// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#include "JFJochSimpleChartView.h"

#include <QMenu>
#include <QClipboard>
#include <QApplication>
#include <QCategoryAxis>
#include <QRegularExpression>

JFJochSimpleChartView::JFJochSimpleChartView(QWidget *parent)
    : QChartView(new QChart(), parent) {
    chart()->legend()->hide();
    setFixedHeight(300);
    setRenderHint(QPainter::Antialiasing);
    setMouseTracking(true);
    //setRubberBand(QChartView::RubberBand::HorizontalRubberBand);
}

void JFJochSimpleChartView::UpdateData(const std::vector<float> &in_x, const std::vector<float> &in_y,
                                       QString legend_x, QString legend_y, bool in_one_over_d) {
    one_over_d = in_one_over_d;
    x = in_x;
    y = in_y;

    // Remove hover line if any
    if (m_hoverLine) {
        chart()->scene()->removeItem(m_hoverLine);
        delete m_hoverLine;
        m_hoverLine = nullptr;
    }
    m_series = nullptr;

    chart()->removeAllSeries();
    // Remove all axes to avoid duplicates
    for (auto ax: chart()->axes()) chart()->removeAxis(ax);

    if (x.empty() || x.size() != y.size()) return;

    auto *series = new QLineSeries(this);
    for (size_t i = 0; i < x.size(); ++i) series->append(x[i], y[i]);
    chart()->addSeries(series);
    m_series = series;

    // Compute Y range
    double ymin = 0.0, ymax = 0.0;
    {
        auto [minYIt, maxYIt] = std::minmax_element(y.begin(), y.end());
        ymin = static_cast<double>(*minYIt);
        ymax = static_cast<double>(*maxYIt);
        if (ymin == ymax) {
            const double eps = (std::abs(ymax) > 0.0) ? std::abs(ymax) * 1e-6 : 1.0;
            ymin -= eps;
            ymax += eps;
        }
    }

    // Hidden value axis (left): range + grid
    auto *axYvalue = new QValueAxis();
    axYvalue->setTitleText(legend_y);
    axYvalue->setRange(ymin, ymax);
    axYvalue->setTickCount(5);              // ensure ticks exist now (avoid 0 before layout)
    axYvalue->setLabelsVisible(false);      // hide numeric labels (grid only)
    chart()->addAxis(axYvalue, Qt::AlignRight);
    series->attachAxis(axYvalue);

    // SI formatter (Plotly/D3-like ".3~s")
    int precision = 3;
    const auto formatSI = [precision](double v) -> QString {
        if (v == 0.0 || std::isnan(v)) return QStringLiteral("0");
        static const struct { int exp; const char* pre; } si[] = {
            {24,"Y"},{21,"Z"},{18,"E"},{15,"P"},{12,"T"},{9,"G"},{6,"M"},{3,"k"},
            {0,""},{-3,"m"},{-6,"µ"},{-9,"n"},{-12,"p"},{-15,"f"},{-18,"a"},{-21,"z"},{-24,"y"}
        };
        double av = std::fabs(v);
        int chosenExp = 0; const char* chosenPre = "";
        if (av > 0.0) {
            int exp10 = static_cast<int>(std::floor(std::log10(av)));
            int exp3 = (exp10 >= 0) ? (exp10 / 3) * 3 : -(((-exp10 + 2) / 3) * 3);
            if (exp3 > 24) exp3 = 24;
            if (exp3 < -24) exp3 = -24;
            for (auto &e : si) if (e.exp == exp3) { chosenExp = e.exp; chosenPre = e.pre; break; }
        }
        const double scaled = v / std::pow(10.0, chosenExp);
        QString num = QString::number(scaled, 'g', std::max(1, precision)); // ~ trimming effect
        return (chosenPre && *chosenPre) ? num + QStringLiteral(" ") + QString::fromUtf8(chosenPre) : num;
    };

    // Visible category axis (right) with formatted labels
    auto *axYcat = new QCategoryAxis();
    axYcat->setLabelsPosition(QCategoryAxis::AxisLabelsPositionOnValue);
    axYcat->setGridLineVisible(false);
    axYcat->setMinorGridLineVisible(false);
    axYcat->setTitleText(legend_y);
    axYcat->setLabelsVisible(true);         // make sure labels are actually shown

    // Build ticks from hidden axis tick count immediately (stable even before layout)
    const int tickCountY = std::max(2, axYvalue->tickCount());
    const double ystep = (ymax - ymin) / (tickCountY - 1);
    for (int i = 0; i < tickCountY; ++i) {
        const double yv = (i == tickCountY - 1) ? ymax : (ymin + i * ystep);
        axYcat->append(formatSI(yv), yv);
    }
    chart()->addAxis(axYcat, Qt::AlignLeft);
    series->attachAxis(axYcat);

    // Give a bit more room on the right so labels are not clipped
    QMargins m = chart()->margins();
    if (m.right() < 12) {
        m.setRight(12);
        chart()->setMargins(m);
    }

    // Build X range
    const float xmin = x[0], xmax = x[x.size() - 1];

    if (one_over_d) {
        auto *axXTop = new QValueAxis();
        axXTop->setRange(xmin, xmax);
        axXTop->setTickCount(5);
        axXTop->setLabelsVisible(false);
        chart()->addAxis(axXTop, Qt::AlignTop);
        series->attachAxis(axXTop);

        auto *axXcat = new QCategoryAxis();
        axXcat->setLabelsPosition(QCategoryAxis::AxisLabelsPositionOnValue);
        axXcat->setGridLineVisible(false);
        axXcat->setMinorGridLineVisible(false);
        axXcat->setTitleText(legend_x);

        const int tickCount = axXTop->tickCount();
        const double step = (tickCount > 1) ? (xmax - xmin) / (tickCount - 1) : 0.0;
        for (int i = 0; i < tickCount; ++i) {
            const double xv = xmin + i * step;
            const QString lab = (std::abs(xv) < 1e-12)
                                    ? QStringLiteral("∞")
                                    : QString::number(1.0 / sqrtf(xv), 'f', 2);
            axXcat->append(lab, xv);
        }
        chart()->addAxis(axXcat, Qt::AlignBottom);
        series->attachAxis(axXcat);
    } else {
        auto *axX = new QValueAxis();
        axX->setRange(xmin, xmax);
        axX->setTitleText(legend_x);
        chart()->addAxis(axX, Qt::AlignBottom);
        series->attachAxis(axX);
    }
}


void JFJochSimpleChartView::ClearData() {
    x.clear();
    y.clear();
    m_series = nullptr;
    if (m_hoverLine) {
        chart()->scene()->removeItem(m_hoverLine);
        delete m_hoverLine;
        m_hoverLine = nullptr;
    }
    chart()->removeAllSeries();
}

void JFJochSimpleChartView::contextMenuEvent(QContextMenuEvent *event) {
    QMenu menu(this);
    QAction *copyXY = menu.addAction("Copy (x y) points");
    copyXY->setEnabled(!x.empty() && x.size() == y.size());

    QAction *chosen = menu.exec(event->globalPos());
    if (chosen == copyXY) {
        QString out;
        out.reserve(static_cast<int>(x.size() * 16)); // rough prealloc
        for (size_t i = 0; i < x.size() && i < y.size(); ++i) {
            out.append(QString::number(x[i], 'g', 10));
            out.append(' ');
            out.append(QString::number(y[i], 'g', 10));
            if (i + 1 < x.size()) out.append('\n');
        }
        QClipboard *cb = QApplication::clipboard();
        cb->setText(out);
    }
}

void JFJochSimpleChartView::mouseMoveEvent(QMouseEvent *event) {
    QChartView::mouseMoveEvent(event);
    if (!m_series || x.empty() || x.size() != y.size())
        return;

    // Map mouse position to chart coordinates
    const QPointF chartPos = chart()->mapToValue(event->pos(), m_series);
    const double xVal = chartPos.x();

    // Find closest index in x[]
    auto it = std::lower_bound(x.begin(), x.end(), static_cast<float>(xVal));
    if (it == x.end() && !x.empty())
        it = std::prev(x.end());
    if (it == x.end())
        return;

    size_t idx = static_cast<size_t>(std::distance(x.begin(), it));
    if (idx > 0) {
        const float xPrev = x[idx - 1];
        if (std::abs(xPrev - xVal) < std::abs(x[idx] - xVal))
            --idx;
    }

    const float xNearest = x[idx];
    const float yNearest = y[idx];

    // Map that data point to scene coords to get the x position
    const QPointF ptOnSeries = chart()->mapToPosition(QPointF(xNearest, yNearest), m_series);
    const QRectF plotArea = chart()->plotArea();

    if (!m_hoverLine) {
        m_hoverLine = new QGraphicsLineItem;
        m_hoverLine->setPen(QPen(QColor(200, 0, 0, 150), 1.0));
        chart()->scene()->addItem(m_hoverLine);
    }

    m_hoverLine->setLine(QLineF(ptOnSeries.x(), plotArea.top(),
                                ptOnSeries.x(), plotArea.bottom()));

    // Send to status bar
    emit writeStatusBar(getText(idx), 6000);
}

QString JFJochSimpleChartView::getText(size_t idx) {
    if (idx > x.size())
        return {};

    if (one_over_d)
        return QString("d = %1 Å, y = %2")
                .arg(1 / sqrt(x[idx]), 0, 'g', 4)
                .arg(y[idx], 0, 'g', 6);
    else
        return QString("x = %1, y = %2")
                .arg(x[idx], 0, 'g', 6)
                .arg(y[idx], 0, 'g', 6);
}

void JFJochSimpleChartView::leaveEvent(QEvent *event) {
    QChartView::leaveEvent(event);
    if (m_hoverLine) {
        chart()->scene()->removeItem(m_hoverLine);
        delete m_hoverLine;
        m_hoverLine = nullptr;
    }
    emit writeStatusBar(QString(), 6000); // clear status bar when leaving
}