/*
    * 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
    *
    *      http://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.generic;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  import java.util.Objects;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.classfile.AccessFlags;
  import org.apache.bcel.classfile.Annotations;
  import org.apache.bcel.classfile.Attribute;
  import org.apache.bcel.classfile.ConstantPool;
  import org.apache.bcel.classfile.Field;
  import org.apache.bcel.classfile.JavaClass;
  import org.apache.bcel.classfile.Method;
  import org.apache.bcel.classfile.RuntimeInvisibleAnnotations;
  import org.apache.bcel.classfile.RuntimeVisibleAnnotations;
  import org.apache.bcel.classfile.SourceFile;
  import org.apache.bcel.classfile.Utility;
  import org.apache.bcel.util.BCELComparator;
  import org.apache.commons.lang3.ArrayUtils;
  
  /**
   * Template class for building up a java class. May be initialized with an existing Java class (file).
   *
   * @see JavaClass
   */
  public class ClassGen extends AccessFlags implements Cloneable {
  
      private static BCELComparator<ClassGen> bcelComparator = new BCELComparator<ClassGen>() {
  
          @Override
          public boolean equals(final ClassGen a, final ClassGen b) {
              return a == b || a != null && b != null && Objects.equals(a.getClassName(), b.getClassName());
          }
  
          @Override
          public int hashCode(final ClassGen o) {
              return o != null ? Objects.hashCode(o.getClassName()) : 0;
          }
      };
  
      /**
       * @return Comparison strategy object
       */
      public static BCELComparator<ClassGen> getComparator() {
          return bcelComparator;
      }
  
      /**
       * @param comparator Comparison strategy object
       */
      public static void setComparator(final BCELComparator<ClassGen> comparator) {
          bcelComparator = comparator;
      }
  
      /*
       * Corresponds to the fields found in a JavaClass object.
       */
      private String className;
      private String superClassName;
      private final String fileName;
      private int classNameIndex = -1;
      private int superclassNameIndex = -1;
      private int major = Const.MAJOR_1_1;
      private int minor = Const.MINOR_1_1;
      private ConstantPoolGen cp; // Template for building up constant pool
      // ArrayLists instead of arrays to gather fields, methods, etc.
      private final List<Field> fieldList = new ArrayList<>();
      private final List<Method> methodList = new ArrayList<>();
  
      private final List<Attribute> attributeList = new ArrayList<>();
  
      private final List<String> interfaceList = new ArrayList<>();
  
      private final List<AnnotationEntryGen> annotationList = new ArrayList<>();
  
      private List<ClassObserver> observers;
  
      /**
       * Initialize with existing class.
       *
      * @param clazz JavaClass object (e.g. read from file)
      */
     public ClassGen(final JavaClass clazz) {
         super(clazz.getAccessFlags());
         classNameIndex = clazz.getClassNameIndex();
         superclassNameIndex = clazz.getSuperclassNameIndex();
         className = clazz.getClassName();
         superClassName = clazz.getSuperclassName();
         fileName = clazz.getSourceFileName();
         cp = new ConstantPoolGen(clazz.getConstantPool());
         major = clazz.getMajor();
         minor = clazz.getMinor();
         final Attribute[] attributes = clazz.getAttributes();
         // J5TODO: Could make unpacking lazy, done on first reference
         final AnnotationEntryGen[] annotations = unpackAnnotations(attributes);
         Collections.addAll(interfaceList, clazz.getInterfaceNames());
         for (final Attribute attribute : attributes) {
             if (!(attribute instanceof Annotations)) {
                 addAttribute(attribute);
             }
         }
         Collections.addAll(annotationList, annotations);
         Collections.addAll(methodList, clazz.getMethods());
         Collections.addAll(fieldList, clazz.getFields());
     }
 
     /**
      * Convenience constructor to set up some important values initially.
      *
      * @param className fully qualified class name
      * @param superClassName fully qualified superclass name
      * @param fileName source file name
      * @param accessFlags access qualifiers
      * @param interfaces implemented interfaces
      */
     public ClassGen(final String className, final String superClassName, final String fileName, final int accessFlags, final String[] interfaces) {
         this(className, superClassName, fileName, accessFlags, interfaces, new ConstantPoolGen());
     }
 
     /**
      * Convenience constructor to set up some important values initially.
      *
      * @param className fully qualified class name
      * @param superClassName fully qualified superclass name
      * @param fileName source file name
      * @param accessFlags access qualifiers
      * @param interfaces implemented interfaces
      * @param cp constant pool to use
      */
     public ClassGen(final String className, final String superClassName, final String fileName, final int accessFlags, final String[] interfaces,
         final ConstantPoolGen cp) {
         super(accessFlags);
         this.className = className;
         this.superClassName = superClassName;
         this.fileName = fileName;
         this.cp = cp;
         // Put everything needed by default into the constant pool and the vectors
         if (fileName != null) {
             addAttribute(new SourceFile(cp.addUtf8("SourceFile"), 2, cp.addUtf8(fileName), cp.getConstantPool()));
         }
         classNameIndex = cp.addClass(className);
         superclassNameIndex = cp.addClass(superClassName);
         if (interfaces != null) {
             Collections.addAll(interfaceList, interfaces);
         }
     }
 
     public void addAnnotationEntry(final AnnotationEntryGen a) {
         annotationList.add(a);
     }
 
     /**
      * Add an attribute to this class.
      *
      * @param a attribute to add
      */
     public void addAttribute(final Attribute a) {
         attributeList.add(a);
     }
 
     /**
      * Convenience method.
      *
      * Add an empty constructor to this class that does nothing but calling super().
      *
      * @param accessFlags rights for constructor
      */
     public void addEmptyConstructor(final int accessFlags) {
         final InstructionList il = new InstructionList();
         il.append(InstructionConst.THIS); // Push 'this'
         il.append(new INVOKESPECIAL(cp.addMethodref(superClassName, Const.CONSTRUCTOR_NAME, "()V")));
         il.append(InstructionConst.RETURN);
         final MethodGen mg = new MethodGen(accessFlags, Type.VOID, Type.NO_ARGS, null, Const.CONSTRUCTOR_NAME, className, il, cp);
         mg.setMaxStack(1);
         addMethod(mg.getMethod());
     }
 
     /**
      * Add a field to this class.
      *
      * @param f field to add
      */
     public void addField(final Field f) {
         fieldList.add(f);
     }
 
     /**
      * Add an interface to this class, i.e., this class has to implement it.
      *
      * @param name interface to implement (fully qualified class name)
      */
     public void addInterface(final String name) {
         interfaceList.add(name);
     }
 
     /**
      * Add a method to this class.
      *
      * @param m method to add
      */
     public void addMethod(final Method m) {
         methodList.add(m);
     }
 
     /**
      * Add observer for this object.
      */
     public void addObserver(final ClassObserver o) {
         if (observers == null) {
             observers = new ArrayList<>();
         }
         observers.add(o);
     }
 
     @Override
     public Object clone() {
         try {
             return super.clone();
         } catch (final CloneNotSupportedException e) {
             throw new UnsupportedOperationException("Clone Not Supported", e); // never happens
         }
     }
 
     public boolean containsField(final Field f) {
         return fieldList.contains(f);
     }
 
     /**
      * @return field object with given name, or null
      */
     public Field containsField(final String name) {
         for (final Field f : fieldList) {
             if (f.getName().equals(name)) {
                 return f;
             }
         }
         return null;
     }
 
     /**
      * @return method object with given name and signature, or null
      */
     public Method containsMethod(final String name, final String signature) {
         for (final Method m : methodList) {
             if (m.getName().equals(name) && m.getSignature().equals(signature)) {
                 return m;
             }
         }
         return null;
     }
 
     /**
      * Return value as defined by given BCELComparator strategy. By default two ClassGen objects are said to be equal when
      * their class names are equal.
      *
      * @see Object#equals(Object)
      */
     @Override
     public boolean equals(final Object obj) {
         return obj instanceof ClassGen && bcelComparator.equals(this, (ClassGen) obj);
     }
 
     // J5TODO: Should we make calling unpackAnnotations() lazy and put it in here?
     public AnnotationEntryGen[] getAnnotationEntries() {
         return annotationList.toArray(AnnotationEntryGen.EMPTY_ARRAY);
     }
 
     public Attribute[] getAttributes() {
         return attributeList.toArray(Attribute.EMPTY_ARRAY);
     }
 
     public String getClassName() {
         return className;
     }
 
     public int getClassNameIndex() {
         return classNameIndex;
     }
 
     public ConstantPoolGen getConstantPool() {
         return cp;
     }
 
     public Field[] getFields() {
         return fieldList.toArray(Field.EMPTY_ARRAY);
     }
 
     public String getFileName() {
         return fileName;
     }
 
     public String[] getInterfaceNames() {
         return interfaceList.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
     }
 
     public int[] getInterfaces() {
         final int size = interfaceList.size();
         final int[] interfaces = new int[size];
         Arrays.setAll(interfaces, i -> cp.addClass(interfaceList.get(i)));
         return interfaces;
     }
 
     /**
      * @return the (finally) built up Java class object.
      */
     public JavaClass getJavaClass() {
         final int[] interfaces = getInterfaces();
         final Field[] fields = getFields();
         final Method[] methods = getMethods();
         Attribute[] attributes = null;
         if (annotationList.isEmpty()) {
             attributes = getAttributes();
         } else {
             // TODO: Sometime later, trash any attributes called 'RuntimeVisibleAnnotations' or 'RuntimeInvisibleAnnotations'
             final Attribute[] annAttributes = AnnotationEntryGen.getAnnotationAttributes(cp, getAnnotationEntries());
             attributes = new Attribute[attributeList.size() + annAttributes.length];
             attributeList.toArray(attributes);
             System.arraycopy(annAttributes, 0, attributes, attributeList.size(), annAttributes.length);
         }
         // Must be last since the above calls may still add something to it
         final ConstantPool cp = this.cp.getFinalConstantPool();
         return new JavaClass(classNameIndex, superclassNameIndex, fileName, major, minor, super.getAccessFlags(), cp, interfaces, fields, methods,
             attributes);
     }
 
     /**
      * @return major version number of class file
      */
     public int getMajor() {
         return major;
     }
 
     public Method getMethodAt(final int pos) {
         return methodList.get(pos);
     }
 
     public Method[] getMethods() {
         return methodList.toArray(Method.EMPTY_ARRAY);
     }
 
     /**
      * @return minor version number of class file
      */
     public int getMinor() {
         return minor;
     }
 
     public String getSuperclassName() {
         return superClassName;
     }
 
     public int getSuperclassNameIndex() {
         return superclassNameIndex;
     }
 
     /**
      * Return value as defined by given BCELComparator strategy. By default return the hash code of the class name.
      *
      * @see Object#hashCode()
      */
     @Override
     public int hashCode() {
         return bcelComparator.hashCode(this);
     }
 
     /**
      * Remove an attribute from this class.
      *
      * @param a attribute to remove
      */
     public void removeAttribute(final Attribute a) {
         attributeList.remove(a);
     }
 
     /**
      * Remove a field to this class.
      *
      * @param f field to remove
      */
     public void removeField(final Field f) {
         fieldList.remove(f);
     }
 
     /**
      * Remove an interface from this class.
      *
      * @param name interface to remove (fully qualified name)
      */
     public void removeInterface(final String name) {
         interfaceList.remove(name);
     }
 
     /**
      * Remove a method from this class.
      *
      * @param m method to remove
      */
     public void removeMethod(final Method m) {
         methodList.remove(m);
     }
 
     /**
      * Remove observer for this object.
      */
     public void removeObserver(final ClassObserver o) {
         if (observers != null) {
             observers.remove(o);
         }
     }
 
     /**
      * Replace given field with new one. If the old one does not exist add the new_ field to the class anyway.
      */
     public void replaceField(final Field old, final Field newField) {
         if (newField == null) {
             throw new ClassGenException("Replacement method must not be null");
         }
         final int i = fieldList.indexOf(old);
         if (i < 0) {
             fieldList.add(newField);
         } else {
             fieldList.set(i, newField);
         }
     }
 
     /**
      * Replace given method with new one. If the old one does not exist add the newMethod method to the class anyway.
      */
     public void replaceMethod(final Method old, final Method newMethod) {
         if (newMethod == null) {
             throw new ClassGenException("Replacement method must not be null");
         }
         final int i = methodList.indexOf(old);
         if (i < 0) {
             methodList.add(newMethod);
         } else {
             methodList.set(i, newMethod);
         }
     }
 
     public void setClassName(final String name) {
         className = Utility.pathToPackage(name);
         classNameIndex = cp.addClass(name);
     }
 
     public void setClassNameIndex(final int classNameIndex) {
         this.classNameIndex = classNameIndex;
         this.className = Utility.pathToPackage(cp.getConstantPool().getConstantString(classNameIndex, Const.CONSTANT_Class));
     }
 
     public void setConstantPool(final ConstantPoolGen constantPool) {
         cp = constantPool;
     }
 
     /**
      * Sets major version number of class file, default value is 45 (JDK 1.1)
      *
      * @param major major version number
      */
     public void setMajor(final int major) { // TODO could be package-protected - only called by test code
         this.major = major;
     }
 
     public void setMethodAt(final Method method, final int pos) {
         methodList.set(pos, method);
     }
 
     public void setMethods(final Method[] methods) {
         methodList.clear();
         Collections.addAll(methodList, methods);
     }
 
     /**
      * Sets minor version number of class file, default value is 3 (JDK 1.1)
      *
      * @param minor minor version number
      */
     public void setMinor(final int minor) { // TODO could be package-protected - only called by test code
         this.minor = minor;
     }
 
     public void setSuperclassName(final String name) {
         superClassName = Utility.pathToPackage(name);
         superclassNameIndex = cp.addClass(name);
     }
 
     public void setSuperclassNameIndex(final int superclassNameIndex) {
         this.superclassNameIndex = superclassNameIndex;
         superClassName = Utility.pathToPackage(cp.getConstantPool().getConstantString(superclassNameIndex, Const.CONSTANT_Class));
     }
 
     /**
      * Look for attributes representing annotations and unpack them.
      */
     private AnnotationEntryGen[] unpackAnnotations(final Attribute[] attrs) {
         final List<AnnotationEntryGen> annotationGenObjs = new ArrayList<>();
         for (final Attribute attr : attrs) {
             if (attr instanceof RuntimeVisibleAnnotations) {
                 final RuntimeVisibleAnnotations rva = (RuntimeVisibleAnnotations) attr;
                 rva.forEach(a -> annotationGenObjs.add(new AnnotationEntryGen(a, getConstantPool(), false)));
             } else if (attr instanceof RuntimeInvisibleAnnotations) {
                 final RuntimeInvisibleAnnotations ria = (RuntimeInvisibleAnnotations) attr;
                 ria.forEach(a -> annotationGenObjs.add(new AnnotationEntryGen(a, getConstantPool(), false)));
             }
         }
         return annotationGenObjs.toArray(AnnotationEntryGen.EMPTY_ARRAY);
     }
 
     /**
      * Call notify() method on all observers. This method is not called automatically whenever the state has changed, but
      * has to be called by the user after they have finished editing the object.
      */
     public void update() {
         if (observers != null) {
             for (final ClassObserver observer : observers) {
                 observer.notify(this);
             }
         }
     }
 }