/*
 *        Polygon Reduction Demo by Stan Melax (c) 1998
 *  Permission to use any of this code wherever you want is granted..
 *  Although, please do acknowledge authorship if appropriate.
 *
 *  This module contains the window setup code, mouse input, timing
 *  routines, and that sort of stuff.  The interesting modules
 *  to see are bunnygut.cpp and progmesh.cpp.
 *
 *  The windows 95 specific code for this application was taken from
 *  an example of processing mouse events in an OpenGL program using
 *  the Win32 API from the www.opengl.org web site.
 *
 *  Under Project->Settings, Link Options, General Category
 *  Add:
 *        Opengl32.lib glu32.lib winmm.lib
 *  to the Object/Library Modules
 *
 *  You will need have OpenGL libs and include files to compile this
 *  Go to the www.opengl.org web site if you need help with this.
 */


#include <windows.h>	/* must include this before GL/gl.h */
#include <GL/gl.h>		/* OpenGL header file */
#include <GL/glu.h>		/* OpenGL utilities header file */
#include <stdio.h>
#include <sys/types.h>
#include <sys/timeb.h>
#include <time.h>

#include "vector.h"
#include "font.h"

// Functions and Variables from bunny module
extern void       InitModel();
extern void       RenderModel();
extern Vector     model_position;      // position of bunny
extern Quaternion model_orientation;   // orientation of bunny

// Global Variables
float   DeltaT = 0.1f;
float   FPS;
int 	Width  = 512;
int 	Height = 512;
int     MouseX = 0;
int     MouseY = 0;
Vector  MouseVector;      // 3D direction mouse points
Vector  OldMouseVector;
int     MouseState=0;     // true iff left button down
float 	ViewAngle=45.0f;

HDC hDC;                /* device context */
HPALETTE hPalette = 0;  /* custom palette (if needed) */


void CalcFPSDeltaT(){
	static int timeinit=0;
	static int start,start2,current,last;
	static int frame=0, frame2=0;
	if(!timeinit){
		frame=0;
		start=timeGetTime();
		timeinit=1;
	}
	frame++;
	frame2++;
	current=timeGetTime(); // found in winmm.lib
	double dif=(double)(current-start)/CLOCKS_PER_SEC;
	double rv = (dif)? (double)frame/(double)dif:-1.0;
	if(dif>2.0 && frame >10) {
		start  = start2;
		frame  = frame2;
		start2 = timeGetTime();
		frame2 = 0;
	}
	DeltaT = (float)(current-last)/CLOCKS_PER_SEC;
	if(current==last) {
		DeltaT = 0.1f/CLOCKS_PER_SEC;  // it just cant be 0
	}
	// if(DeltaT>1.0) DeltaT=1.0;
	FPS = (float)rv;
	last = current;
}


void ComputeMouseVector(){
	OldMouseVector=MouseVector;
	float spread = (float)tan(ViewAngle/2*3.14/180);
	float y = spread * ((Height-MouseY)-Height/2.0f) /(Height/2.0f);
    float x = spread * (MouseX-Width/2.0f)  /(Height/2.0f);
    Vector v(x ,y,-1);
    // v=UserOrientation *v;
    v=normalize(v);
	MouseVector = v;
}

Quaternion VirtualTrackBall(Vector cop,Vector cor,Vector dir1,Vector dir2) {
	// Implement track ball functionality to spin stuf on the screen
	//  cop   center of projection
	//  cor   center of rotation
	//  dir1  old mouse direction
	//  dir2  new mouse direction
	// pretend there is a sphere around cor.  Then find the points
	// where dir1 and dir2 intersect that sphere.  Find the
	// rotation that takes the first point to the second.
	float m;
	// compute plane
	Vector nrml = cor - cop;
	float fudgefactor = 1.0f/(magnitude(nrml) * 0.25f); // since trackball proportional to distance from cop
	nrml = normalize(nrml);
	float dist = -(nrml^cor);
	Vector u= planelineintersection(nrml,dist,cop,cop+dir1);
	u=u-cor;
	u=u*fudgefactor;
	m= magnitude(u);
	if(m>1) {u=u*1.0f/m;}
	else {
		u=u - (nrml * (float)sqrt(1-m*m));
	}
	Vector v= planelineintersection(nrml,dist,cop,cop+dir2);
	v=v-cor;
	v=v*fudgefactor;
	m= magnitude(v);
	if(m>1) {v=v*1.0f/m;}
	else {
		v=v - (nrml * (float)sqrt(1-m*m));
	}
	Vector axis = u*v;
	float angle;
	m=magnitude(axis);
	if(m>1)m=1; // avoid potential floating point error
	Quaternion q(Vector(1.0f,0.0f,0.0f),0.0f);
	if(m>0 && (angle=(float)asin(m))>3.14/180) {
 			axis = normalize(axis);
  			q=Quaternion(axis,angle);
	}
	return q;
}

void SpinIt(){
	// Change the orientation of the bunny according to mouse drag
	Quaternion q=VirtualTrackBall(Vector(0,0,0),model_position,
	                              OldMouseVector,MouseVector);
	model_orientation=q*model_orientation;
}

void Reshape(int width, int height){
	// called initially and when the window changes size
	Width=width;
	Height=height;
    glViewport(0, 0, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(ViewAngle, (float)width/height, 0.1, 50.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void PrintStats(){
	char buf[1024];buf[0]='\0';
	sprintf(buf,"FPS: %5.2f   ",FPS);
	PostString(buf,0,-1,0);
}

void Display(){
	// main drawing routine - called every frame
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();
	glLoadIdentity();
	// camera at default (zero) position and orientation
	RenderModel();
	PrintStats();
	glLoadIdentity();
	RenderStrings();
    glPopMatrix();
    glFlush();
    SwapBuffers(hDC);			/* nop if singlebuffered */
}


LONG WINAPI WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    static PAINTSTRUCT ps;
    static GLboolean left  = GL_FALSE;	/* left button currently down? */
    static GLboolean right = GL_FALSE;	/* right button currently down? */
    static int omx, omy, mx, my;

    switch(uMsg) {
    case WM_PAINT:
		BeginPaint(hWnd, &ps);
		EndPaint(hWnd, &ps);
		return 0;
    case WM_SIZE:
		Reshape(LOWORD(lParam), HIWORD(lParam));
		PostMessage(hWnd, WM_PAINT, 0, 0);
		return 0;
    case WM_CHAR:
		switch (wParam) {
			case 27: /* ESC key */
			    PostQuitMessage(0);
			    break;
		}
		return 0;

	case WM_LBUTTONDOWN:
	    /* if we don't set the capture we won't get mouse move
           messages when the mouse moves outside the window. */
		SetCapture(hWnd);
		MouseX = LOWORD(lParam);
		MouseY = HIWORD(lParam);
		ComputeMouseVector();
		MouseState = 1;
		return 0;

    case WM_LBUTTONUP:
		MouseX = LOWORD(lParam);
		MouseY = HIWORD(lParam);
	    if(MouseX & 1 << 15) MouseX -= (1 << 16);
	    if(MouseY & 1 << 15) MouseY -= (1 << 16);
		ComputeMouseVector();
		if(MouseState) SpinIt();
		MouseState=0;
		/* remember to release the capture when we are finished. */
		ReleaseCapture();
		return 0;

    case WM_MOUSEMOVE:
		MouseX = LOWORD(lParam);
		MouseY = HIWORD(lParam);
	    /* Win32 is pretty braindead about the x, y position that
	       it returns when the mouse is off the left or top edge
	       of the window (due to them being unsigned). therefore,
	       roll the Win32's 0..2^16 pointer co-ord range to the
	       more amenable (and useful) 0..+/-2^15. */
	    if(MouseX & 1 << 15) MouseX -= (1 << 16);
	    if(MouseY & 1 << 15) MouseY -= (1 << 16);
		ComputeMouseVector();
		if(MouseState) SpinIt();
		return 0;

    case WM_PALETTECHANGED:
		if (hWnd == (HWND)wParam) break;
		/* fall through to WM_QUERYNEWPALETTE */
    case WM_QUERYNEWPALETTE:
		if (hPalette) {
		    UnrealizeObject(hPalette);
		    SelectPalette(hDC, hPalette, FALSE);
		    RealizePalette(hDC);
		    return TRUE;
		}
		return FALSE;

    case WM_CLOSE:
		PostQuitMessage(0);
		return 0;
    }
    return DefWindowProc(hWnd, uMsg, wParam, lParam);
}

HWND CreateOpenGLWindow(char* title)
{
	// make a double-buffered, rgba, opengl window
    int         n, pf;
    HWND        hWnd;
    WNDCLASS    wc;
    LOGPALETTE* lpPal;
    PIXELFORMATDESCRIPTOR pfd;
    static HINSTANCE hInstance = 0;

    /* only register the window class once - use hInstance as a flag. */
    if (!hInstance) {
		hInstance = GetModuleHandle(nullptr);
		wc.style         = CS_OWNDC;
		wc.lpfnWndProc   = (WNDPROC)WindowProc;
		wc.cbClsExtra    = 0;
		wc.cbWndExtra    = 0;
		wc.hInstance     = hInstance;
		wc.hIcon         = LoadIcon(nullptr, IDI_WINLOGO);
		wc.hCursor       = LoadCursor(nullptr, IDC_ARROW);
		wc.hbrBackground = nullptr;
		wc.lpszMenuName  = nullptr;
		wc.lpszClassName = "OpenGL";

		if (!RegisterClass(&wc)) {
			MessageBox(nullptr, "RegisterClass() failed:  "
				   "Cannot register window class.", "Error", MB_OK);
			return nullptr;
		}
    }

    hWnd = CreateWindow("OpenGL", title, WS_OVERLAPPEDWINDOW |
			WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
			0,0,Width,Height, nullptr, nullptr, hInstance, nullptr);

    if (hWnd == nullptr) {
		MessageBox(nullptr, "CreateWindow() failed:  Cannot create a window.",
			   "Error", MB_OK);
		return nullptr;
    }

    hDC = GetDC(hWnd);

    /* there is no guarantee that the contents of the stack that become
       the pfd are zeroed, therefore _make sure_ to clear these bits. */
    memset(&pfd, 0, sizeof(pfd));
    pfd.nSize        = sizeof(pfd);
    pfd.nVersion     = 1;
    pfd.dwFlags      = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
    pfd.iPixelType   = PFD_TYPE_RGBA;
    pfd.cDepthBits   = 32;
    pfd.cColorBits   = 32;

    pf = ChoosePixelFormat(hDC, &pfd);
    if (pf == 0) {
		MessageBox(nullptr, "ChoosePixelFormat() failed:  "
			   "Cannot find a suitable pixel format.", "Error", MB_OK);
		return 0;
    }

    if (SetPixelFormat(hDC, pf, &pfd) == FALSE) {
		MessageBox(nullptr, "SetPixelFormat() failed:  "
			   "Cannot set format specified.", "Error", MB_OK);
		return 0;
    }

    DescribePixelFormat(hDC, pf, sizeof(PIXELFORMATDESCRIPTOR), &pfd);

    if (pfd.dwFlags & PFD_NEED_PALETTE ||
		pfd.iPixelType == PFD_TYPE_COLORINDEX) {

		n = 1 << pfd.cColorBits;
		if (n > 256) n = 256;

		lpPal = (LOGPALETTE*)malloc(sizeof(LOGPALETTE) +
						sizeof(PALETTEENTRY) * n);
		memset(lpPal, 0, sizeof(LOGPALETTE) + sizeof(PALETTEENTRY) * n);
		lpPal->palVersion = 0x300;
		lpPal->palNumEntries = n;

		GetSystemPaletteEntries(hDC, 0, n, &lpPal->palPalEntry[0]);

		/* if the pixel type is RGBA, then we want to make an RGB ramp,
		   otherwise (color index) set individual colors. */
		if (pfd.iPixelType == PFD_TYPE_RGBA) {
			int redMask = (1 << pfd.cRedBits) - 1;
			int greenMask = (1 << pfd.cGreenBits) - 1;
			int blueMask = (1 << pfd.cBlueBits) - 1;
			int i;

			/* fill in the entries with an RGB color ramp. */
			for (i = 0; i < n; ++i) {
			lpPal->palPalEntry[i].peRed =
				(((i >> pfd.cRedShift)   & redMask)   * 255)/redMask;
			lpPal->palPalEntry[i].peGreen =
				(((i >> pfd.cGreenShift) & greenMask) * 255)/greenMask;
			lpPal->palPalEntry[i].peBlue =
				(((i >> pfd.cBlueShift)  & blueMask)  * 255)/blueMask;
			lpPal->palPalEntry[i].peFlags = 0;
			}
		} else {
			lpPal->palPalEntry[0].peRed = 0;
			lpPal->palPalEntry[0].peGreen = 0;
			lpPal->palPalEntry[0].peBlue = 0;
			lpPal->palPalEntry[0].peFlags = PC_NOCOLLAPSE;
			lpPal->palPalEntry[1].peRed = 255;
			lpPal->palPalEntry[1].peGreen = 0;
			lpPal->palPalEntry[1].peBlue = 0;
			lpPal->palPalEntry[1].peFlags = PC_NOCOLLAPSE;
			lpPal->palPalEntry[2].peRed = 0;
			lpPal->palPalEntry[2].peGreen = 255;
			lpPal->palPalEntry[2].peBlue = 0;
			lpPal->palPalEntry[2].peFlags = PC_NOCOLLAPSE;
			lpPal->palPalEntry[3].peRed = 0;
			lpPal->palPalEntry[3].peGreen = 0;
			lpPal->palPalEntry[3].peBlue = 255;
			lpPal->palPalEntry[3].peFlags = PC_NOCOLLAPSE;
		}

		hPalette = CreatePalette(lpPal);
		if (hPalette) {
			SelectPalette(hDC, hPalette, FALSE);
			RealizePalette(hDC);
		}

		free(lpPal);
    }

    ReleaseDC(hDC, hWnd);
    return hWnd;
}

int APIENTRY WinMain(HINSTANCE hCurrentInst, HINSTANCE hPreviousInst,
	LPSTR lpszCmdLine, int nCmdShow)
{
    HGLRC hRC;				/* opengl context */
    HWND  hWnd;				/* window */
    MSG   msg;				/* message */

	// InitModel() initializes some data structures and
	// does the progressive mesh polygon reduction algorithm
	// on the model.
	CalcFPSDeltaT(); // to time the algorithm
	InitModel();
	CalcFPSDeltaT();

	hWnd = CreateOpenGLWindow("bunnylod by Stan Melax");
    if (hWnd == nullptr) exit(1);

    hDC = GetDC(hWnd);
    hRC = wglCreateContext(hDC);
    wglMakeCurrent(hDC, hRC);
    ShowWindow(hWnd, nCmdShow);
	glEnable(GL_DEPTH_TEST);

	PostString("Demo by Stan Melax (c)1998",5,-5,20);
	PostString("Model by Viewpoint Datalabs (c)1996",5,-4,20);
	char buf[128];
	PostString("Mesh Reduction Algorithm (non-optimized)",1,0,5);
	sprintf(buf,"was executed in %5.3f seconds",DeltaT);
	PostString(buf,2,1,6);

    while (1) {
		while(PeekMessage(&msg, hWnd, 0, 0, PM_NOREMOVE)) {
		    if(GetMessage(&msg, hWnd, 0, 0)) {
				TranslateMessage(&msg);
				DispatchMessage(&msg);
		    } else {
				goto quit; // This 'goto' was in the sample code
		    }
		}
		CalcFPSDeltaT();
		Display();
    }

  quit:
    wglMakeCurrent(nullptr, nullptr);
    ReleaseDC(hDC, hWnd);
    wglDeleteContext(hRC);
    DestroyWindow(hWnd);
    if (hPalette) DeleteObject(hPalette);
    return msg.wParam;
}