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package com.fitbur.bytebuddy.implementation.bytecode.member;

import com.fitbur.bytebuddy.implementation.Implementation;
import com.fitbur.bytebuddy.implementation.bytecode.StackManipulation;
import com.fitbur.bytebuddy.utility.JavaInstance;
import com.fitbur.bytebuddy.jar.asm.MethodVisitor;
import com.fitbur.bytebuddy.jar.asm.Opcodes;

/**
 * An exact invocation of a method handle with a polymorphic signature.
 */
public class HandleInvocation implements StackManipulation {

    /**
     * The name of the {@code java.lang.invoke.MethodHandle} type.
     */
    private static final String METHOD_HANDLE_NAME = "java/lang/invoke/MethodHandle";

    /**
     * The name of the {@code invokeExact} method.
     */
    private static final String INVOKE_EXACT = "invokeExact";

    /**
     * The method type of the invoked handle.
     */
    private final JavaInstance.MethodType methodType;

    /**
     * Creates a public invocation of a method handle.
     *
     * @param methodType The method type of the invoked handle.
     */
    public HandleInvocation(JavaInstance.MethodType methodType) {
        this.methodType = methodType;
    }

    @Override
    public boolean isValid() {
        return true;
    }

    @Override
    public Size apply(MethodVisitor methodVisitor, Implementation.Context implementationContext) {
        methodVisitor.visitMethodInsn(Opcodes.INVOKEVIRTUAL, METHOD_HANDLE_NAME, INVOKE_EXACT, methodType.getDescriptor(), false);
        int size = methodType.getReturnType().getStackSize().getSize() - methodType.getParameterTypes().getStackSize();
        return new Size(size, Math.max(size, 0));
    }

    @Override
    public boolean equals(Object other) {
        return this == other || !(other == null || getClass() != other.getClass())
                && methodType.equals(((HandleInvocation) other).methodType);
    }

    @Override
    public int hashCode() {
        return methodType.hashCode();
    }

    @Override
    public String toString() {
        return "HandleInvocation{" +
                "methodType=" + methodType +
                '}';
    }
}