/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2010-2014 - Hans-Kristian Arntzen
 *  Copyright (C) 2011-2017 - Daniel De Matteis
 * 
 *  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 <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/inotify.h>
#include <linux/joystick.h>

#include <fcntl.h>
#include <sys/epoll.h>

#include <compat/strl.h>
#include <string/stdstring.h>

#include "../input_config.h"
#include "../input_driver.h"

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

#define NUM_BUTTONS 32
#define NUM_AXES 32

struct linuxraw_joypad
{
   int fd;
   uint64_t buttons;
   int16_t axes[NUM_AXES];

   char *ident;
};

static struct linuxraw_joypad linuxraw_pads[MAX_USERS];
static int linuxraw_epoll                              = 0;
static int linuxraw_inotify                            = 0;
static bool linuxraw_hotplug                           = false;

static void linuxraw_poll_pad(struct linuxraw_joypad *pad)
{
   struct js_event event;
   
   while (read(pad->fd, &event, sizeof(event)) == (ssize_t)sizeof(event))
   {
      unsigned type = event.type & ~JS_EVENT_INIT;

      switch (type)
      {
         case JS_EVENT_BUTTON:
            if (event.number < NUM_BUTTONS)
            {
               if (event.value)
                  BIT64_SET(pad->buttons, event.number);
               else
                  BIT64_CLEAR(pad->buttons, event.number);
            }
            break;

         case JS_EVENT_AXIS:
            if (event.number < NUM_AXES)
               pad->axes[event.number] = event.value;
            break;
      }
   }
}

static bool linuxraw_joypad_init_pad(const char *path, struct linuxraw_joypad *pad)
{
   if (pad->fd >= 0)
      return false;

   /* Device can have just been created, but not made accessible (yet).
      IN_ATTRIB will signal when permissions change. */
   if (access(path, R_OK) < 0)
      return false;

   pad->fd = open(path, O_RDONLY | O_NONBLOCK);

   *pad->ident = '\0';

   if (pad->fd >= 0)
   {
      if (ioctl(pad->fd,
               JSIOCGNAME(sizeof(input_device_names[0])), pad->ident) >= 0)
      {
         RARCH_LOG("[Device]: Found pad: %s on %s.\n", pad->ident, path);
      }
      else
         RARCH_ERR("[Device]: Didn't find ident of %s.\n", path);

      if (!epoll_add(&linuxraw_epoll, pad->fd, pad))
         goto error;

      return true;
   }

error:
   RARCH_ERR("[Device]: Failed to open pad %s (error: %s).\n", path, strerror(errno));
   return false;
}

static const char *linuxraw_joypad_name(unsigned pad)
{
   if (pad >= MAX_USERS || string_is_empty(linuxraw_pads[pad].ident))
      return NULL;

   return linuxraw_pads[pad].ident;
}

static void handle_plugged_pad(void)
{
   int i, rc;
   size_t event_size  = sizeof(struct inotify_event) + NAME_MAX + 1;
   uint8_t *event_buf = (uint8_t*)calloc(1, event_size);

   if (!event_buf)
      return;

   while ((rc = read(linuxraw_inotify, event_buf, event_size)) >= 0)
   {
      struct inotify_event *event = (struct inotify_event*)&event_buf[0];

      /* Can read multiple events in one read() call. */

      for (i = 0; i < rc; i += event->len + sizeof(struct inotify_event))
      {
         unsigned idx;

         event = (struct inotify_event*)&event_buf[i];

         if (strstr(event->name, "js") != event->name)
            continue;

         idx = strtoul(event->name + 2, NULL, 0);
         if (idx >= MAX_USERS)
            continue;

         if (event->mask & IN_DELETE)
         {
            if (linuxraw_pads[idx].fd >= 0)
            {
               if (linuxraw_hotplug)
                  input_autoconfigure_disconnect(idx, linuxraw_pads[idx].ident);

               close(linuxraw_pads[idx].fd);
               linuxraw_pads[idx].buttons = 0;
               memset(linuxraw_pads[idx].axes, 0, sizeof(linuxraw_pads[idx].axes));
               linuxraw_pads[idx].fd = -1;
               *linuxraw_pads[idx].ident = '\0';

               if (!input_autoconfigure_connect(
                     NULL,
                     NULL,
                     linuxraw_joypad_name(idx),
                     idx,
                     0,
                     0))
                  input_config_set_device_name(idx, NULL);
            }
         }
         /* Sometimes, device will be created before access to it is established. */
         else if (event->mask & (IN_CREATE | IN_ATTRIB))
         {
            char path[PATH_MAX_LENGTH];

            path[0] = '\0';

            snprintf(path, sizeof(path), "/dev/input/%s", event->name);

            if (     !string_is_empty(linuxraw_pads[idx].ident) 
                  && linuxraw_joypad_init_pad(path, &linuxraw_pads[idx]))
            {
               if (!input_autoconfigure_connect(
                     linuxraw_pads[idx].ident,
                     NULL,
                     linuxraw_joypad.ident,
                     idx,
                     0,
                     0))
                  input_config_set_device_name(idx, linuxraw_joypad_name(idx));
            }
         }
      }
   }

   free(event_buf);
}

static void linuxraw_joypad_poll(void)
{
   int i, ret;
   struct epoll_event events[MAX_USERS + 1];

retry:
   ret = epoll_waiting(&linuxraw_epoll, events, MAX_USERS + 1, 0);
   if (ret < 0 && errno == EINTR)
      goto retry;

   for (i = 0; i < ret; i++)
   {
      struct linuxraw_joypad *ptr = (struct linuxraw_joypad*)
         events[i].data.ptr;

      if (ptr)
         linuxraw_poll_pad(ptr);
      else
         handle_plugged_pad();
   }
}

static bool linuxraw_joypad_init(void *data)
{
   unsigned i;

   if (!epoll_new(&linuxraw_epoll))
      return false;

   for (i = 0; i < MAX_USERS; i++)
   {
      char path[PATH_MAX_LENGTH];
      struct linuxraw_joypad *pad = (struct linuxraw_joypad*)&linuxraw_pads[i];

      path[0]                     = '\0';

      pad->fd                     = -1;
      pad->ident                  = input_device_names[i];
      
      snprintf(path, sizeof(path), "/dev/input/js%u", i);

      if (!input_autoconfigure_connect(
            pad->ident,
            NULL,
            "linuxraw",
            i,
            0,
            0))
         input_config_set_device_name(i, pad->ident);

      if (linuxraw_joypad_init_pad(path, pad))
         linuxraw_poll_pad(pad);
   }

   linuxraw_inotify = inotify_init();

   if (linuxraw_inotify >= 0)
   {
      fcntl(linuxraw_inotify, F_SETFL, fcntl(linuxraw_inotify, F_GETFL) | O_NONBLOCK);
      inotify_add_watch(linuxraw_inotify, "/dev/input", IN_DELETE | IN_CREATE | IN_ATTRIB);
      epoll_add(&linuxraw_epoll, linuxraw_inotify, NULL);
   }

   linuxraw_hotplug = true;

   return true;
}

static void linuxraw_joypad_destroy(void)
{
   unsigned i;

   for (i = 0; i < MAX_USERS; i++)
   {
      if (linuxraw_pads[i].fd >= 0)
         close(linuxraw_pads[i].fd);
   }

   memset(linuxraw_pads, 0, sizeof(linuxraw_pads));

   for (i = 0; i < MAX_USERS; i++)
      linuxraw_pads[i].fd = -1;

   if (linuxraw_inotify >= 0)
      close(linuxraw_inotify);
   linuxraw_inotify = -1;

   epoll_free(&linuxraw_epoll);

   linuxraw_hotplug = false;
}

static bool linuxraw_joypad_button(unsigned port, uint16_t joykey)
{
   const struct linuxraw_joypad *pad = (const struct linuxraw_joypad*)
      &linuxraw_pads[port];

   return joykey < NUM_BUTTONS && BIT64_GET(pad->buttons, joykey);
}

static uint64_t linuxraw_joypad_get_buttons(unsigned port)
{
   const struct linuxraw_joypad *pad = (const struct linuxraw_joypad*)
      &linuxraw_pads[port];

   return pad->buttons;
}

static int16_t linuxraw_joypad_axis(unsigned port, uint32_t joyaxis)
{
   int16_t val = 0;
   const struct linuxraw_joypad *pad = NULL;

   if (joyaxis == AXIS_NONE)
      return 0;

   pad = (const struct linuxraw_joypad*)&linuxraw_pads[port];

   if (AXIS_NEG_GET(joyaxis) < NUM_AXES)
   {
      val = pad->axes[AXIS_NEG_GET(joyaxis)];
      if (val > 0)
         val = 0;
      /* Kernel returns values in range [-0x7fff, 0x7fff]. */
   }
   else if (AXIS_POS_GET(joyaxis) < NUM_AXES)
   {
      val = pad->axes[AXIS_POS_GET(joyaxis)];
      if (val < 0)
         val = 0;
   }

   return val;
}

static bool linuxraw_joypad_query_pad(unsigned pad)
{
   return pad < MAX_USERS && linuxraw_pads[pad].fd >= 0;
}


input_device_driver_t linuxraw_joypad = {
   linuxraw_joypad_init,
   linuxraw_joypad_query_pad,
   linuxraw_joypad_destroy,
   linuxraw_joypad_button,
   linuxraw_joypad_get_buttons,
   linuxraw_joypad_axis,
   linuxraw_joypad_poll,
   NULL,
   linuxraw_joypad_name,
   "linuxraw",
};
