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

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

extern uint8 romdisk[];
KOS_INIT_ROMDISK(romdisk);

/* storage for one texture  */
int texture[1];

/* Image type - contains height, width, and data */
struct Image
{
    unsigned long sizeX;
    unsigned long sizeY;
    char *data;
};
typedef struct Image Image;

// quick and dirty bitmap loader...for 24 bit bitmaps with 1 plane only.
// See http://www.dcs.ed.ac.uk/~mxr/gfx/2d/BMP.txt for more info.
int ImageLoad(char *filename, Image *image)
{
    FILE *file;
    unsigned long size;        // size of the image in bytes.
    unsigned long i;           // standard counter.
    unsigned short int planes; // number of planes in image (must be 1)
    unsigned short int bpp;    // number of bits per pixel (must be 24)
    char temp;                 // temporary color storage for bgr-rgb conversion.

    // make sure the file is there.
    if ((file = fopen(filename, "rb")) == NULL)
    {
        printf("File Not Found : %s\n", filename);
        return 0;
    }

    // seek through the bmp header, up to the width/height:
    fseek(file, 18, SEEK_CUR);

    // read the width
    if ((i = fread(&image->sizeX, 4, 1, file)) != 1)
    {
        printf("Error reading width from %s.\n", filename);
        return 0;
    }
    printf("Width of %s: %lu\n", filename, image->sizeX);

    // read the height
    if ((i = fread(&image->sizeY, 4, 1, file)) != 1)
    {
        printf("Error reading height from %s.\n", filename);
        return 0;
    }
    printf("Height of %s: %lu\n", filename, image->sizeY);

    // calculate the size (assuming 24 bits or 3 bytes per pixel).
    size = image->sizeX * image->sizeY * 3;

    // read the planes
    if ((fread(&planes, 2, 1, file)) != 1)
    {
        printf("Error reading planes from %s.\n", filename);
        return 0;
    }
    if (planes != 1)
    {
        printf("Planes from %s is not 1: %u\n", filename, planes);
        return 0;
    }

    // read the bpp
    if ((i = fread(&bpp, 2, 1, file)) != 1)
    {
        printf("Error reading bpp from %s.\n", filename);
        return 0;
    }
    if (bpp != 24)
    {
        printf("Bpp from %s is not 24: %u\n", filename, bpp);
        return 0;
    }

    // seek past the rest of the bitmap header.
    fseek(file, 24, SEEK_CUR);

    // read the data.
    image->data = (char *)malloc(size);
    if (image->data == NULL)
    {
        printf("Error allocating memory for color-corrected image data");
        return 0;
    }

    if ((i = fread(image->data, size, 1, file)) != 1)
    {
        printf(stderr, "Error reading image data from %s.\n", filename);
        return 0;
    }

    for (i = 0; i < size; i += 3)
    { // reverse all of the colors. (bgr -> rgb)
        temp = image->data[i];
        image->data[i] = image->data[i + 2];
        image->data[i + 2] = temp;
    }

    // we're done.
    return 1;
}

char colors[8][3] = {{255, 0, 0},
                     {255, 128, 0},
                     {255, 255, 0},
                     {128, 255,0},
                     {0, 255, 0},
                     {0, 255, 128},
                     {0, 255, 255},
                     {0, 128, 255}};

int marker = 0;

char *miplevel(int w, int h, char *data)
{
    GLuint sx, sy, i;
    //GLubyte *prevData = data;
    GLubyte *thisData = malloc(w * h * 3);

    /* Do the minification */
    for (sx = 0; sx < w * h; sx++)
    {
        for (i = 0; i < 3; i++)
        {
            thisData[(sx*3) + i] = colors[marker][i];
        }
    }
    marker++;
    return thisData;
}

// 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 (!ImageLoad("/rd/NeHe.bmp", image1))
    {
        exit(1);
    }

    // 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_MIPMAP_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, 3, image1->sizeX, image1->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, image1->data);

    GLuint thisWidth = image1->sizeX;
    int levels = 0;
    while(thisWidth > 1){
        thisWidth /= 2;
        char *newData = miplevel(thisWidth, thisWidth, image1->data);
        glTexImage2D(GL_TEXTURE_2D, ++levels, 3, thisWidth, thisWidth, 0, GL_RGB, GL_UNSIGNED_BYTE, newData);
        free(newData);
    }
};

/* 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);
}

void DrawQuad()
{
    glBegin(GL_QUADS);
    glTexCoord2f(0.0f, 0.0f);
    glVertex3f(-1.0f, -1.0f, 0.0f); // Bottom Left Of The Texture and Quad
    glTexCoord2f(1.0f, 0.0f);
    glVertex3f(1.0f, -1.0f, 0.0f); // Bottom Right Of The Texture and Quad
    glTexCoord2f(1.0f, 1.0f);
    glVertex3f(1.0f, 1.0f, 0.0f); // Top Right Of The Texture and Quad
    glTexCoord2f(0.0f, 1.0f);
    glVertex3f(-1.0f, 1.0f, 0.0f); // Top Left Of The Texture and Quad
    glEnd();                       // done with the polygon.
}

static GLboolean mipmap_enabled = GL_FALSE;
static GLuint timer = 0;
static GLint mipbias = -7;

void movebias(void) {
    mipbias++;
    if(mipbias > 7){
        mipbias = -7;
    }
}

/* The main drawing function. */
void DrawGLScene()
{
    timer++;
    if (timer > 60)
    {
        timer = 0;
        mipmap_enabled = !mipmap_enabled;

        if (mipmap_enabled)
        {
            printf("Enabling mipmaps!\n");
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
            movebias();
        }
        else
        {
            printf("Disabling mipmaps!\n");
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        }
    }

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    glClearColor(0.5, 0.5, 0.5, 1.0);

    glBindTexture(GL_TEXTURE_2D, texture[0]);
    glTexEnvi(GL_TEXTURE_FILTER_CONTROL_EXT, GL_TEXTURE_LOD_BIAS_EXT, mipbias);

    glTranslatef(-0.5f, 0.0f, -2.5f);
    DrawQuad();

    glTranslatef(1.0f, 0.0f, -5.0f);
    DrawQuad();

    glTranslatef(1.5f, 0.0f, -5.0f);
    DrawQuad();

    glTranslatef(2.0f, 0.0f, -5.0f);
    DrawQuad();

    glTranslatef(3.5f, 0.0f, -5.0f);
    DrawQuad();

    glKosSwapBuffers();
}

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

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

    while (1)
    {
        DrawGLScene();
    }

    return 0;
}