//========================================================================
// SceneNodes.cpp - defines the base class for the 3D graphics scene graph, and
//                  derived classes like RootNode, Alpha scene nodes, Camera, Grids, etc.                  
//
// Part of the GameCode4 Application
//
// GameCode4 is the sample application that encapsulates much of the source code
// discussed in "Game Coding Complete - 4th Edition" by Mike McShaffry and David
// "Rez" Graham, published by Charles River Media. 
// ISBN-10: 1133776574 | ISBN-13: 978-1133776574
//
// If this source code has found it's way to you, and you think it has helped you
// in any way, do the authors a favor and buy a new copy of the book - there are 
// detailed explanations in it that compliment this code well. Buy a copy at Amazon.com
// by clicking here: 
//    http://www.amazon.com/gp/product/1133776574/ref=olp_product_details?ie=UTF8&me=&seller=
//
// There's a companion web site at http://www.mcshaffry.com/GameCode/
// 
// The source code is managed and maintained through Google Code: 
//    http://code.google.com/p/gamecode4/
//
// (c) Copyright 2012 Michael L. McShaffry and David Graham
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser GPL v3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See 
// http://www.gnu.org/licenses/lgpl-3.0.txt for more details.
//
// You should have received a copy of the GNU Lesser GPL v3
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
//========================================================================

#include "../Unix/GameCodeStd.h"

#include "../Actors/RenderComponent.h"
#include "../Actors/TransformComponent.h"

#include "SceneNodes.h"
#include "Scene.h"

#include <glm/gtx/string_cast.hpp>

////////////////////////////////////////////////////
// SceneNodeProperties Implementation
////////////////////////////////////////////////////

SceneNodeProperties::SceneNodeProperties(void)
{
    m_ActorId = INVALID_ACTOR_ID;
    m_Radius = 0;
    m_RenderPass = RenderPass_0;
    m_AlphaType = AlphaOpaque;
}


//
// SceneNodeProperties::Transform			- Chapter 16, page 528
//
void SceneNodeProperties::Transform(glm::mat4 *toWorld, glm::mat4 *fromWorld) const
{
	if (toWorld)
		*toWorld = m_ToWorld;
	
	if (fromWorld)
		*fromWorld = m_FromWorld;
}


////////////////////////////////////////////////////
// SceneNode Implementation
////////////////////////////////////////////////////

SceneNode::SceneNode(
		ActorId actorId,
		WeakBaseRenderComponentPtr renderComponent,
		RenderPass renderPass,
		const glm::mat4 to,
		std::optional<const glm::mat4> from
) { 
	m_pParent= NULL;
	m_Props.m_ActorId = actorId;
	m_Props.m_Name = (renderComponent) ? renderComponent->VGetName() : "SceneNode";
	m_Props.m_RenderPass = renderPass;
	m_Props.m_AlphaType = AlphaOpaque;
	m_RenderComponent = renderComponent;
	VSetTransform(to, from); 
	SetRadius(0);

	// [mrmike] - these lines were moved to VOnRestore() post press
	//Color color = (renderComponent) ? renderComponent->GetColor() : g_White;
	//m_Props.m_Material.SetDiffuse(color);
}


SceneNode::~SceneNode()
{
}

//
// SceneNode::VOnRestore					- Chapter 16, page 532
//
int SceneNode::VOnRestore(Scene *pScene)
{
	Color color = (m_RenderComponent) ? m_RenderComponent->GetColor() : g_White;
	m_Props.m_Material.SetDiffuse(color);

	// This is meant to be called from any class
	// that inherits from SceneNode and overloads
	// VOnRestore()

	SceneNodeList::iterator i = m_Children.begin();
	SceneNodeList::iterator end = m_Children.end();
	while (i != end)
	{
		(*i)->VOnRestore(pScene);
		++i;
	}
	return 0;
}

//
// SceneNode::VSetTransform					- Chapter 16, page 531
//
void SceneNode::VSetTransform(
		const glm::mat4 toWorld,
		std::optional<const glm::mat4> fromWorld
) {
	m_Props.m_ToWorld = toWorld;
	if (!fromWorld)
	{
		m_Props.m_FromWorld = glm::inverse(m_Props.m_ToWorld);
	}
	else
	{
		m_Props.m_FromWorld = *fromWorld;
	}
}

//
// SceneNode::VPostRender					- Chapter 16, page 532
//
int SceneNode::VPreRender(Scene *pScene)
{
	StrongActorPtr pActor = MakeStrongPtr(g_pApp->GetGameLogic()->VGetActor(m_Props.m_ActorId));
	if (pActor)
	{
		std::shared_ptr<TransformComponent> pTc = MakeStrongPtr(pActor->GetComponent<TransformComponent>(TransformComponent::g_Name));
		if (pTc)
		{
			m_Props.m_ToWorld = pTc->GetTransform();
		}
	}

	pScene->PushAndSetMatrix(m_Props.m_ToWorld);
	return 0;
}

//
// SceneNode::VIsVisible				- Chapter 16, page 533
//
bool SceneNode::VIsVisible(Scene *pScene) const
{
	// transform the location of this node into the camera space
	// of the camera attached to the scene

	// glm::mat4 toWorld, fromWorld;
	// pScene->GetCamera()->VGet()->Transform(&toWorld, &fromWorld);

	// glm::vec3 pos = GetWorldPosition();

	// glm::vec3 fromWorldPos = fromWorld.Xform(pos);

	// Frustum const &frustum = pScene->GetCamera()->GetFrustum();

	// bool isVisible = frustum.Inside(fromWorldPos, VGet()->Radius());
	// return isVisible;
	return true;
}

//
// SceneNode::VPostRender					- Chapter 16, page 532
//
int SceneNode::VPostRender(Scene *pScene)
{
	pScene->PopMatrix();
	return 0;
}

//
// SceneNode::VOnUpdate					- Chapter 16, page 532
//
int SceneNode::VOnUpdate(Scene *pScene, uint64_t const elapsedMs)
{
	// This is meant to be called from any class
	// that inherits from SceneNode and overloads
	// VOnUpdate()

	SceneNodeList::iterator i = m_Children.begin();
	SceneNodeList::iterator end = m_Children.end();

	while (i != end)
	{
		(*i)->VOnUpdate(pScene, elapsedMs);
		++i;
	}
	return 0;
}

//
// SceneNode::VRenderChildren					- Chapter 16, page 533
//
int SceneNode::VRenderChildren(Scene *pScene)
{
	// Iterate through the children
	SceneNodeList::iterator i = m_Children.begin();
	SceneNodeList::iterator end = m_Children.end();

	while (i != end)
	{
		if ((*i)->VPreRender(pScene) == 0)
		{
			// You could short-circuit rendering
			// if an object returns E_FAIL from
			// VPreRender()

			// Don't render this node if you can't see it
			if ((*i)->VIsVisible(pScene))
			{
				float alpha = (*i)->VGet()->m_Material.GetAlpha();
				if (alpha==fOPAQUE)
				{
					(*i)->VRender(pScene);
				}
	// 			else if (alpha!=fTRANSPARENT)
	// 			{
	// 				// The object isn't totally transparent
	// 				AlphaSceneNode *asn = GCC_NEW AlphaSceneNode;
	// 			}
				(*i)->VRenderChildren(pScene);
			}

			// [mrmike] post-press fix - if the parent is not visible, the childrend
			//           shouldn't be visible either.
			// (*i)->VRenderChildren(pScene);
		}
		(*i)->VPostRender(pScene);
		++i;
	}
	return 0;
}

//
// SceneNode::VAddChild					- Chapter 16, page 535
//
bool SceneNode::VAddChild(std::shared_ptr<ISceneNode> ikid)
{
	m_Children.push_back(ikid); 

	std::shared_ptr<SceneNode> kid = static_pointer_cast<SceneNode>(ikid);

	kid->m_pParent = this;					// [mrmike] Post-press fix - the parent was never set!

	// The radius of the sphere should be fixed right here
	glm::vec3 kidPos = geometry::GetPosition(kid->VGet()->ToWorld());
	
	// [mrmike] - Post-press fix. This was not correct! subtracting the parents's position from the kidPos
	//            created a HUGE radius, depending on the location of the parent, which could be anywhere
	//            in the game world.

	//Vec3 dir = kidPos - m_Props.ToWorld().GetPosition();
	//float newRadius = dir.Length() + kid->VGet()->Radius();
	
	float newRadius = glm::length(kidPos) + kid->VGet()->Radius(); 

	if (newRadius > m_Props.m_Radius)
		m_Props.m_Radius = newRadius;

	return true;
}

//
// SceneNode::VRemoveChild					- not in the book
//
//   If an actor is destroyed it should be removed from the scene graph.
//   Generally the HumanView will recieve a message saying the actor has been
//   destroyed, and it will then call Scene::RemoveChild which will traverse 
//   the scene graph to find the child that needs removing.
//
bool SceneNode::VRemoveChild(ActorId id)
{
	for(SceneNodeList::iterator i=m_Children.begin(); i!=m_Children.end(); ++i)
	{
		const SceneNodeProperties* pProps = (*i)->VGet();
		if(pProps->GetActorId() != INVALID_ACTOR_ID && id == pProps->GetActorId())
		{
			i = m_Children.erase(i);	//this can be expensive for vectors
			return true;
		}
	}
	return false;
}



////////////////////////////////////////////////////
// RootNode Implementation
////////////////////////////////////////////////////

//
// RootNode::RootNode					- Chapter 16, page 545
//
RootNode::RootNode()
: SceneNode(INVALID_ACTOR_ID, WeakBaseRenderComponentPtr(), RenderPass_0, glm::mat4(1.0f))
{
	m_Children.reserve(RenderPass_Last);

	std::shared_ptr<SceneNode> staticGroup(GCC_NEW SceneNode(INVALID_ACTOR_ID,  WeakBaseRenderComponentPtr(),  RenderPass_Static, glm::mat4(1.0f)));
	m_Children.push_back(staticGroup);	// RenderPass_Static = 0

	std::shared_ptr<SceneNode> actorGroup(GCC_NEW SceneNode(INVALID_ACTOR_ID,  WeakBaseRenderComponentPtr(),  RenderPass_Actor, glm::mat4(1.0f)));
	m_Children.push_back(actorGroup);	// RenderPass_Actor = 1

	std::shared_ptr<SceneNode> skyGroup(GCC_NEW SceneNode(INVALID_ACTOR_ID,  WeakBaseRenderComponentPtr(),  RenderPass_Sky, glm::mat4(1.0f)));
	m_Children.push_back(skyGroup);	// RenderPass_Sky = 2

	std::shared_ptr<SceneNode> invisibleGroup(GCC_NEW SceneNode(INVALID_ACTOR_ID,  WeakBaseRenderComponentPtr(),  RenderPass_NotRendered, glm::mat4(1.0f)));
	m_Children.push_back(invisibleGroup);	// RenderPass_NotRendered = 3
}

//
// RootNode::VAddChild					- Chapter 16, page 546
//
bool RootNode::VAddChild(std::shared_ptr<ISceneNode> kid)
{
	// The Root node has children that divide the scene graph into render passes.
	// Scene nodes will get added to these children based on the value of the
	// render pass member variable.

	RenderPass pass = kid->VGet()->GetRenderPass();
	if ((unsigned)pass >= m_Children.size() || !m_Children[pass])
	{
		GCC_ASSERT(0 && "There is no such render pass");
		return false;
	}

	return m_Children[pass]->VAddChild(kid);
}

//
// RootNode::VRemoveChild						- not described in the book 
//
//   Returns false if nothing was removed
//
bool RootNode::VRemoveChild(ActorId id)
{
	bool anythingRemoved = false;
	for(int i=RenderPass_0; i<RenderPass_Last; ++i)
	{
		if(m_Children[i]->VRemoveChild(id))
		{
			anythingRemoved = true;
		}
	}
	return anythingRemoved;
}

//
// RootNode::VRenderChildren					- Chapter 16, page 547
//
int RootNode::VRenderChildren(Scene *pScene)
{
	// This code creates fine control of the render passes.

	for (int pass = RenderPass_0; pass < RenderPass_Last; ++pass)
	{
		switch(pass)
		{
			case RenderPass_Static:
			case RenderPass_Actor:
				m_Children[pass]->VRenderChildren(pScene);
				break;

			case RenderPass_Sky:
			{
				std::shared_ptr<IRenderState> skyPass = pScene->GetRenderer()->VPrepareSkyBoxPass();
				m_Children[pass]->VRenderChildren(pScene);
				break;
			}
		}
	}

	return 0;
}


////////////////////////////////////////////////////
// CameraNode Implementation
////////////////////////////////////////////////////


//
// CameraNode::VRender					- Chapter 16, page 550
//
int CameraNode::VRender(Scene *pScene)
{
	if (m_DebugCamera)
	{
		// m_Frustum.Render();
	}

	return 1;
}

//
// CameraNode::VOnRestore				- Chapter 16, page 550
//
int CameraNode::VOnRestore(Scene *pScene)
{
	Point p = g_pApp->GetScreenSize();
	m_Frustum.SetAspect((float) p.x / (float) p.y);
	m_Projection = glm::perspective(
		m_Frustum.m_Fov,
		m_Frustum.m_Aspect,
		m_Frustum.m_Near,
		m_Frustum.m_Far
	);

	// [munnellg] this isn't necessary, but we'll do it to
	// preserve book code
	pScene->GetRenderer()->VSetProjectionTransform(m_Projection);
	return 0;
}

//
// CameraNode::SetView					- Chapter 16, page 550
//
//    Note: this is incorrectly called CameraNode::SetView in the book
//
int CameraNode::SetViewTransform(Scene *pScene)
{
	// TODO(munnellg) - implement
	// If there is a target, make sure the camera is
	// rigidly attached right behind the target
	if(m_pTarget)
	{
		glm::mat4 mat = m_pTarget->VGet()->ToWorld();
		glm::vec4 at = m_CamOffsetVector;
		glm::vec4 atWorld = mat * at;
		glm::vec3 pos = geometry::GetPosition(mat) + glm::vec3(atWorld);
		geometry::SetPosition(mat, pos);
		VSetTransform(mat);
	}

	m_View = VGet()->FromWorld();

	// [munnellg] this isn't necessary, but we'll do it to
	// preserve book code
	pScene->GetRenderer()->VSetViewTransform(m_View);
	return 0;
}

//
// CameraNode::GetWorldViewProjection			- not described in the book
//
//    Returns the concatenation of the world and view projection, which is generally sent into vertex shaders
//
glm::mat4 CameraNode::GetWorldViewProjection(Scene *pScene)
{
	glm::mat4 world = pScene->GetTopMatrix();
	glm::mat4 view = VGet()->FromWorld();
	return m_Projection * view * world;
}



////////////////////////////////////////////////////
// D3DGrid9 Implementation
//
// D3D9 classes are not covered in the 4th edition. They are included here for those 
// people that don't have D3D11 compatible video cards. 
//
// The code is somewhat similar to the D3DGrid11 class, which IS discussed in Chapter 16 
// of the 4th edition.
// 
////////////////////////////////////////////////////

OpenGLGrid::OpenGLGrid(ActorId actorId, WeakBaseRenderComponentPtr renderComponent, const glm::mat4 pMatrix)
	: SceneNode(actorId, renderComponent, RenderPass_0, pMatrix)
{
	m_bTextureHasAlpha = false;
	m_numIndices = 0;
	m_vbo = 0;
	m_vao = 0;
	m_ebo = 0;
}

OpenGLGrid::~OpenGLGrid()
{
	glDeleteVertexArrays(1, &m_vao);
	glDeleteBuffers(1, &m_vbo);
	glDeleteBuffers(1, &m_ebo);
}

int OpenGLGrid::VOnRestore(Scene *pScene)
{
	// clear out any existing buffers
	glDeleteVertexArrays(1, &m_vao);
	glDeleteBuffers(1, &m_vbo);
	glDeleteBuffers(1, &m_ebo);

	// TODO(munnellg) - these VOnRestore calls need to have their results checked
	SceneNode::VOnRestore(pScene);

	// TODO(munnellg) - release shaders if allocating before creating shader so we don't leak memory
	m_ShaderProgram.OnRestore(pScene);

	GridRenderComponent* grc = static_cast<GridRenderComponent*>(m_RenderComponent);
	int squares = grc->GetDivision();

	SetRadius(sqrt(squares * squares / 2.0f) );

	// Create the vertex buffer - we'll need enough verts
	// to populate the grid. If we want a 2x2 grid, we'll
	// need 3x3 set of verts.
	m_numVerts = (squares+1)*(squares+1);	// Create vertex buffer

	// Fill the vertex buffer. We are setting the tu and tv texture
    // coordinates, which range from 0.0 to 1.0
    VertexUnlitTextured *pVerts = GCC_NEW VertexUnlitTextured[m_numVerts];
    GCC_ASSERT(pVerts && "Out of memory in OpenGLGrid::VOnRestore");
    if (!pVerts)
    	return 1;

    for( int j=0; j<(squares+1); j++ )
    {
    	for (int i=0; i<(squares+1); i++)
    	{
    		// Which vertex are we setting?
    		int index = i + (j * (squares+1) );
    		VertexUnlitTextured *vert = &pVerts[index];

    		// Default position of the grid is centered on the origin flat on
    		// the XZ plane
    		float x = (float)i - (squares/2.0f);
    		float y = (float)j - (squares/2.0f);
    		vert->Pos = glm::vec3(x,0.f,y);
    		vert->Normal = glm::vec3(0.0f, 1.0f, 0.0f);

    		// The texture coordinates are set to x,y to make the 
    		// texture tile along with units - 1.0, 2.0, 3.0, etc
    		vert->Uv.x       = x;
    		vert->Uv.y       = y;
    	}
    }

    // The number of indicies equals the number of polygons times 3
	// since there are 3 indicies per polygon. Each grid square contains
	// two polygons. The indicies are 16 bit, since our grids won't
	// be that big!

	m_numPolys = squares * squares * 2;

	m_numIndices = m_numPolys * 3;
	GLuint *pIndices = GCC_NEW GLuint[m_numIndices];

	GCC_ASSERT(pIndices && "Out of memory in OpenGLGrid::VOnRestore");
	if (!pIndices)
	{
		delete[] pVerts;
		return 1;
	}

	// Loop through the grid squares and calc the values
	// of each index. Each grid square has two triangles:
	//
	//		A - B
	//		| / |
	//		C - D

	
	GLuint *current = pIndices;
	for( int j=0; j<squares; j++ )
	{
		for (int i=0; i<squares; i++)
		{
			// Triangle #1 ACB
			*(current) = GLuint(i + (j*(squares+1)));
			*(current+1) = GLuint(i + ((j+1)*(squares+1)));
			*(current+2) = GLuint((i+1) + (j*(squares+1)));

			*(current+3) = GLuint((i+1) + (j*(squares+1)));
			*(current+4) = GLuint(i + ((j+1)*(squares+1)));
			*(current+5) = GLuint((i+1) + ((j+1)*(squares+1)));
			current += 6;
		}
	}

	glCreateVertexArrays(1, &m_vao);

	glCreateBuffers(1, &m_vbo);
	glNamedBufferStorage(m_vbo, sizeof(VertexUnlitTextured) * m_numVerts, pVerts, 0);

	glVertexArrayVertexBuffer(m_vao, 0, m_vbo, 0, sizeof(VertexUnlitTextured));

	glEnableVertexArrayAttrib(m_vao, 0);
	glVertexArrayAttribFormat(m_vao, 0, 3, GL_FLOAT, GL_FALSE, 0);
	glVertexArrayAttribBinding(m_vao, 0, 0);

	glEnableVertexArrayAttrib(m_vao, 1);
	glVertexArrayAttribFormat(m_vao, 1, 3, GL_FLOAT, GL_FALSE, offsetof(VertexUnlitTextured, Normal));
	glVertexArrayAttribBinding(m_vao, 1, 0);

	glEnableVertexArrayAttrib(m_vao, 2);
	glVertexArrayAttribFormat(m_vao, 2, 2, GL_FLOAT, GL_FALSE,  offsetof(VertexUnlitTextured, Uv));
	glVertexArrayAttribBinding(m_vao, 2, 0);
	
	delete[] pVerts;

	glCreateBuffers(1, &m_ebo);
	glNamedBufferStorage(m_ebo, sizeof(GLuint) * m_numIndices, pIndices, 0);
	glVertexArrayElementBuffer(m_vao, m_ebo);

	delete[] pIndices;

	return 0;
}

int OpenGLGrid::VRender(Scene *pScene)
{
	GridRenderComponent* grc = static_cast<GridRenderComponent*>(m_RenderComponent);
	m_ShaderProgram.SetTexture(grc->GetTextureResource());
	m_ShaderProgram.SetupRender(pScene, this);

	glBindVertexArray(m_vao);
	glDrawElements(GL_TRIANGLES, m_numIndices, GL_UNSIGNED_INT, 0);
	glBindVertexArray(0);

	return 0;
}