/*
 * Copyright 2014 - 2017 Blazebit.
 *
 * 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 com.blazebit.persistence.criteria.impl.expression;

import com.blazebit.persistence.criteria.impl.BlazeCriteriaBuilderImpl;
import com.blazebit.persistence.criteria.impl.ParameterVisitor;
import com.blazebit.persistence.criteria.impl.RenderContext;

import javax.persistence.criteria.Expression;

/**
 * @author Christian Beikov
 * @since 1.2.0
 */
public class IsNullPredicate extends AbstractSimplePredicate {

    private static final long serialVersionUID = 1L;

    private final Expression<?> operand;

    public IsNullPredicate(BlazeCriteriaBuilderImpl criteriaBuilder, boolean negated, Expression<?> operand) {
        super(criteriaBuilder, negated);
        this.operand = operand;
    }

    @Override
    public AbstractPredicate copyNegated() {
        return new IsNullPredicate(criteriaBuilder, !isNegated(), operand);
    }

    @Override
    public void visitParameters(ParameterVisitor visitor) {
        visitor.visit(operand);
    }

    @Override
    public void render(RenderContext context) {
        context.apply(operand);

        if (isNegated()) {
            context.getBuffer().append(" IS NOT NULL");
        } else {
            context.getBuffer().append(" IS NULL");
        }
    }

}