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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;

import com.blazebit.persistence.MultipleSubqueryInitiator;
import com.blazebit.persistence.WhereBuilder;
import com.blazebit.persistence.criteria.BlazeCommonAbstractCriteria;
import com.blazebit.persistence.criteria.BlazeRoot;
import com.blazebit.persistence.criteria.BlazeSubquery;
import com.blazebit.persistence.criteria.impl.expression.AbstractSelection;
import com.blazebit.persistence.criteria.impl.expression.SubqueryExpression;
import com.blazebit.persistence.criteria.impl.path.RootImpl;

import javax.persistence.criteria.Expression;
import javax.persistence.criteria.Predicate;
import javax.persistence.metamodel.EntityType;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * @author Christian Beikov
 * @since 1.2.0
 */
public class AbstractModificationCriteriaQuery implements BlazeCommonAbstractCriteria {

    protected final BlazeCriteriaBuilderImpl criteriaBuilder;

    private RootImpl root;
    private Predicate restriction;
    private List> subqueries;

    protected AbstractModificationCriteriaQuery(BlazeCriteriaBuilderImpl criteriaBuilder) {
        this.criteriaBuilder = criteriaBuilder;
    }

    public BlazeRoot from(Class entityClass) {
        return from(entityClass, null);
    }

    public BlazeRoot from(EntityType entityType) {
        return from(entityType, null);
    }

    public BlazeRoot from(Class entityClass, String alias) {
        EntityType entityType = criteriaBuilder.getEntityMetamodel()
                .entity(entityClass);
        if (entityType == null) {
            throw new IllegalArgumentException(entityClass + " is not an entity");
        }
        return from(entityType, alias);
    }

    public BlazeRoot from(EntityType entityType, String alias) {
        root = new RootImpl(criteriaBuilder, entityType, alias, false);
        return root;
    }

    public BlazeRoot getRoot() {
        return root;
    }

    protected void setRestriction(Expression restriction) {
        if (restriction == null) {
            this.restriction = null;
        } else {
            this.restriction = criteriaBuilder.wrap(restriction);
        }
    }

    public void setRestriction(Predicate... restrictions) {
        if (restrictions == null || restrictions.length == 0) {
            this.restriction = null;
        } else {
            this.restriction = criteriaBuilder.and(restrictions);
        }
    }

    @Override
    public Predicate getRestriction() {
        return restriction;
    }

    @Override
    public  BlazeSubquery subquery(Class subqueryType) {
        SubqueryExpression subquery = new SubqueryExpression(criteriaBuilder, subqueryType, this);
        internalGetSubqueries().add(subquery);
        return subquery;
    }

    public List> internalGetSubqueries() {
        if (subqueries == null) {
            subqueries = new ArrayList>();
        }
        return subqueries;
    }

    protected void renderWhere(WhereBuilder wb, RenderContextImpl context) {
        if (restriction == null) {
            return;
        }

        context.setClauseType(RenderContext.ClauseType.WHERE);
        context.getBuffer().setLength(0);
        ((AbstractSelection) restriction).render(context);
        String expression = context.takeBuffer();
        Map> aliasToSubqueries = context.takeAliasToSubqueryMap();

        if (aliasToSubqueries.isEmpty()) {
            wb.setWhereExpression(expression);
        } else {
            MultipleSubqueryInitiator initiator = wb.setWhereExpressionSubqueries(expression);

            for (Map.Entry> subqueryEntry : aliasToSubqueries.entrySet()) {
                context.pushSubqueryInitiator(initiator.with(subqueryEntry.getKey()));
                subqueryEntry.getValue().renderSubquery(context);
                context.popSubqueryInitiator();
            }

            initiator.end();
        }
    }

}