// Copyright (C) 2015 Jérôme Leclercq
// This file is part of the "Nazara Engine - Graphics module"
// For conditions of distribution and use, see copyright notice in Config.hpp

#include <Nazara/Graphics/Camera.hpp>
#include <Nazara/Graphics/Scene.hpp>
#include <Nazara/Renderer/Renderer.hpp>
#include <Nazara/Renderer/RenderTarget.hpp>
#include <Nazara/Graphics/Debug.hpp>

NzCamera::NzCamera() :
m_targetRegion(0.f, 0.f, 1.f, 1.f),
m_target(nullptr),
m_frustumUpdated(false),
m_projectionMatrixUpdated(false),
m_viewMatrixUpdated(false),
m_viewportUpdated(false),
m_aspectRatio(0.f),
m_fov(70.f),
m_zFar(100.f),
m_zNear(1.f)
{
}

void NzCamera::EnsureFrustumUpdate() const
{
	if (!m_frustumUpdated)
		UpdateFrustum();
}

void NzCamera::EnsureProjectionMatrixUpdate() const
{
	if (!m_projectionMatrixUpdated)
		UpdateProjectionMatrix();
}

void NzCamera::EnsureViewMatrixUpdate() const
{
	if (!m_viewMatrixUpdated)
		UpdateViewMatrix();
}

void NzCamera::EnsureViewportUpdate() const
{
	if (!m_viewportUpdated)
		UpdateViewport();
}

float NzCamera::GetAspectRatio() const
{
	return m_aspectRatio;
}

NzVector3f NzCamera::GetEyePosition() const
{
	return GetPosition(nzCoordSys_Global);
}

NzVector3f NzCamera::GetForward() const
{
	return NzNode::GetForward();
}

float NzCamera::GetFOV() const
{
	return m_fov;
}

const NzFrustumf& NzCamera::GetFrustum() const
{
	if (!m_frustumUpdated)
		UpdateFrustum();

	return m_frustum;
}

NzVector3f NzCamera::GetGlobalForward() const
{
	return NzVector3f::Forward();
}

NzVector3f NzCamera::GetGlobalRight() const
{
	return NzVector3f::Right();
}

NzVector3f NzCamera::GetGlobalUp() const
{
	return NzVector3f::Up();
}

const NzMatrix4f& NzCamera::GetProjectionMatrix() const
{
	if (!m_projectionMatrixUpdated)
		UpdateProjectionMatrix();

	return m_projectionMatrix;
}

const NzRenderTarget* NzCamera::GetTarget() const
{
	return m_target;
}

const NzRectf& NzCamera::GetTargetRegion() const
{
	return m_targetRegion;
}

const NzMatrix4f& NzCamera::GetViewMatrix() const
{
	if (!m_viewMatrixUpdated)
		UpdateViewMatrix();

	return m_viewMatrix;
}

const NzRecti& NzCamera::GetViewport() const
{
	#if NAZARA_GRAPHICS_SAFE
	if (!m_target)
	{
		NazaraError("Camera has no render target");
		return m_viewport;
	}
	#endif

	if (!m_viewportUpdated)
		UpdateViewport();

	return m_viewport;
}

float NzCamera::GetZFar() const
{
	return m_zFar;
}

float NzCamera::GetZNear() const
{
	return m_zNear;
}

void NzCamera::SetFOV(float fov)
{
	#if NAZARA_GRAPHICS_SAFE
	if (NzNumberEquals(fov, 0.f))
	{
		NazaraError("FOV must be different from zero");
		return;
	}
	#endif

	m_fov = fov;

	m_frustumUpdated = false;
	m_projectionMatrixUpdated = false;
}

void NzCamera::SetTarget(const NzRenderTarget* renderTarget)
{
	m_target = renderTarget;

	if (m_target)
	{
		m_targetReleaseSlot.Connect(m_target->OnRenderTargetRelease, this, &NzCamera::OnRenderTargetRelease);
		m_targetResizeSlot.Connect(m_target->OnRenderTargetSizeChange, this, &NzCamera::OnRenderTargetSizeChange);
	}
	else
	{
		m_targetReleaseSlot.Disconnect();
		m_targetResizeSlot.Disconnect();
	}

	m_frustumUpdated = false;
	m_projectionMatrixUpdated = false;
	m_viewportUpdated = false;
}

void NzCamera::SetTarget(const NzRenderTarget& renderTarget)
{
	SetTarget(&renderTarget);
}

void NzCamera::SetTargetRegion(const NzRectf& region)
{
	m_targetRegion = region;

	m_frustumUpdated = false;
	m_projectionMatrixUpdated = false;
	m_viewportUpdated = false;
}

void NzCamera::SetViewport(const NzRecti& viewport)
{
	#if NAZARA_GRAPHICS_SAFE
	if (!m_target)
	{
		NazaraError("Camera has no render target");
		return;
	}
	#endif

	// On calcule la région nécessaire pour produire ce viewport avec la taille actuelle de la cible
	float invWidth = 1.f/m_target->GetWidth();
	float invHeight = 1.f/m_target->GetHeight();

	SetTargetRegion(NzRectf(invWidth * viewport.x, invHeight * viewport.y, invWidth * viewport.width, invHeight * viewport.height));
}

void NzCamera::SetZFar(float zFar)
{
	m_zFar = zFar;

	m_frustumUpdated = false;
	m_projectionMatrixUpdated = false;
}

void NzCamera::SetZNear(float zNear)
{
	#if NAZARA_GRAPHICS_SAFE
	if (zNear < 0.f || NzNumberEquals(zNear, 0.f))
	{
		NazaraError("ZNear shall be a strictly positive number");
		return;
	}
	#endif

	m_zNear = zNear;

	m_frustumUpdated = false;
	m_projectionMatrixUpdated = false;
}

void NzCamera::ApplyView() const
{
	#if NAZARA_GRAPHICS_SAFE
	if (!m_target)
	{
		NazaraError("Camera has no render target");
		return;
	}
	#endif

	if (!m_projectionMatrixUpdated)
		UpdateProjectionMatrix();

	if (!m_viewMatrixUpdated)
		UpdateViewMatrix();

	if (!m_viewportUpdated)
		UpdateViewport();

	NzRenderer::SetMatrix(nzMatrixType_Projection, m_projectionMatrix);
	NzRenderer::SetMatrix(nzMatrixType_View, m_viewMatrix);
	NzRenderer::SetTarget(m_target);
	NzRenderer::SetViewport(m_viewport);
}

void NzCamera::InvalidateNode()
{
	NzNode::InvalidateNode();

	// Le frustum et la view matrix dépendent des paramètres du node, invalidons-les
	m_frustumUpdated = false;
	m_viewMatrixUpdated = false;
}

void NzCamera::OnRenderTargetRelease(const NzRenderTarget* renderTarget)
{
	if (renderTarget == m_target)
		m_target = nullptr;
	else
		NazaraInternalError("Not listening to " + NzString::Pointer(renderTarget));
}

void NzCamera::OnRenderTargetSizeChange(const NzRenderTarget* renderTarget)
{
	if (renderTarget == m_target)
	{
		m_frustumUpdated = false;
		m_projectionMatrixUpdated = false;
		m_viewportUpdated = false;
	}
	else
		NazaraInternalError("Not listening to " + NzString::Pointer(renderTarget));
}

void NzCamera::UpdateFrustum() const
{
	if (!m_projectionMatrixUpdated)
		UpdateProjectionMatrix();

	if (!m_viewMatrixUpdated)
		UpdateViewMatrix();

	m_frustum.Extract(m_viewMatrix, m_projectionMatrix);
	m_frustumUpdated = true;
}

void NzCamera::UpdateProjectionMatrix() const
{
	#if NAZARA_GRAPHICS_SAFE
	// Il n'y a pas grand chose à faire d'autre qu'un avertissement à ce stade
	if (m_zNear >= m_zFar)
		NazaraWarning("ZNear is greater or equal to ZFar (" + NzString::Number(m_zNear) + " >= " + NzString::Number(m_zFar) + ").");
	#endif

	if (!m_viewportUpdated)
		UpdateViewport(); // Peut affecter l'aspect ratio

	m_projectionMatrix.MakePerspective(m_fov, m_aspectRatio, m_zNear, m_zFar);
	m_projectionMatrixUpdated = true;
}

void NzCamera::UpdateViewMatrix() const
{
	if (!m_derivedUpdated)
		UpdateDerived();

	m_viewMatrix.MakeViewMatrix(m_derivedPosition, m_derivedRotation);
	m_viewMatrixUpdated = true;
}

void NzCamera::UpdateViewport() const
{
	#if NAZARA_GRAPHICS_SAFE
	if (!m_target)
	{
		NazaraError("Camera has no render target");
		return;
	}
	#endif

	unsigned int width = m_target->GetWidth();
	unsigned int height = std::max(m_target->GetHeight(), 1U);

	float vWidth = width * m_targetRegion.width;
	float vHeight = height * m_targetRegion.height;
	float aspectRatio = vWidth/vHeight;

	if (!NzNumberEquals(m_aspectRatio, aspectRatio, 0.001f))
	{
		m_aspectRatio = aspectRatio;
		m_frustumUpdated = false;
		m_projectionMatrixUpdated = false;
	}

	m_viewport.x = static_cast<int>(width * m_targetRegion.x);
	m_viewport.y = static_cast<int>(height * m_targetRegion.y);
	m_viewport.width = static_cast<int>(vWidth);
	m_viewport.height = static_cast<int>(vHeight);
	m_viewportUpdated = true;
}