#include "statistics.h"

#include <wx/ffile.h>
#include "globalFunctions.h"
#include "statusHandler.h"
#include "../algorithm.h"
#include <limits>
#include <wx/stopwatch.h>


RetrieveStatistics::RetrieveStatistics() :
        timer(new wxStopWatch) {}


RetrieveStatistics::~RetrieveStatistics()
{   //write statistics to a file
    wxFFile outputFile(wxT("statistics.dat"), wxT("w"));

    outputFile.Write(wxT("Time(ms);Objects;Data\n"));

    for (std::vector<statEntry>::const_iterator i = data.begin(); i != data.end(); ++i)
    {
        outputFile.Write(globalFunctions::numberToWxString(int(i->time)));
        outputFile.Write(wxT(";"));
        outputFile.Write(globalFunctions::numberToWxString(i->objects));
        outputFile.Write(wxT(";"));
        outputFile.Write(globalFunctions::numberToWxString(float(i->value)));
        outputFile.Write(wxT("\n"));
    }
}


void RetrieveStatistics::writeEntry(const double value, const int objects)
{
    statEntry newEntry;
    newEntry.value   = value;
    newEntry.objects = objects;
    newEntry.time    = timer->Time();
    data.push_back(newEntry);
}


//########################################################################################

inline
bool isNull(const double number)
{
    return globalFunctions::abs(number) <= std::numeric_limits<double>::epsilon();
}


inline
wxString Statistics::formatRemainingTime(const double timeInMs) const
{
    bool unitSec = true;
    double remainingTime = timeInMs / 1000;
    wxString unit = _(" sec");
    if (remainingTime > 55)
    {
        unitSec = false;
        remainingTime /= 60;
        unit = _(" min");
        if (remainingTime > 59)
        {
            remainingTime /= 60;
            unit = _(" hour(s)");
            if (remainingTime > 23)
            {
                remainingTime /= 24;
                unit = _(" day(s)");
            }
        }
    }


    int formattedTime = globalFunctions::round(remainingTime);

    //reduce precision to 5 seconds
    if (unitSec && formattedTime % 5 != 0)
        formattedTime += 5 - formattedTime % 5; //"ceiling"


    //avoid "jumping back and forth" when fluctuating around .5
    if (remainingTimeLast < formattedTime)
    {
        if (unitSec)
        {
            formattedTime = globalFunctions::round(remainingTime);
            formattedTime -= formattedTime % 5; //"floor"
        }
        else
            formattedTime = int(remainingTime); //"floor"
    }
    remainingTimeLast = formattedTime;

    return globalFunctions::numberToWxString(formattedTime) + unit;
    //+ wxT("(") + globalFunctions::numberToWxString(globalFunctions::round(timeInMs / 1000)) + wxT(")");
}


Statistics::Statistics(const int totalObjectCount,
                       const double totalDataAmount,
                       const unsigned windowSizeRemainingTime,
                       const unsigned windowSizeBytesPerSecond) :
        objectsTotal(totalObjectCount),
        dataTotal(totalDataAmount),
        windowSizeRemTime(windowSizeRemainingTime),
        windowSizeBPS(windowSizeBytesPerSecond),
        windowMax(std::max(windowSizeRemainingTime, windowSizeBytesPerSecond)),
        remainingTimeLast(256*256*256*100), //something "big"
        timer(new wxStopWatch) {}


void Statistics::addMeasurement(const int objectsCurrent, const double dataCurrent)
{
    record newEntry;
    newEntry.objects = objectsCurrent;
    newEntry.data    = dataCurrent;
    newEntry.time    = timer->Time();

    //insert new record
    measurements.push_back(newEntry);

    //remove all records earlier than "currentTime - windowSize"
    const long newBegin = newEntry.time - windowMax;
    while (measurements.size() > 0 && measurements.front().time < newBegin)
        measurements.pop_front();
}


wxString Statistics::getRemainingTime() const
{
    if (measurements.size() > 0)
    {
        //find start of records "window"
        const record backElement = measurements.back();
        const long frontTime = backElement.time - windowSizeRemTime;
        std::list<record>::const_iterator frontElement = measurements.end();
        do
        {
            --frontElement;
        }
        while (frontElement != measurements.begin() && frontElement->time > frontTime);

        const double timeDelta = backElement.time - frontElement->time;
        const double dataDelta = backElement.data - frontElement->data;

        const double dataRemaining = dataTotal    - backElement.data;

        if (!isNull(dataDelta))
            return formatRemainingTime(dataRemaining * timeDelta / dataDelta);
    }

    return wxT("-"); //fallback
}


wxString Statistics::getBytesPerSecond() const
{
    if (measurements.size() > 0)
    {
        //find start of records "window"
        const long frontTime = measurements.back().time - windowSizeBPS;
        std::list<record>::const_iterator frontElement = measurements.end();
        do
        {
            --frontElement;
        }
        while (frontElement != measurements.begin() && frontElement->time > frontTime);

        const double timeDelta = measurements.back().time - frontElement->time;
        const double dataDelta = measurements.back().data - frontElement->data;

        if (!isNull(timeDelta))
            return FreeFileSync::formatFilesizeToShortString(dataDelta * 1000 / timeDelta) + _("/sec");
    }

    return wxT("-"); //fallback
}


void Statistics::pauseTimer()
{
    timer->Pause();
}


void Statistics::resumeTimer()
{
    timer->Resume();
}

/*
class for calculation of remaining time:
----------------------------------------
"filesize |-> time" is an affine linear function f(x) = z_1 + z_2 x

For given n measurements, sizes x_0, ..., x_n and times f_0, ..., f_n, the function f (as a polynom of degree 1) can be lineary approximated by

z_1 = (r - s * q / p) / ((n + 1) - s * s / p)
z_2 = (q - s * z_1) / p = (r - (n + 1) z_1) / s

with
p := x_0^2 + ... + x_n^2
q := f_0 x_0 + ... + f_n x_n
r := f_0 + ... + f_n
s := x_0 + ... + x_n

=> the time to process N files with amount of data D is:    N * z_1 + D * z_2

Problem:
--------
Times f_0, ..., f_n can be very small so that precision of the PC clock is poor.
=> Times have to be accumulated to enhance precision:
Copying of m files with sizes x_i and times f_i (i = 1, ..., m) takes sum_i f(x_i) := m * z_1 + z_2 * sum x_i = sum f_i
With X defined as the accumulated sizes and F the accumulated times this gives: (in theory...)
m * z_1 + z_2 * X = F   <=>
z_1 + z_2 * X / m = F / m

=> we obtain a new (artificial) measurement with size X / m and time F / m to be used in the linear approximation above


Statistics::Statistics(const int totalObjectCount, const double totalDataAmount, const unsigned recordCount) :
        objectsTotal(totalObjectCount),
        dataTotal(totalDataAmount),
        recordsMax(recordCount),
        objectsLast(0),
        dataLast(0),
        timeLast(wxGetLocalTimeMillis()),
        z1_current(0),
        z2_current(0),
        dummyRecordPresent(false) {}


wxString Statistics::getRemainingTime(const int objectsCurrent, const double dataCurrent)
{
    //add new measurement point
    const int m = objectsCurrent - objectsLast;
    if (m != 0)
    {
        objectsLast = objectsCurrent;

        const double X = dataCurrent - dataLast;
        dataLast = dataCurrent;

        const wxLongLong timeCurrent = wxGetLocalTimeMillis();
        const double F = (timeCurrent - timeLast).ToDouble();
        timeLast = timeCurrent;

        record newEntry;
        newEntry.x_i = X / m;
        newEntry.f_i = F / m;

        //remove dummy record
        if (dummyRecordPresent)
        {
            measurements.pop_back();
            dummyRecordPresent = false;
        }

        //insert new record
        measurements.push_back(newEntry);
        if (measurements.size() > recordsMax)
            measurements.pop_front();
    }
    else //dataCurrent increased without processing new objects:
    {    //modify last measurement until m != 0
        const double X = dataCurrent - dataLast; //do not set dataLast, timeLast variables here, but write dummy record instead
        if (!isNull(X))
        {
            const wxLongLong timeCurrent = wxGetLocalTimeMillis();
            const double F = (timeCurrent - timeLast).ToDouble();

            record modifyEntry;
            modifyEntry.x_i = X;
            modifyEntry.f_i = F;

            //insert dummy record
            if (!dummyRecordPresent)
            {
                measurements.push_back(modifyEntry);
                if (measurements.size() > recordsMax)
                    measurements.pop_front();
                dummyRecordPresent = true;
            }
            else //modify dummy record
                measurements.back() = modifyEntry;
        }
    }

    //calculate remaining time based on stored measurement points
    double p = 0;
    double q = 0;
    double r = 0;
    double s = 0;
    for (std::list<record>::const_iterator i = measurements.begin(); i != measurements.end(); ++i)
    {
        const double x_i = i->x_i;
        const double f_i = i->f_i;
        p += x_i * x_i;
        q += f_i * x_i;
        r += f_i;
        s += x_i;
    }

    if (!isNull(p))
    {
        const double n   = measurements.size();
        const double tmp = (n - s * s / p);

        if (!isNull(tmp) && !isNull(s))
        {
            const double z1 = (r - s * q / p) / tmp;
            const double z2 = (r - n * z1) / s;    //not (n + 1) here, since n already is the number of measurements

            //refresh current values for z1, z2
            z1_current = z1;
            z2_current = z2;
        }
    }

    return formatRemainingTime((objectsTotal - objectsCurrent) * z1_current + (dataTotal - dataCurrent) * z2_current);
}

*/