/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.eagle.log.entity;

import org.apache.eagle.log.base.taggedlog.TaggedLogAPIEntity;
import org.apache.eagle.log.entity.meta.EntityConstants;
import org.apache.eagle.log.entity.meta.EntityDefinition;
import org.apache.eagle.log.entity.meta.EntityDefinitionManager;
import org.apache.eagle.common.DateTimeUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.Date;

public class GenericEntityScanStreamReader extends StreamReader {
    private static final Logger LOG = LoggerFactory.getLogger(GenericEntityScanStreamReader.class);

    private EntityDefinition entityDef;
    private SearchCondition condition;
    private String prefix;
    private long lastTimestamp = 0;
    private long firstTimestamp = 0;

    public GenericEntityScanStreamReader(String serviceName, SearchCondition condition, String prefix)
        throws InstantiationException, IllegalAccessException {
        this.prefix = prefix;
        checkNotNull(serviceName, "serviceName");
        this.entityDef = EntityDefinitionManager.getEntityByServiceName(serviceName);
        checkNotNull(entityDef, "EntityDefinition");
        this.condition = condition;
    }

    public GenericEntityScanStreamReader(EntityDefinition entityDef, SearchCondition condition, String prefix)
        throws InstantiationException, IllegalAccessException {
        this.prefix = prefix;
        checkNotNull(entityDef, "entityDef");
        this.entityDef = entityDef;
        checkNotNull(entityDef, "EntityDefinition");
        this.condition = condition;
    }

    @Override
    public long getLastTimestamp() {
        return lastTimestamp;
    }

    private void checkNotNull(Object o, String message) {
        if (o == null) {
            throw new IllegalArgumentException(message + " should not be null");
        }
    }

    public EntityDefinition getEntityDefinition() {
        return entityDef;
    }

    public SearchCondition getSearchCondition() {
        return condition;
    }

    @Override
    public void readAsStream() throws Exception {
        Date start = null;
        Date end = null;
        // shortcut to avoid read when pageSize=0
        if (condition.getPageSize() <= 0) {
            return; // return nothing
        }
        // Process the time range if needed
        if (entityDef.isTimeSeries()) {
            start = new Date(condition.getStartTime());
            end = new Date(condition.getEndTime());
        } else {
            // start = DateTimeUtil.humanDateToDate(EntityConstants.FIXED_READ_START_HUMANTIME);
            // end = DateTimeUtil.humanDateToDate(EntityConstants.FIXED_READ_END_HUMANTIME);
            start = new Date(EntityConstants.FIXED_READ_START_TIMESTAMP);
            end = new Date(EntityConstants.FIXED_READ_END_TIMESTAMP);
        }
        byte[][] outputQualifiers = null;
        if (!condition.isOutputAll()) {
            // Generate the output qualifiers
            outputQualifiers = HBaseInternalLogHelper.getOutputQualifiers(entityDef,
                                                                          condition.getOutputFields());
        }
        HBaseLogReader2 reader = new HBaseLogReader2(entityDef, condition.getPartitionValues(), start, end,
                                                     condition.getFilter(), condition.getStartRowkey(),
                                                     outputQualifiers, this.prefix);
        try {
            reader.open();
            InternalLog log;
            int count = 0;
            while ((log = reader.read()) != null) {
                TaggedLogAPIEntity entity = HBaseInternalLogHelper.buildEntity(log, entityDef);
                if (lastTimestamp < entity.getTimestamp()) {
                    lastTimestamp = entity.getTimestamp();
                }
                if (firstTimestamp > entity.getTimestamp() || firstTimestamp == 0) {
                    firstTimestamp = entity.getTimestamp();
                }

                entity.setSerializeVerbose(condition.isOutputVerbose());
                entity.setSerializeAlias(condition.getOutputAlias());

                for (EntityCreationListener l : listeners) {
                    l.entityCreated(entity);
                }
                if (++count == condition.getPageSize()) {
                    break;
                }
            }
        } catch (IOException ioe) {
            LOG.error("Fail reading log", ioe);
            throw ioe;
        } finally {
            reader.close();
        }
    }

    @Override
    public long getFirstTimestamp() {
        return this.firstTimestamp;
    }
}