#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <limits.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>


#include "joey.h"


void         convertColor(char *filename, char *basename, bool showIt);
void         convertStencil(char *filename, char *basename);
bool         fileExists(char *filename);
Uint32       getPixel(SDL_Surface *surface, int x, int y);
SDL_Surface *loadImage(char *filename);


void convertColor(char *filename, char *basename, bool showIt) {

	int          colors = INT_MAX;
	SDL_Color   *c      = NULL;
	SDL_Surface *image  = loadImage(filename);

	if (image == NULL) return;

	colors = image->format->palette->ncolors;
	c      = image->format->palette->colors;

	jlImgT *img = NULL;
	jlImgCreate(img);

	for (int x=0; x<colors; x++) {
		img->palette[x].r = c[x].r / 16;
		img->palette[x].g = c[x].g / 16;
		img->palette[x].b = c[x].b / 16;
		//printf("Palette %03d = R%03d G%03d B%03d\n", x, img->palette[x].r, img->palette[x].g, img->palette[x].b);
	}

	if (colors < 16) {
		for (int x=colors; x<16; x++) {
			img->palette[x].r = 0;
			img->palette[x].g = 0;
			img->palette[x].b = 0;
			//printf("Palette %03d = R000 G000 B000 (added)\n", x);
		}
	}

	int p = 0;
	for (int y=0; y<image->h; y++) {
		for (int x=0; x<image->w; x+=2) {
			//printf("%02X %02X ", getPixel(image, x, y), getPixel(image, x + 1, y));
			// These are backwards - no idea why yet.
			img->pixels[p].r   = (unsigned char)getPixel(image, x, y);
			img->pixels[p++].l = (unsigned char)getPixel(image, x + 1, y);
		}
	}

	jlImgSave(img, basename);

	SDL_FreeSurface(image);

	if (showIt) {
		jlImgDisplay(img);
		jlDisplayPresent();
		jlKeyWaitForAny();
	}

	jlImgFree(img);
}


void convertStencil(char *filename, char *basename) {

	// Stencil files aren't required
	if (!fileExists(filename)) return;

	int          bytes      = 0;
	byte         data       = 0;
	int          bits       = 0;
	SDL_Surface *image      = loadImage(filename);
	char         name[2048];
	FILE        *out;

	snprintf(name, 2048, "%s.stn", basename);
	out = fopen(name, "wb");
	if (!out) {
		fprintf(stderr, "Unable to save stencil:  %s\n", name);
		return;
	}

	fputc('S', out);
	fputc('T', out);
	fputc('N', out);
	fputc( 0,  out);

	for (int y=0; y<image->h; y++) {
		for (int x=0; x<image->w; x++) {
			data <<= 1;
			data |= (getPixel(image, x, y) == 0);
			bits++;
			if (bits > 7) {
				bytes++;
				bits = 0;
				fputc(data, out);
			}
		}
	}

	fclose(out);
}


bool fileExists(char *filename) {
	FILE *file;
	if ((file = fopen(filename, "r+"))) {
		fclose(file);
		return true;
	}
	return false;
}


#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-align"

Uint32 getPixel(SDL_Surface *surface, int x, int y) {

	int bpp = surface->format->BytesPerPixel;
	Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;

	switch(bpp) {
		case 1:
			return *p;
			break;

		case 2:
			// Generates cast increases required alignment of target type [-Wcast-align] warning.  Harmless on x86.
			return *(Uint16 *)p;
			break;

		case 3:
			if (SDL_BYTEORDER == SDL_BIG_ENDIAN)
				return (Uint32)(p[0] << 16 | p[1] << 8 | p[2]);
			else
				return (Uint32)(p[0] | p[1] << 8 | p[2] << 16);
			break;

		case 4:
			// Generates cast increases required alignment of target type [-Wcast-align] warning.  Harmless on x86.
			return *(Uint32 *)p;
			break;

		default:
			return 0;
	}
}

#pragma GCC diagnostic pop


SDL_Surface *loadImage(char *filename) {

	if (!fileExists(filename)) {
		fprintf(stderr, "Unable to load image:  %s\n", filename);
		return NULL;
	}

	SDL_Surface *image = IMG_Load(filename);
	int colors = INT_MAX;

	if (image->format->palette != NULL) {
		colors = image->format->palette->ncolors;
	}

	//printf("%s = %dx%d, %d bits per pixel, %d colors\n", filename, image->w, image->h, image->format->BitsPerPixel, colors);

	if (image->w != 320 || image->h != 200 || colors > 16) {
		fprintf(stderr, "Image must be 320x200 pixels, 8 bits per pixel, with 16 or fewer colors.\n");
		free(image);
		image = NULL;
	}

	return image;
}


int main(int argc, char *argv[]) {

	if (argc < 3) {
		printf("Usage:  %s [color.png] [stencil.png] [outfile] {anyting}\n", argv[0]);
		printf("(If {anything} is provided, image will be displayed as converted until keypress.)\n");
		return 1;
	}

	jlUtilStartup("IMG/STN Converter");

	int imageFlags = IMG_INIT_JPG | IMG_INIT_PNG | IMG_INIT_TIF;
	int imageResult = IMG_Init(imageFlags);
	if ((imageResult & imageFlags) != imageFlags) {
		fprintf(stderr, "Failed to initialize SDL2_Image:  %s\n", IMG_GetError());
		jlUtilShutdown();
	}

	convertColor(argv[1], argv[3], argc > 4);
	convertStencil(argv[2], argv[3]);

	IMG_Quit();
	jlUtilShutdown();
}