#include <stdlib.h>
#include <stdio.h>
//#include <OpenGL/gl.h>

#include <objc/message.h>
#include <objc/runtime.h>

typedef struct CMPoint
    {
    double x;
    double y;
    } CMPoint;

typedef struct CMSize
    {
    double width;
    double height;
    } CMSize;

typedef struct CMRect
    {
    CMPoint origin;
    CMSize size;
    } CMRect;

typedef struct AppDel
    {
    Class isa;
    id window; // Will be an NSWindow later.
    } AppDelegate;

enum
    {
    NSBorderlessWindowMask      = 0,
    NSTitledWindowMask          = 1 << 0,
    NSClosableWindowMask        = 1 << 1,
    NSMiniaturizableWindowMask  = 1 << 2,
    NSResizableWindowMask       = 1 << 3,
    };

typedef id(*CMacsSimpleMessage)(id, SEL);
typedef void(*CMacsVoidMessage)(id, SEL);
typedef void(*CMacsVoidMessage1)(id, SEL, void *);
typedef id(*CMacsRectMessage1)(id, SEL, CMRect);
typedef id(*CMacsWindowInitMessage)(id, SEL, CMRect, int, int, bool);

CMacsSimpleMessage cmacs_simple_msgSend = (CMacsSimpleMessage)objc_msgSend;
CMacsVoidMessage cmacs_void_msgSend  = (CMacsVoidMessage)objc_msgSend;
CMacsVoidMessage1 cmacs_void_msgSend1 = (CMacsVoidMessage1)objc_msgSend;
CMacsRectMessage1 cmacs_rect_msgSend1 = (CMacsRectMessage1)objc_msgSend;
CMacsWindowInitMessage cmacs_window_init_msgSend = (CMacsWindowInitMessage)objc_msgSend;

#define GLCALLTYPE

#define GL_COLOR_BUFFER_BIT                                 0x00004000
typedef unsigned int GLbitfield;
typedef unsigned char GLboolean;
typedef signed char GLbyte;
typedef char GLchar;
typedef float GLclampf;
typedef unsigned int GLenum;
typedef int GLfixed;
typedef float GLfloat;
typedef unsigned short GLhalf;
typedef long long GLint64;
typedef int GLint;
typedef intptr_t GLintptr;
typedef short GLshort;
typedef int GLsizei;
typedef size_t GLsizeiptr;
typedef struct __GLsync *GLsync;
typedef unsigned char GLubyte;
typedef unsigned long long GLuint64;
typedef unsigned int GLuint;
typedef unsigned short GLushort;
typedef void GLvoid;

void (GLCALLTYPE* glClearColor) (GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha) = 0;
void (GLCALLTYPE* glClear) (GLbitfield mask) = 0;
void (GLCALLTYPE* glFlush) (void) = 0;

// This is a simple -drawRect implementation for our class. We could have
// used a NSTextField  or something of that sort instead, but I felt that this
// stuck with the C-based mentality of the application.
void View_drawRect(id self, SEL _cmd, CMRect rect)
    {
    printf( "rect %f, %f, %f, %f\n", rect.origin.x, rect.origin.y, rect.size.width, rect.size.height );

    glClearColor(1, 0, 1, 0);
    glClear(GL_COLOR_BUFFER_BIT);
    //drawAnObject();
    glFlush();
    }

BOOL AppDel_didFinishLaunching(AppDelegate *self, SEL _cmd, id notification) {
    self->window = cmacs_simple_msgSend((id)objc_getClass("NSWindow"), sel_getUid("alloc"));

    /// Create an instance of the window.
    self->window = cmacs_window_init_msgSend(self->window, sel_getUid("initWithContentRect:styleMask:backing:defer:"), (CMRect){0,0,1024,460}, (NSTitledWindowMask | NSClosableWindowMask | NSResizableWindowMask | NSMiniaturizableWindowMask), 0, false);

    /// Create an instance of our view class.
    ///
    /// Relies on the view having declared a constructor that allocates a class pair for it.
    id view = cmacs_rect_msgSend1(cmacs_simple_msgSend((id)objc_getClass("View"), sel_getUid("alloc")), sel_getUid("initWithFrame:"), (CMRect){ 0, 0, 320, 480 });

    // here we simply add the view to the window.
    cmacs_void_msgSend1(self->window, sel_getUid("setContentView:"), view);
    cmacs_simple_msgSend(self->window, sel_getUid("becomeFirstResponder"));

    // Shows our window in the bottom-left hand corner of the screen.
    cmacs_void_msgSend1(self->window, sel_getUid("makeKeyAndOrderFront:"), self);
    return YES;
}

void RunApplication(void)
    {
    // Once again, just like the app delegate, we tell the runtime to
    // create a new class, this time a subclass of 'UIView' and named 'View'.
    Class ViewClass = objc_allocateClassPair((Class)objc_getClass("NSOpenGLView"), "View", 0);

    // and again, we tell the runtime to add a function called -drawRect:
    // to our custom view. Note that there is an error in the type-specification
    // of this method, as I do not know the @encode sequence of 'CGRect' off
    // of the top of my head. As a result, there is a chance that the rect
    // parameter of the method may not get passed properly.
    class_addMethod(ViewClass, sel_getUid("drawRect:"), (IMP) View_drawRect, "v@:");

    // And again, we tell the runtime that this class is now valid to be used.
    // At this point, the application should run and display the screenshot shown below.
    objc_registerClassPair(ViewClass);

    // Create app delegate
    Class AppDelClass = objc_allocateClassPair( (Class) objc_getClass("NSObject"), "AppDelegate", 0 );
    class_addMethod(AppDelClass, sel_getUid( "applicationDidFinishLaunching:" ), (IMP) AppDel_didFinishLaunching, "i@:@" );
    objc_registerClassPair(AppDelClass);

    // Run
    id app = cmacs_simple_msgSend((id)objc_getClass("NSApplication"), sel_getUid("sharedApplication"));

    if (app == NULL)
        {
        fprintf(stderr,"Failed to initialized NSApplication...  terminating...\n");
        return;
        }

    id appDelObj = cmacs_simple_msgSend((id)objc_getClass("AppDelegate"), sel_getUid("alloc"));
    appDelObj = cmacs_simple_msgSend(appDelObj, sel_getUid("init"));

    cmacs_void_msgSend1(app, sel_getUid("setDelegate:"), appDelObj);
    cmacs_void_msgSend(app, sel_getUid("run"));
    }


#include <dlfcn.h>
#include <stdlib.h>
#include <string.h>

void* GLGetProcAddress (const char* name)
    {
    static void* image = NULL;
    if (NULL == image)
        image = dlopen("/System/Library/Frameworks/OpenGL.framework/Versions/Current/OpenGL", RTLD_LAZY);

    return (image ? dlsym(image, (const char *)name) : NULL);
    }


int main( int argc, char** argv )
    {
    glClearColor = GLGetProcAddress( "glClearColor" );
    glClear = GLGetProcAddress( "glClear" );
    glFlush = GLGetProcAddress( "glFlush" );
    printf( "hello world\n" );
    RunApplication();
    return 0;
    }