/*
Copyright 2019 Intel Corporation

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.
*/

const PDH_FMT_LONG = 0x00000100;
const PDH_FMT_DOUBLE = 0x00000200;

var promise = require('promise');
if (process.platform == 'win32')
{
    var GM = require('_GenericMarshal');
    GM.kernel32 = GM.CreateNativeProxy('kernel32.dll');
    GM.kernel32.CreateMethod('GlobalMemoryStatusEx');

    GM.pdh = GM.CreateNativeProxy('pdh.dll');
    GM.pdh.CreateMethod('PdhAddEnglishCounterA');
    GM.pdh.CreateMethod('PdhCloseQuery');
    GM.pdh.CreateMethod('PdhCollectQueryData');
    GM.pdh.CreateMethod('PdhGetFormattedCounterValue');
    GM.pdh.CreateMethod('PdhGetFormattedCounterArrayA');
    GM.pdh.CreateMethod('PdhOpenQueryA');
    GM.pdh.CreateMethod('PdhRemoveCounter');
}

function windows_cpuUtilization()
{
    var p = new promise(function (res, rej) { this._res = res; this._rej = rej; });
    p.counter = GM.CreateVariable(16);
    p.cpu = GM.CreatePointer();
    p.cpuTotal = GM.CreatePointer();
    var err = 0;
    if ((err = GM.pdh.PdhOpenQueryA(0, 0, p.cpu).Val) != 0) { p._rej(err); return; }

    // This gets the CPU Utilization for each proc
    if ((err = GM.pdh.PdhAddEnglishCounterA(p.cpu.Deref(), GM.CreateVariable('\\Processor(*)\\% Processor Time'), 0, p.cpuTotal).Val) != 0) { p._rej(err); return; }

    if ((err = GM.pdh.PdhCollectQueryData(p.cpu.Deref()).Val != 0)) { p._rej(err); return; }
    p._timeout = setTimeout(function (po)
    {
        var u = { cpus: [] };
        var bufSize = GM.CreateVariable(4);
        var itemCount = GM.CreateVariable(4);
        var buffer, szName, item;
        var e;
        if ((e = GM.pdh.PdhCollectQueryData(po.cpu.Deref()).Val != 0)) { po._rej(e); return; }

        if ((e = GM.pdh.PdhGetFormattedCounterArrayA(po.cpuTotal.Deref(), PDH_FMT_DOUBLE, bufSize, itemCount, 0).Val) == -2147481646)
        {
            buffer = GM.CreateVariable(bufSize.toBuffer().readUInt32LE());
        }
        else
        {
            po._rej(e);
            return;
        }
        if ((e = GM.pdh.PdhGetFormattedCounterArrayA(po.cpuTotal.Deref(), PDH_FMT_DOUBLE, bufSize, itemCount, buffer).Val) != 0) { po._rej(e); return; }
        for(var i=0;i<itemCount.toBuffer().readUInt32LE();++i)
        {
            item = buffer.Deref(i * 24, 24);
            szName = item.Deref(0, GM.PointerSize).Deref();
            if (szName.String == '_Total')
            {
                u.total = item.Deref(16, 8).toBuffer().readDoubleLE().toFixed(2);
            }
            else
            {
                u.cpus[parseInt(szName.String)] = item.Deref(16, 8).toBuffer().readDoubleLE().toFixed(2);
            }
        }

        GM.pdh.PdhRemoveCounter(po.cpuTotal.Deref());
        GM.pdh.PdhCloseQuery(po.cpu.Deref());
        p._res(u);
    }, 100, p);

    return (p);
}
function windows_memUtilization()
{
    var info = GM.CreateVariable(64);
    info.Deref(0, 4).toBuffer().writeUInt32LE(64);
    GM.kernel32.GlobalMemoryStatusEx(info);

    var ret =
        {
            MemTotal: require('bignum').fromBuffer(info.Deref(8, 8).toBuffer(), { endian: 'little' }),
            MemFree: require('bignum').fromBuffer(info.Deref(16, 8).toBuffer(), { endian: 'little' })
        };

    ret.percentFree = ((ret.MemFree.div(require('bignum')('1048576')).toNumber() / ret.MemTotal.div(require('bignum')('1048576')).toNumber()) * 100).toFixed(2);
    ret.percentConsumed = ((ret.MemTotal.sub(ret.MemFree).div(require('bignum')('1048576')).toNumber() / ret.MemTotal.div(require('bignum')('1048576')).toNumber()) * 100).toFixed(2);
    ret.MemTotal = ret.MemTotal.toString();
    ret.MemFree = ret.MemFree.toString();
    return (ret);
}

function linux_cpuUtilization()
{
    var ret = { cpus: [] };
    var info = require('fs').readFileSync('/proc/stat');
    var lines = info.toString().split('\n');
    var columns;
    var x, y;
    var sum, idle, utilization;
    for (var i in lines)
    {
        columns = lines[i].split(' ');
        if (!columns[0].startsWith('cpu')) { break; }

        x = 0, sum = 0;
        while (columns[++x] == '');
        for (y = x; y < columns.length; ++y) { sum += parseInt(columns[y]); }
        idle = parseInt(columns[3 + x]);
        utilization = (100 - ((idle / sum) * 100)).toFixed(2);
        if (!ret.total)
        {
            ret.total = utilization;
        }
        else
        {
            ret.cpus.push(utilization);
        }
    }

    var p = new promise(function (res, rej) { this._res = res; this._rej = rej; });
    p._res(ret);
    return (p);
}
function linux_memUtilization()
{
    var ret = {};

    var info = require('fs').readFileSync('/proc/meminfo').toString().split('\n');
    var tokens;
    for(var i in info)
    {
        tokens = info[i].split(' ');
        switch(tokens[0])
        {
            case 'MemTotal:':
                ret.total = parseInt(tokens[tokens.length - 2]);
                break;
            case 'MemFree:':
                ret.free = parseInt(tokens[tokens.length - 2]);
                break;
        }
    }
    ret.percentFree = ((ret.free / ret.total) * 100).toFixed(2);
    ret.percentConsumed = (((ret.total - ret.free) / ret.total) * 100).toFixed(2);
    return (ret);
}

function macos_cpuUtilization()
{
    var ret = new promise(function (res, rej) { this._res = res; this._rej = rej; });
    var child = require('child_process').execFile('/bin/sh', ['sh']);
    child.stdout.str = '';
    child.stdout.on('data', function (chunk) { this.str += chunk.toString(); });
    child.stdin.write('top -l 1 | grep -E "^CPU"\nexit\n');
    child.waitExit();

    var lines = child.stdout.str.split('\n');
    if (lines[0].length > 0)
    {
        var usage = lines[0].split(':')[1];
        var bdown = usage.split(',');

        var tot = parseFloat(bdown[0].split('%')[0].trim()) + parseFloat(bdown[1].split('%')[0].trim());
        ret._res({total: tot, cpus: []});
    }
    else
    {
        ret._rej('parse error');
    }

    return (ret);
}
function macos_memUtilization()
{
    var mem = { };
    var ret = new promise(function (res, rej) { this._res = res; this._rej = rej; });
    var child = require('child_process').execFile('/bin/sh', ['sh']);
    child.stdout.str = '';
    child.stdout.on('data', function (chunk) { this.str += chunk.toString(); });
    child.stdin.write('top -l 1 | grep -E "^Phys"\nexit\n');
    child.waitExit();

    var lines = child.stdout.str.split('\n');
    if (lines[0].length > 0)
    {
        var usage = lines[0].split(':')[1];
        var bdown = usage.split(',');

        mem.MemTotal = parseInt(bdown[0].trim().split(' ')[0]);
        mem.MemFree = parseInt(bdown[1].trim().split(' ')[0]);
        mem.percentFree = ((mem.MemFree / mem.MemTotal) * 100).toFixed(2);
        mem.percentConsumed = (((mem.MemTotal - mem.MemFree)/ mem.MemTotal) * 100).toFixed(2);
        return (mem);
    }
    else
    {
        throw ('Parse Error');
    }
}

switch(process.platform)
{
    case 'linux':
        module.exports = { cpuUtilization: linux_cpuUtilization, memUtilization: linux_memUtilization };
        break;
    case 'win32':
        module.exports = { cpuUtilization: windows_cpuUtilization, memUtilization: windows_memUtilization };
        break;
    case 'darwin':
        module.exports = { cpuUtilization: macos_cpuUtilization, memUtilization: macos_memUtilization };
        break;
}

