/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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
    *
   *   https://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 org.apache.commons.compress.harmony.unpack200.bytecode;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.TreeSet;
  
  import org.apache.commons.compress.harmony.unpack200.Segment;
  
  /**
   * The Class constant pool
   */
  public class ClassConstantPool {
  
      protected HashSet<ClassFileEntry> entriesContainsSet = new HashSet<>();
      protected HashSet<ClassFileEntry> othersContainsSet = new HashSet<>();
  
      private final HashSet<ClassFileEntry> mustStartClassPool = new HashSet<>();
  
      protected Map<ClassFileEntry, Integer> indexCache;
  
      private final List<ClassFileEntry> others = new ArrayList<>(500);
      private final List<ClassFileEntry> entries = new ArrayList<>(500);
  
      private boolean resolved;
  
      public ClassFileEntry add(final ClassFileEntry entry) {
          if (entry instanceof ByteCode) {
              return null;
          }
          if (entry instanceof ConstantPoolEntry) {
              if (entriesContainsSet.add(entry)) {
                  entries.add(entry);
              }
          } else if (othersContainsSet.add(entry)) {
              others.add(entry);
          }
  
          return entry;
      }
  
      public void addNestedEntries() {
          boolean added = true;
  
          // initial assignment
          final List<ClassFileEntry> parents = new ArrayList<>(512);
          final List<ClassFileEntry> children = new ArrayList<>(512);
  
          // adding old entries
          parents.addAll(entries);
          parents.addAll(others);
  
          // while there any parents to traverse and at least one change in target
          // storage was made
          while (added || parents.size() > 0) {
  
              children.clear();
  
              final int entriesOriginalSize = entries.size();
              final int othersOriginalSize = others.size();
  
              // get the parents' children and add them to buffer
              // concurrently add parents to target storage
              for (int indexParents = 0; indexParents < parents.size(); indexParents++) {
                  final ClassFileEntry entry = parents.get(indexParents);
  
                  // traverse children
                  final ClassFileEntry[] entryChildren = entry.getNestedClassFileEntries();
                  children.addAll(Arrays.asList(entryChildren));
  
                  final boolean isAtStart = entry instanceof ByteCode && ((ByteCode) entry).nestedMustStartClassPool();
  
                  if (isAtStart) {
                      mustStartClassPool.addAll(Arrays.asList(entryChildren));
                  }
  
                 // add parent
                 add(entry);
             }
 
             added = !(entries.size() == entriesOriginalSize && others.size() == othersOriginalSize);
 
             // parents are not needed anymore
             // children now become parents
             parents.clear();
             parents.addAll(children);
         }
     }
 
     public ClassFileEntry addWithNestedEntries(final ClassFileEntry entry) {
         add(entry);
         for (final ClassFileEntry nestedEntry : entry.getNestedClassFileEntries()) {
             addWithNestedEntries(nestedEntry);
         }
         return entry;
     }
 
     public List<ClassFileEntry> entries() {
         return Collections.unmodifiableList(entries);
     }
 
     public ClassFileEntry get(int i) {
         if (!resolved) {
             throw new IllegalStateException("Constant pool is not yet resolved; this does not make any sense");
         }
         return entries.get(--i);
     }
 
     public int indexOf(final ClassFileEntry entry) {
         if (!resolved) {
             throw new IllegalStateException("Constant pool is not yet resolved; this does not make any sense");
         }
         if (null == indexCache) {
             throw new IllegalStateException("Index cache is not initialized!");
         }
         final Integer entryIndex = indexCache.get(entry);
         // If the entry isn't found, answer -1, otherwise answer the entry.
         if (entryIndex != null) {
             return entryIndex.intValue() + 1;
         }
         return -1;
     }
 
     private void initialSort() {
         final TreeSet<ClassFileEntry> inCpAll = new TreeSet<>(Comparator.comparingInt(arg0 -> ((ConstantPoolEntry) arg0).getGlobalIndex()));
         final TreeSet<ClassFileEntry> cpUtf8sNotInCpAll = new TreeSet<>(Comparator.comparing(arg0 -> ((CPUTF8) arg0).underlyingString()));
         final TreeSet<ClassFileEntry> cpClassesNotInCpAll = new TreeSet<>(Comparator.comparing(arg0 -> ((CPClass) arg0).getName()));
 
         for (final ClassFileEntry entry2 : entries) {
             final ConstantPoolEntry entry = (ConstantPoolEntry) entry2;
             if (entry.getGlobalIndex() == -1) {
                 if (entry instanceof CPUTF8) {
                     cpUtf8sNotInCpAll.add(entry);
                 } else if (entry instanceof CPClass) {
                     cpClassesNotInCpAll.add(entry);
                 } else {
                     throw new Error("error");
                 }
             } else {
                 inCpAll.add(entry);
             }
         }
         entries.clear();
         entries.addAll(inCpAll);
         entries.addAll(cpUtf8sNotInCpAll);
         entries.addAll(cpClassesNotInCpAll);
     }
 
     public void resolve(final Segment segment) {
         initialSort();
         sortClassPool();
 
         resolved = true;
 
         entries.forEach(entry -> entry.resolve(this));
         others.forEach(entry -> entry.resolve(this));
     }
 
     public int size() {
         return entries.size();
     }
 
     protected void sortClassPool() {
         // Now that everything has been resolved, do one
         // final sort of the class pool. This fixes up
         // references to objects which need to be at the
         // start of the class pool
 
         final List<ClassFileEntry> startOfPool = new ArrayList<>(entries.size());
         final List<ClassFileEntry> finalSort = new ArrayList<>(entries.size());
 
         for (final ClassFileEntry entry : entries) {
             if (mustStartClassPool.contains(entry)) {
                 startOfPool.add(entry);
             } else {
                 finalSort.add(entry);
             }
         }
 
         // copy over and rebuild the cache
         //
         indexCache = new HashMap<>(entries.size());
         int index = 0;
 
         entries.clear();
 
         for (final ClassFileEntry entry : startOfPool) {
             indexCache.put(entry, Integer.valueOf(index));
 
             if (entry instanceof CPLong || entry instanceof CPDouble) {
                 entries.add(entry); // these get 2 slots because of their size
                 entries.add(entry);
                 index += 2;
             } else {
                 entries.add(entry);
                 index += 1;
             }
         }
 
         for (final ClassFileEntry entry : finalSort) {
             indexCache.put(entry, Integer.valueOf(index));
 
             if (entry instanceof CPLong || entry instanceof CPDouble) {
                 entries.add(entry); // these get 2 slots because of their size
                 entries.add(entry);
                 index += 2;
             } else {
                 entries.add(entry);
                 index += 1;
             }
         }
 
     }
 }