/*-
 * ============LICENSE_START=======================================================
 * SDC
 * ================================================================================
 * Copyright (C) 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=========================================================
 */
package org.openecomp.sdc.common.monitoring;

import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.lang.management.RuntimeMXBean;
import java.lang.management.ThreadMXBean;
import java.util.HashMap;
import java.util.Map;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.hyperic.sigar.FileSystem;
import org.hyperic.sigar.Sigar;
import org.openecomp.sdc.common.impl.ExternalConfiguration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MonitoringMetricsFetcher {

    private static Logger monitoringLogger = LoggerFactory.getLogger("asdc.fe.monitoring.fetcher");
    private static volatile MonitoringMetricsFetcher instance;
    private static RuntimeMXBean runtimeMXBean;
    private static ThreadMXBean threadMXBean;
    private static MemoryMXBean memoryMXBean;
    private static MBeanServer platformMBeanServer;
    private static Sigar sigarSession;
    private static String appName;
    private static String jvmName = "Unknown";
    private final String PROCESS_CPU_TIME_ATTR = "ProcessCpuTime";
    private static String FE_JVM_NAME = "jetty-fe";
    private static String BE_JVM_NAME = "jetty-be";

    private MonitoringMetricsFetcher() {
    }

    public static MonitoringMetricsFetcher getInstance() {
        if (instance == null) {
            instance = init();
        }
        return instance;
    }

    public MonitoringEvent getMonitoringMetrics() {
        MonitoringEvent monitoringEvent = new MonitoringEvent();
        monitoringEvent.setHostid(getFQDN());
        monitoringEvent.setHostcpu(getHostCpuTime());
        monitoringEvent.setHostmem(getHostUsedMemory());
        monitoringEvent.setHostdisk(getHostUsedDisk().toString());
        monitoringEvent.setJvmid(jvmName);
        monitoringEvent.setJvmcpu(getJvmCpuTime());
        monitoringEvent.setJvmmem(getJvmUsedHeapMemory());
        monitoringEvent.setJvmtnum(getJvmThreads());
        monitoringEvent.setAppid(appName);
        // this is probably from healthcheck
        monitoringEvent.setAppstat("appStatus");
        return monitoringEvent;
    }

    private static synchronized MonitoringMetricsFetcher init() {
        if (instance == null) {
            instance = new MonitoringMetricsFetcher();
            threadMXBean = ManagementFactory.getThreadMXBean();
            memoryMXBean = ManagementFactory.getMemoryMXBean();
            runtimeMXBean = ManagementFactory.getRuntimeMXBean();
            platformMBeanServer = ManagementFactory.getPlatformMBeanServer();
            sigarSession = new Sigar();
            appName = ExternalConfiguration.getAppName();
            monitoringLogger.debug("appName is {}", appName);
            // Accoridng to Yaki, there is no "calculated" jvmName like it was

            // in TAS,

            // just "jetty-be" or "jetty-fe"
            if (appName.contains("fe")) {
                jvmName = FE_JVM_NAME;
            } else if (appName.contains("be")) {
                jvmName = BE_JVM_NAME;
            } else {
                monitoringLogger.warn("Couldn't determine jvmName, appName is expected to contain \"be\" or \"fe\" string");
            }
        }
        return instance;
    }

    /**
     * Returns the number of live threads for this JVM
     *
     * @return number of live threads
     */
    private Integer getJvmThreads() {
        return threadMXBean.getThreadCount();
    }

    /**
     * Returns the number of used heap memory (bytes)
     *
     * @return the number of used heap memory (bytes)
     */
    private long getJvmUsedHeapMemory() {
        return memoryMXBean.getHeapMemoryUsage().getUsed();
    }

    /**
     * Returns the jvm cpu time (msec)
     *
     * @return the jvm cpu time (msec)
     */
    private long getJvmCpuTime() {
        long cpuTime = -1;
        try {
            cpuTime = (long) platformMBeanServer.getAttribute(new ObjectName(ManagementFactory.OPERATING_SYSTEM_MXBEAN_NAME), PROCESS_CPU_TIME_ATTR);
        } catch (Exception e) {
            monitoringLogger.error("Couldn't measure JVM CPU time", e);
        }
        return cpuTime;
    }

    /**
     * Returns the host total cpu time (msec)
     *
     * @return the host total cpu time (msec)
     */
    private long getHostCpuTime() {
        long cpuTime = -1;
        try {
            cpuTime = sigarSession.getCpu().getTotal();
        } catch (Exception e) {
            monitoringLogger.error("Couldn't measure host CPU time", e);
        }
        return cpuTime;
    }

    /**
     * Returns the host used memory(msec)
     *
     * @return the host used memory(msec)
     */
    private Double getHostUsedMemory() {
        Double memory = -1.0;
        try {
            memory = sigarSession.getMem().getUsedPercent();
        } catch (Exception e) {
            monitoringLogger.error("Couldn't measure host used memory", e);
        }
        return memory;
    }

    /**
     * Returns the percentage of all available FS
     *
     * @return the host avail disk(bytes)
     */
    private Map<String, Double> getHostUsedDisk() {
        Map<String, Double> res = new HashMap<>();
        try {
            FileSystem[] fileSystemList = sigarSession.getFileSystemList();
            for (FileSystem fileSystem : fileSystemList) {
                String dirName = fileSystem.getDirName();
                double usePercent = sigarSession.getFileSystemUsage(dirName).getUsePercent() * 100;
                res.put(dirName, usePercent);
            }
        } catch (Exception e) {
            monitoringLogger.error("Couldn't measure host used disk", e);
        }
        return res;
    }

    /**
     * Returns the FQDN
     *
     * @return the FQDN
     */
    private String getFQDN() {
        String fqdn = "";
        try {
            fqdn = sigarSession.getFQDN();
        } catch (Exception e) {
            monitoringLogger.error("Couldn't get FQDN", e);
        }
        return fqdn;
    }
}