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/*
 * Copyright 2014 - 2021 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.function;

import com.blazebit.persistence.criteria.impl.BlazeCriteriaBuilderImpl;
import com.blazebit.persistence.criteria.impl.ParameterVisitor;
import com.blazebit.persistence.criteria.impl.RenderContext;
import com.blazebit.persistence.criteria.impl.expression.AbstractExpression;
import com.blazebit.persistence.criteria.impl.expression.LiteralExpression;

import javax.persistence.criteria.CriteriaBuilder.Coalesce;
import javax.persistence.criteria.Expression;
import java.util.ArrayList;
import java.util.List;

/**
 * @author Christian Beikov
 * @since 1.2.0
 */
public class CoalesceFunction extends AbstractExpression implements Coalesce {

    private static final long serialVersionUID = 1L;

    private final List> expressions;
    private Class javaType;

    public CoalesceFunction(BlazeCriteriaBuilderImpl criteriaBuilder, Class javaType) {
        super(criteriaBuilder, javaType);
        this.javaType = javaType;
        this.expressions = new ArrayList>();
    }

    @Override
    public Class getJavaType() {
        return javaType;
    }

    @Override
    public Coalesce value(T value) {
        return value(new LiteralExpression(criteriaBuilder, value));
    }

    @Override
    @SuppressWarnings({"unchecked"})
    public Coalesce value(Expression value) {
        expressions.add(value);
        if (javaType == null) {
            javaType = (Class) value.getJavaType();
        }
        return this;
    }

    public List> getExpressions() {
        return expressions;
    }

    @Override
    public void visitParameters(ParameterVisitor visitor) {
        for (Expression expr : getExpressions()) {
            visitor.visit(expr);
        }
    }

    @Override
    public void render(RenderContext context) {
        final List> exprs = getExpressions();
        final StringBuilder buffer = context.getBuffer();
        buffer.append("COALESCE(");
        for (int i = 0; i < exprs.size(); i++) {
            if (i != 0) {
                buffer.append(',');
            }

            context.apply(exprs.get(i));
        }
        buffer.append(')');
    }
}