/*
    * Portions of this software was developed by employees of the National Institute
    * of Standards and Technology (NIST), an agency of the Federal Government and is
    * being made available as a public service. Pursuant to title 17 United States
    * Code Section 105, works of NIST employees are not subject to copyright
    * protection in the United States. This software may be subject to foreign
    * copyright. Permission in the United States and in foreign countries, to the
    * extent that NIST may hold copyright, to use, copy, modify, create derivative
    * works, and distribute this software and its documentation without fee is hereby
   * granted on a non-exclusive basis, provided that this notice and disclaimer
   * of warranty appears in all copies.
   *
   * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
   * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
   * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
   * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
   * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
   * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
   * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
   * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
   * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
   * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
   * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
   */
  
  package gov.nist.secauto.metaschema.schemagen;
  
  import gov.nist.secauto.metaschema.core.model.IAssemblyDefinition;
  import gov.nist.secauto.metaschema.core.model.IAssemblyInstance;
  import gov.nist.secauto.metaschema.core.model.IChoiceInstance;
  import gov.nist.secauto.metaschema.core.model.IDefinition;
  import gov.nist.secauto.metaschema.core.model.IFieldInstance;
  import gov.nist.secauto.metaschema.core.model.IFlagDefinition;
  import gov.nist.secauto.metaschema.core.model.IFlagInstance;
  import gov.nist.secauto.metaschema.core.model.IModule;
  import gov.nist.secauto.metaschema.core.model.INamedInstance;
  import gov.nist.secauto.metaschema.core.model.ModelWalker;
  import gov.nist.secauto.metaschema.core.util.ObjectUtils;
  
  import java.util.Collection;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import edu.umd.cs.findbugs.annotations.NonNull;
  
  public class ModuleIndex {
    private final Map<IDefinition, DefinitionEntry> index = new ConcurrentHashMap<>();
  
    @NonNull
    public static ModuleIndex indexDefinitions(@NonNull IModule module) {
      Collection<? extends IAssemblyDefinition> definitions = module.getExportedRootAssemblyDefinitions();
      ModuleIndex index = new ModuleIndex();
      if (!definitions.isEmpty()) {
        IndexVisitor visitor = new IndexVisitor(index);
        for (IAssemblyDefinition definition : definitions) {
          assert definition != null;
  
          // add the root definition to the index
          index.getEntry(definition).incrementReferenceCount();
  
          // walk the definition
          visitor.walk(ObjectUtils.requireNonNull(definition));
        }
      }
      return index;
    }
  
    public boolean hasEntry(@NonNull IDefinition definition) {
      return index.containsKey(definition);
    }
  
    @NonNull
    public DefinitionEntry getEntry(@NonNull IDefinition definition) {
      return ObjectUtils.notNull(index.computeIfAbsent(
          definition,
          k -> new ModuleIndex.DefinitionEntry(ObjectUtils.notNull(k))));
    }
  
    @NonNull
    public Collection<DefinitionEntry> getDefinitions() {
      return ObjectUtils.notNull(index.values());
    }
  
    private static class IndexVisitor
        extends ModelWalker<ModuleIndex> {
      private final ModuleIndex index;
  
      public IndexVisitor(@NonNull ModuleIndex index) {
        this.index = index;
      }
  
      @Override
      protected ModuleIndex getDefaultData() {
        return index;
      }
  
     @Override
     protected boolean visit(IFlagInstance instance, ModuleIndex data) {
       return handleInstance(instance);
     }
 
     @Override
     protected boolean visit(IFieldInstance instance, ModuleIndex data) {
       return handleInstance(instance);
     }
 
     @Override
     protected boolean visit(IAssemblyInstance instance, ModuleIndex data) {
       return handleInstance(instance);
     }
 
     @Override
     protected void visit(IFlagDefinition def, ModuleIndex data) {
       // do nothing
     }
     //
     // @Override
     // protected boolean visit(IAssemblyDefinition def, ModuleIndex data) {
     // // only walk if the definition hasn't already been visited
     // return !index.hasEntry(def);
     // }
 
     /**
      * Updates the index entry for the definition associated with the reference.
      *
      * @param instance
      *          the instance to process
      * @return {@code true} if this is the first time handling the definition this
      *         instance references, or {@code false} otherwise
      */
     private boolean handleInstance(INamedInstance instance) {
       IDefinition definition = instance.getDefinition();
       // check if this will be a new entry, which needs to be called before getEntry,
       // which will create it
       final boolean exists = getDefaultData().hasEntry(definition);
       DefinitionEntry entry = getDefaultData().getEntry(definition);
       entry.incrementReferenceCount();
 
       if (isChoice(instance)) {
         entry.markUsedAsChoice();
       }
 
       if (isChoiceSibling(instance)) {
         entry.markAsChoiceSibling();
       }
       return !exists;
     }
 
     private static boolean isChoice(@NonNull INamedInstance instance) {
       return instance.getParentContainer() instanceof IChoiceInstance;
     }
 
     private static boolean isChoiceSibling(@NonNull INamedInstance instance) {
       IDefinition containingDefinition = instance.getContainingDefinition();
       return containingDefinition instanceof IAssemblyDefinition
           && !((IAssemblyDefinition) containingDefinition).getChoiceInstances().isEmpty();
     }
   }
 
   public static class DefinitionEntry {
     @NonNull
     private final IDefinition definition;
     private final AtomicInteger referenceCount = new AtomicInteger(); // 0
     private final AtomicBoolean usedAsChoice = new AtomicBoolean(); // false
     private final AtomicBoolean choiceSibling = new AtomicBoolean(); // false
 
     public DefinitionEntry(@NonNull IDefinition definition) {
       this.definition = definition;
     }
 
     public IDefinition getDefinition() {
       return definition;
     }
 
     public boolean isReferenced() {
       return getReferenceCount() > 0;
     }
 
     public int getReferenceCount() {
       return referenceCount.get();
     }
 
     public int incrementReferenceCount() {
       return referenceCount.incrementAndGet();
     }
 
     public int incrementReferenceCount(int increment) {
       return referenceCount.addAndGet(increment);
     }
 
     public boolean isInline() {
       return getDefinition().isInline();
     }
 
     public void markUsedAsChoice() {
       usedAsChoice.compareAndSet(false, true);
     }
 
     public boolean isUsedAsChoice() {
       return usedAsChoice.get();
     }
 
     public void markAsChoiceSibling() {
       choiceSibling.compareAndSet(false, true);
     }
 
     public boolean isChoiceSibling() {
       return choiceSibling.get();
     }
   }
 }