/*******************************************************************************
 * ============LICENSE_START==================================================
 * * org.onap.dmaap
 * * ===========================================================================
 * * Copyright © 2017 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.
 * * ============LICENSE_END====================================================
 * *
 * * ECOMP is a trademark and service mark of AT&T Intellectual Property.
 * *
 ******************************************************************************/


package org.onap.dmaap.datarouter.reports;

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import org.onap.dmaap.datarouter.provisioning.utils.ProvDbUtils;

/**
 * Generate a per-file latency report.  It reports on the details related to one file published
 * on one feed. This report can be further reduced in order to generate more specific reports
 * based on feed ID or node name. The report is a .csv file containing the following columns:
 * <table>
 * <tr><td>recordid</td><td>the unique record ID assigned to a particular incoming feed</td></tr>
 * <tr><td>feedid</td><td>the Feed ID for this record</td></tr>
 * <tr><td>uri</td><td>the URI of the file delivered</td></tr>
 * <tr><td>size</td><td>the size of the file delivered</td></tr>
 * <tr><td>min</td><td>the minimum latency in delivering this feed to a subscriber (in ms)</td></tr>
 * <tr><td>max</td><td>the maximum latency in delivering this feed to a subscriber (in ms)</td></tr>
 * <tr><td>avg</td><td>the average latency in delivering this feed to all subscribers (in ms)</td></tr>
 * <tr><td>fanout</td><td>the number of subscribers this feed was delivered to</td></tr>
 * </table>
 *
 * @author Robert P. Eby
 * @version $Id: LatencyReport.java,v 1.1 2013/10/28 18:06:53 eby Exp $
 */
public class LatencyReport extends ReportBase {

    private class Event {
        public final String type;
        public final long time;

        public Event(String t, long tm) {
            type = t;
            time = tm;
        }
    }

    private class Counters {
        public final String id;
        public final int feedid;
        public final long clen;
        public final String fileid;
        public final List<Event> events;

        public Counters(String i, int fid, long c, String s) {
            id = i;
            feedid = fid;
            clen = c;
            fileid = s;
            events = new ArrayList<>();
        }

        private long pubtime;

        public void addEvent(String t, long tm) {
            events.add(new Event(t, tm));
            if (t.equals("pub"))
                pubtime = tm;
        }

        public long min() {
            long min = Long.MAX_VALUE;
            for (Event e : events) {
                if (e.type.equals("del")) {
                    min = Math.min(min, e.time - pubtime);
                }
            }
            return min;
        }

        public long max() {
            long max = 0;
            for (Event e : events) {
                if (e.type.equals("del")) {
                    max = Math.max(max, e.time - pubtime);
                }
            }
            return max;
        }

        public long avg() {
            long total = 0, c = 0;
            for (Event e : events) {
                if (e.type.equals("del")) {
                    total += e.time - pubtime;
                    c++;
                }
            }
            return (c == 0) ? 0 : total / c;
        }

        public int fanout() {
            int n = 0;
            for (Event e : events) {
                if (e.type.equals("del")) {
                    n++;
                }
            }
            return n;
        }

        @Override
        public String toString() {
            return feedid + "," + fileid + "," + clen + "," + min() + "," + max() + "," + avg() + "," + fanout();
        }
    }

    @Override
    public void run() {
        long start = System.currentTimeMillis();
        try (Connection conn = ProvDbUtils.getInstance().getConnection();
            PreparedStatement ps = conn.prepareStatement(
                "select EVENT_TIME, TYPE, PUBLISH_ID, FEED_FILEID, FEEDID, CONTENT_LENGTH from LOG_RECORDS where "
                    + "EVENT_TIME >= ? and EVENT_TIME <= ? order by PUBLISH_ID, EVENT_TIME")) {
            ps.setLong(1, from);
            ps.setLong(2, to);
            try(ResultSet rs = ps.executeQuery()) {
                try (PrintWriter os = new PrintWriter(outfile)) {
                    os.println("recordid,feedid,uri,size,min,max,avg,fanout");
                    Counters c = null;
                    while (rs.next()) {
                        long etime = rs.getLong("EVENT_TIME");
                        String type = rs.getString("TYPE");
                        String id = rs.getString("PUBLISH_ID");
                        String fid = rs.getString("FEED_FILEID");
                        int feed = rs.getInt("FEEDID");
                        long clen = rs.getLong("CONTENT_LENGTH");
                        if (c != null && !id.equals(c.id)) {
                            String line = id + "," + c.toString();
                            os.println(line);
                            c = null;
                        }
                        if (c == null) {
                            c = new Counters(id, feed, clen, fid);
                        }
                        if (feed != c.feedid)
                            System.err.println("Feed ID mismatch, " + feed + " <=> " + c.feedid);
                        if (clen != c.clen)
                            System.err.println("Cont Len mismatch, " + clen + " <=> " + c.clen);
                        c.addEvent(type, etime);
                    }
                }
            }
        } catch (FileNotFoundException e) {
            System.err.println("File cannot be written: " + outfile);
        } catch (SQLException e) {
            logger.error("SQLException: " + e.getMessage());
        }
        logger.debug("Query time: " + (System.currentTimeMillis() - start) + " ms");
    }
}