/* Copyright (C) 2019
 *
 * This file is part of the osdev components suite
 *
 * 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; either version 2, or (at your option) any
 * later version.
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA
 */
#include "ihistogram.h"

// std
#include <algorithm>
#include <iomanip>
#include <numeric>
#include <sstream>

namespace osdev {
namespace components {
namespace mqtt {
namespace measurement {

IHistogram::~IHistogram() = default;

namespace {

std::pair<int, std::size_t> largestValueUnderThreshold(const std::vector<std::size_t>& hist, double thresholdValue)
{
    int bin = -1;
    std::size_t maxValue = 0;
    // do not use the outlier bins for this calculation.
    for (std::size_t i = 1; i < hist.size() - 1; ++i) {
        if (hist[i] > maxValue && hist[i] < thresholdValue) {
            bin = static_cast<int>(i);
            maxValue = hist[i];
        }
    }
    return { bin, maxValue };
}

} // namespace

std::string visualizeHistogram(const IHistogram& histogram)
{
    const std::size_t diagramHeight = 10;
    auto histData = histogram.histogramData(); // take a snapshot of the histogram data.
    const auto& hist = histData.data();

    std::ostringstream oss;
    oss << "Histogram for " << histogram.id() << "\\n";
    auto minmax = std::minmax_element(hist.begin(), hist.end());

    auto minCountValueString = std::to_string(*minmax.first);
    auto maxCountValueString = std::to_string(*minmax.second);

    auto countValueFieldWidth = static_cast<std::int32_t>(std::max(minCountValueString.size(), maxCountValueString.size()));
    auto verticalSize = (*minmax.second - *minmax.first) / static_cast<double>(diagramHeight);

    auto totalMeasurements = std::accumulate(hist.begin(), hist.end(), 0);
    oss << "Total nr of measurements: " << totalMeasurements << ", Nr of buckets: " << histogram.numBuckets() << ", bucket width: " << histogram.bucketWidth() << ", vertical resolution: " << verticalSize << "\\n";
    auto binValuePair = largestValueUnderThreshold(hist, verticalSize);
    if (binValuePair.first >= 0) {
        oss << "Largest value under threshold: " << binValuePair.second << " in bin " << binValuePair.first << "\\n";
    }
    if (hist.front() > 0) {
        oss << "Outliers to the left: " << hist.front() << ", smallest value: " << histData.smallestValueString() << histogram.unit() << "\\n";
    }
    if (hist.back() > 0) {
        oss << "Outliers to the right: " << hist.back() << ", largest value: " << histData.largestValueString() << histogram.unit() << "\\n";
    }

    oss << "\\nSince last clear:\\n"
        << "  number of values : " << histData.numberOfValuesSinceLastClear() << "\\n"
        << "  smallest value   : " << histData.smallestValueSinceLastClearString() << histogram.unit() << "\\n"
        << "  largest value    : " << histData.largestValueSinceLastClearString() << histogram.unit() << "\\n"
        << "  average value    : " << histData.averageValueSinceLastClearString() << histogram.unit() << "\\n\\n";

    oss << std::setw(countValueFieldWidth) << maxCountValueString << " |";
    for (std::size_t line = 0; line < diagramHeight; ++line) {
        for (const auto& cnt : hist) {
            if ((cnt - *minmax.first) > (diagramHeight - line - 1) * verticalSize) {
                oss << '*';
            }
            else {
                oss << ' ';
            }
        }
        oss << "|\\n";
        if (line + 1 < diagramHeight) {
            oss << std::setw(countValueFieldWidth + 2) << '|';
        }
    }
    oss << std::setw(countValueFieldWidth) << minCountValueString << " |/" << std::string(hist.size() - 2, '-') << "\\| " << histogram.unit() << "\\n";

    auto minValueString = histogram.minValueString();
    auto maxValueString = histogram.maxValueString();
    auto valueFieldWidth = std::max(minValueString.size(), maxValueString.size());

    for (std::size_t line = 0; line < valueFieldWidth; ++line) {
        oss << std::setw(countValueFieldWidth + 3 + static_cast<int>(line)) << "";
        oss << (line < minValueString.size() ? minValueString[line] : ' ');

        if (line < maxValueString.size()) {
            oss << std::string(histogram.numBuckets() - 1, ' ') << maxValueString[line];
        }
        oss << "\\n";
    }

    // Add the non zero data to the log for later analysis
    // format: binnumber:value;binnumber:value;....
    bool first = true;
    for (std::size_t idx = 0; idx < hist.size(); ++idx) {
        if (hist[idx] > 0) {
            if (!first) {
                oss << ';';
            }
            else {
                oss << "\\n";
                first = false;
            }
            oss << idx << ':' << hist[idx];
        }
    }

    return oss.str();
}

std::ostream& operator<<(std::ostream& os, const IHistogram& rhs)
{
    return os << rhs.toString();
}

}       // End namespace measurement
}       // End namespace mqtt
}       // End namespace components
}       // End namespace osdev