/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2018 - 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 <stdint.h>
#include <stddef.h>

#include <boolean.h>
#include <retro_miscellaneous.h>
#include <emscripten/html5.h>

#include "../input_driver.h"

#include "../../tasks/tasks_internal.h"
#include "../../verbosity.h"

#define CLAMPDOUBLE(x) MIN(1.0, MAX(-1.0, (x)))

static EM_BOOL rwebpad_gamepad_cb(int event_type,
   const EmscriptenGamepadEvent *gamepad_event, void *user_data)
{
   unsigned vid = 0;
   unsigned pid = 0;

   if (strncmp(gamepad_event->mapping, "standard",
       sizeof(gamepad_event->mapping)) == 0)
   {
      /* give a dummy vid/pid for automapping */
      vid = 1;
      pid = 1;
   }

   switch (event_type)
   {
      case EMSCRIPTEN_EVENT_GAMEPADCONNECTED:
         input_autoconfigure_connect(
               gamepad_event->id,    /* name */
               NULL,                 /* display name */
               rwebpad_joypad.ident, /* driver */
               gamepad_event->index, /* idx */
               vid,                  /* vid */
               pid);                 /* pid */
         break;
      case EMSCRIPTEN_EVENT_GAMEPADDISCONNECTED:
         input_autoconfigure_disconnect(gamepad_event->index,
               rwebpad_joypad.ident);
         break;
      default:
         break;
   }

   return EM_TRUE;
}

static bool rwebpad_joypad_init(void *data)
{
   EMSCRIPTEN_RESULT r = emscripten_sample_gamepad_data();
   if (r == EMSCRIPTEN_RESULT_NOT_SUPPORTED)
      return false;

   /* callbacks needs to be registered for gamepads to connect */
   r = emscripten_set_gamepadconnected_callback(NULL, false,
      rwebpad_gamepad_cb);

   r = emscripten_set_gamepaddisconnected_callback(NULL, false,
      rwebpad_gamepad_cb);

   return true;
}

static const char *rwebpad_joypad_name(unsigned pad)
{
   static EmscriptenGamepadEvent gamepad_state;
   EMSCRIPTEN_RESULT r = emscripten_get_gamepad_status(pad, &gamepad_state);
   if (r == EMSCRIPTEN_RESULT_SUCCESS)
      return gamepad_state.id;
   return "";
}

static int16_t rwebpad_joypad_button(unsigned port, uint16_t joykey)
{
   EmscriptenGamepadEvent gamepad_state;
   EMSCRIPTEN_RESULT r                  = emscripten_get_gamepad_status(
         port, &gamepad_state);

   if (port >= DEFAULT_MAX_PADS)
      return 0;
   if (r != EMSCRIPTEN_RESULT_SUCCESS)
      return 0;
   if (joykey < gamepad_state.numButtons)
      return gamepad_state.digitalButton[joykey];
   return 0;
}

static void rwebpad_joypad_get_buttons(unsigned port_num, input_bits_t *state)
{
   EmscriptenGamepadEvent gamepad_state;
   EMSCRIPTEN_RESULT r = emscripten_get_gamepad_status(
         port_num, &gamepad_state);

   if (r == EMSCRIPTEN_RESULT_SUCCESS)
   {
      unsigned i;

      for (i = 0; i < gamepad_state.numButtons; i++)
      {
         if (gamepad_state.digitalButton[i])
            BIT256_SET_PTR(state, i);
      }
   }
   else
      BIT256_CLEAR_ALL_PTR(state);
}

static int16_t rwebpad_joypad_axis_state(
      EmscriptenGamepadEvent *gamepad_state,
      unsigned port, uint32_t joyaxis)
{
   if (AXIS_NEG_GET(joyaxis) < gamepad_state->numAxes)
   {
      int16_t val = CLAMPDOUBLE(
            gamepad_state->axis[AXIS_NEG_GET(joyaxis)]) * 0x7FFF;
      if (val < 0)
         return val;
   }
   else if (AXIS_POS_GET(joyaxis) < gamepad_state->numAxes)
   {
      int16_t val = CLAMPDOUBLE(
            gamepad_state->axis[AXIS_POS_GET(joyaxis)]) * 0x7FFF;
      if (val > 0)
         return val;
   }
   return 0;
}

static int16_t rwebpad_joypad_axis(unsigned port, uint32_t joyaxis)
{
   EmscriptenGamepadEvent gamepad_state;
   EMSCRIPTEN_RESULT r = emscripten_get_gamepad_status(port, &gamepad_state);
   if (r != EMSCRIPTEN_RESULT_SUCCESS)
      return 0;
   return rwebpad_joypad_axis_state(&gamepad_state, port, joyaxis);
}

static int16_t rwebpad_joypad_state(
      rarch_joypad_info_t *joypad_info,
      const struct retro_keybind *binds,
      unsigned port)
{
   unsigned i;
   EmscriptenGamepadEvent gamepad_state;
   int16_t ret                          = 0;
   uint16_t port_idx                    = joypad_info->joy_idx;
   EMSCRIPTEN_RESULT r                  = emscripten_get_gamepad_status(
         port_idx, &gamepad_state);
   if (r != EMSCRIPTEN_RESULT_SUCCESS)
      return 0;
   if (port_idx >= DEFAULT_MAX_PADS)
      return 0;

   for (i = 0; i < RARCH_FIRST_CUSTOM_BIND; i++)
   {
      /* Auto-binds are per joypad, not per user. */
      const uint64_t joykey  = (binds[i].joykey != NO_BTN)
         ? binds[i].joykey  : joypad_info->auto_binds[i].joykey;
      const uint32_t joyaxis = (binds[i].joyaxis != AXIS_NONE)
         ? binds[i].joyaxis : joypad_info->auto_binds[i].joyaxis;
      if (
               (uint16_t)joykey != NO_BTN 
            && (joykey < gamepad_state.numButtons)
            && gamepad_state.digitalButton[(uint16_t)joykey]
         )
         ret |= ( 1 << i);
      else if (joyaxis != AXIS_NONE &&
            ((float)abs(rwebpad_joypad_axis_state(
                  &gamepad_state, port_idx, joyaxis)) 
             / 0x8000) > joypad_info->axis_threshold)
         ret |= (1 << i);
   }

   return ret;
}

static void rwebpad_joypad_poll(void)
{
   emscripten_sample_gamepad_data();
}

static bool rwebpad_joypad_query_pad(unsigned pad)
{
   EmscriptenGamepadEvent gamepad_state;
   EMSCRIPTEN_RESULT r = emscripten_get_gamepad_status(pad, &gamepad_state);

   if (r == EMSCRIPTEN_RESULT_SUCCESS)
      return gamepad_state.connected == EM_TRUE;
   return false;
}

static void rwebpad_joypad_destroy(void) { }

input_device_driver_t rwebpad_joypad = {
   rwebpad_joypad_init,
   rwebpad_joypad_query_pad,
   rwebpad_joypad_destroy,
   rwebpad_joypad_button,
   rwebpad_joypad_state,
   rwebpad_joypad_get_buttons,
   rwebpad_joypad_axis,
   rwebpad_joypad_poll,
   NULL,
   rwebpad_joypad_name,
   "rwebpad",
};