IllegalStateException e) {
             log.warn("Encountered IllegalStateException while getting appDescriptor: ", e.getMessage(), e);
         }
         return Optional.empty();
     }
 
     private boolean isAppVisibleForUser(AppLauncherGroupEntryDefinition entry, AppDescriptor appDescriptor, User user) {
         AccessDefinition permissions = appDescriptor.getPermissions();
         return entry.isEnabled() && appDescriptor.isEnabled() && (permissions == null || permissions.hasAccess(user));
     }
 
     private boolean isGroupVisibleForUser(AppLauncherGroupDefinition group, User user) {
         AccessDefinition permissions = group.getPermissions();
         return (permissions == null || permissions.hasAccess(user));
     }
 }