#include "mednafen/mednafen-types.h"
#include "mednafen/mednafen.h"
#include "mednafen/git.h"
#include "mednafen/general.h"
#include <iostream>
#include "libretro.h"

static MDFNGI *game;
static retro_video_refresh_t video_cb;
static retro_audio_sample_t audio_cb;
static retro_audio_sample_batch_t audio_batch_cb;
static retro_environment_t environ_cb;
static retro_input_poll_t input_poll_cb;
static retro_input_state_t input_state_cb;

static MDFN_Surface *surf;

static uint16_t conv_buf[680 * 480] __attribute__((aligned(16)));
static uint32_t mednafen_buf[680 * 480] __attribute__((aligned(16)));

void retro_init()
{
   MDFN_PixelFormat pix_fmt(MDFN_COLORSPACE_RGB, 16, 8, 0, 24);
   surf = new MDFN_Surface(mednafen_buf, 680, 512, 680, pix_fmt);

   std::vector<MDFNGI*> ext;
   MDFNI_InitializeModules(ext);

   std::vector<MDFNSetting> settings;

   // FIXME: This will not work on Windows ...
   std::string home = getenv("HOME");
   home += "/.mednafen";
   MDFNI_Initialize(home.c_str(), settings);

   // Hints that we need a fairly powerful system to run this.
   unsigned level = 3;
   environ_cb(RETRO_ENVIRONMENT_SET_PERFORMANCE_LEVEL, &level);
}

void retro_deinit()
{
   delete surf;
   surf = NULL;
}

void retro_reset()
{
   MDFNI_Reset();
}

bool retro_load_game_special(unsigned, const struct retro_game_info *, size_t)
{
   return false;
}

bool retro_load_game(const struct retro_game_info *info)
{
   game = MDFNI_LoadGame("psx", info->path);
   return game;
}

void retro_unload_game()
{
   MDFNI_CloseGame();
}

#ifndef __SSE2__
#error "SSE2 required."
#endif

#include <emmintrin.h>

// PSX core should be able to output ARGB1555 directly,
// so we can avoid this conversion step.
// Done in SSE2 here because any system that can run this
// core to begin with will be at least that powerful (as of writing).
static inline void convert_surface()
{
   const uint32_t *pix = surf->pixels;
   for (unsigned i = 0; i < 680 * 480; i += 8)
   {
      __m128i pix0 = _mm_load_si128((const __m128i*)(pix + i + 0));
      __m128i pix1 = _mm_load_si128((const __m128i*)(pix + i + 4));

      __m128i red0   = _mm_and_si128(pix0, _mm_set1_epi32(0xf80000));
      __m128i green0 = _mm_and_si128(pix0, _mm_set1_epi32(0x00f800));
      __m128i blue0  = _mm_and_si128(pix0, _mm_set1_epi32(0x0000f8));
      __m128i red1   = _mm_and_si128(pix1, _mm_set1_epi32(0xf80000));
      __m128i green1 = _mm_and_si128(pix1, _mm_set1_epi32(0x00f800));
      __m128i blue1  = _mm_and_si128(pix1, _mm_set1_epi32(0x0000f8));

      red0   = _mm_srli_epi32(red0,   19 - 10); 
      green0 = _mm_srli_epi32(green0, 11 -  5); 
      blue0  = _mm_srli_epi32(blue0,   3 -  0); 

      red1   = _mm_srli_epi32(red1,   19 - 10); 
      green1 = _mm_srli_epi32(green1, 11 -  5); 
      blue1  = _mm_srli_epi32(blue1,   3 -  0); 

      __m128i res0 = _mm_or_si128(_mm_or_si128(red0, green0), blue0);
      __m128i res1 = _mm_or_si128(_mm_or_si128(red1, green1), blue1);

      _mm_store_si128((__m128i*)(conv_buf + i), _mm_packs_epi32(res0, res1));
   }
}

// Hardcoded for PSX. No reason to parse lots of structures ...
// See mednafen/psx/input/gamepad.cpp
static void update_input()
{
   static uint16_t input_buf[2];
   input_buf[0] = input_buf[1] = 0;
   static unsigned map[] = {
      RETRO_DEVICE_ID_JOYPAD_SELECT,
      -1u,
      -1u,
      RETRO_DEVICE_ID_JOYPAD_START,
      RETRO_DEVICE_ID_JOYPAD_UP,
      RETRO_DEVICE_ID_JOYPAD_RIGHT,
      RETRO_DEVICE_ID_JOYPAD_DOWN,
      RETRO_DEVICE_ID_JOYPAD_LEFT,
      RETRO_DEVICE_ID_JOYPAD_L2,
      RETRO_DEVICE_ID_JOYPAD_R2,
      RETRO_DEVICE_ID_JOYPAD_L,
      RETRO_DEVICE_ID_JOYPAD_R,
      RETRO_DEVICE_ID_JOYPAD_X,
      RETRO_DEVICE_ID_JOYPAD_A,
      RETRO_DEVICE_ID_JOYPAD_B,
      RETRO_DEVICE_ID_JOYPAD_Y,
   };

   for (unsigned j = 0; j < 2; j++)
   {
      for (unsigned i = 0; i < 16; i++)
         input_buf[j] |= map[i] != -1u &&
            input_state_cb(j, RETRO_DEVICE_JOYPAD, 0, map[i]) ? (1 << i) : 0;
   }

   // Possible endian bug ...
   game->SetInput(0, "gamepad", &input_buf[0]);
   game->SetInput(1, "gamepad", &input_buf[1]);
}

void retro_run()
{
   input_poll_cb();

   update_input();

   static int16_t sound_buf[0x10000];
   static MDFN_Rect rects[480];

   EmulateSpecStruct spec = {0}; 
   spec.surface = surf;
   spec.SoundRate = 44100;
   spec.SoundBuf = sound_buf;
   spec.LineWidths = rects;
   spec.SoundBufMaxSize = sizeof(sound_buf) / 2;
   spec.SoundVolume = 1.0;
   spec.soundmultiplier = 1.0;

   MDFNI_Emulate(&spec);

   unsigned width = rects[0].w;
   unsigned height = spec.DisplayRect.h;

   convert_surface();
   video_cb(conv_buf, width, height, 680 << 1);

   audio_batch_cb(spec.SoundBuf, spec.SoundBufSize);
}

void retro_get_system_info(struct retro_system_info *info)
{
   memset(info, 0, sizeof(*info));
   info->library_name     = "Mednafen PSX";
   info->library_version  = "0.9.22";
   info->need_fullpath    = true;
   info->valid_extensions = "cue|CUE";
}

void retro_get_system_av_info(struct retro_system_av_info *info)
{
   memset(info, 0, sizeof(*info));
   // Just assume NTSC for now. TODO: Verify FPS.
   info->timing.fps            = 59.97;
   info->timing.sample_rate    = 44100;
   info->geometry.base_width   = game->nominal_width;
   info->geometry.base_height  = game->nominal_height;
   info->geometry.max_width    = 680;
   info->geometry.max_height   = 480;
   info->geometry.aspect_ratio = 4.0 / 3.0;
}

unsigned retro_get_region(void)
{
   return RETRO_REGION_NTSC;
}

unsigned retro_api_version(void)
{
   return RETRO_API_VERSION;
}

// TODO: Allow for different kinds of joypads?
void retro_set_controller_port_device(unsigned, unsigned)
{}

void retro_set_environment(retro_environment_t cb)
{
   environ_cb = cb;
}

void retro_set_audio_sample(retro_audio_sample_t cb)
{
   audio_cb = cb;
}

void retro_set_audio_sample_batch(retro_audio_sample_batch_t cb)
{
   audio_batch_cb = cb;
}

void retro_set_input_poll(retro_input_poll_t cb)
{
   input_poll_cb = cb;
}

void retro_set_input_state(retro_input_state_t cb)
{
   input_state_cb = cb;
}

void retro_set_video_refresh(retro_video_refresh_t cb)
{
   video_cb = cb;
}

size_t retro_serialize_size(void)
{
   return 0;
}

bool retro_serialize(void *, size_t)
{
   return false;
}

bool retro_unserialize(const void *, size_t)
{
   return false;
}

void *retro_get_memory_data(unsigned)
{
   return NULL;
}

size_t retro_get_memory_size(unsigned)
{
   return 0;
}

void retro_cheat_reset(void)
{}

void retro_cheat_set(unsigned, bool, const char *)
{}