//-------------------------------------------------------------------------------
///
/// \file       xmlload.cpp 
/// \author     Cem Yuksel (www.cemyuksel.com)
/// \version    4.0
/// \date       August 21, 2019
///
/// \brief Example source for CS 6620 - University of Utah.
///
//-------------------------------------------------------------------------------

#include "scene.h"
#include "objects.h"
#include "materials.h"
#include "lights.h"
#include "tinyxml/tinyxml.h"

//-------------------------------------------------------------------------------

extern Node rootNode;
extern Camera camera;
extern RenderImage renderImage;
extern MaterialList materials;
extern LightList lights;

//-------------------------------------------------------------------------------

#ifdef WIN32
#define COMPARE(a,b) (_stricmp(a,b)==0)
#else
#define COMPARE(a,b) (strcasecmp(a,b)==0)
#endif

//-------------------------------------------------------------------------------

void LoadScene(TiXmlElement *element);
void LoadNode(Node *node, TiXmlElement *element, int level=0);
void LoadTransform( Transformation *trans, TiXmlElement *element, int level );
void LoadMaterial(TiXmlElement *element);
void LoadLight(TiXmlElement *element);
void ReadVector(TiXmlElement *element, Vec3f &v);
void ReadColor (TiXmlElement *element, Color  &c);
void ReadFloat (TiXmlElement *element, float  &f, char const *name="value");

//-------------------------------------------------------------------------------

struct NodeMtl
{
	Node *node;
	char const *mtlName;
};

std::vector<NodeMtl> nodeMtlList;

//-------------------------------------------------------------------------------

int LoadScene(char const *filename)
{
	TiXmlDocument doc(filename);
	if ( ! doc.LoadFile() ) {
		printf("Failed to load the file \"%s\"\n", filename);
		return 0;
	}

	TiXmlElement *xml = doc.FirstChildElement("xml");
	if ( ! xml ) {
		printf("No \"xml\" tag found.\n");
		return 0;
	}

	TiXmlElement *scene = xml->FirstChildElement("scene");
	if ( ! scene ) {
		printf("No \"scene\" tag found.\n");
		return 0;
	}

	TiXmlElement *cam = xml->FirstChildElement("camera");
	if ( ! cam ) {
		printf("No \"camera\" tag found.\n");
		return 0;
	}

	nodeMtlList.clear();

	rootNode.Init();
	materials.DeleteAll();
	lights.DeleteAll();
	LoadScene( scene );

	// Assign materials
	int numNodes = nodeMtlList.size();
	for ( int i=0; i<numNodes; i++ ) {
		Material *mtl = materials.Find( nodeMtlList[i].mtlName );
		if ( mtl ) nodeMtlList[i].node->SetMaterial(mtl);
	}
	nodeMtlList.clear();

	// Load Camera
	camera.Init();
	camera.dir += camera.pos;
	TiXmlElement *camChild = cam->FirstChildElement();
	while ( camChild ) {
		if      ( COMPARE( camChild->Value(), "position"  ) ) ReadVector(camChild,camera.pos);
		else if ( COMPARE( camChild->Value(), "target"    ) ) ReadVector(camChild,camera.dir);
		else if ( COMPARE( camChild->Value(), "up"        ) ) ReadVector(camChild,camera.up);
		else if ( COMPARE( camChild->Value(), "fov"       ) ) ReadFloat (camChild,camera.fov);
		else if ( COMPARE( camChild->Value(), "width"     ) ) camChild->QueryIntAttribute("value", &camera.imgWidth);
		else if ( COMPARE( camChild->Value(), "height"    ) ) camChild->QueryIntAttribute("value", &camera.imgHeight);
		camChild = camChild->NextSiblingElement();
	}
	camera.dir -= camera.pos;
	camera.dir.Normalize();
	Vec3f x = camera.dir ^ camera.up;
	camera.up = (x ^ camera.dir).GetNormalized();

	renderImage.Init( camera.imgWidth, camera.imgHeight );

	return 1;
}

//-------------------------------------------------------------------------------

void PrintIndent(int level) { for ( int i=0; i<level; i++) printf("   "); }

//-------------------------------------------------------------------------------

void LoadScene(TiXmlElement *element)
{
	for ( TiXmlElement *child = element->FirstChildElement(); child!=nullptr; child = child->NextSiblingElement() ) {

		if ( COMPARE( child->Value(), "object" ) ) {
			LoadNode( &rootNode, child );
		} else if ( COMPARE( child->Value(), "material" ) ) {
			LoadMaterial( child );
		} else if ( COMPARE( child->Value(), "light" ) ) {
			LoadLight( child );
		}
	}
}

//-------------------------------------------------------------------------------

void LoadNode(Node *parent, TiXmlElement *element, int level)
{
	Node *node = new Node;
	parent->AppendChild(node);

	// name
	char const* name = element->Attribute("name");
	node->SetName(name);
	PrintIndent(level);
	printf("object [");
	if ( name ) printf("%s",name);
	printf("]");

	// material
	char const* mtlName = element->Attribute("material");
	if ( mtlName ) {
		printf(" <%s>", mtlName);
		NodeMtl nm;
		nm.node = node;
		nm.mtlName = mtlName;
		nodeMtlList.push_back(nm);
	}

	// type
	char const* type = element->Attribute("type");
	if ( type ) {
		if ( COMPARE(type,"sphere") ) {
			node->SetNodeObj( &theSphere );
			printf(" - Sphere");
		} else {
			printf(" - UNKNOWN TYPE");
		}
	}


	printf("\n");


	for ( TiXmlElement *child = element->FirstChildElement(); child!=nullptr; child = child->NextSiblingElement() ) {
		if ( COMPARE( child->Value(), "object" ) ) {
			LoadNode(node,child,level+1);
		}
	}
	LoadTransform( node, element, level );

}

//-------------------------------------------------------------------------------

void LoadTransform( Transformation *trans, TiXmlElement *element, int level )
{
	for ( TiXmlElement *child = element->FirstChildElement(); child!=nullptr; child = child->NextSiblingElement() ) {
		if ( COMPARE( child->Value(), "scale" ) ) {
			Vec3f s(1,1,1);
			ReadVector( child, s );
			trans->Scale(s.x,s.y,s.z);
			PrintIndent(level);
			printf("   scale %f %f %f\n",s.x,s.y,s.z);
		} else if ( COMPARE( child->Value(), "rotate" ) ) {
			Vec3f s(0,0,0);
			ReadVector( child, s );
			s.Normalize();
			float a;
			ReadFloat(child,a,"angle");
			trans->Rotate(s,a);
			PrintIndent(level);
			printf("   rotate %f degrees around %f %f %f\n", a, s.x, s.y, s.z);
		} else if ( COMPARE( child->Value(), "translate" ) ) {
			Vec3f t(0,0,0);
			ReadVector(child,t);
			trans->Translate(t);
			PrintIndent(level);
			printf("   translate %f %f %f\n",t.x,t.y,t.z);
		}
	}
}

//-------------------------------------------------------------------------------

void LoadMaterial(TiXmlElement *element)
{
	Material *mtl = nullptr;

	// name
	char const* name = element->Attribute("name");
	printf("Material [");
	if ( name ) printf("%s",name);
	printf("]");

	// type
	char const* type = element->Attribute("type");
	if ( type ) {
		if ( COMPARE(type,"blinn") ) {
			printf(" - Blinn\n");
			MtlBlinn *m = new MtlBlinn();
			mtl = m;
			for ( TiXmlElement *child = element->FirstChildElement(); child!=nullptr; child = child->NextSiblingElement() ) {
				Color c(1,1,1);
				float f=1;
				if ( COMPARE( child->Value(), "diffuse" ) ) {
					ReadColor( child, c );
					m->SetDiffuse(c);
					printf("   diffuse %f %f %f\n",c.r,c.g,c.b);
				} else if ( COMPARE( child->Value(), "specular" ) ) {
					ReadColor( child, c );
					m->SetSpecular(c);
					printf("   specular %f %f %f\n",c.r,c.g,c.b);
				} else if ( COMPARE( child->Value(), "glossiness" ) ) {
					ReadFloat( child, f );
					m->SetGlossiness(f);
					printf("   glossiness %f\n",f);
				} else if ( COMPARE( child->Value(), "reflection" ) ) {
					ReadColor( child, c );
					m->SetReflection(c);
					printf("   reflection %f %f %f\n",c.r,c.g,c.b);
				} else if ( COMPARE( child->Value(), "refraction" ) ) {
					ReadColor( child, c );
					m->SetRefraction(c);
					ReadFloat( child, f, "index" );
					m->SetRefractionIndex(f);
					printf("   refraction %f %f %f (index %f)\n",c.r,c.g,c.b,f);
				} else if ( COMPARE( child->Value(), "absorption" ) ) {
					ReadColor( child, c );
					m->SetAbsorption(c);
					printf("   absorption %f %f %f\n",c.r,c.g,c.b);
				}
			}
		} else {
			printf(" - UNKNOWN\n");
		}
	}

	if ( mtl ) {
		mtl->SetName(name);
		materials.push_back(mtl);
	}
}

//-------------------------------------------------------------------------------

void LoadLight(TiXmlElement *element)
{
	Light *light = nullptr;

	// name
	char const* name = element->Attribute("name");
	printf("Light [");
	if ( name ) printf("%s",name);
	printf("]");

	// type
	char const* type = element->Attribute("type");
	if ( type ) {
		if ( COMPARE(type,"ambient") ) {
			printf(" - Ambient\n");
			AmbientLight *l = new AmbientLight();
			light = l;
			for ( TiXmlElement *child = element->FirstChildElement(); child!=nullptr; child = child->NextSiblingElement() ) {
				if ( COMPARE( child->Value(), "intensity" ) ) {
					Color c(1,1,1);
					ReadColor( child, c );
					l->SetIntensity(c);
					printf("   intensity %f %f %f\n",c.r,c.g,c.b);
				}
			}
		} else if ( COMPARE(type,"direct") ) {
			printf(" - Direct\n");
			DirectLight *l = new DirectLight();
			light = l;
			for ( TiXmlElement *child = element->FirstChildElement(); child!=nullptr; child = child->NextSiblingElement() ) {
				if ( COMPARE( child->Value(), "intensity" ) ) {
					Color c(1,1,1);
					ReadColor( child, c );
					l->SetIntensity(c);
					printf("   intensity %f %f %f\n",c.r,c.g,c.b);
				} else if ( COMPARE( child->Value(), "direction" ) ) {
					Vec3f v(1,1,1);
					ReadVector( child, v );
					l->SetDirection(v);
					printf("   direction %f %f %f\n",v.x,v.y,v.z);
				}
			}
		} else if ( COMPARE(type,"point") ) {
			printf(" - Point\n");
			PointLight *l = new PointLight();
			light = l;
			for ( TiXmlElement *child = element->FirstChildElement(); child!=nullptr; child = child->NextSiblingElement() ) {
				if ( COMPARE( child->Value(), "intensity" ) ) {
					Color c(1,1,1);
					ReadColor( child, c );
					l->SetIntensity(c);
					printf("   intensity %f %f %f\n",c.r,c.g,c.b);
				} else if ( COMPARE( child->Value(), "position" ) ) {
					Vec3f v(0,0,0);
					ReadVector( child, v );
					l->SetPosition(v);
					printf("   position %f %f %f\n",v.x,v.y,v.z);
				}
			}
		} else {
			printf(" - UNKNOWN\n");
		}
	}

	if ( light ) {
		light->SetName(name);
		lights.push_back(light);
	}

}

//-------------------------------------------------------------------------------

void ReadVector(TiXmlElement *element, Vec3f &v)
{
	double x = (double) v.x;
	double y = (double) v.y;
	double z = (double) v.z;
	element->QueryDoubleAttribute( "x", &x );
	element->QueryDoubleAttribute( "y", &y );
	element->QueryDoubleAttribute( "z", &z );
	v.x = (float) x;
	v.y = (float) y;
	v.z = (float) z;

	float f=1;
	ReadFloat( element, f );
	v *= f;
}

//-------------------------------------------------------------------------------

void ReadColor(TiXmlElement *element, Color &c)
{
	double r = (double) c.r;
	double g = (double) c.g;
	double b = (double) c.b;
	element->QueryDoubleAttribute( "r", &r );
	element->QueryDoubleAttribute( "g", &g );
	element->QueryDoubleAttribute( "b", &b );
	c.r = (float) r;
	c.g = (float) g;
	c.b = (float) b;

	float f=1;
	ReadFloat( element, f );
	c *= f;
}

//-------------------------------------------------------------------------------

void ReadFloat (TiXmlElement *element, float &f, char const *name)
{
	double d = (double) f;
	element->QueryDoubleAttribute( name, &d );
	f = (float) d;
}

//-------------------------------------------------------------------------------