/*
 * tbzsdl12.c: the part of the SDL 1.2 API that TecnoballZ uses, on top of SDL2, for the fredygames.com
 * browser build (Emscripten). See tbzsdl12.h.
 *
 * The game draws into an 8-bit, palettized SDL_Surface (the "screen" of SDL_SetVideoMode). Each
 * SDL_UpdateRect/SDL_Flip converts it to 32 bits, uploads it to a streaming texture and presents it,
 * then gives the browser a turn (the build uses Asyncify).
 *
 * Copyright (C) 2026 FredyGames. GNU GPL version 3 or later, like TecnoballZ.
 */
#include "tbzsdl12.h"
#include <string.h>
#ifdef __EMSCRIPTEN__
#include <emscripten.h>
#endif

#undef SDL_PollEvent
#undef SDL_CreateRGBSurface
#undef unicode

static SDL_Window *window = NULL;
static SDL_Renderer *renderer = NULL;
static SDL_Texture *texture = NULL;
static SDL_Surface *screen = NULL;
static SDL_Surface *rgb = NULL;
static Uint8 keystate[1024];

/* folds an SDL2 key symbol to the index the game uses (see tbzsdl12.h) */
static int
fold_key (SDL_Keycode sym, SDL_Scancode scancode)
{
  if (sym >= 0 && sym < 256)
    return sym;
  return 256 + (int) scancode;
}

const SDL_VideoInfo *
SDL_GetVideoInfo (void)
{
  static SDL_VideoInfo info;
  return &info;
}

SDL_Rect **
SDL_ListModes (SDL_PixelFormat * format, Uint32 flags)
{
  (void) format;
  (void) flags;
  return (SDL_Rect **) - 1;
}

int
SDL_VideoModeOK (int width, int height, int bpp, Uint32 flags)
{
  (void) width;
  (void) height;
  (void) flags;
  return bpp > 0 ? bpp : 8;
}

SDL_Surface *
SDL_SetVideoMode (int width, int height, int bpp, Uint32 flags)
{
  (void) flags;
  if (window == NULL)
    {
      window = SDL_CreateWindow ("TecnoballZ", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, width,
                                 height, 0);
      if (window == NULL)
        return NULL;
      renderer = SDL_CreateRenderer (window, -1, 0);
      if (renderer == NULL)
        return NULL;
    }
  else
    SDL_SetWindowSize (window, width, height);
  if (texture != NULL)
    SDL_DestroyTexture (texture);
  if (screen != NULL)
    SDL_FreeSurface (screen);
  if (rgb != NULL)
    SDL_FreeSurface (rgb);
  texture = SDL_CreateTexture (renderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_STREAMING, width,
                               height);
  screen = SDL_CreateRGBSurfaceWithFormat (0, width, height, bpp > 0 ? bpp : 8,
                                           bpp == 8 || bpp == 0 ? SDL_PIXELFORMAT_INDEX8 :
                                           SDL_PIXELFORMAT_ARGB8888);
  rgb = SDL_CreateRGBSurfaceWithFormat (0, width, height, 32, SDL_PIXELFORMAT_ARGB8888);
  return screen;
}

int
SDL_Flip (SDL_Surface * surface)
{
  if (surface != screen || texture == NULL)
    return -1;
  SDL_BlitSurface (screen, NULL, rgb, NULL);
  SDL_UpdateTexture (texture, NULL, rgb->pixels, rgb->pitch);
  SDL_RenderClear (renderer);
  SDL_RenderCopy (renderer, texture, NULL, NULL);
  SDL_RenderPresent (renderer);
#ifdef __EMSCRIPTEN__
  emscripten_sleep (0);
#endif
  return 0;
}

void
SDL_UpdateRect (SDL_Surface * surface, Sint32 x, Sint32 y, Uint32 w, Uint32 h)
{
  (void) x;
  (void) y;
  (void) w;
  (void) h;
  SDL_Flip (surface);
}

int
SDL_SetPalette (SDL_Surface * surface, int flags, const SDL_Color * colors, int firstcolor,
                int ncolors)
{
  SDL_Color full[256];
  int i;
  (void) flags;
  if (surface == NULL || surface->format->palette == NULL)
    return 0;
  /* SDL 1.2 ignores the alpha of palette colors; SDL2 uses it, so every color is made opaque */
  if (ncolors > 256 - firstcolor)
    ncolors = 256 - firstcolor;
  for (i = 0; i < ncolors; i++)
    {
      full[i] = colors[i];
      full[i].a = 255;
    }
  return SDL_SetPaletteColors (surface->format->palette, full, firstcolor, ncolors) == 0;
}

void
SDL_WM_SetCaption (const char *title, const char *icon)
{
  (void) icon;
  if (window != NULL && title != NULL)
    SDL_SetWindowTitle (window, title);
}

SDL_GrabMode
SDL_WM_GrabInput (SDL_GrabMode mode)
{
  /* in the browser, grabbing means pointer lock: the paddle follows the relative mouse motion */
  if (mode == SDL_GRAB_QUERY)
    return SDL_GetRelativeMouseMode ()? SDL_GRAB_ON : SDL_GRAB_OFF;
  SDL_SetRelativeMouseMode (mode == SDL_GRAB_ON ? SDL_TRUE : SDL_FALSE);
  return mode;
}

void
SDL_WarpMouse (Uint16 x, Uint16 y)
{
  if (window != NULL)
    SDL_WarpMouseInWindow (window, x, y);
}

char *
SDL_VideoDriverName (char *namebuf, int maxlen)
{
  const char *name = SDL_GetCurrentVideoDriver ();
  if (namebuf == NULL || maxlen <= 0 || name == NULL)
    return NULL;
  strncpy (namebuf, name, maxlen - 1);
  namebuf[maxlen - 1] = '\0';
  return namebuf;
}

int
SDL_EnableUNICODE (int enable)
{
  (void) enable;
  return 1;
}

Uint8 *
SDL_GetKeyState (int *numkeys)
{
  if (numkeys != NULL)
    *numkeys = (int) sizeof (keystate);
  return keystate;
}

/* the character a key types, as SDL 1.2 put it in keysym.unicode (only what the game's text input
 * needs: letters, digits and a few signs; shift gives capitals) */
static Uint32
key_character (const SDL_Keysym * keysym)
{
  SDL_Keycode sym = keysym->sym;
  int shift = (keysym->mod & KMOD_SHIFT) != 0;
  if (sym >= SDLK_a && sym <= SDLK_z)
    return shift ? (Uint32) (sym - 'a' + 'A') : (Uint32) sym;
  if (sym >= 32 && sym < 127)
    return (Uint32) sym;
  return 0;
}

int
tbz_PollEvent (SDL_Event * event)
{
  int got = SDL_PollEvent (event);
  if (got && event != NULL && (event->type == SDL_KEYDOWN || event->type == SDL_KEYUP))
    {
      int index = fold_key (event->key.keysym.sym, event->key.keysym.scancode);
      if (index >= 0 && index < (int) sizeof (keystate))
        keystate[index] = event->type == SDL_KEYDOWN ? SDL_PRESSED : SDL_RELEASED;
      event->key.keysym.unused = key_character (&event->key.keysym);
      event->key.keysym.sym = index;
    }
  return got;
}

SDL_Surface *
tbz_CreateRGBSurface (Uint32 flags, int width, int height, int depth, Uint32 rmask, Uint32 gmask,
                      Uint32 bmask, Uint32 amask)
{
  (void) flags;
  if (depth <= 8)
    return SDL_CreateRGBSurfaceWithFormat (0, width, height, 8, SDL_PIXELFORMAT_INDEX8);
  return SDL_CreateRGBSurface (0, width, height, depth, rmask, gmask, bmask, amask);
}