/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2013 - Jason Fetters
 * 
 *  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 <IOKit/hid/IOHIDManager.h>
#include "../RetroArch/apple_input.h"

// NOTE: I pieced this together through trial and error, any corrections are welcome

static IOHIDManagerRef g_hid_manager;
static uint32_t g_num_pads;

static void hid_input_callback(void* inContext, IOReturn inResult, void* inSender, IOHIDValueRef inIOHIDValueRef)
{
   IOHIDElementRef element = IOHIDValueGetElement(inIOHIDValueRef);
   IOHIDDeviceRef device = IOHIDElementGetDevice(element);

   uint32_t type = IOHIDElementGetType(element);
   uint32_t page = IOHIDElementGetUsagePage(element);
   uint32_t use = IOHIDElementGetUsage(element);

   // Mouse handler
   if (IOHIDDeviceConformsTo(device, kHIDPage_GenericDesktop, kHIDUsage_GD_Mouse))
   {
      if (type == kIOHIDElementTypeInput_Button && page == kHIDPage_Button)
      {
         CFIndex state = IOHIDValueGetIntegerValue(inIOHIDValueRef);
      
         if (state)  g_current_input_data.mouse_buttons |= (1 << (use - 1));
         else        g_current_input_data.mouse_buttons &= ~(1 << (use - 1));
      }
      else if (type == kIOHIDElementTypeInput_Misc && page == kHIDPage_GenericDesktop)
      {
         static const uint32_t axis_use_ids[2] = { 48, 49 };

         for (int i = 0; i < 2; i ++)
            if (use == axis_use_ids[i])
               g_current_input_data.mouse_delta[i] += IOHIDValueGetIntegerValue(inIOHIDValueRef);
      }
   }
   // Joystick handler
   else if (IOHIDDeviceConformsTo(device, kHIDPage_GenericDesktop, kHIDUsage_GD_Joystick))
   {
      uint32_t slot = (uint32_t)inContext;
      if (slot >= 4)
         return;

      if (type == kIOHIDElementTypeInput_Button && page == kHIDPage_Button)
      {
         CFIndex state = IOHIDValueGetIntegerValue(inIOHIDValueRef);

         if (state)  g_current_input_data.pad_buttons[slot] |= (1 << (use - 1));
         else        g_current_input_data.pad_buttons[slot] &= ~(1 << (use - 1));
      }
      else if (type == kIOHIDElementTypeInput_Misc && page == kHIDPage_GenericDesktop)
      {
         static const uint32_t axis_use_ids[4] = { 48, 49, 50, 53 };
         for (int i = 0; i < 4; i ++)
         {
            if (use == axis_use_ids[i])
            {
               CFIndex min = IOHIDElementGetPhysicalMin(element);
               CFIndex max = IOHIDElementGetPhysicalMax(element) - min;
               CFIndex state = IOHIDValueGetIntegerValue(inIOHIDValueRef) - min;
            
               float val = (float)state / (float)max;
               g_current_input_data.pad_axis[slot][i] = ((val * 2.0f) - 1.0f) * 32767.0f;
            }
         }
      }
   }
}

static void hid_device_attached(void* inContext, IOReturn inResult, void* inSender, IOHIDDeviceRef inDevice)
{
   void* context = 0;

   if (IOHIDDeviceConformsTo(inDevice, kHIDPage_GenericDesktop, kHIDUsage_GD_Joystick))
   {
      if (g_num_pads > 4)
         return;
      context = (void*)(g_num_pads++);
   }

   IOHIDDeviceOpen(inDevice, kIOHIDOptionsTypeNone);
   IOHIDDeviceScheduleWithRunLoop(inDevice, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
   IOHIDDeviceRegisterInputValueCallback(inDevice, hid_input_callback, context);
}

static void hid_device_removed(void* inContext, IOReturn inResult, void* inSender, IOHIDDeviceRef inDevice)
{
   IOHIDDeviceClose(inDevice, kIOHIDOptionsTypeNone);
}

static CFMutableDictionaryRef build_matching_dictionary(uint32_t page, uint32_t use)
{
   CFMutableDictionaryRef matcher = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);

   CFNumberRef pagen = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &page);
   CFDictionarySetValue(matcher, CFSTR(kIOHIDDeviceUsagePageKey), pagen);
   CFRelease(pagen);

   CFNumberRef usen = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &use);
   CFDictionarySetValue(matcher, CFSTR(kIOHIDDeviceUsageKey), usen);
   CFRelease(usen);

   return matcher;
}

void osx_pad_init()
{
   if (!g_hid_manager)
   {
      g_hid_manager = IOHIDManagerCreate(kCFAllocatorDefault, kIOHIDOptionsTypeNone);

      CFMutableArrayRef matcher = CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks);

      CFMutableDictionaryRef mouse = build_matching_dictionary(kHIDPage_GenericDesktop, kHIDUsage_GD_Mouse);
      CFArrayAppendValue(matcher, mouse);
      CFRelease(mouse);

      CFMutableDictionaryRef joystick = build_matching_dictionary(kHIDPage_GenericDesktop, kHIDUsage_GD_Joystick);
      CFArrayAppendValue(matcher, joystick);
      CFRelease(joystick);

      IOHIDManagerSetDeviceMatchingMultiple(g_hid_manager, matcher);
      CFRelease(matcher);

      IOHIDManagerRegisterDeviceMatchingCallback(g_hid_manager, hid_device_attached, 0);
      IOHIDManagerRegisterDeviceRemovalCallback(g_hid_manager, hid_device_removed, 0);
      IOHIDManagerScheduleWithRunLoop(g_hid_manager, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);

      IOHIDManagerOpen(g_hid_manager, kIOHIDOptionsTypeNone);
   }
}

void osx_pad_quit()
{
   if (g_hid_manager)
   {
      IOHIDManagerClose(g_hid_manager, kIOHIDOptionsTypeNone);
      IOHIDManagerUnscheduleFromRunLoop(g_hid_manager, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
      
      CFRelease(g_hid_manager);
   }

   g_hid_manager = 0;
}