#include "rangeslider.h"
#include <QPainter>
#include <QMouseEvent>
#include <QDebug>
#include <cmath>

RangeSlider::RangeSlider(int style_,QWidget *parent)
    : QWidget(parent) {
    setMinimumSize(20, 240);
    style = style_;
}

void RangeSlider::setRange(int min, int max) {
    m_min = min;
    m_max = max;
    m_lower = qBound(m_min, m_lower, m_max);
    m_upper = qBound(m_lower, m_upper, m_max);
    update();
}

void RangeSlider::setSliderWidth(int width) {
    sliderWidth = width;
    update();  // 更新界面
}

float RangeSlider::lowerValue() const { return m_lower; }
float RangeSlider::upperValue() const { return m_upper; }

float RangeSlider::valueToY(float value) const {
    double ratio = (value - m_min) / double(m_max - m_min);
    return height() - handleRadius - ratio * (height() - 2 * handleRadius);
}

float RangeSlider::yToValue(float y) const {
   double ratio = (height() - handleRadius - y) / double(height() - 2 * handleRadius);
   ratio = qBound(0.0, ratio, 1.0);
   float rawValue = m_min + ratio * (m_max - m_min);
   float steppedValue = qRound(rawValue * 10) / 10.0f;
   return qBound(m_min, steppedValue, m_max);
}

RangeSlider::HandleType RangeSlider::handleHitTest(float y) const {
    int yLower = valueToY(m_lower);
    int yUpper = valueToY(m_upper);
    if (qAbs(y - yLower) <= handleRadius + 2) return LowerHandle;
    if (qAbs(y - yUpper) <= handleRadius + 2) return UpperHandle;
    return NoHandle;
}

void RangeSlider::mousePressEvent(QMouseEvent *event) {
    currentHandle = handleHitTest(event->pos().y());
}

void RangeSlider::mouseMoveEvent(QMouseEvent *event) {
    if (currentHandle == NoHandle) return;

    float val = yToValue(event->pos().y());
    if (currentHandle == LowerHandle) {
        m_lower = qBound(m_min, val, m_upper);
    } else if (currentHandle == UpperHandle) {
        m_upper = qBound(m_lower, val, m_max);
    }
    update();
    emit rangeChanged(m_lower, m_upper);
}

void RangeSlider::mouseReleaseEvent(QMouseEvent *) {
    currentHandle = NoHandle;
}

void RangeSlider::paintEvent(QPaintEvent *) {
    QPainter p(this);
    p.setRenderHint(QPainter::Antialiasing);

    int x = width() / 2;
    int yLower = valueToY(m_lower);
    int yUpper = valueToY(m_upper);

    // Draw Temperature-style background (gradient)
    drawTemperatureStyle(&p);

    // Draw selected range (green)
    // Draw selected range (green)
    p.setPen(Qt::NoPen);
    p.setBrush(Qt::green);
    p.drawRect(x - sliderWidth / 2, yUpper, sliderWidth, yLower - yUpper);

    // Draw simple black handles (lines)
    p.setPen(QPen(Qt::black, 2));
    p.drawLine(x - sliderWidth / 2, yLower, x + sliderWidth, yLower);
    p.drawLine(x - sliderWidth / 2, yUpper, x + sliderWidth, yUpper);

    // Draw ticks
    drawTicks(&p);
}
void RangeSlider::setLowerValue(float val) {
    m_lower = qBound(m_min, val, m_upper);
    update();
    emit rangeChanged(m_lower, m_upper);
}

void RangeSlider::setUpperValue(float val) {
    m_upper = qBound(m_lower, val, m_max);
    update();
    emit rangeChanged(m_lower, m_upper);
}
void RangeSlider::drawTemperatureStyle(QPainter *p) {
    int x = width() / 2;
    int yTop = handleRadius;
    int yBottom = height() - handleRadius;

    // Draw border (black)
    p->setPen(Qt::black);
    p->setBrush(Qt::NoBrush);
    p->drawRect(x - sliderWidth / 2, yTop, sliderWidth, yBottom - yTop);

    // Draw yellow outside the range
    if(style != 0){
        p->setBrush(Qt::red);
        p->drawRect(x - sliderWidth / 2, yTop, sliderWidth, valueToY(m_lower) - yTop);  // Above lower range
        p->drawRect(x - sliderWidth / 2, valueToY(m_upper), sliderWidth, yBottom - valueToY(m_upper));  // Below upper range
    }else{
        p->setBrush(Qt::yellow);
        p->drawRect(x - sliderWidth / 2, yTop, sliderWidth, valueToY(m_lower) - yTop);  // Above lower range
        p->drawRect(x - sliderWidth / 2, valueToY(m_upper), sliderWidth, yBottom - valueToY(m_upper));  // Below upper range
    }

    // Draw green inside the range
    p->setBrush(Qt::green);
    p->drawRect(x - sliderWidth / 2, valueToY(m_upper), sliderWidth, valueToY(m_lower) - valueToY(m_upper));  // Green area
}
int RangeSlider::niceStep(int range, int maxLabels) {
    double rawStep = static_cast<double>(range) / maxLabels;

    // 取一个"好看"的步长
    double magnitude = pow(10, floor(log10(rawStep)));     // 10 的整数次幂
    double residual = rawStep / magnitude;

    double niceResidual;
    if (residual < 1.5)
        niceResidual = 1;
    else if (residual < 3)
        niceResidual = 2;
    else if (residual < 7)
        niceResidual = 5;
    else
        niceResidual = 10;

    return static_cast<int>(niceResidual * magnitude);
}
void RangeSlider::drawTicks(QPainter *p) {
    int range = m_max - m_min;
    int labelStep = niceStep(range, 10);
    int minorStep = qMax(1, labelStep / 5);

    int x = width() / 2 + handleRadius + 4;
    p->setFont(QFont("Arial", 8));

    for (int val = m_min; val <= m_max; val += minorStep) {
        int y = valueToY(val);

        if (val % labelStep == 0) {
            p->setPen(QPen(Qt::black, 1.5));  // 主刻度
            p->drawLine(x, y, x + 6, y);
            p->drawText(x + 10, y + 4, QString::number(val));
        } else {
            p->setPen(QPen(Qt::gray, 1));     // 次刻度
            p->drawLine(x, y, x + 3, y);
        }
    }
}