#include "nmVTKPlanarPolygonInteractorStyle.h"

#include <QtGlobal>

#include <vtkMath.h>
#include <vtkObjectFactory.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

#include <cmath>
#include <cstring>
#include <limits>

vtkStandardNewMacro(nmVTKPlanarPolygonInteractorStyle);

namespace {

const double PLANAR_POLYGON_RAY_EPSILON = 1.0e-12;

bool isFinitePoint(const QPointF& oPoint)
{
    return vtkMath::IsFinite(oPoint.x()) &&
            vtkMath::IsFinite(oPoint.y());
}

bool displayToWorld(vtkRenderer* pRenderer,
                    double dX,
                    double dY,
                    double dZ,
                    double dWorld[3])
{
    if(pRenderer == nullptr || dWorld == nullptr ||
       !vtkMath::IsFinite(dX) || !vtkMath::IsFinite(dY) ||
       !vtkMath::IsFinite(dZ)) {
        return false;
    }

    // VTK 返回齐次世界坐标，必须先除以 w 才能参与射线计算。
    pRenderer->SetDisplayPoint(dX, dY, dZ);
    pRenderer->DisplayToWorld();
    const double* pHomogeneous = pRenderer->GetWorldPoint();
    if(pHomogeneous == nullptr ||
       !vtkMath::IsFinite(pHomogeneous[0]) ||
       !vtkMath::IsFinite(pHomogeneous[1]) ||
       !vtkMath::IsFinite(pHomogeneous[2]) ||
       !vtkMath::IsFinite(pHomogeneous[3]) ||
       std::fabs(pHomogeneous[3]) <=
           std::numeric_limits<double>::epsilon()) {
        return false;
    }

    const double dInverseW = 1.0 / pHomogeneous[3];
    dWorld[0] = pHomogeneous[0] * dInverseW;
    dWorld[1] = pHomogeneous[1] * dInverseW;
    dWorld[2] = pHomogeneous[2] * dInverseW;
    return vtkMath::IsFinite(dWorld[0]) &&
            vtkMath::IsFinite(dWorld[1]) &&
            vtkMath::IsFinite(dWorld[2]);
}

double coordinateScale(const QPointF& oLeft, const QPointF& oRight)
{
    double dScale = 1.0;
    dScale = qMax(dScale, std::fabs(oLeft.x()));
    dScale = qMax(dScale, std::fabs(oLeft.y()));
    dScale = qMax(dScale, std::fabs(oRight.x()));
    dScale = qMax(dScale, std::fabs(oRight.y()));
    return dScale;
}

bool isSamePoint(const QPointF& oLeft, const QPointF& oRight)
{
    const double dScale = coordinateScale(oLeft, oRight);
    const double dTolerance = 1.0e-10 * dScale;
    const double dX = oLeft.x() - oRight.x();
    const double dY = oLeft.y() - oRight.y();
    return dX * dX + dY * dY <= dTolerance * dTolerance;
}

bool hasNonZeroArea(const QVector<QPointF>& vecPoints)
{
    if(vecPoints.size() < 3) {
        return false;
    }

    // 以首点为局部原点计算面积，避免大坐标下的精度损失。
    const QPointF oOrigin = vecPoints.first();
    double dMinimumX = oOrigin.x();
    double dMaximumX = oOrigin.x();
    double dMinimumY = oOrigin.y();
    double dMaximumY = oOrigin.y();
    double dTwiceArea = 0.0;
    for(int nIndex = 0; nIndex < vecPoints.size(); ++nIndex) {
        const QPointF& oCurrent = vecPoints[nIndex];
        const QPointF& oNext =
                vecPoints[(nIndex + 1) % vecPoints.size()];
        const double dCurrentX = oCurrent.x() - oOrigin.x();
        const double dCurrentY = oCurrent.y() - oOrigin.y();
        const double dNextX = oNext.x() - oOrigin.x();
        const double dNextY = oNext.y() - oOrigin.y();
        dTwiceArea += dCurrentX * dNextY - dNextX * dCurrentY;
        dMinimumX = qMin(dMinimumX, oCurrent.x());
        dMaximumX = qMax(dMaximumX, oCurrent.x());
        dMinimumY = qMin(dMinimumY, oCurrent.y());
        dMaximumY = qMax(dMaximumY, oCurrent.y());
    }
    const double dScale = qMax(1.0,
            qMax(dMaximumX - dMinimumX, dMaximumY - dMinimumY));
    return vtkMath::IsFinite(dTwiceArea) &&
            std::fabs(dTwiceArea) > 1.0e-12 * dScale * dScale;
}

}

nmVTKPlanarPolygonInteractorStyle::
nmVTKPlanarPolygonInteractorStyle()
    : m_bCompleted(false)
{
}

nmVTKPlanarPolygonInteractorStyle::
~nmVTKPlanarPolygonInteractorStyle()
{
}

void nmVTKPlanarPolygonInteractorStyle::OnLeftButtonDown()
{
    if(m_bCompleted || this->Interactor == nullptr) {
        return;
    }

    // 单击追加顶点，VTK 将双击的第二次按下标记为 RepeatCount > 0。
    if(this->Interactor->GetRepeatCount() > 0) {
        completePolygon();
        return;
    }
    appendCurrentPoint();
}

void nmVTKPlanarPolygonInteractorStyle::OnRightButtonDown()
{
    // 绘制模式下右键专用于取消，不传递给默认相机或右键菜单。
    if(!m_bCompleted) {
        cancelPolygon();
    }
}

void nmVTKPlanarPolygonInteractorStyle::OnKeyPress()
{
    if(m_bCompleted || this->Interactor == nullptr) {
        return;
    }

    const char* pKeySym = this->Interactor->GetKeySym();
    if(pKeySym == nullptr) {
        return;
    }
    // Enter 完成、Backspace/Delete 撤回末点、Escape 取消，均由业务状态机收口。
    if(std::strcmp(pKeySym, "Return") == 0 ||
       std::strcmp(pKeySym, "KP_Enter") == 0) {
        completePolygon();
    } else if(std::strcmp(pKeySym, "BackSpace") == 0 ||
              std::strcmp(pKeySym, "Delete") == 0) {
        removeLastPoint();
    } else if(std::strcmp(pKeySym, "Escape") == 0) {
        cancelPolygon();
    }
}

void nmVTKPlanarPolygonInteractorStyle::OnChar()
{
    // 字符命令在绘制模式没有业务含义，不能触发基类的退出或相机复位。
}

void nmVTKPlanarPolygonInteractorStyle::reset()
{
    m_vecPoints.clear();
    m_bCompleted = false;
}

QVector<QPointF>
nmVTKPlanarPolygonInteractorStyle::getPoints() const
{
    return m_vecPoints;
}

int nmVTKPlanarPolygonInteractorStyle::getPointCount() const
{
    return m_vecPoints.size();
}

bool nmVTKPlanarPolygonInteractorStyle::isCompleted() const
{
    return m_bCompleted;
}

bool nmVTKPlanarPolygonInteractorStyle::projectEventPositionToPlane(
        QPointF& oPoint)
{
    if(this->Interactor == nullptr) {
        return false;
    }
    int* pEventPosition = this->Interactor->GetEventPosition();
    if(pEventPosition == nullptr) {
        return false;
    }

    this->FindPokedRenderer(pEventPosition[0], pEventPosition[1]);
    vtkRenderer* pRenderer = this->CurrentRenderer;
    if(pRenderer == nullptr) {
        return false;
    }

    // 将同一屏幕点的近、远裁剪面坐标连成射线，再与 z=0 网格平面求交。
    double dNearPoint[3];
    double dFarPoint[3];
    if(!displayToWorld(pRenderer,
                       pEventPosition[0], pEventPosition[1], 0.0,
                       dNearPoint) ||
       !displayToWorld(pRenderer,
                       pEventPosition[0], pEventPosition[1], 1.0,
                       dFarPoint)) {
        return false;
    }

    const double dDirectionZ = dFarPoint[2] - dNearPoint[2];
    const double dRayScale = qMax(1.0,
            qMax(std::fabs(dNearPoint[2]), std::fabs(dFarPoint[2])));
    if(std::fabs(dDirectionZ) <=
       PLANAR_POLYGON_RAY_EPSILON * dRayScale) {
        return false;
    }

    const double dParameter = -dNearPoint[2] / dDirectionZ;
    const QPointF oCandidate(
                dNearPoint[0] +
                    dParameter * (dFarPoint[0] - dNearPoint[0]),
                dNearPoint[1] +
                    dParameter * (dFarPoint[1] - dNearPoint[1]));
    if(!isFinitePoint(oCandidate)) {
        return false;
    }
    oPoint = oCandidate;
    return true;
}

bool nmVTKPlanarPolygonInteractorStyle::appendCurrentPoint()
{
    QPointF oPoint;
    if(!projectEventPositionToPlane(oPoint) ||
       (!m_vecPoints.isEmpty() &&
        isSamePoint(m_vecPoints.last(), oPoint))) {
        return false;
    }

    // 连续重合点不入队，否则会生成零长边并干扰后续三角化。
    m_vecPoints.append(oPoint);
    this->InvokeEvent(PolygonChangedEvent);
    renderInteractor();
    return true;
}

bool nmVTKPlanarPolygonInteractorStyle::completePolygon()
{
    if(m_bCompleted) {
        return true;
    }
    if(!hasNonZeroArea(m_vecPoints)) {
        this->InvokeEvent(PolygonInvalidEvent);
        return false;
    }

    // 先发变更事件绘制闭合边，再通知业务层离开 VTK 交互栈。
    m_bCompleted = true;
    this->InvokeEvent(PolygonChangedEvent);
    renderInteractor();
    this->InvokeEvent(PolygonCompletedEvent);
    return true;
}

void nmVTKPlanarPolygonInteractorStyle::removeLastPoint()
{
    if(m_vecPoints.isEmpty()) {
        return;
    }
    m_vecPoints.remove(m_vecPoints.size() - 1);
    this->InvokeEvent(PolygonChangedEvent);
    renderInteractor();
}

void nmVTKPlanarPolygonInteractorStyle::cancelPolygon()
{
    this->InvokeEvent(PolygonCancelledEvent);
}

void nmVTKPlanarPolygonInteractorStyle::renderInteractor()
{
    if(this->Interactor != nullptr) {
        this->Interactor->Render();
    }
}