//-------------------------------------------------------------------------------
///
/// \file       scene.h 
/// \author     Cem Yuksel (www.cemyuksel.com)
/// \version    7.0
/// \date       August 21, 2019
///
/// \brief Example source for CS 6620 - University of Utah.
///
//-------------------------------------------------------------------------------

#ifndef _SCENE_H_INCLUDED_
#define _SCENE_H_INCLUDED_

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

#define TEXTURE_SAMPLE_COUNT 32

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

#include <string.h>
#define _USE_MATH_DEFINES
#include <math.h>

#include <vector>
#include <atomic>

#include "lodepng.h"

#include "cyVector.h"
#include "cyMatrix.h"
#include "cyColor.h"
using namespace cy;

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

#define BIGFLOAT 1.0e30f

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

class Ray
{
public:
	Vec3f p, dir;

	Ray() {}
	Ray( Vec3f const &_p, Vec3f const &_dir ) : p(_p), dir(_dir) {}
	Ray( Ray const &r ) : p(r.p), dir(r.dir) {}
	void Normalize() { dir.Normalize(); }
};

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

class Box
{
public:
	Vec3f pmin, pmax;

	// Constructors
	Box() { Init(); }
	Box(Vec3f const &_pmin, Vec3f const &_pmax) : pmin(_pmin), pmax(_pmax) {}
	Box(float xmin, float ymin, float zmin, float xmax, float ymax, float zmax ) : pmin(xmin,ymin,zmin), pmax(xmax,ymax,zmax) {}
	Box(float const *dim) : pmin(dim[0],dim[1],dim[2]), pmax(dim[3],dim[4],dim[5]) {}

	// Initializes the box, such that there exists no point inside the box (i.e. it is empty).
	void Init() { pmin.Set(BIGFLOAT,BIGFLOAT,BIGFLOAT); pmax.Set(-BIGFLOAT,-BIGFLOAT,-BIGFLOAT); }

	// Returns true if the box is empty; otherwise, returns false.
	bool IsEmpty() const { return pmin.x>pmax.x || pmin.y>pmax.y || pmin.z>pmax.z; }

	// Returns one of the 8 corner point of the box in the following order:
	// 0:(x_min,y_min,z_min), 1:(x_max,y_min,z_min)
	// 2:(x_min,y_max,z_min), 3:(x_max,y_max,z_min)
	// 4:(x_min,y_min,z_max), 5:(x_max,y_min,z_max)
	// 6:(x_min,y_max,z_max), 7:(x_max,y_max,z_max)
	Vec3f Corner( int i ) const	// 8 corners of the box
	{
		Vec3f p;
		p.x = (i & 1) ? pmax.x : pmin.x;
		p.y = (i & 2) ? pmax.y : pmin.y;
		p.z = (i & 4) ? pmax.z : pmin.z;
		return p;
	}

	// Enlarges the box such that it includes the given point p.
	void operator += (Vec3f const &p)
	{
		for ( int i=0; i<3; i++ ) {
			if ( pmin[i] > p[i] ) pmin[i] = p[i];
			if ( pmax[i] < p[i] ) pmax[i] = p[i];
		}
	}

	// Enlarges the box such that it includes the given box b.
	void operator += (const Box &b)
	{
		for ( int i=0; i<3; i++ ) {
			if ( pmin[i] > b.pmin[i] ) pmin[i] = b.pmin[i];
			if ( pmax[i] < b.pmax[i] ) pmax[i] = b.pmax[i];
		}
	}

	// Returns true if the point is inside the box; otherwise, returns false.
	bool IsInside(Vec3f const &p) const { for ( int i=0; i<3; i++ ) if ( pmin[i] > p[i] || pmax[i] < p[i] ) return false; return true; }

	// Returns true if the ray intersects with the box for any parameter that is smaller than t_max; otherwise, returns false.
	bool IntersectRay(Ray const &r, float t_max) const;
};

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

class Node;

#define HIT_NONE			0
#define HIT_FRONT			1
#define HIT_BACK			2
#define HIT_FRONT_AND_BACK	(HIT_FRONT|HIT_BACK)

struct HitInfo
{
	float       z;		// the distance from the ray center to the hit point
	Vec3f       p;		// position of the hit point
	Vec3f       N;		// surface normal at the hit point
	Vec3f       uvw;	// texture coordinate at the hit point
	Vec3f       duvw[2];// derivatives of the texture coordinate
	Node const *node;	// the object node that was hit
	bool        front;	// true if the ray hits the front side, false if the ray hits the back side
	int         mtlID;	// sub-material index

	HitInfo() { Init(); }
	void Init() { z=BIGFLOAT; node=nullptr; front=true; uvw.Set(0.5f,0.5f,0.5f); duvw[0].Zero(); duvw[1].Zero(); mtlID=0; }
};

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

class ItemBase
{
private:
	char *name;					// The name of the item

public:
	ItemBase() : name(nullptr) {}
	virtual ~ItemBase() { if ( name ) delete [] name; }

	char const* GetName() const { return name ? name : ""; }
	void SetName(char const *newName)
	{
		if ( name ) delete [] name;
		if ( newName ) {
			int n = strlen(newName);
			name = new char[n+1];
			for ( int i=0; i<n; i++ ) name[i] = newName[i];
			name[n] = '\0';
		} else { name = nullptr; }
	}
};

template <class T> class ItemList : public std::vector<T*>
{
public:
	virtual ~ItemList() { DeleteAll(); }
	void DeleteAll() { int n=(int)this->size(); for ( int i=0; i<n; i++ ) if ( this->at(i) ) delete this->at(i); }
};


template <class T> class ItemFileList
{
public:
	void Clear() { list.DeleteAll(); }
	void Append( T* item, char const *name ) { list.push_back( new FileInfo(item,name) ); }
	T* Find( char const *name ) const { int n=list.size(); for ( int i=0; i<n; i++ ) if ( list[i] && strcmp(name,list[i]->GetName())==0 ) return list[i]->GetObj(); return nullptr; }

private:
	class FileInfo : public ItemBase
	{
	private:
		T *item;
	public:
		FileInfo() : item(nullptr) {}
		FileInfo(T *_item, char const *name) : item(_item) { SetName(name); }
		~FileInfo() { Delete(); }
		void Delete() { if (item) delete item; item=nullptr; }
		void SetObj(T *_item) { Delete(); item=_item; }
		T* GetObj() { return item; }
	};

	ItemList<FileInfo> list;
};

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

class Transformation
{
private:
	Matrix3f tm;			// Transformation matrix to the local space
	Vec3f    pos;			// Translation part of the transformation matrix
	mutable Matrix3f itm;	// Inverse of the transformation matrix (cached)
public:
	Transformation() : pos(0,0,0) { tm.SetIdentity(); itm.SetIdentity(); }
	Matrix3f const& GetTransform       () const { return tm; }
	Vec3f    const& GetPosition        () const { return pos; }
	Matrix3f const&	GetInverseTransform() const { return itm; }

	Vec3f TransformTo  ( Vec3f const &p ) const { return itm * (p - pos); }	// Transform to the local coordinate system
	Vec3f TransformFrom( Vec3f const &p ) const { return tm*p + pos; }	// Transform from the local coordinate system

	// Transforms a vector to the local coordinate system (same as multiplication with the inverse transpose of the transformation)
	Vec3f VectorTransformTo( Vec3f const &dir ) const { return TransposeMult(tm,dir); }

	// Transforms a vector from the local coordinate system (same as multiplication with the inverse transpose of the transformation)
	Vec3f VectorTransformFrom( Vec3f const &dir ) const { return TransposeMult(itm,dir); }

	void Translate( Vec3f const &p ) { pos+=p; }
	void Rotate   ( Vec3f const &axis, float degrees ) { Matrix3f m; m.SetRotation(axis,degrees*(float)M_PI/180.0f); Transform(m); }
	void Scale    ( float sx, float sy, float sz )     { Matrix3f m; m.Zero(); m[0]=sx; m[4]=sy; m[8]=sz; Transform(m); }
	void Transform( Matrix3f const &m ) { tm=m*tm; pos=m*pos; tm.GetInverse(itm); }

	void InitTransform() { pos.Zero(); tm.SetIdentity(); itm.SetIdentity(); }

private:
	// Multiplies the given vector with the transpose of the given matrix
	static Vec3f TransposeMult( Matrix3f const &m, Vec3f const &dir )
	{
		Vec3f d;
		d.x = m.GetColumn(0) % dir;
		d.y = m.GetColumn(1) % dir;
		d.z = m.GetColumn(2) % dir;
		return d;
	}
};

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

class Material;

// Base class for all object types
class Object
{
public:
	virtual bool IntersectRay( Ray const &ray, HitInfo &hInfo, int hitSide=HIT_FRONT ) const=0;
	virtual Box  GetBoundBox() const=0;
	virtual void ViewportDisplay(const Material *mtl) const {}	// used for OpenGL display
};

typedef ItemFileList<Object> ObjFileList;

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

class Light : public ItemBase
{
public:
	virtual Color Illuminate(Vec3f const &p, Vec3f const &N) const=0;
	virtual Vec3f Direction (Vec3f const &p) const=0;
	virtual bool  IsAmbient () const { return false; }
	virtual void  SetViewportLight(int lightID) const {}	// used for OpenGL display
};

class LightList : public ItemList<Light> {};

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

class Material : public ItemBase
{
public:
	// The main method that handles the shading by calling all the lights in the list.
	// ray: incoming ray,
	// hInfo: hit information for the point that is being shaded, lights: the light list,
	// bounceCount: permitted number of additional bounces for reflection and refraction.
	virtual Color Shade(Ray const &ray, const HitInfo &hInfo, const LightList &lights, int bounceCount) const=0;

	virtual void SetViewportMaterial(int subMtlID=0) const {}	// used for OpenGL display
};

class MaterialList : public ItemList<Material>
{
public:
	Material* Find( char const *name ) { int n=size(); for ( int i=0; i<n; i++ ) if ( at(i) && strcmp(name,at(i)->GetName())==0 ) return at(i); return nullptr; }
};

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

class Texture : public ItemBase
{
public:
	// Evaluates the color at the given uvw location.
	virtual Color Sample(Vec3f const &uvw) const=0;

	// Evaluates the color around the given uvw location using the derivatives duvw
	// by calling the Sample function multiple times.
	virtual Color Sample(Vec3f const &uvw, Vec3f const duvw[2], bool elliptic=true) const
	{
		Color c = Sample(uvw);
		if ( duvw[0].LengthSquared() + duvw[1].LengthSquared() == 0 ) return c;
		for ( int i=1; i<TEXTURE_SAMPLE_COUNT; i++ ) {
			float x=0, y=0, fx=0.5f, fy=1.0f/3.0f;
			for ( int ix=i; ix>0; ix/=2 ) { x+=fx*(ix%2); fx/=2; }	// Halton sequence (base 2)
			for ( int iy=i; iy>0; iy/=3 ) { y+=fy*(iy%3); fy/=3; }	// Halton sequence (base 3)
			if ( elliptic ) {
				float r = sqrtf(x)*0.5f;
				x = r*sinf(y*(float)M_PI*2);
				y = r*cosf(y*(float)M_PI*2);
			} else {
				if ( x > 0.5f ) x-=1;
				if ( y > 0.5f ) y-=1;
			}
			c += Sample( uvw + x*duvw[0] + y*duvw[1] );
		}
		return c / float(TEXTURE_SAMPLE_COUNT);
	}

	virtual bool SetViewportTexture() const { return false; }	// used for OpenGL display

protected:

	// Clamps the uvw values for tiling textures, such that all values fall between 0 and 1.
	static Vec3f TileClamp(Vec3f const &uvw)
	{
		Vec3f u;
		u.x = uvw.x - (int) uvw.x;
		u.y = uvw.y - (int) uvw.y;
		u.z = uvw.z - (int) uvw.z;
		if ( u.x < 0 ) u.x += 1;
		if ( u.y < 0 ) u.y += 1;
		if ( u.z < 0 ) u.z += 1;
		return u;
	}
};

typedef ItemFileList<Texture> TextureList;

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

// This class handles textures with texture transformations.
// The uvw values passed to the Sample methods are transformed
// using the texture transformation.
class TextureMap : public Transformation
{
public:
	TextureMap() : texture(nullptr) {}
	TextureMap(Texture *tex) : texture(tex) {}
	void SetTexture(Texture *tex) { texture = tex; }

	virtual Color Sample(Vec3f const &uvw) const { return texture ? texture->Sample(TransformTo(uvw)) : Color(0,0,0); }
	virtual Color Sample(Vec3f const &uvw, Vec3f const duvw[2], bool elliptic=true) const
	{
		if ( texture == nullptr ) return Color(0,0,0);
		Vec3f u = TransformTo(uvw);
		Vec3f d[2];
		d[0] = TransformTo(duvw[0]+uvw)-u;
		d[1] = TransformTo(duvw[1]+uvw)-u;
		return texture->Sample(u,d,elliptic);
	}

	bool SetViewportTexture() const { if ( texture ) return texture->SetViewportTexture(); return false; }	// used for OpenGL display

private:
	Texture *texture;
};

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

// This class keeps a TextureMap and a color. This is useful for keeping material
// color parameters that can also be textures. If no texture is specified, it
// automatically uses the color value. Otherwise, the texture value is multiplied
// by the color value.
class TexturedColor
{
private:
	Color color;
	TextureMap *map;
public:
	TexturedColor() : color(0,0,0), map(nullptr) {}
	TexturedColor(float r, float g, float b) : color(r,g,b), map(nullptr) {}
	virtual ~TexturedColor() { if ( map ) delete map; }

	void SetColor(const Color &c) { color=c; }
	void SetTexture(TextureMap *m) { if ( map ) delete map; map=m; }

	Color GetColor() const { return color; }
	const TextureMap* GetTexture() const { return map; }

	Color Sample(Vec3f const &uvw) const { return ( map ) ? color*map->Sample(uvw) : color; }
	Color Sample(Vec3f const &uvw, Vec3f const duvw[2], bool elliptic=true) const { return ( map ) ? color*map->Sample(uvw,duvw,elliptic) : color; }

	// Returns the color value at the given direction for environment mapping.
	Color SampleEnvironment(Vec3f const &dir) const
	{ 
		float z = asinf(-dir.z)/float(M_PI)+0.5f;
		float x = dir.x / (fabs(dir.x)+fabs(dir.y));
		float y = dir.y / (fabs(dir.x)+fabs(dir.y));
		return Sample( Vec3f(0.5f,0.5f,0.0f) + z*(x*Vec3f(0.5f,0.5f,0) + y*Vec3f(-0.5f,0.5f,0)) );
	}

};

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

class Node : public ItemBase, public Transformation
{
private:
	Node **child;				// Child nodes
	int numChild;				// The number of child nodes
	Object *obj;				// Object reference (merely points to the object, but does not own the object, so it doesn't get deleted automatically)
	Material *mtl;				// Material used for shading the object
	Box childBoundBox;			// Bounding box of the child nodes, which does not include the object of this node, but includes the objects of the child nodes
public:
	Node() : child(nullptr), numChild(0), obj(nullptr), mtl(nullptr) {}
	virtual ~Node() { DeleteAllChildNodes(); }

	void Init() { DeleteAllChildNodes(); obj=nullptr; mtl=nullptr; childBoundBox.Init(); SetName(nullptr); InitTransform(); } // Initialize the node deleting all child nodes

	// Hierarchy management
	int	 GetNumChild() const { return numChild; }
	void SetNumChild(int n, int keepOld=false)
	{
		if ( n < 0 ) n=0;	// just to be sure
		Node **nc = nullptr;	// new child pointer
		if ( n > 0 ) nc = new Node*[n];
		for ( int i=0; i<n; i++ ) nc[i] = nullptr;
		if ( keepOld ) {
			int sn = Min(n,numChild);
			for ( int i=0; i<sn; i++ ) nc[i] = child[i];
		}
		if ( child ) delete [] child;
		child = nc;
		numChild = n;
	}
	Node const* GetChild( int i ) const       { return child[i]; }
	Node*       GetChild( int i )             { return child[i]; }
	void        SetChild( int i, Node *node ) { child[i]=node; }
	void        AppendChild( Node *node )     { SetNumChild(numChild+1,true); SetChild(numChild-1,node); }
	void        RemoveChild( int i )          { for ( int j=i; j<numChild-1; j++) child[j]=child[j+1]; SetNumChild(numChild-1); }
	void        DeleteAllChildNodes()         { for ( int i=0; i<numChild; i++ ) { child[i]->DeleteAllChildNodes(); delete child[i]; } SetNumChild(0); }

	// Bounding Box
	const Box& ComputeChildBoundBox()
	{
		childBoundBox.Init();
		for ( int i=0; i<numChild; i++ ) {
			Box childBox = child[i]->ComputeChildBoundBox();
			Object *cobj = child[i]->GetNodeObj();
			if ( cobj ) childBox += cobj->GetBoundBox();
			if ( ! childBox.IsEmpty() ) {
				// transform the box from child coordinates
				for ( int j=0; j<8; j++ ) childBoundBox += child[i]->TransformFrom( childBox.Corner(j) );
			}
		}
		return childBoundBox;
	}
	const Box& GetChildBoundBox() const { return childBoundBox; }

	// Object management
	Object const * GetNodeObj() const { return obj; }
	Object*        GetNodeObj()       { return obj; }
	void           SetNodeObj(Object *object) { obj=object; }

	// Material management
	const Material* GetMaterial() const { return mtl; }
	void            SetMaterial(Material *material) { mtl=material; }

	// Transformations
	Ray ToNodeCoords( Ray const &ray ) const
	{
		Ray r;
		r.p   = TransformTo(ray.p);
		r.dir = TransformTo(ray.p + ray.dir) - r.p;
		return r;
	}
	void FromNodeCoords( HitInfo &hInfo ) const
	{
		hInfo.p = TransformFrom(hInfo.p);
		hInfo.N = VectorTransformFrom(hInfo.N).GetNormalized();
	}
};

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

class Camera
{
public:
	Vec3f pos, dir, up;
	float fov;
	int imgWidth, imgHeight;

	void Init()
	{
		pos.Set(0,0,0);
		dir.Set(0,0,-1);
		up.Set(0,1,0);
		fov = 40;
		imgWidth = 200;
		imgHeight = 150;
	}
};

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

class RenderImage
{
private:
	Color24 *img;
	float   *zbuffer;
	uint8_t *zbufferImg;
	int      width, height;
	std::atomic<int> numRenderedPixels;
public:
	RenderImage() : img(nullptr), zbuffer(nullptr), zbufferImg(nullptr), width(0), height(0), numRenderedPixels(0) {}
	void Init(int w, int h)
	{
		width=w;
		height=h;
		if (img) delete [] img;
		img = new Color24[width*height];
		if (zbuffer) delete [] zbuffer;
		zbuffer = new float[width*height];
		if (zbufferImg) delete [] zbufferImg;
		zbufferImg = nullptr;
		ResetNumRenderedPixels();
	}

	int      GetWidth  () const { return width; }
	int      GetHeight () const { return height; }
	Color24* GetPixels ()       { return img; }
	float*   GetZBuffer()       { return zbuffer; }
	uint8_t* GetZBufferImage()  { return zbufferImg; }

	void ResetNumRenderedPixels ()       { numRenderedPixels=0; }
	int  GetNumRenderedPixels   () const { return numRenderedPixels; }
	void IncrementNumRenderPixel(int n)  { numRenderedPixels+=n; }
	bool IsRenderDone           () const { return numRenderedPixels >= width*height; }

	void ComputeZBufferImage()
	{
		int size = width * height;
		if (zbufferImg) delete [] zbufferImg;
		zbufferImg = new uint8_t[size];

		float zmin=BIGFLOAT, zmax=0;
		for ( int i=0; i<size; i++ ) {
			if ( zbuffer[i] == BIGFLOAT ) continue;
			if ( zmin > zbuffer[i] ) zmin = zbuffer[i];
			if ( zmax < zbuffer[i] ) zmax = zbuffer[i];
		}
		for ( int i=0; i<size; i++ ) {
			if ( zbuffer[i] == BIGFLOAT ) zbufferImg[i] = 0;
			else {
				float f = (zmax-zbuffer[i])/(zmax-zmin);
				int c = int(f * 255);
				if ( c < 0 ) c = 0;
				if ( c > 255 ) c = 255;
				zbufferImg[i] = c;
			}
		}
	}

	bool SaveImage (char const *filename) const { return SavePNG(filename,&img[0].r,3); }
	bool SaveZImage(char const *filename) const { return SavePNG(filename,zbufferImg,1); }

private:
	bool SavePNG(char const *filename, uint8_t *data, int compCount) const
	{
		LodePNGColorType colortype;
		switch( compCount ) {
			case 1: colortype = LCT_GREY; break;
			case 3: colortype = LCT_RGB;  break;
			default: return false;
		}
		unsigned int error = lodepng::encode(filename,data,width,height,colortype,8);
		return error == 0;
	}
};

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

#endif