#include "opentrack/options.hpp"
using namespace options;
#include "qfunctionconfigurator/qfunctionconfigurator.h"
#include <QPainter>
#include <QPaintEvent>
#include <QPen>
#include <QPixmap>
#include <cmath>
#include <algorithm>

static const int pointSize = 5;

QFunctionConfigurator::QFunctionConfigurator(QWidget *parent) :
    QWidget(parent),
    _config(nullptr),
    moving_control_point_idx(-1),
    _draw_function(true)
{
    update_range();
    setMouseTracking(true);
}

void QFunctionConfigurator::setConfig(Map* config, const QString& name) {
    mem<QSettings> iniFile = group::ini_file();
    if (name != "")
        config->loadSettings(*iniFile, name);
    _config = config;
    _draw_function = true;
    update_range();
    update();
}

void QFunctionConfigurator::drawBackground()
{
    if (!_config)
        return;
    _background = QPixmap(width(), height());

    QPainter painter(&_background);
    painter.fillRect(rect(), QColor::fromRgb(204, 204, 204));

    QColor bg_color(112, 154, 209);
    painter.fillRect(pixel_bounds, bg_color);

    QFont font;
    font.setPointSize(8);
    painter.setFont(font);
    QFontMetrics metrics(font);

    QPen pen(QColor(55, 104, 170, 127), 1, Qt::SolidLine);

    const int xstep = 10, ystep = 10;
    const double maxx = _config->maxInput();
    const double maxy = _config->maxOutput();

    // horizontal grid
    for (int i = 0; i < maxy; i += xstep)
    {
        double y = pixel_bounds.height() - i * c.y() + pixel_bounds.y();
        drawLine(&painter,
                 QPointF(pixel_bounds.x(), y),
                 QPointF(pixel_bounds.x() + pixel_bounds.width(), y),
                 pen);
        painter.drawText(QRectF(10,
                                y - metrics.height()/2,
                                pixel_bounds.left(),
                                metrics.height()),
                         QString::number(i));
    }

    {
        const double i = maxy;
        double y = pixel_bounds.height() - i * c.y() + pixel_bounds.y();
        drawLine(&painter,
                 QPointF(pixel_bounds.x(), y),
                 QPointF(pixel_bounds.x() + pixel_bounds.width(), y),
                 pen);
        painter.drawText(QRectF(10,
                                y - metrics.height()/2,
                                pixel_bounds.x() - 10,
                                metrics.height()),
                         QString::number(i));
    }

    // vertical grid
    for (int i = 0; i < maxx; i += ystep)
    {
        double x = pixel_bounds.x() + i * c.x();
        drawLine(&painter,
                 QPointF(x, pixel_bounds.y()),
                 QPointF(x, pixel_bounds.y() + pixel_bounds.height()),
                 pen);
        const QString text = QString::number(i);
        painter.drawText(QRectF(x - metrics.width(text)/2,
                                pixel_bounds.height() + 10 + metrics.height(),
                                metrics.width(text),
                                metrics.height()),
                         text);
    }
    {
        const double i = maxx;
        double x = pixel_bounds.x() + i * c.x();
        drawLine(&painter,
                 QPointF(x, pixel_bounds.y()),
                 QPointF(x, pixel_bounds.y() + pixel_bounds.height()),
                 pen);
        const QString text = QString::number(i);
        painter.drawText(QRectF(x - metrics.width(text)/2,
                                pixel_bounds.height() + 10 + metrics.height(),
                                metrics.width(text),
                                metrics.height()),
                         text);
    }
}

void QFunctionConfigurator::drawFunction()
{
    if (!_config)
        return;

    _function = QPixmap(_background);
    QPainter painter(&_function);
    painter.setRenderHint(QPainter::Antialiasing, true);

    QList<QPointF> points = _config->getPoints();

    for (int i = 0; i < points.size(); i++) {
        drawPoint(&painter,
                  point_to_pixel(points[i]),
                  QColor(200, 200, 210, 120));
    }

    QPen pen(spline_color, 1.2, Qt::SolidLine);

    const double max = _config->maxInput();
    const double step = std::max(1e-2, max / 1000.);

    QPointF prev = point_to_pixel(QPointF(0, 0));
    for (double i = 0; i < max; i += step) {
        double val = _config->getValue(i);
        QPointF cur = point_to_pixel(QPointF(i, val));
        drawLine(&painter, prev, cur, pen);
        prev = cur;
    }
}

void QFunctionConfigurator::paintEvent(QPaintEvent *e)
{
    QPainter p(this);

    if (_background.isNull())
        drawBackground();

    if (_draw_function) {
        _draw_function = false;
        drawFunction();
    }

    p.drawPixmap(e->rect(), _function);

    if (_config) {
        QPen pen(Qt::white, 1, Qt::SolidLine);
        QList<QPointF> points = _config->getPoints();
        if (points.size() && moving_control_point_idx >= 0 && moving_control_point_idx < points.size()) {
            if (points[0].x() > 1e-2)
                points.prepend(QPointF(0, 0));
            QPointF prev = point_to_pixel(points[0]);
            for (int i = 1; i < points.size(); i++) {
                auto tmp = point_to_pixel(points[i]);
                drawLine(&p, prev, tmp, pen);
                prev = tmp;
            }
        }

        // If the Tracker is active, the 'Last Point' it requested is recorded.
        // Show that point on the graph, with some lines to assist.
        // This new feature is very handy for tweaking the curves!
        QPointF last;
        if (_config->getLastPoint(last)) {
            QPointF pixel_pos = point_to_pixel(last);
            drawPoint(&p, pixel_pos, QColor(255, 0, 0, 120));
        }
    }
}

void QFunctionConfigurator::drawPoint(QPainter *painter, const QPointF &pos, QColor colBG )
{
    painter->save();
    painter->setPen(QColor(50, 100, 120, 200));
    painter->setBrush( colBG );
    painter->drawEllipse(QRectF(pos.x() - pointSize,
                                pos.y() - pointSize,
                                pointSize*2, pointSize*2));
    painter->restore();
}

void QFunctionConfigurator::drawLine(QPainter *painter, const QPointF &start, const QPointF &end, QPen &pen)
{
    painter->save();
    painter->setPen(pen);
    painter->setBrush(Qt::NoBrush);
    painter->drawLine(start, end);
    painter->restore();
}

void QFunctionConfigurator::mousePressEvent(QMouseEvent *e)
{
    if (!_config)
        return;
    QList<QPointF> points = _config->getPoints();
    if (e->button() == Qt::LeftButton) {
        bool bTouchingPoint = false;
        moving_control_point_idx = -1;
        if (_config) {
            for (int i = 0; i < points.size(); i++) {
                if (point_within_pixel(points[i], e->pos())) {
                    bTouchingPoint = true;
                    moving_control_point_idx = i;
                    break;
                }
            }
            if (!bTouchingPoint) {
                bool too_close = false;
                const auto pos = e->pos();

                for (int i = 0; i < points.size(); i++)
                {
                    const QPointF pt = point_to_pixel(points[i]);
                    const auto x = pt.x() - pos.x();
                    if (point_closeness_limit * point_closeness_limit >= x * x)
                    {
                        too_close = true;
                        break;
                    }
                }

                if (!too_close)
                    _config->addPoint(pixel_coord_to_point(e->pos()));
            }
        }
    }

    if (e->button() == Qt::RightButton) {
        if (_config) {
            int found_pt = -1;
            for (int i = 0; i < points.size(); i++) {
                if (point_within_pixel(points[i], e->pos())) {
                    found_pt = i;
                    break;
                }
            }

            if (found_pt != -1) {
                _config->removePoint(found_pt);
            }
            moving_control_point_idx = -1;
        }
    }
    _draw_function = true;
    update();
}

void QFunctionConfigurator::mouseMoveEvent(QMouseEvent *e)
{
    if (!_config)
        return;

    QList<QPointF> points = _config->getPoints();

    if (moving_control_point_idx != -1 && moving_control_point_idx < points.size()) {
        setCursor(Qt::ClosedHandCursor);

        bool overlap = false;

        QPoint pix = e->pos();
        QPointF new_pt = pixel_coord_to_point(pix);

        for (int i = 0; i < 2; i++)
        {
            bool bad = false;
            if (moving_control_point_idx + 1 < points.size())
            {
                auto other = points[moving_control_point_idx+1];
                auto other_pix = point_to_pixel(other);
                bad = pix.x() + point_closeness_limit > other_pix.x();
                if (i == 0 && bad)
                {
                    pix.setX(other_pix.x() - point_closeness_limit - 1);
                    new_pt = pixel_coord_to_point(pix);
                }
                else
                    overlap |= bad;
            }
            if (moving_control_point_idx != 0)
            {
                auto other = points[moving_control_point_idx-1];
                auto other_pix = point_to_pixel(other);
                bad = pix.x() - point_closeness_limit < other_pix.x();
                if (i == 0 && bad)
                {
                    pix.setX(other_pix.x() + point_closeness_limit + 1);
                    new_pt = pixel_coord_to_point(pix);
                }
                else
                    overlap |= bad;
            }
            if (!bad)
                break;
        }

        if (!overlap)
        {
            points[moving_control_point_idx] = new_pt;
            _config->movePoint(moving_control_point_idx, new_pt);
            _draw_function = true;
            update();
        }
    }
    else {
        bool is_on_point = false;
        for (int i = 0; i < points.size(); i++) {
            const QPoint pos = e->pos();
            if (point_within_pixel(points[i], pos)) {
                is_on_point = true;
                break;
            }
        }

        if (is_on_point) {
            setCursor(Qt::OpenHandCursor);
        }
        else {
            setCursor(Qt::ArrowCursor);
        }
    }
}

void QFunctionConfigurator::mouseReleaseEvent(QMouseEvent *e)
{
    if (!_config)
        return;

    if (e->button() == Qt::LeftButton) {
        mouseMoveEvent(e);
        setCursor(Qt::ArrowCursor);
        moving_control_point_idx = -1;

        _draw_function = true;
        update();
    }
}

void QFunctionConfigurator::update_range()
{
    if (!_config)
        return;

    const double w = width(), h = height();
    const double mwl = 40, mhl = 20;
    const double mwr = 15, mhr = 35;

    pixel_bounds = QRectF(mwl, mhl, (w - mwl - mwr), (h - mhl - mhr));
    c = QPointF(pixel_bounds.width() / _config->maxInput(), pixel_bounds.height() / _config->maxOutput());
    _draw_function = true;

    _background = QPixmap();
    _function = QPixmap();
    
    update();
}

bool QFunctionConfigurator::point_within_pixel(const QPointF &pt, const QPointF &pixel)
{
    QPointF pixel2 = point_to_pixel(pt);
    return pixel2.x() >= pixel.x() - pointSize && pixel2.x() < pixel.x() + pointSize &&
           pixel2.y() >= pixel.y() - pointSize && pixel2.y() < pixel.y() + pointSize;
}

QPointF QFunctionConfigurator::pixel_coord_to_point(const QPointF& point)
{
    if (!_config)
        return QPointF(-1, -1);

    double x = (point.x() - pixel_bounds.x()) / c.x();
    double y = (pixel_bounds.height() - point.y() + pixel_bounds.y()) / c.y();

    if (x < 0)
        x = 0;
    if (x > _config->maxInput())
        x = _config->maxInput();

    if (y < 0)
        y = 0;
    if (y > _config->maxOutput())
        y = _config->maxOutput();

    return QPointF(x, y);
}

QPointF QFunctionConfigurator::point_to_pixel(const QPointF& point)
{
    return QPointF(pixel_bounds.x() + point.x() * c.x(),
                   pixel_bounds.y() + pixel_bounds.height() - point.y() * c.y());
}

void QFunctionConfigurator::resizeEvent(QResizeEvent *)
{
    update_range();
}