/*
    * 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.bcel.classfile;
  
  import java.io.DataInput;
  import java.io.DataOutputStream;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.stream.Stream;
  
  import org.apache.commons.lang3.stream.Streams;
  
  /**
   * Represents one annotation in the annotation table
   *
   * @since 6.0
   */
  public class AnnotationEntry implements Node {
  
      /**
       * Empty array of AnnotationEntry objects.
       */
      public static final AnnotationEntry[] EMPTY_ARRAY = {};
  
      /**
       * Creates annotation entries from attributes.
       *
       * @param attributes the attributes.
       * @return the annotation entries.
       */
      public static AnnotationEntry[] createAnnotationEntries(final Attribute[] attributes) {
          // Find attributes that contain annotation data
          return Streams.of(attributes).filter(Annotations.class::isInstance).flatMap(e -> Stream.of(((Annotations) e).getAnnotationEntries()))
                  .toArray(AnnotationEntry[]::new);
      }
  
      /**
       * Factory method to create an AnnotionEntry from a DataInput.
       *
       * @param input the input stream.
       * @param constantPool the constant pool.
       * @param isRuntimeVisible whether the annotation is runtime visible.
       * @return the entry.
       * @throws IOException if an I/O error occurs.
       */
      public static AnnotationEntry read(final DataInput input, final ConstantPool constantPool, final boolean isRuntimeVisible) throws IOException {
          final AnnotationEntry annotationEntry = new AnnotationEntry(input.readUnsignedShort(), constantPool, isRuntimeVisible);
          final int numElementValuePairs = input.readUnsignedShort();
          for (int i = 0; i < numElementValuePairs; i++) {
              annotationEntry.elementValuePairs
                  .add(new ElementValuePair(input.readUnsignedShort(), ElementValue.readElementValue(input, constantPool), constantPool));
          }
          return annotationEntry;
      }
  
      private final int typeIndex;
  
      private final ConstantPool constantPool;
  
      private final boolean isRuntimeVisible;
  
      private final List<ElementValuePair> elementValuePairs;
  
      /**
       * Constructs an AnnotationEntry.
       *
       * @param typeIndex the type index.
       * @param constantPool the constant pool.
       * @param isRuntimeVisible whether the annotation is runtime visible.
       */
      public AnnotationEntry(final int typeIndex, final ConstantPool constantPool, final boolean isRuntimeVisible) {
          this.typeIndex = typeIndex;
          this.constantPool = constantPool;
          this.isRuntimeVisible = isRuntimeVisible;
          this.elementValuePairs = new ArrayList<>();
      }
  
      /**
       * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
       * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
       *
       * @param v Visitor object.
      */
     @Override
     public void accept(final Visitor v) {
         v.visitAnnotationEntry(this);
     }
 
     /**
      * Adds an element name value pair.
      *
      * @param elementNameValuePair the element name value pair.
      */
     public void addElementNameValuePair(final ElementValuePair elementNameValuePair) {
         elementValuePairs.add(elementNameValuePair);
     }
 
     /**
      * Dumps this annotation entry to a DataOutputStream.
      *
      * @param dos the output stream.
      * @throws IOException if an I/O error occurs.
      */
     public void dump(final DataOutputStream dos) throws IOException {
         dos.writeShort(typeIndex); // u2 index of type name in cpool
         dos.writeShort(elementValuePairs.size()); // u2 element_value pair
         // count
         for (final ElementValuePair envp : elementValuePairs) {
             envp.dump(dos);
         }
     }
 
     /**
      * Gets the annotation type name.
      *
      * @return the annotation type name.
      */
     public String getAnnotationType() {
         return constantPool.getConstantUtf8(typeIndex).getBytes();
     }
 
     /**
      * Gets the annotation type index.
      *
      * @return the annotation type index.
      */
     public int getAnnotationTypeIndex() {
         return typeIndex;
     }
 
     /**
      * Gets the constant pool.
      *
      * @return the constant pool.
      */
     public ConstantPool getConstantPool() {
         return constantPool;
     }
 
     /**
      * Gets the element value pairs in this annotation entry.
      *
      * @return the element value pairs in this annotation entry.
      */
     public ElementValuePair[] getElementValuePairs() {
         // TODO return List
         return elementValuePairs.toArray(ElementValuePair.EMPTY_ARRAY);
     }
 
     /**
      * Gets the number of element value pairs in this annotation entry.
      *
      * @return the number of element value pairs in this annotation entry.
      */
     public final int getNumElementValuePairs() {
         return elementValuePairs.size();
     }
 
     /**
      * Gets the type index.
      *
      * @return the type index.
      */
     public int getTypeIndex() {
         return typeIndex;
     }
 
     /**
      * Gets whether this annotation is runtime visible.
      *
      * @return true if this annotation is runtime visible.
      */
     public boolean isRuntimeVisible() {
         return isRuntimeVisible;
     }
 
     /**
      * Gets a short string representation of this annotation.
      *
      * @return a short string representation of this annotation.
      */
     public String toShortString() {
         final StringBuilder result = new StringBuilder();
         result.append("@");
         result.append(getAnnotationType());
         final ElementValuePair[] evPairs = getElementValuePairs();
         if (evPairs.length > 0) {
             result.append("(");
             for (final ElementValuePair element : evPairs) {
                 result.append(element.toShortString());
                 result.append(", ");
             }
             // remove last ", "
             result.setLength(result.length() - 2);
             result.append(")");
         }
         return result.toString();
     }
 
     @Override
     public String toString() {
         return toShortString();
     }
 }