/*
 * Created on 27 sep 2010
 */

package interpreter.api.util;

import java.lang.reflect.Method;
import java.util.Arrays;

import interpreter.api.BytecodeMethod;
import interpreter.api.BytecodeMethodReplacement;
import interpreter.api.ExecutionFrame;

public class JavaBytecodeMethodBridge implements BytecodeMethodReplacement
{
   private final BytecodeMethod method;
   private final Method         javaMethod;
   private final Class< ? >     dc;
   private final Class< ? >     rt;
   private final Class< ? >[]   ps;

   public JavaBytecodeMethodBridge(BytecodeMethod method, Class< ? > javaClass) throws Exception
   {
      this.method = method;

      this.javaMethod = javaClass.getMethod(method.name, method.parameterTypes);
      this.dc = javaMethod.getDeclaringClass();
      this.rt = javaMethod.getReturnType();
      this.ps = javaMethod.getParameterTypes();

      if (!Arrays.equals(ps, this.method.parameterTypes))
         throw new IllegalStateException();
   }

   @Override
   public ExecutionFrame call(ExecutionFrame callSite)
   {
      try
      {
         Object[] args = InterpreterTypeUtil.loadValuesFromLocals(callSite, this.method.isStatic, ps);

         Object target = this.method.isStatic ? null : InterpreterTypeUtil.loadValueFromLocals(callSite, 0, dc);

         Object ret = javaMethod.invoke(target, args);
         if (ret != null && rt != void.class && !rt.isPrimitive())
            callSite.pushInt(callSite.thread.process.heap.ensureObject(ret));
         else
            InterpreterTypeUtil.pushTypedValueOnStack(callSite, rt, ret);

         InterpreterTypeUtil.returnTypedValue(callSite.thread, rt); // pops target
      }
      catch (Exception exc)
      {
         throw new RuntimeException(exc);
      }

      return null;
   }
}