////////////////////////////////////////////////////////////////////////////////
   // MillScript: an Open Spice interpreter and batch website creation tool
   // Copyright (C) 2001-2004 Open World Ltd
   // Copyright (C) 2005 Kevin Rogers
   //
   // This file is part of MillScript.
   //
   // MillScript is free software; you can redistribute it and/or modify it under
   // the terms of the GNU General Public License as published by the Free
  // Software Foundation; either version 2 of the License, or (at your option)
  // any later version.
  //
  // MillScript is distributed in the hope that it will be useful, but WITHOUT
  // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  // FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  // more details.
  //
  // You should have received a copy of the GNU General Public License along with
  // MillScript; if not, write to the Free Software Foundation, Inc., 59 Temple
  // Place, Suite 330, Boston, MA  02111-1307  USA
  ////////////////////////////////////////////////////////////////////////////////
  package org.millscript.millscript.functions;
  
  import org.millscript.millscript.alert.Alerts;
  import org.millscript.millscript.vm.Machine;
  
  import java.lang.reflect.Method;
  import java.util.Arrays;
  
  /**
   * This class implements the MillScript <code>javaFunction</code> function.
   */
  public class JavaFunctionFunction extends Function {
  
      /**
       * @see org.millscript.millscript.functions.Function#apply(org.millscript.millscript.vm.Machine, int)
       */
      @Override
      public void apply( final Machine mc, final int nargs ) {
          if ( nargs < 2 ) {
              throw(
                  Alerts.eval(
                      "Insufficient arguments",
                      "javaFunction requires at least two arguments"
                  ).mishap()
              );
          }
          int num = nargs - 2;
          Class[] ptypes = new Class[ num ];
          for ( int i = num - 1; i >= 0; i-- ) {
              String cname = mc.popString();
              try {
                  ptypes[ i ] = ParameterType.findClass( cname );
              } catch ( ClassNotFoundException ex ) {
                  throw(
                      Alerts.eval(
                          "No such class",
                          "There does not appear to be a class by that name"
                      ).culprit( "class name", cname ).mishap()
                  );
              }
          }
          String methodName = mc.popString();
          String className = mc.popString();
          mc.pushObject( javaFunction( className, methodName, ptypes ) );
      }
  
      /**
       * Returns a <code>Function</code> to access the method with the specified
       * parameters in the specified Java class.
       *
       * @param className the Java class containing the method
       * @param methodName    the Java method we want to invoke
       * @param ptypes    the parameter types for the method
       * @return  a <code>Function</code> to invoke the specified method
       */
      static Function javaFunction( final String className, final String methodName, final Class[] ptypes ) {
          try {
              Class c = Class.forName( className );
              Method[] methods = c.getMethods();
              for ( int i = 0; i < methods.length; i++ ) {
                  Method method = methods[ i ];
                  if (
                      method.getName().equals( methodName ) &&
                      Arrays.equals( method.getParameterTypes(), ptypes )
                  ) {
                      // Make a function to invoke this method
                      return JMethod.make( method );
                  }
              }
          } catch ( ClassNotFoundException ex ) {
              throw(
                  Alerts.eval(
                      "Class cannot be found",
                      null
                  ).culprit( "class name", className ).mishap()
              );
          }
          throw(
             Alerts.eval(
                 "No such method for this class",
                 "The class does not define a method of that name"
             ).
             culprit( "method name", methodName ).
             culprit( "class name", className ).
             mishap()
         );
     }
 
 }