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

#include "gl.h"
#include "glext.h"
#include "glu.h"
#include "glkos.h"

extern uint8 romdisk[];
KOS_INIT_ROMDISK(romdisk);

/* floats for x rotation, y rotation, z rotation */
float xrot, yrot, zrot;
/* storage for one texture  */
int texture[1];

typedef struct {
    unsigned int height;
    unsigned int width;
    unsigned int palette_width;
    char* palette;
    char* data;
} Image;

int LoadPalettedTex(const char* filename, Image* image) {
    struct {
        char	id[4];	// 'DTEX'
        short	width;
        short	height;
        int		type;
        int		size;
    } header;

    FILE* filein = NULL;
    filein = fopen(filename, "rb");
    if(!filein) {
        printf("Unable to open file\n");
        return 0;
    }

    fread(&header, sizeof(header), 1, filein);

    if((header.type & (7 << 27)) >> 27 != 6) {
        printf("Not PAL8BPP format\n");
        return 0;
    }

    image->width = header.width;
    image->height = header.height;
    image->data = (char*) malloc(sizeof(char) * header.size);

    fread(image->data, header.size, sizeof(char), filein);
    fclose(filein);

    char palette_filename[100];

    strcpy(palette_filename, filename);
    strcat(palette_filename, ".pal");

    filein = fopen(palette_filename, "rb");
    if(!filename) {
        printf("Unable to open the palette file\n");
        return 0;
    }

    struct {
        char id[4];
        int numcolors;
    } palette_header;
    fread(&palette_header, sizeof(palette_header), 1, filein);

    image->palette = (unsigned int*) malloc(sizeof(unsigned int) * palette_header.numcolors);
    image->palette_width = palette_header.numcolors;

    fread(image->palette, sizeof(unsigned int), palette_header.numcolors, filein);

    unsigned int i = 0;
    for(; i < palette_header.numcolors; ++i) {
        unsigned int* p = (unsigned int*) image->palette;

        // Swap the colours around from ARGB to RGBA
        char r = (p[i] & 0x00FF0000) >> 16;
        char g = (p[i] & 0x0000FF00) >> 8;
        char b = (p[i] & 0x000000FF);
        char a = (p[i] & 0xFF000000) >> 24;

        image->palette[i * 4] = r;
        image->palette[i * 4 + 1] = g;
        image->palette[i * 4 + 2] = b;
        image->palette[i * 4 + 3] = a;
    }

    return 1;
}

// Load Bitmaps And Convert To Textures
void LoadGLTextures() {
    // Load Texture
    Image *image1;

    // allocate space for texture
    image1 = (Image *) malloc(sizeof(Image));
    if (image1 == NULL) {
        printf("Error allocating space for image");
        exit(0);
    }

    if (!LoadPalettedTex("/rd/NeHe.tex", image1)) {
        exit(1);
    }

    glEnable(GL_SHARED_TEXTURE_PALETTE_EXT);
    glColorTableEXT(GL_SHARED_TEXTURE_PALETTE_EXT, GL_RGBA8, image1->palette_width, GL_RGBA, GL_UNSIGNED_BYTE, image1->palette);

    // Create Texture
    glGenTextures(1, &texture[0]);
    glBindTexture(GL_TEXTURE_2D, texture[0]);   // 2d texture (x and y size)

    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR); // scale linearly when image bigger than texture
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR); // scale linearly when image smalled than texture

    // 2d texture, level of detail 0 (normal), 3 components (red, green, blue), x size from image, y size from image,
    // border 0 (normal), rgb color data, unsigned byte data, and finally the data itself.
    glTexImage2D(GL_TEXTURE_2D, 0, GL_COLOR_INDEX8_EXT, image1->width, image1->height, 0, GL_COLOR_INDEX, GL_UNSIGNED_BYTE_TWID_KOS, image1->data);
}

/* A general OpenGL initialization function.  Sets all of the initial parameters. */
void InitGL(int Width, int Height)	        // We call this right after our OpenGL window is created.
{
    LoadGLTextures();
    glEnable(GL_TEXTURE_2D);
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);		// This Will Clear The Background Color To Black
    glClearDepth(1.0);				// Enables Clearing Of The Depth Buffer
    glDepthFunc(GL_LESS);				// The Type Of Depth Test To Do
    glEnable(GL_DEPTH_TEST);			// Enables Depth Testing
    glShadeModel(GL_SMOOTH);			// Enables Smooth Color Shading

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();				// Reset The Projection Matrix

    gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);	// Calculate The Aspect Ratio Of The Window

    glMatrixMode(GL_MODELVIEW);
}

/* The function called when our window is resized (which shouldn't happen, because we're fullscreen) */
void ReSizeGLScene(int Width, int Height)
{
    if (Height == 0)				// Prevent A Divide By Zero If The Window Is Too Small
        Height = 1;

    glViewport(0, 0, Width, Height);		// Reset The Current Viewport And Perspective Transformation

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);
    glMatrixMode(GL_MODELVIEW);
}


/* The main drawing function. */
void DrawGLScene()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Clear The Screen And The Depth Buffer
    glLoadIdentity();				// Reset The View

    glTranslatef(0.0f,0.0f,-5.0f);              // move 5 units into the screen.

    glRotatef(xrot,1.0f,0.0f,0.0f);		// Rotate On The X Axis
    glRotatef(yrot,0.0f,1.0f,0.0f);		// Rotate On The Y Axis
    glRotatef(zrot,0.0f,0.0f,1.0f);		// Rotate On The Z Axis

    glBindTexture(GL_TEXTURE_2D, texture[0]);   // choose the texture to use.

    glBegin(GL_QUADS);		                // begin drawing a cube

    // Front Face (note that the texture's corners have to match the quad's corners)
    glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);	// Bottom Left Of The Texture and Quad
    glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);	// Bottom Right Of The Texture and Quad
    glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);	// Top Right Of The Texture and Quad
    glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);	// Top Left Of The Texture and Quad

    // Back Face
    glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);	// Bottom Right Of The Texture and Quad
    glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);	// Top Right Of The Texture and Quad
    glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);	// Top Left Of The Texture and Quad
    glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);	// Bottom Left Of The Texture and Quad

    // Top Face
    glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);	// Top Left Of The Texture and Quad
    glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,  1.0f,  1.0f);	// Bottom Left Of The Texture and Quad
    glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,  1.0f,  1.0f);	// Bottom Right Of The Texture and Quad
    glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);	// Top Right Of The Texture and Quad

    // Bottom Face
    glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);	// Top Right Of The Texture and Quad
    glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);	// Top Left Of The Texture and Quad
    glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);	// Bottom Left Of The Texture and Quad
    glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);	// Bottom Right Of The Texture and Quad

    // Right face
    glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);	// Bottom Right Of The Texture and Quad
    glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);	// Top Right Of The Texture and Quad
    glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);	// Top Left Of The Texture and Quad
    glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);	// Bottom Left Of The Texture and Quad

    // Left Face
    glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);	// Bottom Left Of The Texture and Quad
    glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);	// Bottom Right Of The Texture and Quad
    glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);	// Top Right Of The Texture and Quad
    glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);	// Top Left Of The Texture and Quad

    glEnd();                                    // done with the polygon.

    xrot+=1.5f;		                // X Axis Rotation
    yrot+=1.5f;		                // Y Axis Rotation
    zrot+=1.5f; // Z Axis Rotation
             //
    // swap buffers to display, since we're double buffered.
    glKosSwapBuffers();
}

int main(int argc, char **argv)
{
    glKosInit();

    InitGL(640, 480);
    ReSizeGLScene(640, 480);

    while(1) {
        DrawGLScene();
    }

    return 0;
}