/*-
 * ============LICENSE_START=======================================================
 *  Copyright (C) 2021 Nordix Foundation.
 *  Modifications Copyright (C) 2021 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 * ============LICENSE_END=========================================================
 */

package org.onap.policy.models.dao;

import java.sql.Timestamp;
import java.util.Map;
import javax.persistence.TypedQuery;
import lombok.Data;
import org.onap.policy.models.base.PfConcept;

/**
 * This abstract class is used as a base for the filter implementations.
 */

@Data
public abstract class PfFilter {
    private static final String WHERE      = " WHERE ";
    private static final String AND        = " AND ";
    private static final String ORDER      = " ORDER BY ";

    private String nameFilter;
    private String timeStampStartFilter;
    private String timeStampEndFilter;
    private String timeStampFilter;
    private String nameParameter;
    private String keyPrefix;

    /**
     * Generates the "WHERE" (and "ORDER BY") clause for a JPA query.
     */
    public String genWhereClause(PfFilterParametersIntfc parameters) {
        if (parameters == null) {
            return "";
        }

        var builder = new ClauseBuilder(WHERE, AND);

        if (parameters.getFilterMap() != null) {
            for (String key : parameters.getFilterMap().keySet()) {
                builder.addCondition(getKeyPrefix(), key, "= :", key);
            }
        }

        if (parameters.getName() != null) {
            builder.addCondition(getNameFilter());
        }

        if (parameters.getStartTime() != null) {
            builder.addCondition(getTimeStampStartFilter());
        }

        if (parameters.getEndTime() != null) {
            builder.addCondition(getTimeStampEndFilter());
        }

        return builder.toString();
    }

    /**
     * Generates the "ORDER BY" clause for a JPA query.
     */
    public String genOrderClause(PfFilterParametersIntfc parameters) {
        if (parameters == null) {
            return "";
        }

        var builder = new ClauseBuilder(ORDER, ", ");

        if (parameters.getRecordNum() > 0) {
            builder.addCondition(getTimeStampFilter(), parameters.getSortOrder());
        }

        return builder.toString();
    }

    /**
     * Sets the JPA query parameters, based on the filter parameters.
     * @param query query to populate
     */
    public <T extends PfConcept> void setParams(TypedQuery<T> query, PfFilterParametersIntfc parameters) {
        if (parameters == null) {
            return;
        }

        if (parameters.getFilterMap() != null) {
            for (Map.Entry<String, Object> entry : parameters.getFilterMap().entrySet()) {
                query.setParameter(entry.getKey(), entry.getValue());
            }
        }
        if (parameters.getName() != null) {
            query.setParameter(this.getNameParameter(), parameters.getName());
        }
        if (parameters.getStartTime() != null) {
            query.setParameter("startTime", Timestamp.from(parameters.getStartTime()));
        }
        if (parameters.getEndTime() != null) {
            query.setParameter("endTime", Timestamp.from(parameters.getEndTime()));
        }
        if (parameters.getRecordNum() > 0) {
            query.setMaxResults(parameters.getRecordNum());
        }
    }

    private static class ClauseBuilder {
        private final StringBuilder builder = new StringBuilder();
        private final String separator;

        private String currentSeparator;

        public ClauseBuilder(String clause, String separator) {
            this.separator = separator;
            this.currentSeparator = clause;
        }

        @Override
        public String toString() {
            return builder.toString();
        }

        public void addCondition(String...condition) {
            builder.append(currentSeparator);
            currentSeparator = separator;

            for (String text: condition) {
                builder.append(text);
            }
        }
    }
}