#include <vhex/display/image.h>
#include <vhex/defs/utils.h>

/* image_valid(): Check if an image is valid */
bool image_valid(image_t const *img)
{
	if(img == NULL)
		return (false);

	if(IMAGE_IS_RGB16(img->format)) {
		return (img->data != NULL);
	}
	if(IMAGE_IS_P8(img->format) || IMAGE_IS_P4(img->format)) {
		return (
			(img->data != NULL)
			&& (img->palette != NULL)
			&& (img->color_count != 0)
		);
	}

	return (false);
}

/* image_alpha(): Get the alpha value for an image format */
int image_alpha(int format)
{
	switch(format)
	{
		case IMAGE_RGB565A:
			return (0x0001);
		case IMAGE_P8_RGB565A:
			return (0);
		case IMAGE_P4_RGB565A:
			return (0);
		default:
			/* A value that cannot be found in any pixel of any format */
			return (0x10000);
	}
}

/* image_get_pixel(): Read a pixel from the data array */
int image_get_pixel(image_t const *img, int x, int y)
{
	if((unsigned)x >= img->width || (unsigned)y >= img->height)
		return (0);

	void *data = img->data + (y * img->stride);
	uint8_t *data_u8 = data;
	uint16_t *data_u16 = data;

	if(IMAGE_IS_RGB16(img->format)) {
		return (data_u16[x]);
	}
	else if(IMAGE_IS_P8(img->format)) {
		return ((int8_t)data_u8[x]);
	}
	else if(IMAGE_IS_P4(img->format)) {
		if(x & 1) {
			return (data_u8[x >> 1] & 0x0f);
		} else {
			return (data_u8[x >> 1] >> 4);
		}
	}

	return (0);
}

/* image_decode_pixel(): Decode a pixel value */
int image_decode_pixel(image_t const *img, int pixel)
{
	if(IMAGE_IS_RGB16(img->format))
		return (pixel);
	else if(IMAGE_IS_P8(img->format))
		return (img->palette[pixel]);
	else if(IMAGE_IS_P4(img->format))
		return (img->palette[pixel]);
	return (-1);
}

/* image_data_size(): Compute the size of the [data] array */
int image_data_size(image_t const *img)
{
    return (img->stride * img->height);
}