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/*
 * Copyright 2018 Fryske Akademy.
 *
 * 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.fryske_akademy.jpa;

/*-
 * #%L
 * ejbCrudApi
 * %%
 * Copyright (C) 2018 Fryske Akademy
 * %%
 * 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.
 * #L%
 */
import java.io.Serializable;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.enterprise.context.ApplicationScoped;
import javax.inject.Named;
import javax.persistence.Parameter;
import javax.persistence.PersistenceException;
import javax.persistence.Query;
import javax.persistence.TypedQuery;
import org.fryske_akademy.ejb.CrudReadService.SORTORDER;

/**
 * Stateless, threadsafe builder containing function for building dynamic jpql
 * where and order by clause based on {@link Param} and functions for setting
 * parameters in a Query, also based on {@link Param}. Supports all comparison
 * expressions except between when building jpql.
 *
 * @author eduard
 */
@ApplicationScoped
@Named
public class JpqlBuilderImpl implements JpqlBuilder, Serializable {

    private static final Logger LOGGER = Logger.getLogger(JpqlBuilder.class.getName());


    /**
     *
     * builds an order by clause, uses {@link #ENTITY_PREFIX}.
     *
     * @param sort
     * @return
     */
    @Override
    public String orderClause(Map sort) {
        if (sort != null && !sort.isEmpty()) {
            StringBuilder srt = new StringBuilder("");
            boolean first = true;
            for (Map.Entry entry : sort.entrySet()) {
                String sortField = entry.getKey();
                if (sortField == null || entry.getValue() == SORTORDER.NONE) {
                    continue;
                }
                srt.append((first) ? " order by" : ",")
                        .append(ENTITY_PREFIX).append(sortField).append(" ").append(entry.getValue());
                first = false;
            }
            return srt.toString();
        }
        return "";
    }

    /**
     * builds a where clause, calls {@link #whereCondition(org.fryske_akademy.ejb.Param)
     * }
     * for every entry, uses {@link #TABLE_ALIAS} as alias for the table
     *
     * @param params
     * @return
     */
    @Override
    public String whereClause(List params) {
        if (params != null && !params.isEmpty()) {
            StringBuilder where = new StringBuilder("");
            boolean first = true;
            for (Param param : params) {
                where.append((first) ? " where" : param.getAndOr()).append(whereCondition(param));
                first = false;
            }
            return where.toString();
        }
        return "";
    }

    /**
     * builds a where condition, prepares ql parameters later filled in
     * {@link #setWhereParams(javax.persistence.Query, java.util.List) }.
     * Collection as {@link Param#getParamValue() } with operator "member of"
     * supported!, in that case multiple member of conditions will be
     * constructed using a parameter key {@link Param#getParamKey() } with an
     * index number appended, these parameters and later filled by
     * {@link #setParam(javax.persistence.Query, org.fryske_akademy.ejb.Param) }.
     * Supports all comparison operators in {@link Param#getOperator() } except
     * between, for null and empty comparison {@link Param#getNot() }
     * and {@link Param#getParamValue() } are ignored.
     *
     * @param param
     * @return
     */
    @Override
    public String whereCondition(Param param) {
        if (param.getOperator().toLowerCase().contains("member of")) {
            if (param.getParamValue() instanceof Collection) {
                if (!((Collection) param.getParamValue()).isEmpty()) {
                    StringBuilder rv = new StringBuilder(" (");
                    AtomicBoolean first = new AtomicBoolean(true);
                    AtomicInteger i = new AtomicInteger();
                    ((Collection) param.getParamValue()).forEach((t) -> {
                        if (first.get()) {
                            first.set(false);
                        } else {
                            rv.append(" or ");
                        }
                        rv.append(":").append(param.getParamKey()).append(i.getAndIncrement()).append(param.getNot()).append(param.getOperator()).append(ENTITY_PREFIX).append(param.getPropertyPath());
                    });
                    return rv.append(')').toString();
                } else {
                    throw new PersistenceException("\"member of\" needs a non empty collection");
                }
            } else {
                return " :" + param.getParamKey() + param.getNot() + param.getOperator() + ENTITY_PREFIX + param.getPropertyPath();
            }
        } else if (param.getOperator().toLowerCase().contains("in")) {
            return ENTITY_PREFIX + param.getPropertyPath() + param.getNot() + param.getOperator() + "( :" + param.getParamKey() + " )";
        } else if (param.getOperator().toLowerCase().contains("null") || param.getOperator().toLowerCase().contains("empty")) {
            return ENTITY_PREFIX + param.getPropertyPath() + param.getOperator();
        } else {
            return param.isCaseInsensitive() && String.class.equals(param.getParamType())
                    ? param.getNot() + "lower(" + ENTITY_PREFIX + param.getPropertyPath() + ")" + param.getOperator() +"lower(:" + param.getParamKey() + ")"
                    : param.getNot() + ENTITY_PREFIX + param.getPropertyPath() + param.getOperator() + ":" + param.getParamKey();
        }
    }
    public static final String ENTITY_PREFIX = " e.";

    /**
     * Calls {@link #setParam(javax.persistence.Query, org.fryske_akademy.ejb.Param)
     * } for each filter.
     *
     * @param q
     * @param params
     */
    @Override
    public void setWhereParams(Query q, List params) {
        if (params != null && !params.isEmpty()) {
            params.forEach((param) -> {
                setParam(q, param);
            });
        }
    }

    /**
     * When Query is a TypedQuery call {@link Query#setParameter(java.lang.String, java.lang.Object)
     * }
     * otherwise call {@link Query#setParameter(int, java.lang.Object) } with
     * Short.valueOf(key).
     *
     * @param q
     * @param key
     * @param value
     */
    protected void set(Query q, String key, Object value) {
        if (q instanceof TypedQuery) {
            q.setParameter(key, value);
        } else {
            q.setParameter(Short.valueOf(key), value);
        }
    }

    /**
     * Fills parameters prepared in {@link #setWhereParams(javax.persistence.Query, java.util.List)
     * }, if the type of the field in the query is a Short or an Integer and the
     * paramValue is a String, it is converted accordingly. For native queries {@link Param#getParamKey()
     * } should be a numeric positional parameter. When the operator is member
     * of and the value is a Collection a value is set for each entry in the
     * collection, for this a parameter key {@link Param#getParamKey() }
     * with an index number appended is assumed, {@link #whereCondition(org.fryske_akademy.ejb.Param)
     * } prepares this. For the type check either
     * {@link Parameter#getParameterType() } is used, or, when null, {@link Param#getParamType()
     * }. If the query does not contain the parameter and
     * {@link Param#isSkipSetValue() } is true, the parameter isn't set. Via
     * Param you have full control over the Object that is used as paramValue.
     *
     * @param q
     * @param param
     */
    @Override
    public void setParam(Query q, Param param) {
        boolean hasParam = false;
        try {
            q.getParameter(param.getParamKey());
            hasParam = true;
        } catch (IllegalArgumentException | IllegalStateException e) {
        }
        if (param.isSkipSetValue() && !hasParam) {
            if (LOGGER.isLoggable(Level.FINE)) {
                LOGGER.fine("skipping " + param);
            }
            return;
        }
        if (param.isSkipSetValue() && hasParam) {
            if (LOGGER.isLoggable(Level.WARNING)) {
                LOGGER.warning("Param indicates skipping but query contains it, skipping is ignored: " + param);
            }
        }
        if (LOGGER.isLoggable(Level.FINE)) {
            LOGGER.fine("trying to set: " + param);
        }
        if (param.getOperator().toLowerCase().contains("member of") && param.getParamValue() instanceof Collection) {
            AtomicInteger i = new AtomicInteger();
            ((Collection) param.getParamValue()).forEach((t) -> {
                set(q, param.getParamKey() + (i.getAndIncrement()), t);
            });
        } else {
            if (param.getParamValue() instanceof Collection && !param.getOperator().toLowerCase().contains("in")) {
                if (LOGGER.isLoggable(Level.WARNING)) {
                    LOGGER.warning("value for " + param.getParamKey() + " is a collection, you may want to use the \"in\" operator");
                }
            }
            set(q, param.getParamKey(), param.getParamValue());
        }
    }

}




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