//-------------------------------------------------------------------------------
///
/// \file       scene.h 
/// \author     Cem Yuksel (www.cemyuksel.com)
/// \version    1.0
/// \date       August 21, 2019
///
/// \brief Example source for CS 6620 - University of Utah.
///
//-------------------------------------------------------------------------------

#ifndef _SCENE_H_INCLUDED_
#define _SCENE_H_INCLUDED_

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

#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 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
	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

	HitInfo() { Init(); }
	void Init() { z=BIGFLOAT; node=nullptr; front=true; }
};

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

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;
	}
};

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

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

typedef ItemFileList<Object> ObjFileList;

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

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)
public:
	Node() : child(nullptr), numChild(0), obj(nullptr) {}
	virtual ~Node() { DeleteAllChildNodes(); }

	void Init() { DeleteAllChildNodes(); obj=nullptr; 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); }

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

	// 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;
	}
};

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

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