/*
    * 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.Arrays;
  
  import org.apache.bcel.Const;
  import org.apache.bcel.util.Args;
  
  /**
   * This class represents a stack map entry recording the types of local variables and the of stack items at a given
   * byte code offset. See CLDC specification 5.3.1.2.
   *
   * See also https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.4
   *
   * <pre>
   * union stack_map_frame {
   *   same_frame;
   *   same_locals_1_stack_item_frame;
   *   same_locals_1_stack_item_frame_extended;
   *   chop_frame;
   *   same_frame_extended;
   *   append_frame;
   *   full_frame;
   * }
   * </pre>
   *
   * @see StackMap
   * @see StackMapType
   */
  public final class StackMapEntry implements Node, Cloneable {
  
      static final StackMapEntry[] EMPTY_ARRAY = {};
  
      private int frameType;
      private int byteCodeOffset;
      private StackMapType[] typesOfLocals;
      private StackMapType[] typesOfStackItems;
      private ConstantPool constantPool;
  
      /**
       * Constructs object from input stream.
       *
       * @param dataInput Input stream.
       * @throws IOException Thrown if an I/O error occurs.
       */
      StackMapEntry(final DataInput dataInput, final ConstantPool constantPool) throws IOException {
          this(dataInput.readByte() & 0xFF, -1, null, null, constantPool);
  
          if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
              byteCodeOffset = frameType - Const.SAME_FRAME;
          } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
              byteCodeOffset = frameType - Const.SAME_LOCALS_1_STACK_ITEM_FRAME;
              typesOfStackItems = new StackMapType[] { new StackMapType(dataInput, constantPool) };
          } else if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
              byteCodeOffset = dataInput.readUnsignedShort();
              typesOfStackItems = new StackMapType[] { new StackMapType(dataInput, constantPool) };
          } else if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX || frameType == Const.SAME_FRAME_EXTENDED) {
              byteCodeOffset = dataInput.readUnsignedShort();
          } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
              byteCodeOffset = dataInput.readUnsignedShort();
              final int numberOfLocals = frameType - 251;
              typesOfLocals = new StackMapType[numberOfLocals];
              for (int i = 0; i < numberOfLocals; i++) {
                  typesOfLocals[i] = new StackMapType(dataInput, constantPool);
              }
          } else if (frameType == Const.FULL_FRAME) {
              byteCodeOffset = dataInput.readUnsignedShort();
              final int numberOfLocals = dataInput.readUnsignedShort();
              typesOfLocals = new StackMapType[numberOfLocals];
              for (int i = 0; i < numberOfLocals; i++) {
                  typesOfLocals[i] = new StackMapType(dataInput, constantPool);
              }
              final int numberOfStackItems = dataInput.readUnsignedShort();
              typesOfStackItems = new StackMapType[numberOfStackItems];
              for (int i = 0; i < numberOfStackItems; i++) {
                  typesOfStackItems[i] = new StackMapType(dataInput, constantPool);
              }
          } else {
             /* Can't happen */
             throw new ClassFormatException("Invalid frame type found while parsing stack map table: " + frameType);
         }
     }
 
     /**
      * DO NOT USE
      *
      * @param byteCodeOffset byte code offset.
      * @param numberOfLocals NOT USED.
      * @param typesOfLocals array of {@link StackMapType}s of locals.
      * @param numberOfStackItems NOT USED.
      * @param typesOfStackItems array ot {@link StackMapType}s of stack items.
      * @param constantPool The constant pool.
      * @deprecated Since 6.0, use {@link #StackMapEntry(int, int, StackMapType[], StackMapType[], ConstantPool)} instead.
      */
     @java.lang.Deprecated
     public StackMapEntry(final int byteCodeOffset, final int numberOfLocals, final StackMapType[] typesOfLocals, final int numberOfStackItems,
         final StackMapType[] typesOfStackItems, final ConstantPool constantPool) {
         this.byteCodeOffset = byteCodeOffset;
         this.typesOfLocals = typesOfLocals != null ? typesOfLocals : StackMapType.EMPTY_ARRAY;
         this.typesOfStackItems = typesOfStackItems != null ? typesOfStackItems : StackMapType.EMPTY_ARRAY;
         this.constantPool = constantPool;
         if (numberOfLocals < 0) {
             throw new IllegalArgumentException("numberOfLocals < 0");
         }
         if (numberOfStackItems < 0) {
             throw new IllegalArgumentException("numberOfStackItems < 0");
         }
     }
 
     /**
      * Create an instance
      *
      * @param tag The frameType to use.
      * @param byteCodeOffset byte code offset.
      * @param typesOfLocals array of {@link StackMapType}s of locals.
      * @param typesOfStackItems array ot {@link StackMapType}s of stack items.
      * @param constantPool The constant pool.
      */
     public StackMapEntry(final int tag, final int byteCodeOffset, final StackMapType[] typesOfLocals, final StackMapType[] typesOfStackItems,
         final ConstantPool constantPool) {
         this.frameType = tag;
         this.byteCodeOffset = byteCodeOffset;
         this.typesOfLocals = typesOfLocals != null ? typesOfLocals : StackMapType.EMPTY_ARRAY;
         this.typesOfStackItems = typesOfStackItems != null ? typesOfStackItems : StackMapType.EMPTY_ARRAY;
         this.constantPool = constantPool;
     }
 
     /**
      * 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.visitStackMapEntry(this);
     }
 
     /**
      * Creates a deep copy of this object.
      *
      * @return deep copy of this object.
      */
     public StackMapEntry copy() {
         final StackMapEntry e;
         try {
             e = (StackMapEntry) clone();
         } catch (final CloneNotSupportedException ex) {
             throw new UnsupportedOperationException("Clone Not Supported", ex);
         }
 
         e.typesOfLocals = new StackMapType[typesOfLocals.length];
         Arrays.setAll(e.typesOfLocals, i -> typesOfLocals[i].copy());
         e.typesOfStackItems = new StackMapType[typesOfStackItems.length];
         Arrays.setAll(e.typesOfStackItems, i -> typesOfStackItems[i].copy());
         return e;
     }
 
     /**
      * Dumps stack map entry
      *
      * @param file Output file stream.
      * @throws IOException Thrown if an I/O error occurs.
      */
     public void dump(final DataOutputStream file) throws IOException {
         file.write(frameType);
         if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
             typesOfStackItems[0].dump(file);
         } else if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
             file.writeShort(byteCodeOffset);
             typesOfStackItems[0].dump(file);
         } else if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX || frameType == Const.SAME_FRAME_EXTENDED) {
             file.writeShort(byteCodeOffset);
         } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
             file.writeShort(byteCodeOffset);
             for (final StackMapType type : typesOfLocals) {
                 type.dump(file);
             }
         } else if (frameType == Const.FULL_FRAME) {
             file.writeShort(byteCodeOffset);
             file.writeShort(Args.requireU2(typesOfLocals.length, "typesOfLocals.length"));
             for (final StackMapType type : typesOfLocals) {
                 type.dump(file);
             }
             file.writeShort(Args.requireU2(typesOfStackItems.length, "typesOfStackItems.length"));
             for (final StackMapType type : typesOfStackItems) {
                 type.dump(file);
             }
         } else if (!(frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX)) {
             /* Can't happen */
             throw new ClassFormatException("Invalid Stack map table tag: " + frameType);
         }
     }
 
     /**
      * Gets the byte code offset.
      *
      * @return The byte code offset.
      */
     public int getByteCodeOffset() {
         return byteCodeOffset;
     }
 
     /**
      * Gets the constant pool.
      *
      * @return Constant pool used by this object.
      */
     public ConstantPool getConstantPool() {
         return constantPool;
     }
 
     /**
      * Gets the frame type.
      *
      * @return The frame type.
      */
     public int getFrameType() {
         return frameType;
     }
 
     /**
      * Calculate stack map entry size.
      */
     int getMapEntrySize() {
         if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
             return 1;
         }
         if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
             return 1 + (typesOfStackItems[0].hasIndex() ? 3 : 1);
         }
         if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
             return 3 + (typesOfStackItems[0].hasIndex() ? 3 : 1);
         }
         if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX || frameType == Const.SAME_FRAME_EXTENDED) {
             return 3;
         }
         if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
             int len = 3;
             for (final StackMapType typesOfLocal : typesOfLocals) {
                 len += typesOfLocal.hasIndex() ? 3 : 1;
             }
             return len;
         }
         if (frameType != Const.FULL_FRAME) {
             throw new IllegalStateException("Invalid StackMap frameType: " + frameType);
         }
         int len = 7;
         for (final StackMapType typesOfLocal : typesOfLocals) {
             len += typesOfLocal.hasIndex() ? 3 : 1;
         }
         for (final StackMapType typesOfStackItem : typesOfStackItems) {
             len += typesOfStackItem.hasIndex() ? 3 : 1;
         }
         return len;
     }
 
     /**
      * Gets the number of locals.
      *
      * @return The number of locals.
      */
     public int getNumberOfLocals() {
         return typesOfLocals.length;
     }
 
     /**
      * Gets the number of stack items.
      *
      * @return The number of stack items.
      */
     public int getNumberOfStackItems() {
         return typesOfStackItems.length;
     }
 
     /**
      * Gets the types of locals.
      *
      * @return The types of locals.
      */
     public StackMapType[] getTypesOfLocals() {
         return typesOfLocals;
     }
 
     /**
      * Gets the types of stack items.
      *
      * @return The types of stack items.
      */
     public StackMapType[] getTypesOfStackItems() {
         return typesOfStackItems;
     }
 
     private boolean invalidFrameType(final int f) {
         // @formatter:off
         return f != Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED
             && !(f >= Const.CHOP_FRAME && f <= Const.CHOP_FRAME_MAX)
             && f != Const.SAME_FRAME_EXTENDED
             && !(f >= Const.APPEND_FRAME && f <= Const.APPEND_FRAME_MAX)
             && f != Const.FULL_FRAME;
         // @formatter:on
     }
 
     /**
      * Sets the byte code offset.
      *
      * @param newOffset The new offset.
      */
     public void setByteCodeOffset(final int newOffset) {
         if (newOffset < 0 || newOffset > 32767) {
             throw new IllegalArgumentException("Invalid StackMap offset: " + newOffset);
         }
 
         if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
             if (newOffset > Const.SAME_FRAME_MAX) {
                 frameType = Const.SAME_FRAME_EXTENDED;
             } else {
                 frameType = newOffset;
             }
         } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
             if (newOffset > Const.SAME_FRAME_MAX) {
                 frameType = Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED;
             } else {
                 frameType = Const.SAME_LOCALS_1_STACK_ITEM_FRAME + newOffset;
             }
         } else if (invalidFrameType(frameType)) {
             throw new IllegalStateException("Invalid StackMap frameType: " + frameType);
         }
         byteCodeOffset = newOffset;
     }
 
     /**
      * Sets the constant pool.
      *
      * @param constantPool Constant pool to be used for this object.
      */
     public void setConstantPool(final ConstantPool constantPool) {
         this.constantPool = constantPool;
     }
 
     /**
      * Sets the frame type.
      *
      * @param ft The frame type.
      */
     public void setFrameType(final int ft) {
         if (ft >= Const.SAME_FRAME && ft <= Const.SAME_FRAME_MAX) {
             byteCodeOffset = ft - Const.SAME_FRAME;
         } else if (ft >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && ft <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
             byteCodeOffset = ft - Const.SAME_LOCALS_1_STACK_ITEM_FRAME;
         } else if (invalidFrameType(ft)) {
             throw new IllegalArgumentException("Invalid StackMap frameType");
         }
         frameType = ft;
     }
 
     /**
      * Sets the number of locals (deprecated).
      *
      * @param n The number of locals.
      * @deprecated Since 6.0
      */
     @java.lang.Deprecated
     public void setNumberOfLocals(final int n) { // TODO unused
     }
 
     /**
      * Sets the number of stack items (deprecated).
      *
      * @param n The number of stack items.
      * @deprecated Since 6.0
      */
     @java.lang.Deprecated
     public void setNumberOfStackItems(final int n) { // TODO unused
     }
 
     /**
      * Sets the types of locals.
      *
      * @param types The types of locals.
      */
     public void setTypesOfLocals(final StackMapType[] types) {
         typesOfLocals = types != null ? types : StackMapType.EMPTY_ARRAY;
     }
 
     /**
      * Sets the types of stack items.
      *
      * @param types The types of stack items.
      */
     public void setTypesOfStackItems(final StackMapType[] types) {
         typesOfStackItems = types != null ? types : StackMapType.EMPTY_ARRAY;
     }
 
     /**
      * @return String representation.
      */
     @Override
     public String toString() {
         final StringBuilder buf = new StringBuilder(64);
         buf.append("(");
         if (frameType >= Const.SAME_FRAME && frameType <= Const.SAME_FRAME_MAX) {
             buf.append("SAME");
         } else if (frameType >= Const.SAME_LOCALS_1_STACK_ITEM_FRAME && frameType <= Const.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
             buf.append("SAME_LOCALS_1_STACK");
         } else if (frameType == Const.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
             buf.append("SAME_LOCALS_1_STACK_EXTENDED");
         } else if (frameType >= Const.CHOP_FRAME && frameType <= Const.CHOP_FRAME_MAX) {
             buf.append("CHOP ").append(String.valueOf(251 - frameType));
         } else if (frameType == Const.SAME_FRAME_EXTENDED) {
             buf.append("SAME_EXTENDED");
         } else if (frameType >= Const.APPEND_FRAME && frameType <= Const.APPEND_FRAME_MAX) {
             buf.append("APPEND ").append(String.valueOf(frameType - 251));
         } else if (frameType == Const.FULL_FRAME) {
             buf.append("FULL");
         } else {
             buf.append("UNKNOWN (").append(frameType).append(")");
         }
         buf.append(", offset delta=").append(byteCodeOffset);
         if (typesOfLocals.length > 0) {
             buf.append(", locals={");
             for (int i = 0; i < typesOfLocals.length; i++) {
                 buf.append(typesOfLocals[i]);
                 if (i < typesOfLocals.length - 1) {
                     buf.append(", ");
                 }
             }
             buf.append("}");
         }
         if (typesOfStackItems.length > 0) {
             buf.append(", stack items={");
             for (int i = 0; i < typesOfStackItems.length; i++) {
                 buf.append(typesOfStackItems[i]);
                 if (i < typesOfStackItems.length - 1) {
                     buf.append(", ");
                 }
             }
             buf.append("}");
         }
         buf.append(")");
         return buf.toString();
     }
 
     /**
      * Updates the distance (as an offset delta) from this StackMap entry to the next. Note that this might cause the
      * frame type to change. Note also that delta may be negative.
      *
      * @param delta offset delta.
      */
     public void updateByteCodeOffset(final int delta) {
         setByteCodeOffset(byteCodeOffset + delta);
     }
 }