/*
    * MIT License
    * Copyright (c) 2006-2025 JMockit developers
    * See LICENSE file for full license text.
    */
   package mockit.asm.annotations;
   
   import edu.umd.cs.findbugs.annotations.NonNull;
   import edu.umd.cs.findbugs.annotations.Nullable;
  
  import java.lang.reflect.Array;
  
  import mockit.asm.constantPool.ConstantPoolGeneration;
  import mockit.asm.constantPool.Item;
  import mockit.asm.types.JavaType;
  import mockit.asm.util.ByteVector;
  
  import org.checkerframework.checker.index.qual.NonNegative;
  
  /**
   * A visitor to visit a Java annotation, in the following order: (<code>visit</code> | <code>visitEnum</code> |
   * <code>visitAnnotation</code> | <code>visitArray</code>)* <code>visitEnd</code>.
   */
  public final class AnnotationVisitor {
      /**
       * The constant pool to which this annotation must be added.
       */
      @NonNull
      private final ConstantPoolGeneration cp;
  
      /**
       * The number of attribute values in this annotation.
       */
      @NonNegative
      private int attributeCount;
  
      /**
       * <code>true<code> if values are named, <code>false</code> otherwise. Annotation writers used for annotation
       * default and annotation arrays use unnamed values.
       */
      private final boolean named;
  
      /**
       * The annotation values in bytecode form. This byte vector only contains the values themselves, i.e. the number of
       * values must be stored as an unsigned short just before these bytes.
       */
      @NonNull
      private final ByteVector bv;
  
      /**
       * Where the number of values of this annotation must be stored in {@link #bv}.
       */
      @NonNegative
      private final int offset;
  
      /**
       * Next annotation visitor. This field is used to store annotation lists.
       */
      @Nullable
      private AnnotationVisitor next;
  
      /**
       * Previous annotation visitor. This field is used to store annotation lists.
       */
      @Nullable
      private AnnotationVisitor prev;
  
      public AnnotationVisitor(@NonNull ConstantPoolGeneration cp, @NonNull String typeDesc) {
          this.cp = cp;
          named = true;
          bv = new ByteVector();
          bv.putShort(cp.newUTF8(typeDesc));
          bv.putShort(0); // reserve space for value count
          offset = 2;
      }
  
      private AnnotationVisitor(@NonNull AnnotationVisitor parent, boolean named) {
          cp = parent.cp;
          this.named = named;
          bv = parent.bv;
          offset = getByteLength() - 2;
      }
  
      @NonNegative
      private int getByteLength() {
          return bv.getLength();
      }
  
      /**
       * Sets the visitor to the {@link #next} annotation.
       */
      public void setNext(@Nullable AnnotationVisitor next) {
          this.next = next;
      }
  
      /**
       * Visits a primitive, String, Class, or array value of the annotation.
       *
       * @param name
      *            the value name
      * @param value
      *            the actual value, whose type must be {@link Byte}, {@link Boolean}, {@link Character}, {@link Short},
      *            {@link Integer}, {@link Long}, {@link Float}, {@link Double}, {@link String}, or {@link JavaType} of
      *            OBJECT or ARRAY sort; this value can also be an array of byte, boolean, short, char, int, long, float
      *            or double values (this is equivalent to using {@link #visitArray} and visiting each array element in
      *            turn, but is more convenient)
      */
     void visit(@Nullable String name, @NonNull Object value) {
         putName(name);
 
         if (value instanceof String) {
             putString('s', (String) value);
         } else if (putValueWhenPrimitive(value)) {
             // OK
         } else if (value instanceof JavaType) {
             putType((JavaType) value);
         } else {
             putElementValuesWhenArray(value);
         }
     }
 
     private void putName(@Nullable String name) {
         attributeCount++;
 
         if (named) {
             // noinspection ConstantConditions
             putString(name);
         }
     }
 
     private boolean putValueWhenPrimitive(@NonNull Object value) {
         if (value instanceof Boolean) {
             putBoolean((Boolean) value);
         } else if (value instanceof Integer) {
             putInteger('I', (Integer) value);
         } else if (value instanceof Double) {
             putDouble((Double) value);
         } else if (value instanceof Float) {
             putFloat((Float) value);
         } else if (value instanceof Long) {
             putLong((Long) value);
         } else if (value instanceof Byte) {
             putInteger('B', (Byte) value);
         } else if (value instanceof Character) {
             putInteger('C', (Character) value);
         } else if (value instanceof Short) {
             putInteger('S', (Short) value);
         } else {
             return false;
         }
 
         return true;
     }
 
     private void putItem(int typeCode, @NonNull Item item) {
         bv.put12(typeCode, item.index);
     }
 
     private void putBoolean(boolean value) {
         putInteger('Z', value ? 1 : 0);
     }
 
     private void putInteger(int typeCode, int value) {
         Item item = cp.newInteger(value);
         putItem(typeCode, item);
     }
 
     private void putDouble(double value) {
         Item item = cp.newDouble(value);
         putItem('D', item);
     }
 
     private void putFloat(float value) {
         Item item = cp.newFloat(value);
         putItem('F', item);
     }
 
     private void putLong(long value) {
         Item item = cp.newLong(value);
         putItem('J', item);
     }
 
     private void putType(@NonNull JavaType type) {
         String typeDescriptor = type.getDescriptor();
         putString('c', typeDescriptor);
     }
 
     private void putString(int b, @NonNull String value) {
         int itemIndex = cp.newUTF8(value);
         bv.put12(b, itemIndex);
     }
 
     private void putString(@NonNull String value) {
         int itemIndex = cp.newUTF8(value);
         bv.putShort(itemIndex);
     }
 
     private void putArrayLength(@NonNegative int length) {
         bv.put12('[', length);
     }
 
     private void putElementValuesWhenArray(@NonNull Object value) {
         if (value instanceof byte[]) {
             putArrayElementValues('B', value);
         } else if (value instanceof boolean[]) {
             putArrayElementValues('Z', value);
         } else if (value instanceof short[]) {
             putArrayElementValues('S', value);
         } else if (value instanceof char[]) {
             putArrayElementValues('C', value);
         } else if (value instanceof int[]) {
             putArrayElementValues('I', value);
         } else if (value instanceof long[]) {
             putArrayElementValues('J', value);
         } else if (value instanceof float[]) {
             putArrayElementValues('F', value);
         } else if (value instanceof double[]) {
             putArrayElementValues('D', value);
         }
     }
 
     private void putArrayElementValues(char elementType, @NonNull Object array) {
         int length = Array.getLength(array);
         putArrayLength(length);
 
         for (int i = 0; i < length; i++) {
             switch (elementType) {
                 case 'J': {
                     long value = Array.getLong(array, i);
                     putLong(value);
                     break;
                 }
                 case 'F': {
                     float value = Array.getFloat(array, i);
                     putFloat(value);
                     break;
                 }
                 case 'D': {
                     double value = Array.getDouble(array, i);
                     putDouble(value);
                     break;
                 }
                 case 'Z': {
                     boolean value = Array.getBoolean(array, i);
                     putBoolean(value);
                     break;
                 }
                 default: {
                     int value = Array.getInt(array, i);
                     putInteger(elementType, value);
                     break;
                 }
             }
         }
     }
 
     /**
      * Visits an enumeration value of the annotation.
      *
      * @param name
      *            the value name
      * @param desc
      *            the class descriptor of the enumeration class
      * @param value
      *            the actual enumeration value
      */
     void visitEnum(@Nullable String name, @NonNull String desc, @NonNull String value) {
         putName(name);
         putString('e', desc);
         putString(value);
     }
 
     /**
      * Visits a nested annotation value of the annotation.
      *
      * @param name
      *            the value name
      * @param desc
      *            the class descriptor of the nested annotation class
      *
      * @return a visitor to visit the actual nested annotation value
      */
     @NonNull
     AnnotationVisitor visitAnnotation(@Nullable String name, @NonNull String desc) {
         putName(name);
 
         // Write tag and type, and reserve space for value count.
         putString('@', desc);
         bv.putShort(0);
 
         return new AnnotationVisitor(this, true);
     }
 
     /**
      * Visits an array value of the annotation. Note that arrays of primitive types can be passed as value to
      * {@link #visit(String, Object)}.
      *
      * @param name
      *            the value name
      *
      * @return a visitor to visit the actual array value elements; the 'name' parameters passed to the methods of this
      *         visitor are ignored
      */
     @NonNull
     AnnotationVisitor visitArray(@Nullable String name) {
         putName(name);
 
         // Write tag, and reserve space for array size.
         putArrayLength(0);
 
         return new AnnotationVisitor(this, false);
     }
 
     /**
      * Visits the end of the annotation.
      */
     @SuppressWarnings("NumericCastThatLosesPrecision")
     void visitEnd() {
         byte[] data = bv.getData();
         data[offset] = (byte) (attributeCount >>> 8);
         data[offset + 1] = (byte) attributeCount;
     }
 
     /**
      * Returns the size of this annotation list.
      */
     @NonNegative
     public int getSize() {
         int size = 0;
         AnnotationVisitor annotation = this;
 
         while (annotation != null) {
             size += annotation.getByteLength();
             annotation = annotation.next;
         }
 
         return size;
     }
 
     /**
      * Puts the annotations of this annotation writer list into the given byte vector.
      */
     public void put(@NonNull ByteVector out) {
         AnnotationVisitor aw = this;
         AnnotationVisitor last = null;
         int n = 0;
         int size = 2;
 
         while (aw != null) {
             n++;
             size += aw.getByteLength();
             aw.prev = last;
             last = aw;
             aw = aw.next;
         }
 
         out.putInt(size);
         out.putShort(n);
         putFromLastToFirst(out, last);
     }
 
     private static void putFromLastToFirst(@NonNull ByteVector out, @Nullable AnnotationVisitor aw) {
         while (aw != null) {
             out.putByteVector(aw.bv);
             aw = aw.prev;
         }
     }
 
     /**
      * Puts the given annotation lists into the given byte vector.
      */
     public static void put(@NonNull ByteVector out, @NonNull AnnotationVisitor[] anns) {
         putNumberAndSizeOfAnnotations(out, anns);
 
         for (AnnotationVisitor ann : anns) {
             AnnotationVisitor last = putNumberOfAnnotations(out, ann);
             putFromLastToFirst(out, last);
         }
     }
 
     private static void putNumberAndSizeOfAnnotations(@NonNull ByteVector out, @NonNull AnnotationVisitor[] anns) {
         int numAnns = anns.length;
         int size = 1 + 2 * numAnns;
 
         for (AnnotationVisitor aw : anns) {
             if (aw != null) {
                 size += aw.getSize();
             }
         }
 
         out.putInt(size).putByte(numAnns);
     }
 
     @Nullable
     private static AnnotationVisitor putNumberOfAnnotations(@NonNull ByteVector out, @Nullable AnnotationVisitor aw) {
         AnnotationVisitor last = null;
         int n = 0;
 
         while (aw != null) {
             n++;
             aw.prev = last;
             last = aw;
             aw = aw.next;
         }
 
         out.putShort(n);
         return last;
     }
 }