/*
 * Copyright (C) 2014, United States Government, as represented by the
 * Administrator of the National Aeronautics and Space Administration.
 * All rights reserved.
 *
 * The Java Pathfinder core (jpf-core) platform is licensed 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 gov.nasa.jpf.jvm.bytecode;

import gov.nasa.jpf.util.InstructionState;
import gov.nasa.jpf.vm.ClassInfo;
import gov.nasa.jpf.vm.ElementInfo;
import gov.nasa.jpf.vm.FieldInfo;
import gov.nasa.jpf.vm.Instruction;
import gov.nasa.jpf.vm.LoadOnJPFRequired;
import gov.nasa.jpf.vm.MJIEnv;
import gov.nasa.jpf.vm.Scheduler;
import gov.nasa.jpf.vm.StackFrame;
import gov.nasa.jpf.vm.ThreadInfo;
import gov.nasa.jpf.vm.bytecode.WriteInstruction;


/**
 * Set static field in class
 * ..., value => ...
 */
public class PUTSTATIC extends JVMStaticFieldInstruction implements WriteInstruction {

  public PUTSTATIC(String fieldName, String clsDescriptor, String fieldDescriptor){
    super(fieldName, clsDescriptor, fieldDescriptor);
  }

  /**
   * where do we get the value from?
   * NOTE: only makes sense in a executeInstruction() context 
   */
  @Override
  public int getValueSlot (StackFrame frame){
    return frame.getTopPos();
  }
    
  @Override
  public Instruction execute (ThreadInfo ti) {
    StackFrame frame = ti.getModifiableTopFrame();
    FieldInfo fieldInfo;
    
    //--- check if this causes a class load by a user defined classloader
    try {
      fieldInfo = getFieldInfo();
    } catch (LoadOnJPFRequired lre) {
      return ti.getPC();
    }
    
    if (fieldInfo == null) {
      return ti.createAndThrowException("java.lang.NoSuchFieldError", (className + '.' + fname));
    }

    //--- check if this has to trigger class initialization
    ClassInfo ciField = fieldInfo.getClassInfo();
    if (!mi.isClinit(ciField) && ciField.initializeClass(ti)) {
      return ti.getPC(); // this returns the next insn in the topmost clinit that just got pushed
    }
    ElementInfo eiFieldOwner = ciField.getModifiableStaticElementInfo();

    //--- check scheduling point due to shared class access
    Scheduler scheduler = ti.getScheduler();
    if (scheduler.canHaveSharedClassCG( ti, this, eiFieldOwner, fieldInfo)){
      eiFieldOwner = scheduler.updateClassSharedness(ti, eiFieldOwner, fi);
      if (scheduler.setsSharedClassCG( ti, this, eiFieldOwner, fieldInfo)){
        return this; // re-execute
      }
    }
    
    // check if this gets re-executed from a exposure CG (which already did the assignment
    if (frame.getAndResetFrameAttr(InstructionState.class) == null){
      lastValue = PutHelper.setField(ti, frame, eiFieldOwner, fieldInfo);
    }
      
    //--- check scheduling point due to exposure through shared class
    if (isReferenceField()){
      int refValue = frame.peek();
      if (refValue != MJIEnv.NULL){
        ElementInfo eiExposed = ti.getElementInfo(refValue);
        if (scheduler.setsSharedClassExposureCG(ti,this,eiFieldOwner,fieldInfo,eiExposed)){
          frame.addFrameAttr( InstructionState.processed);
          return this; // re-execute AFTER assignment
        }
      }        
    }
    
    popOperands(frame);      
    return getNext();
  }
  
  protected void popOperands (StackFrame frame){
    if (size == 1){
      frame.pop(); // .. val => ..
    } else {
      frame.pop(2);  // .. highVal, lowVal => ..
    }
  }
  
  @Override
  public int getLength() {
    return 3; // opcode, index1, index2
  }

  @Override
  public int getByteCode () {
    return 0xB3;
  }

  @Override
  public boolean isRead() {
    return false;
  }
  
  @Override
  public void accept(JVMInstructionVisitor insVisitor) {
	  insVisitor.visit(this);
  }
}