/* RetroArch - A frontend for libretro.
 * Copyright (C) 2010-2014 - Hans-Kristian Arntzen
 * Copyright (C) 2011-2017 - Daniel De Matteis
 * Copyright (C) 2012-2015 - Michael Lelli
 *
 * RetroArch is free software: you can redistribute it and/or modify it under the terms
 * of the GNU General Public License as published by the Free Software Found-
 * ation, either version 3 of the License, or (at your option) any later version.
 *
 * RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with RetroArch.
 * If not, see <http://www.gnu.org/licenses/>.
 */

#include <emscripten/emscripten.h>
#include <emscripten/html5.h>
#if HAVE_WASMFS
#include <emscripten/wasmfs.h>
#endif
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

#include <file/config_file.h>
#include <queues/task_queue.h>
#include <file/file_path.h>
#include <string/stdstring.h>
#include <retro_timers.h>
#include <gfx/video_frame.h>
#include <glsym/glsym.h>

#ifdef HAVE_CONFIG_H
#include "../../config.h"
#endif

#ifndef IS_SALAMANDER
#include <lists/file_list.h>
#endif

#include "../frontend.h"
#include "../frontend_driver.h"
#include "../../configuration.h"
#include "../../content.h"
#include "../../command.h"
#include "../../defaults.h"
#include "../../file_path_special.h"
#include "../../paths.h"
#include "../../retroarch.h"
#include "../../verbosity.h"
#include "../../tasks/tasks_internal.h"
#include "../../cheat_manager.h"
#include "../../audio/audio_driver.h"

void emscripten_mainloop(void);
void PlatformEmscriptenWatchCanvasSize(void) {
   MAIN_THREAD_ASYNC_EM_ASM(
      RPE.observer = new ResizeObserver(function(_e) {
         var container = Module.canvas.parentElement;
         var width = container.offsetWidth;
         var height = container.offsetHeight;
         var w = Module.canvas.width;
         var h = Module.canvas.height;
         if (w == 0 || h == 0 || width == 0 || height == 0) { return; }
         /* Module.print("Setting real canvas size: " + width + " x " + height); */
         var new_w = `${width}px`;
         var new_h = `${height}px`;
         if (Module.canvas.style.width != new_w || Module.canvas.style.height != new_h) {
            Module.canvas.style.width = new_w;
            Module.canvas.style.height = new_h;
         }
         if (!Module.canvas.controlTransferredOffscreen) {
            Module.Browser.setCanvasSize(width, height);
         }
      });
      RPE.observer.observe(Module.canvas.parentElement);
      window.addEventListener("resize", function(e) {
         RPE.observer.unobserve(Module.canvas.parentElement);
         RPE.observer.observe(Module.canvas.parentElement);
      }, false);
   );
}
void PlatformEmscriptenPowerStateInit(void);
bool PlatformEmscriptenPowerStateGetSupported(void);
int PlatformEmscriptenPowerStateGetDischargeTime(void);
float PlatformEmscriptenPowerStateGetLevel(void);
bool PlatformEmscriptenPowerStateGetCharging(void);
uint64_t PlatformEmscriptenGetTotalMem(void);
uint64_t PlatformEmscriptenGetFreeMem(void);

void PlatformEmscriptenCommandReply(const char *msg, size_t len) {
  MAIN_THREAD_EM_ASM({
      var message = UTF8ToString($0,$1);
      RPE.command_reply_queue.push(message);
    }, msg, len);
}
static bool command_flag = false;
size_t PlatformEmscriptenCommandRead(char **into, size_t max_len) {
  if(!command_flag) { return 0; }
  return MAIN_THREAD_EM_ASM_INT({
      var next_command = RPE.command_queue.shift();
      var length = lengthBytesUTF8(next_command);
      if(length > $2) {
        console.error("[CMD] Command too long, skipping",next_command);
        return 0;
      }
      stringToUTF8(next_command, $1, $2);
      if(RPE.command_queue.length == 0) {
        setValue($0, 0, 'i8');
      }
      return length;
    }, &command_flag, into, max_len);
}
void PlatformEmscriptenCommandRaiseFlag() {
  command_flag = true;
}

/* begin exported functions */

/* saves and states */

void cmd_savefiles(void)
{
   command_event(CMD_EVENT_SAVE_FILES, NULL);
}

void cmd_save_state(void)
{
   command_event(CMD_EVENT_SAVE_STATE, NULL);
}

void cmd_load_state(void)
{
   command_event(CMD_EVENT_LOAD_STATE, NULL);
}

void cmd_undo_save_state(void)
{
   command_event(CMD_EVENT_UNDO_SAVE_STATE, NULL);
}

void cmd_undo_load_state(void)
{
   command_event(CMD_EVENT_UNDO_LOAD_STATE, NULL);
}

/* misc */

void cmd_take_screenshot(void)
{
   command_event(CMD_EVENT_TAKE_SCREENSHOT, NULL);
}

void cmd_toggle_menu(void)
{
   command_event(CMD_EVENT_MENU_TOGGLE, NULL);
}

void cmd_reload_config(void)
{
   command_event(CMD_EVENT_RELOAD_CONFIG, NULL);
}

void cmd_toggle_grab_mouse(void)
{
   command_event(CMD_EVENT_GRAB_MOUSE_TOGGLE, NULL);
}

void cmd_toggle_game_focus(void)
{
   command_event(CMD_EVENT_GAME_FOCUS_TOGGLE, NULL);
}

void cmd_reset(void)
{
   command_event(CMD_EVENT_RESET, NULL);
}

void cmd_toggle_pause(void)
{
   command_event(CMD_EVENT_PAUSE_TOGGLE, NULL);
}

void cmd_pause(void)
{
   command_event(CMD_EVENT_PAUSE, NULL);
}

void cmd_unpause(void)
{
   command_event(CMD_EVENT_UNPAUSE, NULL);
}

void cmd_set_volume(float volume)
{
   audio_set_float(AUDIO_ACTION_VOLUME_GAIN, volume);
}

#if defined(HAVE_CG) || defined(HAVE_GLSL) || defined(HAVE_SLANG) || defined(HAVE_HLSL)
bool cmd_set_shader(const char *path)
{
   return command_set_shader(NULL, path);
}
#endif

/* cheats */

void cmd_cheat_set_code(unsigned index, const char *str)
{
   cheat_manager_set_code(index, str);
}

const char *cmd_cheat_get_code(unsigned index)
{
   return cheat_manager_get_code(index);
}

void cmd_cheat_toggle_index(bool apply_cheats_after_toggle, unsigned index)
{
   cheat_manager_toggle_index(apply_cheats_after_toggle,
         config_get_ptr()->bools.notification_show_cheats_applied,
         index);
}

bool cmd_cheat_get_code_state(unsigned index)
{
   return cheat_manager_get_code_state(index);
}

bool cmd_cheat_realloc(unsigned new_size)
{
   return cheat_manager_realloc(new_size, CHEAT_HANDLER_TYPE_EMU);
}

unsigned cmd_cheat_get_size(void)
{
   return cheat_manager_get_size();
}

void cmd_cheat_apply_cheats(void)
{
   cheat_manager_apply_cheats(
         config_get_ptr()->bools.notification_show_cheats_applied);
}

/* end exported functions */

static void frontend_emscripten_get_env(int *argc, char *argv[],
      void *args, void *params_data)
{
   char base_path[PATH_MAX];
   char user_path[PATH_MAX];
   const char *home         = getenv("HOME");

   if (home)
   {
      size_t _len = strlcpy(base_path, home, sizeof(base_path));
      strlcpy(base_path + _len, "/retroarch", sizeof(base_path) - _len);
      _len = strlcpy(user_path, home, sizeof(user_path));
      strlcpy(user_path + _len, "/retroarch/userdata", sizeof(user_path) - _len);
   }
   else
   {
      strlcpy(base_path, "retroarch", sizeof(base_path));
      strlcpy(user_path, "retroarch/userdata", sizeof(user_path));
   }

   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_CORE], base_path,
         "cores", sizeof(g_defaults.dirs[DEFAULT_DIR_CORE]));

   /* bundle data */
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_ASSETS], base_path,
         "bundle/assets", sizeof(g_defaults.dirs[DEFAULT_DIR_ASSETS]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_AUTOCONFIG], base_path,
         "bundle/autoconfig", sizeof(g_defaults.dirs[DEFAULT_DIR_AUTOCONFIG]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_DATABASE], base_path,
         "bundle/database/rdb", sizeof(g_defaults.dirs[DEFAULT_DIR_DATABASE]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_CORE_INFO], base_path,
         "bundle/info", sizeof(g_defaults.dirs[DEFAULT_DIR_CORE_INFO]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_OVERLAY], base_path,
         "bundle/overlays", sizeof(g_defaults.dirs[DEFAULT_DIR_OVERLAY]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_OSK_OVERLAY], base_path,
         "bundle/overlays/keyboards", sizeof(g_defaults.dirs[DEFAULT_DIR_OSK_OVERLAY]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_SHADER], base_path,
         "bundle/shaders", sizeof(g_defaults.dirs[DEFAULT_DIR_SHADER]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_AUDIO_FILTER], base_path,
         "bundle/filters/audio", sizeof(g_defaults.dirs[DEFAULT_DIR_AUDIO_FILTER]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_VIDEO_FILTER], base_path,
         "bundle/filters/video", sizeof(g_defaults.dirs[DEFAULT_DIR_VIDEO_FILTER]));

   /* user data dirs */
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_CHEATS], user_path,
         "cheats", sizeof(g_defaults.dirs[DEFAULT_DIR_CHEATS]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_MENU_CONFIG], user_path,
         "config", sizeof(g_defaults.dirs[DEFAULT_DIR_MENU_CONFIG]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_MENU_CONTENT], user_path,
         "content", sizeof(g_defaults.dirs[DEFAULT_DIR_MENU_CONTENT]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_CORE_ASSETS], user_path,
         "content/downloads", sizeof(g_defaults.dirs[DEFAULT_DIR_CORE_ASSETS]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_PLAYLIST], user_path,
         "playlists", sizeof(g_defaults.dirs[DEFAULT_DIR_PLAYLIST]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_REMAP], g_defaults.dirs[DEFAULT_DIR_MENU_CONFIG],
         "remaps", sizeof(g_defaults.dirs[DEFAULT_DIR_REMAP]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_SRAM], user_path,
         "saves", sizeof(g_defaults.dirs[DEFAULT_DIR_SRAM]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_SCREENSHOT], user_path,
         "screenshots", sizeof(g_defaults.dirs[DEFAULT_DIR_SCREENSHOT]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_SAVESTATE], user_path,
         "states", sizeof(g_defaults.dirs[DEFAULT_DIR_SAVESTATE]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_SYSTEM], user_path,
         "system", sizeof(g_defaults.dirs[DEFAULT_DIR_SYSTEM]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_THUMBNAILS], user_path,
         "thumbnails", sizeof(g_defaults.dirs[DEFAULT_DIR_THUMBNAILS]));
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_LOGS], user_path,
         "logs", sizeof(g_defaults.dirs[DEFAULT_DIR_LOGS]));

   /* cache dir */
   fill_pathname_join(g_defaults.dirs[DEFAULT_DIR_CACHE], "/tmp/",
         "retroarch", sizeof(g_defaults.dirs[DEFAULT_DIR_CACHE]));

   /* history */
   strlcpy(g_defaults.dirs[DEFAULT_DIR_CONTENT_HISTORY],
         user_path, sizeof(g_defaults.dirs[DEFAULT_DIR_CONTENT_HISTORY]));

#ifndef IS_SALAMANDER
   dir_check_defaults("custom.ini");
#endif
}

typedef struct args {
   int argc;
   char **argv;
} args_t;
static bool retro_started = false;
static bool filesystem_ready = false;

#if HAVE_WASMFS
void PlatformEmscriptenMountFilesystems(void *info) {
   char *opfs_mount = getenv("OPFS");
   char *fetch_manifest = getenv("FETCH_MANIFEST");
   if(opfs_mount) {
      int res;
      printf("[OPFS] Mount OPFS at %s\n", opfs_mount);
      backend_t opfs = wasmfs_create_opfs_backend();
      {
         char *parent = strdup(opfs_mount);
         path_parent_dir(parent, strlen(parent));
         if(!path_mkdir(parent)) {
            printf("mkdir error %d\n",errno);
            abort();
         }
         free(parent);
      }
      res = wasmfs_create_directory(opfs_mount, 0777, opfs);
      if(res) {
         printf("[OPFS] error result %d\n",res);
         if(errno) {
            printf("[OPFS] errno %d\n",errno);
            abort();
         }
         abort();
      }
   }
   if(fetch_manifest) {
      /* fetch_manifest should be a path to a manifest file.
         manifest files have this format:

         URL PATH
         URL PATH
         URL PATH
         ...

         Where URL may not contain spaces, but PATH may.
       */
      int max_line_len = 1024;
      printf("[FetchFS] read fetch manifest from %s\n",fetch_manifest);
      FILE *file = fopen(fetch_manifest, "r");
      if(!file) {
        printf("[FetchFS] missing manifest file\n");
        abort();
      }
      char *line = calloc(sizeof(char), max_line_len);
      size_t len = max_line_len;
      while (getline(&line, &len, file) != -1) {
         char *path = strstr(line, " ");
         backend_t fetch;
         int fd;
         if(len <= 2 || !path) {
            printf("[FetchFS] Manifest file has invalid line %s\n",line);
            continue;
         }
         *path = '\0';
         path += 1;
         path[strcspn(path, "\r\n")] = '\0';
         printf("[FetchFS] Fetch %s from %s\n", path, line);
         {
            char *parent = strdup(path);
            path_parent_dir(parent, strlen(parent));
            if(!path_mkdir(parent)) {
               printf("[FetchFS] mkdir error %d\n",errno);
               abort();
            }
            free(parent);
         }
         fetch = wasmfs_create_fetch_backend(line, 16*1024*1024);
         if(!fetch) {
           printf("[FetchFS] couldn't create fetch backend\n");
           abort();
         }
         fd = wasmfs_create_file(path, 0777, fetch);
         if(!fd) {
           printf("[FetchFS] couldn't create fetch file\n");
           abort();
         }
         close(fd);
         len = max_line_len;
      }
      fclose(file);
      free(line);
   }
   filesystem_ready = true;
#if !PROXY_TO_PTHREAD
   while (!retro_started) {
      retro_sleep(1);
   }
#endif
}
#endif /* HAVE_WASMFS */

static enum frontend_powerstate frontend_emscripten_get_powerstate(int *seconds, int *percent)
{
   enum frontend_powerstate ret = FRONTEND_POWERSTATE_NONE;

   if (!PlatformEmscriptenPowerStateGetSupported())
      return ret;

   if (!PlatformEmscriptenPowerStateGetCharging())
      ret = FRONTEND_POWERSTATE_ON_POWER_SOURCE;
   else if (PlatformEmscriptenPowerStateGetLevel() == 1)
      ret = FRONTEND_POWERSTATE_CHARGED;
   else
      ret = FRONTEND_POWERSTATE_CHARGING;

   *seconds = PlatformEmscriptenPowerStateGetDischargeTime();
   *percent = (int)(PlatformEmscriptenPowerStateGetLevel() * 100);

   return ret;
}

static uint64_t frontend_emscripten_get_total_mem(void)
{
   return PlatformEmscriptenGetTotalMem();
}

static uint64_t frontend_emscripten_get_free_mem(void)
{
   return PlatformEmscriptenGetFreeMem();
}

void emscripten_bootup_mainloop(void *argptr) {
   if(retro_started) {
      /* A stale extra call to bootup_mainloop for some reason */
      RARCH_ERR("[Emscripten] unexpected second call to bootup_mainloop after rarch_main called\n");
      return;
   }
   if(filesystem_ready) {
      args_t *args = (args_t*)argptr;
      emscripten_cancel_main_loop();
      emscripten_set_main_loop(emscripten_mainloop, 0, 0);
      emscripten_set_main_loop_timing(EM_TIMING_RAF, 1);
      rarch_main(args->argc, args->argv, NULL);
      retro_started = true;
      free(args);
   }
}

int main(int argc, char *argv[])
{
   args_t *args = calloc(sizeof(args_t), 1);
   args->argc = argc;
   args->argv = argv;
   
   PlatformEmscriptenWatchCanvasSize();
   PlatformEmscriptenPowerStateInit();

   emscripten_set_canvas_element_size("#canvas", 800, 600);
   emscripten_set_element_css_size("#canvas", 800.0, 600.0);
#if HAVE_WASMFS
#if PROXY_TO_PTHREAD
   {
      PlatformEmscriptenMountFilesystems(NULL);
   }
#else /* !PROXY_TO_PTHREAD */
   {
      sthread_t *thread = sthread_create(PlatformEmscriptenMountFilesystems, NULL);
      sthread_detach(thread);
   }
#endif /* PROXY_TO_PTHREAD */
#else /* !HAVE_WASMFS */
   filesystem_ready = true;
#endif /* HAVE_WASMFS */
   emscripten_set_main_loop_arg(emscripten_bootup_mainloop, (void *)args, 0, 0);
   emscripten_set_main_loop_timing(EM_TIMING_RAF, 1);

   return 0;
}

frontend_ctx_driver_t frontend_ctx_emscripten = {
   frontend_emscripten_get_env,         /* environment_get */
   NULL,                                /* init */
   NULL,                                /* deinit */
   NULL,                                /* exitspawn */
   NULL,                                /* process_args */
   NULL,                                /* exec */
   NULL,                                /* set_fork */
   NULL,                                /* shutdown */
   NULL,                                /* get_name */
   NULL,                                /* get_os */
   NULL,                                /* get_rating */
   NULL,                                /* load_content */
   NULL,                                /* get_architecture */
   frontend_emscripten_get_powerstate,  /* get_powerstate */
   NULL,                                /* parse_drive_list */
   frontend_emscripten_get_total_mem,   /* get_total_mem */
   frontend_emscripten_get_free_mem,    /* get_free_mem  */
   NULL,                                /* install_sighandlers */
   NULL,                                /* get_signal_handler_state */
   NULL,                                /* set_signal_handler_state */
   NULL,                                /* destroy_signal_handler_state */
   NULL,                                /* attach_console */
   NULL,                                /* detach_console */
   NULL,                                /* get_lakka_version */
   NULL,                                /* set_screen_brightness */
   NULL,                                /* watch_path_for_changes */
   NULL,                                /* check_for_path_changes */
   NULL,                                /* set_sustained_performance_mode */
   NULL,                                /* get_cpu_model_name */
   NULL,                                /* get_user_language */
   NULL,                                /* is_narrator_running */
   NULL,                                /* accessibility_speak */
   NULL,                                /* set_gamemode        */
   "emscripten",                        /* ident               */
   NULL                                 /* get_video_driver    */
};