#include <GL/glew.h>
#include <IL/il.h>
#include <IL/ilu.h>
#include <stdlib.h>
#include <assert.h>

#include "image.h"


Image *load_image(char *filename)
{
    Image  *img;
    ILuint image_name;
    ILenum error;
    char   *error_str;
    ILint cur_format;

    ilGenImages(1, &image_name);
    ilBindImage(image_name);

    // Force OpenGL-compatible row order.
    ilEnable(IL_ORIGIN_SET);
    ilOriginFunc(IL_ORIGIN_LOWER_LEFT);

    if (ilLoadImage(filename)) {

        cur_format = ilGetInteger(IL_IMAGE_FORMAT);

        if ( cur_format == IL_COLOR_INDEX ) {

            printf("DEBUG: load_image: Image format for \"%s\" is COLOR_INDEX, converting to RGBA\n", filename);

            if ( !ilConvertImage(IL_RGBA, IL_UNSIGNED_BYTE) ) {

                fprintf(stderr, "load_image: Failed to convert color indexed image \"%s\" to RGBA.\n", filename);
                ilDeleteImages(1, &image_name);
                return NULL;
            }
        }

        img = (Image *) malloc(sizeof(Image));
        img->width  = ilGetInteger(IL_IMAGE_WIDTH);
        img->height = ilGetInteger(IL_IMAGE_HEIGHT);
        img->data   = (unsigned char *) malloc(img->width * img->height * 4);

        if( !ilCopyPixels(0, 0, 0, img->width, img->height, 1, IL_RGBA, IL_UNSIGNED_BYTE, img->data) ) {

            error = ilGetError();
            error_str = iluErrorString(error);
            fprintf(stderr, "load_image: Failed to read image data for \"%s\". (Last error given by DevIL was \"%s (code %d)\".)\n", filename, error_str, error);
            free( (void *) img->data );
            free(img);
            ilDeleteImages(1, &image_name);
            return NULL;
        }

    } else {

        fprintf(stderr, "load_image: Failed to load image \"%s\".\n", filename);
        ilDeleteImages(1, &image_name);
        return NULL;
    }

    ilDeleteImages(1, &image_name);

    return img;
}


void draw_image(Image *img, int x, int y)
{
    if ( img != NULL ) {

        glWindowPos2iARB(x, y);
        glDrawPixels(img->width, img->height, GL_RGBA, GL_UNSIGNED_BYTE, img->data);

    } else {
#ifdef DEBUG
        fprintf(stderr, "DEBUG: draw_image: Unable to draw image, img = NULL.\n");
#endif
    }
}


void delete_image(Image *img)
{
    if ( img != NULL ) {

        if ( img->data != NULL ) {

            free(img->data);

        } else {

#ifdef DEBUG
                fprintf(stderr, "DEBUG: delete_image: Warning, img->data is NULL.\n");
#endif
        }

        free(img);

    } else {

#ifdef DEBUG
            fprintf(stderr, "DEBUG draw_image: Warning, img is NULL.\n");
#endif
    }
}