#include "..\Header\OglViewerWidget.h"
#include "..\Header\OutputDevice.h"
#include "..\Header\MainWindow.h"
#include <QMouseEvent>
#include <QDropEvent>
#include <QMimeData>

#define DEFAULT_Z_DISTANCE -4.0


/////////////////////////////////////////////////////////////////////////
// constructor/destructor

OglViewerWidget::OglViewerWidget(QWidget *parent)
	: QOpenGLWidget(parent)
	, m_dataEngine(0)
{
	setFocus();
	setAcceptDrops(true);

	// settings window
	m_settings = new SettingsWindow(m_backgroundColorOff.toVector3D() * 255, m_backgroundColorOn.toVector3D() * 255, m_light.intensities * 255, true, m_light.ambientCoefficient, m_light.attenuationFactor, 1, this);

	connect(m_settings, &SettingsWindow::updateBGColorOff, this, &OglViewerWidget::setBGColorOff);
	connect(m_settings, &SettingsWindow::updateBGColorOn, this, &OglViewerWidget::setBGColorOn);
	connect(m_settings, &SettingsWindow::updateLightColor, this, &OglViewerWidget::setLightColor);
	connect(m_settings, &SettingsWindow::updateAttFac, this, &OglViewerWidget::setAttFac);
	connect(m_settings, &SettingsWindow::updateAmbCoef, this, &OglViewerWidget::setAmbCoef);
}

OglViewerWidget::~OglViewerWidget()
{
	// Make sure the context is current when deleting the texture
	// and the buffers.
	makeCurrent();
	delete m_dataEngine;
	doneCurrent();

	delete m_settings;
}


/////////////////////////////////////////////////////////////////////////
// functions

void OglViewerWidget::initShaders()
{
	// Compile vertex shader
	if (!m_program.addShaderFromSourceFile(QOpenGLShader::Vertex, ":/shaders/vshader.glsl"))
		close();

	// Compile fragment shader
	if (!m_program.addShaderFromSourceFile(QOpenGLShader::Fragment, ":/shaders/fshader.glsl"))
		close();

	// Link shader pipeline
	if (!m_program.link())
		close();

	// Bind shader pipeline for use
	if (!m_program.bind())
		close();
}

void OglViewerWidget::resetView()
{
	m_rotation = QQuaternion();
	m_translation = { 0.0, 0.0, DEFAULT_Z_DISTANCE };
	m_zSpeed = 1;
	update();
}

void OglViewerWidget::updateLightPosition()
{
	QMatrix4x4 rotateBack;
	rotateBack.rotate(m_rotation.inverted());
	QVector3D cameraPosition = rotateBack * (-m_translation);

	m_light.position.setX(cameraPosition.x());
	m_light.position.setY(cameraPosition.y());
	m_light.position.setZ(cameraPosition.z());
}

// OpenGL ///////////////////////////////////////////////////////////////

void OglViewerWidget::initializeGL()
{
	initializeOpenGLFunctions();
	initShaders();

	// Enable depth buffer
	glEnable(GL_DEPTH_TEST);

	//TODO: make this optional
	// Enable back face culling
	//glEnable(GL_CULL_FACE);

	// Enable transparency
	glEnable(GL_BLEND);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

	m_dataEngine = new GeometryEngine(this);
	connect(m_dataEngine, &GeometryEngine::requestResetView, this, &OglViewerWidget::resetView);
	connect(m_dataEngine, &GeometryEngine::requestUpdate, this, static_cast<void(OglViewerWidget::*)(void)>(&OglViewerWidget::update));

	//TODO: better solution
	MainWindow* parent = dynamic_cast<MainWindow*>(parentWidget());
	if (parent != NULL)
		connect(parent, &MainWindow::loadFile, [this](QString value) {m_dataEngine->loadFile(value); });

}

void OglViewerWidget::resizeGL(int w, int h)
{
	// Calculate aspect ratio
	qreal aspect = qreal(w) / qreal(h ? h : 1);

	// Set near plane to 3.0, far plane to 7.0, field of view 45 degrees
	const qreal zNear = 0.1, zFar = 100.0, fov = 45.0;

	// Reset projection
	m_projection.setToIdentity();

	// Set perspective projection
	m_projection.perspective(fov, aspect, zNear, zFar);
}

void OglViewerWidget::paintGL()
{
	// set background color, last value is dirtybit
	if (m_lightOn && m_backgroundColorOn[3] == 1.0)
	{
		glClearColor(m_backgroundColorOn[0], m_backgroundColorOn[1], m_backgroundColorOn[2], 0.0000f);
		m_backgroundColorOn[3] = 0.0;
	}
	else if (!m_lightOn && m_backgroundColorOff[3] == 1.0)
	{
		glClearColor(m_backgroundColorOff[0], m_backgroundColorOff[1], m_backgroundColorOff[2], 0.0000f);
		m_backgroundColorOff[3] = 0.0;
	}

	// Clear color and depth buffer
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	// Calculate view transformation
	QMatrix4x4 view;
	view.translate(m_translation);
	view.rotate(m_rotation);

	// Set view-projection matrix
	m_program.setUniformValue("vp_matrix", m_projection * view);

	// Set Light values
	m_program.setUniformValue("b_light", m_lightOn);
	m_program.setUniformValue("light.position", m_light.position);
	m_program.setUniformValue("light.intensities", m_light.intensities);
	m_program.setUniformValue("light.attenuationFactor", m_light.attenuationFactor);
	m_program.setUniformValue("light.ambientCoefficient", m_light.ambientCoefficient);

	// Set camera position
	QMatrix4x4 rotateBack;
	rotateBack.rotate(m_rotation.inverted());
	m_program.setUniformValue("cameraPosition", rotateBack * (-m_translation));

	// Draw cube geometry
	m_dataEngine->drawGeometry(&m_program, m_wireframe);
}

// Inputs ///////////////////////////////////////////////////////////////

void OglViewerWidget::mousePressEvent(QMouseEvent *e)
{
	// Save mouse press position
	m_mouse.position = QVector2D(e->localPos());

	// Which button has been pressed?
	if (e->button() == Qt::LeftButton)
		m_mouse.left = true;
	else if (e->button() == Qt::RightButton)
		m_mouse.right = true;
}

void OglViewerWidget::mouseReleaseEvent(QMouseEvent *e)
{
	if (e->button() == Qt::LeftButton)
		m_mouse.left = false;
	else if (e->button() == Qt::RightButton)
		m_mouse.right = false;
}

void OglViewerWidget::mouseMoveEvent(QMouseEvent *e)
{
	if (m_mouse.left)
	{
		// get the difference between last press and now
		QVector2D diff = QVector2D(e->localPos()) - m_mouse.position;

		// update the new position
		m_mouse.position = QVector2D(e->localPos());

		// calculate the rotations depending on the active axis
		// XYZ
		if (m_rotDirections.x && m_rotDirections.y && m_rotDirections.z)
		{
			m_rotation = QQuaternion::fromAxisAndAngle(QVector3D(diff.y(), diff.x(), 0.0).normalized(), diff.length() * 0.5) * m_rotation;
		}
		// XY
		else if (m_rotDirections.x && m_rotDirections.y && !m_rotDirections.z)
		{

			float pitch, yaw, roll;
			m_rotation.getEulerAngles(&pitch, &yaw, &roll);

			pitch += diff.y() * 0.5;
			yaw += diff.x() * 0.5;

			if (pitch > 89)
				pitch = 89;
			else if (pitch < -89)
				pitch = -89;

			m_rotation = QQuaternion::fromEulerAngles(pitch, yaw, roll);

		}
		// X
		else if (m_rotDirections.x && !m_rotDirections.y && !m_rotDirections.z)
		{
			m_rotation = QQuaternion::fromAxisAndAngle(QVector3D(0.0, 1.0, 0.0).normalized(), diff.x() * 0.5) * m_rotation;
		}
		// Y
		else if (!m_rotDirections.x && m_rotDirections.y && !m_rotDirections.z)
		{
			m_rotation = QQuaternion::fromAxisAndAngle(QVector3D(1.0, 0.0, 0.0).normalized(), diff.y() * 0.5) * m_rotation;
		}
		// Z
		else if (!m_rotDirections.x && !m_rotDirections.y && m_rotDirections.z)
		{
			m_rotation = QQuaternion::fromAxisAndAngle(QVector3D(0.0, 0.0, 1.0).normalized(), diff.x() * 0.5) * m_rotation;
		}
		// XZ
		else if (m_rotDirections.x && !m_rotDirections.y && m_rotDirections.z)
		{
			float pitch, yaw, roll;
			m_rotation.getEulerAngles(&pitch, &yaw, &roll);
			roll -= diff.y() * 0.5;
			yaw += diff.x() * 0.5;

			m_rotation = QQuaternion::fromEulerAngles(pitch, yaw, roll);
		}
		// YZ
		else if (!m_rotDirections.x && m_rotDirections.y && m_rotDirections.z)
		{
			float pitch, yaw, roll;
			m_rotation.getEulerAngles(&pitch, &yaw, &roll);
			pitch += diff.y() * 0.5;
			roll += diff.x() * 0.5;

			if (pitch > 89)
				pitch = 89;
			else if (pitch < -89)
				pitch = -89;

			m_rotation = QQuaternion::fromEulerAngles(pitch, yaw, roll);
		}

		// request an update
		update();
	}
	else if (m_mouse.right)
	{
		// get the difference between last press and now
		QVector2D diff = QVector2D(e->localPos()) - m_mouse.position;

		// update the new position
		m_mouse.position = QVector2D(e->localPos());

		// calculate the translation
		m_translation += {(float)(diff.x() * 0.01), (float)(diff.y() * -0.01), 0.0};

		// request an update
		update();
	}
}

void OglViewerWidget::wheelEvent(QWheelEvent *e)
{
	m_translation += {0.0, 0.0, (float)m_zSpeed * e->angleDelta().y() / 240};
	update();
}

void OglViewerWidget::keyPressEvent(QKeyEvent *e)
{
	if (e->key() == Qt::Key_Space)
	{
		resetView();
	}
	else if (e->key() == Qt::Key_Escape)
	{
		parentWidget()->close();
	}
	else if (e->key() == Qt::Key_L)
	{
		updateLightPosition();
		update();
	}
	else if (e->key() == Qt::Key_Minus)
	{
		m_zSpeed -= 0.1;
		m_zSpeed < 0.09 ? m_zSpeed = 0 : NULL;
		OutputDevice::getInstance()->print(QString("Zoom speed = %1%").arg(m_zSpeed * 100), 0);
	}
	else if (e->key() == Qt::Key_Plus)
	{
		m_zSpeed += 0.1;
		OutputDevice::getInstance()->print(QString("Zoom speed = %1%").arg(m_zSpeed * 100), 0);
	}
}

void OglViewerWidget::dragEnterEvent(QDragEnterEvent *e)
{
	if (e->mimeData()->hasUrls())
		if(e->mimeData()->urls().size() == 1)
			if(e->mimeData()->urls().first().toLocalFile().endsWith(".msh"))
				e->acceptProposedAction();

}

void OglViewerWidget::dropEvent(QDropEvent * e)
{
	m_dataEngine->loadFile(e->mimeData()->urls().first().toLocalFile());
}


/////////////////////////////////////////////////////////////////////////
// public slots

void OglViewerWidget::toggleAxis(int axis)
{
	switch (axis)
	{
	case 1:
		m_rotDirections.x = !m_rotDirections.x;
		break;
	case 2:
		m_rotDirections.y = !m_rotDirections.y;
		break;
	case 3:
		m_rotDirections.z = !m_rotDirections.z;
		break;
	}
}

void OglViewerWidget::toggleWireframe()
{
	m_wireframe = !m_wireframe;
	update();
}

void OglViewerWidget::toggleLight()
{
	m_lightOn = !m_lightOn;

	if (m_lightOn)
	{
		m_backgroundColorOn[3] = 1.0;
		updateLightPosition();
	}
	else
	{
		m_backgroundColorOff[3] = 1.0;
	}

	update();
}

void OglViewerWidget::showSettings()
{
	m_settings->show();
}

void OglViewerWidget::setBGColorOff(QVector3D value)
{
	m_backgroundColorOff = QVector4D(value / 255, 1.0f);

	if (!m_lightOn)
		update();
}

void OglViewerWidget::setBGColorOn(QVector3D value)
{
	m_backgroundColorOn = QVector4D(value / 255, 1.0f);

	if (m_lightOn)
		update();
}

void OglViewerWidget::setLightColor(QVector3D value)
{
	m_light.intensities = value / 255;

	if (m_lightOn)
		update();
}

void OglViewerWidget::setAttFac(double value)
{
	m_light.attenuationFactor = (float)value;

	if (m_lightOn)
		update();
}

void OglViewerWidget::setAmbCoef(double value)
{
	m_light.ambientCoefficient = (float)value;

	if (m_lightOn)
		update();
}