#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <assert.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;

#pragma pack(push)
#pragma pack(1)

/* PCX header */
typedef struct {
    uint8_t manufacturer;
    uint8_t version;
    uint8_t encoding;
    uint8_t bits_per_pixel;

    uint16_t xmin, ymin;
    uint16_t xmax, ymax;
    uint16_t horz_res, vert_res;

    uint8_t palette[48];
    uint8_t reserved;
    uint8_t num_color_planes;

    uint16_t bytes_per_scan_line;
    uint16_t palette_type;
    uint16_t horz_size, vert_size;

    uint8_t padding[54];
} Header;

#pragma pack(pop)

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

    Header header;

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

    if(header.manufacturer != 0x0a) {
        printf("Invalid file\n");
        return 0;
    }

    /* Read the rest of the file */
    long pos = ftell(filein);
    fseek(filein, 0, SEEK_END);
    long end = ftell(filein);
    fseek(filein, pos, SEEK_SET);

    long size = end - pos;
    uint8_t* buffer = (uint8_t*) malloc(size);
    fread(buffer, 1, size, filein);

    image->width = header.xmax - header.xmin + 1;
    image->height = header.ymax - header.ymin + 1;
    image->data = (char*) malloc(sizeof(char) * image->width * image->height);

    int bitcount = header.bits_per_pixel * header.num_color_planes;
    if(bitcount != 8) {
        printf("Wrong bitcount\n");
        return 0;
    }

    uint8_t palette_marker = buffer[size - 769];

    const uint8_t* palette = (palette_marker == 12) ? &buffer[size - 768] : header.palette;

    image->palette_width = (palette_marker == 12) ? 256 : 16;
    image->palette = (char*) malloc(sizeof(char) * 3 * image->palette_width);
    memcpy(image->palette, palette, sizeof(char) * 3 * image->palette_width);

    int32_t rle_count = 0;
    int32_t rle_value = 0;

    const uint8_t* image_data = buffer;

    uint32_t idx;
    for(idx = 0; idx < (image->width * image->height); idx++) {
        if(rle_count == 0) {
            rle_value = *image_data;
            ++image_data;
            if((rle_value & 0xc0) == 0xc0) {
                rle_count = rle_value & 0x3f;
                rle_value = *image_data;
                ++image_data;
            } else {
                rle_count = 1;
            }
        }

        rle_count--;

        assert(rle_value < 256);

        image->data[idx] = rle_value;
    }

    free(buffer);

    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 (!LoadPalettedPCX("/rd/NeHe.pcx", image1)) {
        exit(1);
    }

    glEnable(GL_SHARED_TEXTURE_PALETTE_EXT);
    glColorTableEXT(GL_SHARED_TEXTURE_PALETTE_EXT, GL_RGBA8, image1->palette_width, GL_RGB, 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, 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;
}