// -----------------------------------------------------------------------------
// https://dataswamp.org/~incal/emacs-init/draw/draw_thread.c
// -----------------------------------------------------------------------------

// Note: This file has nothing to do with threads anymore!

#include "draw_thread.h"
#include "new.h"

#include <emacs-module.h>

#include <SDL2/SDL.h>
#include <SDL2/SDL_ttf.h>

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

// -----------------------------------------------------------------------------

static SDL_Window*   win = NULL;
static SDL_Renderer* rnd = NULL;
static TTF_Font*     fnt = NULL;

// -----------------------------------------------------------------------------

char* my_strdup(const char* s) {
  size_t len = strlen(s) + 1;
  char*  cpy = malloc(len);
  if (cpy) { memcpy(cpy, s, len); }
  return cpy;
}

/* ----------------------------------------------------------------------------- */

emacs_value draw_init (emacs_env* env, ptrdiff_t nargs, emacs_value* args, void* data) {

  if (win || rnd || fnt) {
    draw_quit(env, nargs, args, data);
    if (win || rnd || fnt) {
      printf("[draw_init] error\n");
      exit(EXIT_FAILURE);
    }
  }

  SDL_Init(SDL_INIT_EVERYTHING);
  TTF_Init();
  win = new_window("SDL2 draw thread", 800, 600);
  rnd = new_renderer(win);
  fnt = new_font("/usr/share/fonts/truetype/ocr-a/OCRA.ttf", 28);

  return env->intern(env, "nil");
}

// -----------------------------------------------------------------------------

emacs_value draw_quit (emacs_env*   env,
                       ptrdiff_t    nargs __attribute__((unused)),
                       emacs_value* args  __attribute__((unused)),
                       void*        data  __attribute__((unused))) {
  if (fnt) { TTF_CloseFont       (fnt); }
  if (rnd) { SDL_DestroyRenderer (rnd); }
  if (win) { SDL_DestroyWindow   (win); }
  fnt = NULL;
  rnd = NULL;
  win = NULL;
  TTF_Quit();
  SDL_Quit();
  return env->intern(env, "nil");
}

// -----------------------------------------------------------------------------

void check_all () {
  if (!win) { printf("[win] error\n"); }
  if (!rnd) { printf("[rnd] error\n"); }
  if (!fnt) { printf("[fnt] error\n"); }
  if (!(win && rnd && fnt)) { exit(EXIT_FAILURE); }
}



void render_text (const char* txt) {
  check_all();
  if (!txt) { printf("[text] error\n"); exit(EXIT_FAILURE); }

  SDL_SetRenderDrawColor(rnd, 64, 128, 255, 0);
  SDL_RenderClear(rnd);
  SDL_Color clr = { 64, 255, 255, 0 };

  int max_h;
  int max_w;
  SDL_GetWindowSize(win, &max_w, &max_h);
  int line_h = TTF_FontHeight(fnt);

  int line_num  = 0;
  int longest_w = 0;
  char* buff = my_strdup(txt);
  char* line = strtok(buff, "\n");

  int w;
  while (line) {
    TTF_SizeText(fnt, line, &w, NULL);
    if (longest_w < w) {
      longest_w = w;
    }
    line_num++;
    line = strtok(NULL, "\n");
  }
  free(buff);

  int pxls = 32;
  int frmt = SDL_PIXELFORMAT_RGBA32;

  int ph = line_h * line_num;
  int sw = (longest_w > max_w) ? max_w : longest_w;
  int sh =        (ph > max_h) ? max_h : ph;
  SDL_Surface* main_sur = SDL_CreateRGBSurfaceWithFormat(0, sw, sh, pxls, frmt);
  if (!main_sur) { printf("[main-surface] error\n"); exit(EXIT_FAILURE); }

  int swl = (longest_w > max_w) ? max_w : sw;
  int shl =    (line_h > max_h) ? max_h : line_h;
  SDL_Surface* line_sur = SDL_CreateRGBSurfaceWithFormat(0, swl, shl, pxls, frmt);
  if (!line_sur) { printf("[line-surface] error\n"); exit(EXIT_FAILURE); }
  SDL_Rect line_rect = { 0, 0, line_sur->w, line_sur->h };

  Uint32 fill_clr = SDL_MapRGB(line_sur->format, 0, 0, 0);
  SDL_FillRect(line_sur, NULL, fill_clr);

  char* buff2 = my_strdup(txt);
  char* line2 = strtok(buff2, "\n");
  while (line2) {
    SDL_FillRect(line_sur, NULL, fill_clr);
    line_sur = TTF_RenderText_Solid(fnt, line2, clr);
    SDL_BlitSurface(line_sur, NULL, main_sur, &line_rect);
    line_rect.y += line_sur->h;
    line2 = strtok(NULL, "\n");
  }
  free(buff2);

  SDL_Texture* finl_tex = SDL_CreateTextureFromSurface(rnd, main_sur);
  if (!finl_tex) { printf("[texture] error\n"); exit(EXIT_FAILURE); }
  SDL_RenderCopy(rnd, finl_tex, NULL, NULL);
  SDL_RenderPresent(rnd);

  SDL_FreeSurface    (main_sur);
  SDL_FreeSurface    (line_sur);
  SDL_DestroyTexture (finl_tex);
}

// -----------------------------------------------------------------------------

emacs_value draw_draw (emacs_env* env, ptrdiff_t nargs, emacs_value* args, void* data) {

  if (!(win && rnd && fnt)) {
    draw_init(env, nargs, args, data);
    if (!(win && rnd && fnt)) {
      printf("[draw_draw] error\n");
      exit(EXIT_FAILURE);
    }
  }

  emacs_value ef = env->intern(env, "buffer-substring-no-properties-in-window");
  emacs_value es = env->funcall(env, ef, 0, NULL);
  char txt_str[1024];
  ptrdiff_t l = 0;
  env->copy_string_contents(env, es, NULL,    &l);
  env->copy_string_contents(env, es, txt_str, &l);

  render_text(txt_str);
  return env->intern(env, "nil");
}

// -----------------------------------------------------------------------------