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#include "qssgrendercamera_p.h"

#include <QtQuick3DRuntimeRender/private/qssgrendererutil_p.h>

#include <QtQuick3DUtils/private/qssgutils_p.h>

#include <QtGui/QVector2D>

#include <qmath.h>

QT_BEGIN_NAMESPACE

namespace {

float getAspectRatio(const QRectF &inViewport)
{
    return inViewport.height() != 0 ? inViewport.width() / inViewport.height() : 0.0f;
}

}

QSSGRenderCamera::QSSGRenderCamera(QSSGRenderGraphObject::Type type)
    : QSSGRenderNode(type)
    , clipNear(10)
    , clipFar(10000)
    , fov(qDegreesToRadians(60.0f))
    , fovHorizontal(false)
    , enableFrustumClipping(true)
{
    Q_ASSERT(QSSGRenderCamera::isCamera(type));
    flags.setFlag(Flag::CameraDirty, true);
}

// Code for testing
QSSGCameraGlobalCalculationResult QSSGRenderCamera::calculateGlobalVariables(const QRectF &inViewport)
{
    bool wasDirty = QSSGRenderNode::calculateGlobalVariables();
    return QSSGCameraGlobalCalculationResult{ wasDirty, calculateProjection(inViewport) };
}

bool QSSGRenderCamera::calculateProjection(const QRectF &inViewport)
{
    bool retval = false;

    const bool argumentsChanged = inViewport != previousInViewport;
    if (!argumentsChanged && !flags.testFlag(Flag::CameraDirty))
        return true;
    previousInViewport = inViewport;
    flags.setFlag(Flag::CameraDirty, false);

    switch (type) {
    case QSSGRenderGraphObject::Type::OrthographicCamera:
        retval = computeFrustumOrtho(inViewport);
        break;
    case QSSGRenderGraphObject::Type::PerspectiveCamera:
        retval = computeFrustumPerspective(inViewport);
        break;
    case QSSGRenderGraphObject::Type::CustomCamera:
        retval = true; // Do nothing
        break;
    case QSSGRenderGraphObject::Type::CustomFrustumCamera:
        retval = computeCustomFrustum(inViewport);
        break;
    default:
        Q_UNREACHABLE();
    }

    if (retval) {
        float *writePtr(projection.data());
        frustumScale.setX(writePtr[0]);
        frustumScale.setY(writePtr[5]);
    }
    return retval;
}

//==============================================================================
/**
 *	Compute the projection matrix for a perspective camera
 *	@return true if the computed projection matrix is valid
 */
bool QSSGRenderCamera::computeFrustumPerspective(const QRectF &inViewport)
{
    projection = QMatrix4x4();
    projection.perspective(qRadiansToDegrees(verticalFov(inViewport)), getAspectRatio(inViewport), clipNear, clipFar);
    return true;
}

bool QSSGRenderCamera::computeCustomFrustum(const QRectF &inViewport)
{
    Q_UNUSED(inViewport);
    projection.setToIdentity();
    projection.frustum(left, right, bottom, top, clipNear, clipFar);
    return true;
}

//==============================================================================
/**
 *	Compute the projection matrix for a orthographic camera
 *	@return true if the computed projection matrix is valid
 */
bool QSSGRenderCamera::computeFrustumOrtho(const QRectF &inViewport)
{
    projection = QMatrix4x4();
    float halfWidth = inViewport.width() / 2.0f / horizontalMagnification / dpr;
    float halfHeight = inViewport.height() / 2.0f / verticalMagnification / dpr;
    projection.ortho(-halfWidth, halfWidth, -halfHeight, halfHeight, clipNear, clipFar);
    return true;
}

float QSSGRenderCamera::getOrthographicScaleFactor(const QRectF &inViewport) const
{
    Q_UNUSED(inViewport);
    return qMax(horizontalMagnification, verticalMagnification);
}

static QQuaternion rotationQuaternionForLookAt(const QVector3D &sourcePosition,
                                               const QVector3D &sourceDirection,
                                               const QVector3D &targetPosition,
                                               const QVector3D &upDirection)
{
    QVector3D targetDirection = sourcePosition - targetPosition;
    targetDirection.normalize();

    QVector3D rotationAxis = QVector3D::crossProduct(sourceDirection, targetDirection);

    const QVector3D normalizedAxis = rotationAxis.normalized();
    if (qFuzzyIsNull(normalizedAxis.lengthSquared()))
        rotationAxis = upDirection;

    float dot = QVector3D::dotProduct(sourceDirection, targetDirection);
    float rotationAngle = float(qRadiansToDegrees(qAcos(qreal(dot))));

    return QQuaternion::fromAxisAndAngle(rotationAxis, rotationAngle);
}

void QSSGRenderCamera::lookAt(const QVector3D &inCameraPos, const QVector3D &inUpDir, const QVector3D &inTargetPos)
{
    rotation = rotationQuaternionForLookAt(inCameraPos, getScalingCorrectDirection(), inTargetPos, inUpDir.normalized());
    position = inCameraPos;
    markDirty(TransformDirtyFlag::TransformIsDirty);
}

void QSSGRenderCamera::calculateViewProjectionMatrix(QMatrix4x4 &outMatrix) const
{
    outMatrix = projection * globalTransform.inverted();
}

QSSGRenderRay QSSGRenderCamera::unproject(const QVector2D &inViewportRelativeCoords,
                                              const QRectF &inViewport) const
{
    QSSGRenderRay theRay;
    QVector2D globalCoords = toAbsoluteCoords(inViewport, inViewportRelativeCoords);
    QVector2D normalizedCoords = absoluteToNormalizedCoordinates(inViewport, globalCoords);
    QVector3D &outOrigin(theRay.origin);
    QVector3D &outDir(theRay.direction);
    QVector2D inverseFrustumScale(1.0f / frustumScale.x(), 1.0f / frustumScale.y());
    QVector2D scaledCoords(inverseFrustumScale.x() * normalizedCoords.x(), inverseFrustumScale.y() * normalizedCoords.y());

    if (type == QSSGRenderCamera::Type::OrthographicCamera) {
        outOrigin.setX(scaledCoords.x());
        outOrigin.setY(scaledCoords.y());
        outOrigin.setZ(0.0f);

        outDir.setX(0.0f);
        outDir.setY(0.0f);
        outDir.setZ(-1.0f);
    } else {
        outOrigin.setX(0.0f);
        outOrigin.setY(0.0f);
        outOrigin.setZ(0.0f);

        outDir.setX(scaledCoords.x());
        outDir.setY(scaledCoords.y());
        outDir.setZ(-1.0f);
    }

    outOrigin = mat44::transform(globalTransform, outOrigin);
    QMatrix3x3 theNormalMatrix = calculateNormalMatrix();

    outDir = mat33::transform(theNormalMatrix, outDir);
    outDir.normalize();

    return theRay;
}

QVector3D QSSGRenderCamera::unprojectToPosition(const QVector3D &inGlobalPos, const QSSGRenderRay &inRay) const
{
    QVector3D theCameraDir = getDirection();
    QVector3D theObjGlobalPos = inGlobalPos;
    float theDistance = -1.0f * QVector3D::dotProduct(theObjGlobalPos, theCameraDir);
    QSSGPlane theCameraPlane(theCameraDir, theDistance);
    return QSSGRenderRay::intersect(theCameraPlane, inRay);
}

float QSSGRenderCamera::verticalFov(float aspectRatio) const
{
    return fovHorizontal ? float(2.0 * qAtan(qTan(qreal(fov) / 2.0) / qreal(aspectRatio))) : fov;
}

float QSSGRenderCamera::verticalFov(const QRectF &inViewport) const
{
    return verticalFov(getAspectRatio(inViewport));
}

QT_END_NAMESPACE
