#include "panels/chart/LivePanner.hpp"

#include <QEvent>
#include <QMouseEvent>
#include <QWheelEvent>
#include <qwt_plot.h>
#include <qwt_scale_div.h>

namespace geopro::app {

LivePanner::LivePanner(QwtPlot* plot, int xAxis, int yAxis, QObject* parent)
    : QObject(parent), plot_(plot), xAxis_(xAxis), yAxis_(yAxis) {
    if (plot_ && plot_->canvas()) plot_->canvas()->installEventFilter(this);
}

bool LivePanner::eventFilter(QObject* obj, QEvent* ev) {
    if (!plot_ || obj != plot_->canvas()) return QObject::eventFilter(obj, ev);

    switch (ev->type()) {
    case QEvent::MouseButtonPress: {
        auto* me = static_cast<QMouseEvent*>(ev);
        if (me->button() == Qt::LeftButton) {
            panning_ = true;
            startPos_ = me->pos();
            x0Min_ = plot_->axisScaleDiv(xAxis_).lowerBound();
            x0Max_ = plot_->axisScaleDiv(xAxis_).upperBound();
            y0Min_ = plot_->axisScaleDiv(yAxis_).lowerBound();
            y0Max_ = plot_->axisScaleDiv(yAxis_).upperBound();
            return true;
        }
        break;
    }
    case QEvent::MouseMove: {
        if (!panning_) break;
        auto* me = static_cast<QMouseEvent*>(ev);
        const int W = plot_->canvas()->width();
        const int H = plot_->canvas()->height();
        if (W <= 0 || H <= 0) break;
        const double dxData = (me->pos().x() - startPos_.x()) * (x0Max_ - x0Min_) / W;
        const double dyData = (me->pos().y() - startPos_.y()) * (y0Max_ - y0Min_) / H;
        // 拖右(dx>0)→窗口左移(xmin/xmax 减)，内容随光标右移；
        // 拖下(像素 dy>0)→yLeft 数据向上→窗口上移(ymin/ymax 增)，内容随光标下移。
        plot_->setAxisScale(xAxis_, x0Min_ - dxData, x0Max_ - dxData);
        plot_->setAxisScale(yAxis_, y0Min_ + dyData, y0Max_ + dyData);
        plot_->replot();
        return true;
    }
    case QEvent::MouseButtonRelease: {
        auto* me = static_cast<QMouseEvent*>(ev);
        if (me->button() == Qt::LeftButton) {
            panning_ = false;
            return true;
        }
        break;
    }
    case QEvent::Wheel: {
        // 滚轮缩放（以光标为中心，上滚=放大），并 **消费事件**（return true）避免冒泡到外层
        // 滚动区域触发滚动条。两轴同因子缩放→保持锁定的真实比尺。
        auto* we = static_cast<QWheelEvent*>(ev);
        const int d = we->angleDelta().y();
        if (d == 0) return true;
        const double f = (d > 0) ? (1.0 / 1.15) : 1.15;  // 上滚→区间缩小→放大
        const QPointF pos = we->position();
        const double cx = plot_->invTransform(xAxis_, pos.x());
        const double cy = plot_->invTransform(yAxis_, pos.y());
        const double xMin = plot_->axisScaleDiv(xAxis_).lowerBound();
        const double xMax = plot_->axisScaleDiv(xAxis_).upperBound();
        const double yMin = plot_->axisScaleDiv(yAxis_).lowerBound();
        const double yMax = plot_->axisScaleDiv(yAxis_).upperBound();
        plot_->setAxisScale(xAxis_, cx - (cx - xMin) * f, cx + (xMax - cx) * f);
        plot_->setAxisScale(yAxis_, cy - (cy - yMin) * f, cy + (yMax - cy) * f);
        plot_->replot();
        we->accept();
        return true;
    }
    default:
        break;
    }
    return QObject::eventFilter(obj, ev);
}

}  // namespace geopro::app