/*
 * Copyright 2003-2007 the original author or authors.
 *
 * 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 org.codehaus.groovy.classgen.asm;

import java.lang.reflect.Method;

import org.codehaus.groovy.classgen.ClassGeneratorException;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

/**
 * A helper class to invoke methods more easily in ASM
 * 
 * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
 * @version $Revision$
 */
public class MethodCaller implements Opcodes {

    private int opcode;
    private String internalName;
    private String name;
    private Class theClass;
    private String methodDescriptor;

    public static MethodCaller newStatic(Class theClass, String name) {
        return new MethodCaller(INVOKESTATIC, theClass, name);
    }

    public static MethodCaller newInterface(Class theClass, String name) {
        return new MethodCaller(INVOKEINTERFACE, theClass, name);
    }

    public static MethodCaller newVirtual(Class theClass, String name) {
        return new MethodCaller(INVOKEVIRTUAL, theClass, name);
    }

    public MethodCaller(int opcode, Class theClass, String name) {
        this.opcode = opcode;
        this.internalName = Type.getInternalName(theClass);
        this.theClass = theClass;
        this.name = name;

    }

    public void call(MethodVisitor methodVisitor) {
        methodVisitor.visitMethodInsn(opcode, internalName, name, getMethodDescriptor());
    }

    public String getMethodDescriptor() {
        if (methodDescriptor == null) {
            Method method = getMethod();
            methodDescriptor = Type.getMethodDescriptor(method);
        }
        return methodDescriptor;
    }

    protected Method getMethod() {
        Method[] methods = theClass.getMethods();
        for (int i = 0; i < methods.length; i++) {
            Method method = methods[i];
            if (method.getName().equals(name)) {
                return method;
            }
        }
        throw new ClassGeneratorException("Could not find method: " + name + " on class: " + theClass);
    }
}