/* Copyright (C) 2014 InfiniDB, Inc.
   Copyright (C) 2016 MariaDB Corporation

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; version 2 of
   the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301, USA. */

/***************************************************************************
 * $Id: resourceMonitor.cpp 3072 2013-04-04 19:04:45Z rdempsey $
 *
 *   Author: Zhixuan Zhu
 ***************************************************************************/
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib>
#include <cerrno>
#include <exception>
#include <stdexcept>
#include "liboamcpp.h"

using namespace std;
using namespace oam;

/**
 * constants define
 */
enum HOST_INFO
{
    USER = 0,
    SYSTEM,
    NICE,
    IDLE
};

const string FE_MOUNT_DIR = "/var/log/mariadb/columnstore/";	// FE mount dir
const int MONITOR_FREQ = 15;				// monitor frequency in sec
const int LOG_FREQ = 900;					// log frequency in sec
const int DEBUG = false;

/**
 * global variables
 */
static char cpu[5];
static unsigned int usage[LOG_FREQ / MONITOR_FREQ];
static int usageCount = 0;

/**
 * @brief get cpu usage for cpuNo
 */
unsigned int* getUsage(char* cpuNo);

/**
 * @brief get cpu usage diffence over 3 seconds
 */
unsigned int* diffUsage();

/**
 * @brief calculate overall cpu usage
 */
unsigned int calcCPUusage(unsigned int* times);

/**
 * @brief log cpu usage to active log file
 */
void logCPUactive (unsigned int);

/**
 * @brief log cpu peak and average to stat file
 */
void logCPUstat ();


/*****************************************************************************************
* @brief	main function
*
* purpose:	Get current CPU usage and return current state
*
*****************************************************************************************/
int main (int argc, char** argv)
{
    unsigned int* times;
    unsigned int cpuUsage = 0;
    // set defaults
    unsigned int cpuCritical = 9000,
                 cpuMajor = 8000,
                 cpuMinor = 7000,
                 cpuMinorClear = 6000;

    strcpy (cpu, "cpu");

    // get specific CPU info
    times = diffUsage();

    // no cpus available on the system
    if (times == NULL)
    {
        cout << "No cpus on the system" << endl;
        return 0;
    }

    cpuUsage = calcCPUusage(times);
    logCPUactive(cpuUsage);
    cout << "cpuUsage: " << cpuUsage << endl;

    // Get CPU usage water mark from server configuration and compare
    ServerConfig serverConfig;
    Oam oam;

    try
    {
        oam.getSystemConfig (serverConfig);
        cpuCritical = serverConfig.ServerCPUCriticalThreshold;
        cpuMajor = serverConfig.ServerCPUMajorThreshold;
        cpuMinor = serverConfig.ServerCPUMinorThreshold;
        cpuMinorClear = serverConfig.ServerCPUMinorClearThreshold;
    }
    catch (runtime_error e)
    {
        throw e;
    }

    cout << "critical water: " << serverConfig.ServerCPUCriticalThreshold << endl;

    if (cpuUsage >= cpuCritical)
    {
        cout << "return critical: " << CRITICAL << endl;
        return CRITICAL;
    }
    else if (cpuUsage >= cpuMajor)
    {
        cout << "return major: " << MAJOR << endl;
        return MAJOR;
    }
    else if (cpuUsage >= cpuMinor)
    {
        cout << "return Minor: " << MINOR << endl;
        return MINOR;
    }
    else if (cpuUsage >= cpuMinorClear)
    {
        cout << "return MinorClear: " << WARNING << endl;
        return WARNING;
    }
    else
    {
        cout << "return Below MinorClear: " << NO_SEVERITY << endl;
        return NO_SEVERITY;
    }
}

/*****************************************************************************************
* @brief	diffUsage
*
* purpose:	Compare usage different for changes
*
*****************************************************************************************/
unsigned int* diffUsage()
{
    static unsigned int times1[4];
    unsigned int* times;
    int i;

    times = getUsage(cpu);

    if (times == NULL)
        return NULL;

    memcpy(times1, getUsage(cpu), sizeof(unsigned int) * 4);
    sleep(3);
    times = getUsage(cpu);

    for (i = 0; i < 4; i++)
        times1[i] = times[i] - times1[i];

    return times1;
}

/*****************************************************************************************
* @brief	diffUsage
*
* purpose:	Compare usage different for changes
*
*****************************************************************************************/
unsigned int* getUsage(char* cpuNo)
{
    static unsigned int times[4];
    char tmp[5];
    char str[80];
    FILE* file;

    file = fopen("/proc/stat", "r");

    while (fgets(str, 80, file))
    {
        // search for cpuNo
        if ((strstr (str, cpuNo) != NULL))
        {
            sscanf(str, "%s %u %u %u %u", tmp,
                   &times[0], &times[1], &times[2], &times[3]);
            fclose(file);
            return times;
        }
    }

    fclose(file);
    return NULL;
}

/*****************************************************************************************
* @brief	calcCPUusage
*
* purpose:	Calculate CPU usage
*
*****************************************************************************************/
unsigned int calcCPUusage (unsigned int* times)
{
    unsigned int total = 0;

    for (int i = 0; i < 4; i++)
        total += times[i];

    double load = (double)times[IDLE] * 100.0 / (double)total;
    return (int)((100.0 - load));
}

/*****************************************************************************************
* @brief	logCPUactive
*
* purpose:	Log Peak and Average CPU usage
*
*****************************************************************************************/
void logCPUactive (unsigned int cpuUsage)
{
    // determin the active log file name
    string usageLogFileName = FE_MOUNT_DIR;
    usageLogFileName = usageLogFileName + cpu + ".log";

    if (DEBUG)
        cout << usageLogFileName << endl;

    fstream usageLogFile;
    usageLogFile.open (usageLogFileName.c_str(), ios::in | ios::out);

    if (usageLogFile.fail())
    {
        ofstream file (usageLogFileName.c_str());
        file.close();
        usageLogFile.open(usageLogFileName.c_str(), ios::in | ios::out);

        if (!usageLogFile) cout << "--error" << endl;
    }

    // get the counter
    usageLogFile.seekg(0, ios::beg);
    usageLogFile.read (reinterpret_cast<char*>(&usageCount), sizeof (int));

    if (usageLogFile.eof()) usageLogFile.clear();

    // new iteration
    if (usageCount == 0)
    {
        usageLogFile.seekp(0, ios::beg);
        usageLogFile.write (reinterpret_cast<char*>(&usageCount), sizeof (int));
    }

    usageCount ++;

    // append new usage data to the end
    usageLogFile.seekp (0, ios::end);
    usageLogFile.write (reinterpret_cast<char*>(&cpuUsage), sizeof (int));

    if (DEBUG)
        cout << "usage: " << usageCount << endl;

    // calculate peak and average if it's time to log usage data
    if (usageCount >= LOG_FREQ / MONITOR_FREQ)
    {
        usageLogFile.seekg (4, ios::beg);
        usageLogFile.read ((char*)usage, sizeof(unsigned int) * LOG_FREQ / MONITOR_FREQ);

        if (usageLogFile.eof()) usageLogFile.clear();

        if (DEBUG)
        {
            for (int i = 0; i < usageCount; i++)
            {
                cout << usage [i] << endl;
            }
        }

        logCPUstat();

        // delete the file
        usageLogFile.close();
        unlink (usageLogFileName.c_str());
    }

    // else, update usageCount
    else
    {
        usageLogFile.seekp(0, ios::beg);
        usageLogFile.write (reinterpret_cast<char*>(&usageCount), sizeof (int));
        usageLogFile.close();
    }
}

/*****************************************************************************************
* @brief	logCPUstat
*
* purpose:	Log CPU stat using system API
*
*****************************************************************************************/
void logCPUstat ()
{
    unsigned int max = 0;
    unsigned int sum = 0;
    float average = 0.0;

    for (int i = 0; i < usageCount; i++)
    {
        if (usage[i] > max)
            max = usage[i];

        sum += usage[i];
    }

    average = sum / usageCount;

    // Call system log api to store stats.
    // for now, write on local for testing purpose.
    string statFileName = FE_MOUNT_DIR;
    statFileName = statFileName + cpu + "stat.log";
    ofstream file (statFileName.c_str(), ios::app);
    file << max << "	" << average << endl;
    file.close();
}