/* NOTE: This layer only supports MacOS and Linux, for now. */

#include "core.h"

#include "handmade.h"
#include "sdl_handmade.h"

#include <SDL.h>
#include <sys/mman.h> /* mmap */
#include <stdlib.h>   /* malloc, calloc */
#include <string.h>   /* memset, memcpy */
#include <stdio.h>

#include <sys/stat.h> /* fstat */
#include <fcntl.h>    /* open */
#include <unistd.h>   /* close, write, read, readlink, unlink */
#include <dlfcn.h>    /* dlopen */
#include <sys/stat.h> /* stat */
#if __APPLE__ && __MACH__
#include <mach-o/dyld.h> /* _NSGetExecutablePath */
#endif

/* NOTE: This is so it compiles on ARM. */
#if __x86_64__ || __i386__
#include <x86intrin.h>
#endif

#include "program_icon.c"

#define RESOLUTION_WIDTH  960
#define RESOLUTION_HEIGHT 540

static B32 GlobalRunning;

static U64 GlobalPerfCountFrequency;

#define CONTROLLER_LEFT_THUMB_DEADZONE 8000
#define MAX_CONTROLLERS 4
SDL_GameController *ControllerHandles[MAX_CONTROLLERS];

static offscreen_buffer GlobalBackbuffer;

static S32 str_len(char *str)
{
    S32 count = 0;
    while(*str++)
        count++;
    return count;
}

static U32 SafeTruncateUInt64(U64 Value)
{
	ASSERT(Value <= 0xFFFFFFFF);
	U32 Result = (U32)Value;
    return Result;
}

debug_read_file_result DEBUGPlatformReadEntireFile(thread_context *Thread, const char *Filename)
{
    debug_read_file_result Result;
    memset(&Result, 0, sizeof(Result));

    S32 FileHandle = open(Filename, O_RDONLY);
    if(FileHandle == -1) {
        return Result;
    }

    struct stat FileStatus;
    if(fstat(FileHandle, &FileStatus) == -1) {
        close(FileHandle);
        return Result;
    }
    Result.ContentsSize = SafeTruncateUInt64(FileStatus.st_size);

    Result.Contents = malloc(Result.ContentsSize);
    if(!Result.Contents) {
        Result.ContentsSize = 0;
        close(FileHandle);
        return Result;
    }

    U32 BytesToRead = Result.ContentsSize;
    U8 *NextByteLocation = (U8 *)Result.Contents;
    while(BytesToRead) {
        U32 BytesRead = read(FileHandle, NextByteLocation, BytesToRead);
        if(BytesRead == (U32)-1) {
            free(Result.Contents);
            Result.Contents = 0;
            Result.ContentsSize = 0;
            close(FileHandle);
            return Result;
        }
        BytesToRead -= BytesRead;
        NextByteLocation += BytesRead;
    }

    close(FileHandle);

    return Result;
}

B32 DEBUGPlatformWriteEntireFile(thread_context *Thread, const char *Filename, U32 MemorySize, void *Memory)
{
    S32 FileHandle = open(Filename, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
    if(FileHandle == -1)
	    return FALSE;

    U32 BytesToWrite = MemorySize;
    U8 *NextByteLocation = (U8*)Memory;
    while(BytesToWrite) {
        U32 BytesWritten;

        BytesWritten = write(FileHandle, NextByteLocation, BytesToWrite);
        if(BytesWritten == (U32)-1) {
            close(FileHandle);
            return FALSE;
        }
        BytesToWrite -= BytesWritten;
        NextByteLocation += BytesWritten;
    }

    close(FileHandle);

    return TRUE;
}

void DEBUGPlatformFreeFileMemory(thread_context *Thread, void *Memory)
{
    if(Memory)
        free(Memory);
}

static sdl_window_dimension SDLGetWindowDimension(SDL_Window *Window)
{
    sdl_window_dimension Dimension;
    SDL_GetWindowSize(Window, &Dimension.Width, &Dimension.Height);
    return Dimension;
}

static void SDLResizeTexture(offscreen_buffer *Buffer, SDL_Renderer *Renderer, int Width, int Height)
{
    if(Buffer->Texture)
        SDL_DestroyTexture(Buffer->Texture);

    if(Buffer->Memory)
        free(Buffer->Memory);

    S32 BytesPerPixel = 4;

    Buffer->Texture = SDL_CreateTexture(Renderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_STREAMING, Width, Height);
    Buffer->Memory = malloc(Width * Height * BytesPerPixel);

    Buffer->Height = Height;
    Buffer->Width = Width;
    Buffer->Pitch = Width * BytesPerPixel;
}

static void SDLDisplayBufferInWindow(offscreen_buffer Buffer, SDL_Window *Window, SDL_Renderer *Renderer)
{
    S32 OffsetX = 10;
    S32 OffsetY = 10;

    SDL_SetRenderDrawColor(Renderer, 0, 0, 0, 255);
    SDL_RenderClear(Renderer);

    if(SDL_UpdateTexture(Buffer.Texture, 0, Buffer.Memory, Buffer.Pitch)) {
        /* TODO: Do something about this error! */
    }

    /* TODO: We temporarily introduce the target rectangle to avoid
     *       stretching the canvas. */
    /* SDL_RenderCopy(Renderer, Buffer.Texture, 0, 0); */
    SDL_Rect dest_rect = { OffsetX, OffsetY, RESOLUTION_WIDTH, RESOLUTION_HEIGHT };
    SDL_RenderCopy(Renderer, Buffer.Texture, 0, (const SDL_Rect *)(&dest_rect));
    SDL_RenderPresent(Renderer);
}

static void SDLInitControllers()
{
    S32 MaxJoysticks = SDL_NumJoysticks();
    S32 ControllerIndex = 0;
    for(S32 JoystickIndex = 0; JoystickIndex < MaxJoysticks; JoystickIndex++) {
        if(!SDL_IsGameController(JoystickIndex))
            continue;
        if(ControllerIndex >= MAX_CONTROLLERS)
            break;
        ControllerHandles[ControllerIndex] = SDL_GameControllerOpen(JoystickIndex);
        ControllerIndex++;
    }
}

/*
static void SDLDeinitControllers()
{
    for(S32 ControllerIndex = 0; ControllerIndex < MAX_CONTROLLERS; ControllerIndex++) {
       if(ControllerHandles[ControllerIndex])
           SDL_GameControllerClose(ControllerHandles[ControllerIndex]);
    }
}
*/

static void SDLInitSound(S32 SamplesPerSecond, S32 BufferSize)
{
    SDL_AudioSpec AudioSettings;
    memset(&AudioSettings, 0, sizeof(AudioSettings));

    AudioSettings.freq = SamplesPerSecond;
    AudioSettings.format = AUDIO_S16LSB;
    AudioSettings.channels = 2;
    AudioSettings.samples = BufferSize;

    SDL_OpenAudio(&AudioSettings, 0);

    if(AudioSettings.format != AUDIO_S16LSB) {
        SDL_CloseAudio();
    }
}

static void SDLFillSoundBuffer(sdl_sound_output *SoundOutput, S32 BytesToWrite)
{
    SDL_QueueAudio(1, SoundOutput->Samples, BytesToWrite);
}

static void SDLClearSoundBuffer(sdl_sound_output *SoundOutput)
{
    memset(SoundOutput->Samples, 0, SoundOutput->SecondaryBufferSize);
}

static void SDLProcessKeyboardMessage(game_button_state *NewState, B32 IsDown)
{
    if(NewState->EndedDown != IsDown) {
        NewState->EndedDown = IsDown;
        ++NewState->HalfTransitionCount;
    }
}

static void SDLProcessInputDigitalButton(SDL_GameController *Controller, game_button_state *OldState, SDL_GameControllerButton Button, game_button_state *NewState)
{
    NewState->EndedDown = SDL_GameControllerGetButton(Controller, Button);
    NewState->HalfTransitionCount = (OldState->EndedDown != NewState->EndedDown) ? 1 : 0;
}

static void HandleEvent(SDL_Event *Event)
{
    SDL_Window *Window = SDL_GetWindowFromID(Event->window.windowID);
    SDL_Renderer *Renderer = SDL_GetRenderer(Window);

    switch(Event->type) {
        case SDL_QUIT: {
            GlobalRunning = FALSE;
        } break;

        case SDL_WINDOWEVENT: {
            switch(Event->window.event) {
                /* TODO: We temporarily disable for ease of writing the
                 *       rendering code. */

#if 0
                /* TODO: For now we fix the width and height. */
                case SDL_WINDOWEVENT_SIZE_CHANGED: {
                    sdl_window_dimension Dimension = SDLGetWindowDimension(Window);
                    SDLResizeTexture(&GlobalBackbuffer, Renderer, Dimension.Width, Dimension.Height);
                } break;
#endif

                case SDL_WINDOWEVENT_EXPOSED: {
                } break;

#if 0
                case SDL_WINDOWEVENT_FOCUS_GAINED: {
                    if(SDL_SetWindowOpacity(Window, 1.0f) != 0) {
                        /* TODO: This didn't work . . . SDL_GetError() */
                    }
                } break;

                case SDL_WINDOWEVENT_FOCUS_LOST: {
                    if(SDL_SetWindowOpacity(Window, 0.1f) != 0) {
                        /* TODO: This didn't work . . . SDL_GetError() */
                    }
                } break;
#endif
            }
        } break;
    }
}

static void SDLProcessMessages(sdl_state *SDLState,
                               game_controller_input *KeyboardController)
{
    SDL_Event Event;
    while(SDL_PollEvent(&Event)) {
        switch(Event.type) {
            case SDL_KEYDOWN:
            case SDL_KEYUP: {
                SDL_Keycode KeyCode;
                B32 IsDown, WasDown;

                KeyCode = Event.key.keysym.sym;
                IsDown = (Event.key.state == SDL_PRESSED);
                WasDown = FALSE;
                if(Event.key.state == SDL_RELEASED) {
                    WasDown = TRUE;
                } else if(Event.key.repeat != 0) {
                    WasDown = TRUE;
                }

                if(Event.key.repeat == 0) {
                    if(KeyCode == SDLK_w) {
                        SDLProcessKeyboardMessage(&KeyboardController->MoveUp, IsDown);
                    } else if(KeyCode == SDLK_s) {
                        SDLProcessKeyboardMessage(&KeyboardController->MoveDown, IsDown);
                    } else if(KeyCode == SDLK_a) {
                        SDLProcessKeyboardMessage(&KeyboardController->MoveLeft, IsDown);
                    } else if(KeyCode == SDLK_d) {
                        SDLProcessKeyboardMessage(&KeyboardController->MoveRight, IsDown);
                    } else if(KeyCode == SDLK_q) {
                        SDLProcessKeyboardMessage(&KeyboardController->LeftShoulder, IsDown);
                    } else if(KeyCode == SDLK_e) {
                        SDLProcessKeyboardMessage(&KeyboardController->RightShoulder, IsDown);
                    } else if(KeyCode == SDLK_UP) {
                        SDLProcessKeyboardMessage(&KeyboardController->ActionUp, IsDown);
                    } else if(KeyCode == SDLK_DOWN) {
                        SDLProcessKeyboardMessage(&KeyboardController->ActionDown, IsDown);
                    } else if(KeyCode == SDLK_LEFT) {
                        SDLProcessKeyboardMessage(&KeyboardController->ActionLeft, IsDown);
                    } else if(KeyCode == SDLK_RIGHT) {
                        SDLProcessKeyboardMessage(&KeyboardController->ActionRight, IsDown);
                    } else if(KeyCode == SDLK_ESCAPE) {
                        SDLProcessKeyboardMessage(&KeyboardController->Start, IsDown);
                    } else if(KeyCode == SDLK_SPACE) {
                        SDLProcessKeyboardMessage(&KeyboardController->Back, IsDown);
                    }
                }

                if(WasDown) {
                    /* NOTE: If your window manager already uses an Alt+F4
                     *       keybind to close programs, then we are likely
                     *       to see SDL_QUIT event occur before our
                     *       keybind. */
                    B32 AltKeyWasDown = (Event.key.keysym.mod & KMOD_ALT);
                    if(KeyCode == SDLK_F4 && AltKeyWasDown)
                        GlobalRunning = FALSE;
#if BUILD_INTERNAL
                    if(KeyCode == SDLK_ESCAPE)
                        GlobalRunning = FALSE;
#endif
                }
            } break;

            default: {
                HandleEvent(&Event);
            } break;
        }
    }
}

static F32 SDLProcessInputStickValue(F32 Value, S32 DeadZoneThreshold)
{
    F32 Result = 0.0f;
    if(Value < -(F32)DeadZoneThreshold)
        Result = ((Value + (F32)DeadZoneThreshold) / (32768.0f - (F32)DeadZoneThreshold));
    else if(Value > (F32)DeadZoneThreshold)
        Result = ((Value + (F32)DeadZoneThreshold) / (32767.0f - (F32)DeadZoneThreshold));

    return Result;
}

#define DEFAULT_REFRESH_RATE 60
static S32 SDLGetWindowRefreshRate(SDL_Window *Window)
{
    S32 DisplayIndex = SDL_GetWindowDisplayIndex(Window);

    SDL_DisplayMode Mode;
    if(SDL_GetDesktopDisplayMode(DisplayIndex, &Mode) != 0)
        return DEFAULT_REFRESH_RATE;
    if(Mode.refresh_rate == 0)
        return DEFAULT_REFRESH_RATE;

    return Mode.refresh_rate;
}

static U64 SDLGetWallClock()
{
    return SDL_GetPerformanceCounter();
}

static F32 SDLGetSecondsElapsed(U64 Start, U64 End)
{
    return (F32)(End - Start) / (F32)GlobalPerfCountFrequency;
}

typedef struct sdl_game_code {
    void *GameCodeDLL;
    U32 DLLLastWriteTime;

    void (*UpdateAndRender)(thread_context *Thread, game_memory *, game_input *, game_offscreen_buffer *, game_sound_output_buffer *);

    B32 IsValid;
} sdl_game_code;

static U32 GetLastWriteTime(const char *FileName)
{
    struct stat file_info;
    memset(&file_info, 0, sizeof(file_info));
    if(stat(FileName, &file_info) != 0) {
        /* TODO: Diagnostic. perror("stat failed"); */
    }

    return (U32)file_info.st_mtime;
}

#define GAME_DLL_NAME "libhandmade.so"

static sdl_game_code SDLLoadGameCode(char *DLLPath)
{
    sdl_game_code Result;
    memset(&Result, 0, sizeof(Result));

    Result.GameCodeDLL = dlopen(DLLPath, RTLD_NOW);
    if(Result.GameCodeDLL) {
        Result.DLLLastWriteTime = GetLastWriteTime(DLLPath);

        Result.UpdateAndRender = (void(*)(thread_context *, game_memory *, game_input *, game_offscreen_buffer *, game_sound_output_buffer *)) dlsym(Result.GameCodeDLL, "UpdateAndRender");
        if(!Result.UpdateAndRender) {
            /* TODO: Diagnostic. dlerror() */
        }

        Result.IsValid = Result.UpdateAndRender ? TRUE : FALSE;
    } else {
        /* TODO: Diagnostic. dlerror() */
    }

    if(!Result.IsValid) {
        Result.UpdateAndRender = NULL;
    }

    return Result;
}

static void SDLUnloadGameCode(sdl_game_code *GameCode)
{
    if(GameCode->GameCodeDLL)
        dlclose(GameCode->GameCodeDLL); /* NOTE: Might fail. */
    GameCode->IsValid = FALSE;
    GameCode->UpdateAndRender = NULL;
}

void GetExecutablePath(char *path, size_t path_size)
{
#if __APPLE__ && __MACH__
    U32 size;
#else
    ssize_t size;
#endif

    if(path_size > 0) {
        path[0] = '\0';

#if __APPLE__ && __MACH__
        size = path_size;
        if(_NSGetExecutablePath(path, &size) != 0) { /* NOTE: Not an
                                                              absolute
                                                              path. */
            /* TODO: Diagnostics. */
        }
#else
        size = readlink("/proc/self/exe", path, path_size - 1);
        if(size != -1) {
            path[size] = '\0';
        } else {
            /* TODO: Diagnostics. */
        }
#endif
    }
}

static void SDLGetEXEDirPath(char *path, size_t path_size)
{
    GetExecutablePath(path, path_size);
    U32 len = str_len(path);
    U32 i = len;
    while(path[i] != '/' || i == 0) {
        i--;
    }
    path[i+1] = '\0';
}

static void SDLGetDLLPath(char *path, size_t path_size, char *exe_path)
{
    snprintf(path, path_size, "%s%s", exe_path, GAME_DLL_NAME);
}

#if !(__x86_64__ || __i386__)
U64 __rdtsc()
{
    return 0;
}
#endif

/* TODO: In the future, this should just accept either a bitmap or image
 *       path. This is to be determined. One cool feature this might
 *       support is displaying certain information in the program icon by
 *       drawing into a bitmap. */
void SDLSetProgramIcon(SDL_Window *Window)
{
    U32 Rmask, Gmask, Bmask, Amask;
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
    S32 shift_by = (program_icon.bytes_per_pixel == 3) ? 8 : 0;
    Rmask = 0xff000000 >> shift_by;
    Gmask = 0x00ff0000 >> shift_by;
    Bmask = 0x0000ff00 >> shift_by;
    Amask = 0x000000ff >> shift_by;
#else
    Rmask = 0x000000ff;
    Gmask = 0x0000ff00;
    Bmask = 0x00ff0000;
    Amask = (program_icon.bytes_per_pixel == 3) ? 0 : 0xff000000;
#endif

    SDL_Surface * icon = SDL_CreateRGBSurfaceFrom(
        (void *)program_icon.pixel_data,
        program_icon.width, program_icon.height,
        program_icon.bytes_per_pixel * 8,
        program_icon.bytes_per_pixel * program_icon.width,
        Rmask, Gmask, Bmask, Amask);
    if(icon) {
        SDL_SetWindowIcon(Window, icon);
        SDL_FreeSurface(icon);
    } else {
        /* TODO: This didn't work . . . SDL_GetError() */
    }
}

S32 main(S32 argc, char *argv[])
{
    sdl_state SDLState;
    memset(&SDLState, 0, sizeof(SDLState));

    SDLGetEXEDirPath(SDLState.EXEDirPath, sizeof(SDLState.EXEDirPath));
    SDLGetDLLPath(SDLState.DLLPath, sizeof(SDLState.DLLPath), SDLState.EXEDirPath);

    if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_GAMECONTROLLER | SDL_INIT_AUDIO)) {
        /* TODO: This didn't work . . . */
    }

    SDLInitControllers();

    /* NOTE: Floating windows are not supported oficially by Wayland
     *       protocol. However, SDL_WINDOW_ALWAYS_ON_TOP does work on KDE
     *       under Wayland. I have not tested GNOME. */
    SDL_Window *Window = SDL_CreateWindow("Handmade Hero", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, RESOLUTION_WIDTH+20, RESOLUTION_HEIGHT+20, SDL_WINDOW_RESIZABLE);
                              /*SDL_WINDOW_RESIZABLE |
                                                 SDL_WINDOW_ALWAYS_ON_TOP);*/

    if(Window) {
        SDL_DisplayMode display_mode;
        SDL_GetCurrentDisplayMode(0, &display_mode);

        SDL_Renderer *Renderer = SDL_CreateRenderer(Window, -1, SDL_RENDERER_PRESENTVSYNC);
        SDL_SetWindowPosition(Window, (display_mode.w - RESOLUTION_WIDTH), (display_mode.h - RESOLUTION_HEIGHT));

        /* NOTE: For future reference, the custom window bar should use
         * SDL_SetWindowHitTest to define areas that will be used to
         * drag the window. */

        /* "Wayland needs an event loop and rendering or it won't function."
         * https://github.com/libsdl-org/SDL/issues/7699#issuecomment-1545684792 */
        /* NOTE: This means that we need to readraw to even resize the
         *       window, otherwise the window frame will appear outdated to
         *       its actual size. */
        /* SDL_RenderPresent(Renderer) is enough to display the window. */
        if(Renderer) {
#if BUILD_DEBUG
    void *BaseAddress = (void *)TB(2);
#else
    void *BaseAddress = (void *)(0);
#endif

            SDLSetProgramIcon(Window);
#if 0
            if(SDL_ShowCursor(SDL_DISABLE) < 0) {
                /* TODO: This didn't work . . . SDL_GetError() */
            }
#endif

            GlobalRunning = TRUE;

            //sdl_window_dimension Dimension = SDLGetWindowDimension(Window);
            //SDLResizeTexture(&GlobalBackbuffer, Renderer, Dimension.Width, Dimension.Height);
            SDLResizeTexture(&GlobalBackbuffer, Renderer, RESOLUTION_WIDTH, RESOLUTION_HEIGHT);

            sdl_sound_output SoundOutput;
            memset(&SoundOutput, 0, sizeof(SoundOutput));
            SoundOutput.SamplesPerSecond = 48000;
            SoundOutput.BytesPerSample = sizeof(S16) * 2;
            SoundOutput.SecondaryBufferSize = SoundOutput.SamplesPerSecond * SoundOutput.BytesPerSample;
            SoundOutput.tSine = 0;
            SoundOutput.LatencySampleCount = SoundOutput.SamplesPerSecond / 15;

            SDLInitSound(SoundOutput.SamplesPerSecond, SoundOutput.SamplesPerSecond * SoundOutput.BytesPerSample / 60);
            SDL_PauseAudio(0);

            SoundOutput.Samples = calloc(SoundOutput.SamplesPerSecond, SoundOutput.BytesPerSample);
            /* SoundOutput.Samples =
             *     malloc(SoundOutput.SecondaryBufferSize); */
            /* NOTE: calloc auto clears to zero */
            /* SDLClearSoundBuffer(&SoundOutput); */

            game_memory GameMemory;
            memset(&GameMemory, 0, sizeof(GameMemory));
            GameMemory.PermanentStorageSize = MB(64);
            GameMemory.TransientStorageSize = GB(1);
            GameMemory.DEBUGPlatformReadEntireFile = &DEBUGPlatformReadEntireFile;
            GameMemory.DEBUGPlatformWriteEntireFile = &DEBUGPlatformWriteEntireFile;
            GameMemory.DEBUGPlatformFreeFileMemory = &DEBUGPlatformFreeFileMemory;

            SDLState.TotalSize = GameMemory.PermanentStorageSize + GameMemory.TransientStorageSize;
            /* NOTE: On MacOS and Linux, mmap seems to zero-fill anonymous
             *       memory as a side-effect of security. */
            SDLState.GameMmemoryBlock = mmap(BaseAddress, (size_t)SDLState.TotalSize, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
            GameMemory.PermanentStorage = SDLState.GameMmemoryBlock;
            GameMemory.TransientStorage = (U8 *)(GameMemory.PermanentStorage) + GameMemory.PermanentStorageSize;

            if(SoundOutput.Samples && GameMemory.PermanentStorage && GameMemory.TransientStorage) {
                game_input Input[2];

                U64 LastCounter;
                U64 LastCycleCount;

                S32 MonitorRefreshHz = SDLGetWindowRefreshRate(Window);
                /*GameUpdateHz = MonitorRefreshHz;*/
                S32 GameUpdateHz = 30; /* NOTE: Temporarily target 30 FPS. */
                F32 TargetSecondsPerFrame = 1.0f / (F32)GameUpdateHz;

                game_input *NewInput = &Input[0];
                game_input *OldInput = &Input[1];
                memset(&Input, 0, sizeof(Input));

                GlobalPerfCountFrequency = SDL_GetPerformanceFrequency();

                sdl_game_code Game = SDLLoadGameCode(SDLState.DLLPath);

                while(GlobalRunning) {
                    NewInput->dtForFrame = TargetSecondsPerFrame;

                    LastCounter = SDLGetWallClock();

                    /* NOTE: rdtsc reports clock cylces, however it is not
                     *       meant for really precise profiler work as the
                     *       value returned is varied. */
                    /*       Also, __rdtsc is not available on MacOS ARM; I
                     *       have not checked MacOS x64. */
                    LastCycleCount = __rdtsc();

                    U32 NewDLLWriteTime = GetLastWriteTime(SDLState.DLLPath);
                    if(NewDLLWriteTime > Game.DLLLastWriteTime) {
                        SDLUnloadGameCode(&Game);
                        Game = SDLLoadGameCode(SDLState.DLLPath);
                    }

                    U32 SDLMouseButtons = SDL_GetMouseState(&(NewInput->MouseX), &(NewInput->MouseY));
                    NewInput->MouseZ = 0; /* TODO: Support mouse wheel? */
                    SDLProcessKeyboardMessage(&(NewInput->MouseButtons[0]), SDL_BUTTON_LMASK & SDLMouseButtons);
                    SDLProcessKeyboardMessage(&(NewInput->MouseButtons[1]), SDL_BUTTON_MMASK & SDLMouseButtons);
                    SDLProcessKeyboardMessage(&(NewInput->MouseButtons[2]), SDL_BUTTON_RMASK & SDLMouseButtons);
                    /* WARNING: TODO: SDL_BUTTON_X1MASK and SDL_BUTTON_X2MASK cannot be on at the
                     *                same time for some reason. */
                    SDLProcessKeyboardMessage(&(NewInput->MouseButtons[3]), SDL_BUTTON_X1MASK & SDLMouseButtons);
                    SDLProcessKeyboardMessage(&(NewInput->MouseButtons[4]), SDL_BUTTON_X2MASK & SDLMouseButtons);

                    game_controller_input *OldKeyboardController = GetController(OldInput, 0);
                    game_controller_input *NewKeyboardController = GetController(NewInput, 0);
                    game_controller_input ZeroController;
                    memset(&ZeroController, 0, sizeof(ZeroController));
                    *NewKeyboardController = ZeroController;
                    NewKeyboardController->IsConnected = TRUE;

                    for(U32 ButtonIndex = 0; ButtonIndex < ARRAY_SIZE(NewKeyboardController->Buttons); ButtonIndex++) {
                        NewKeyboardController->Buttons[ButtonIndex].EndedDown = OldKeyboardController->Buttons[ButtonIndex].EndedDown;
                    }

                    SDLProcessMessages(&SDLState, NewKeyboardController);

                    for(U32 ControllerIndex = 0; ControllerIndex < MAX_CONTROLLERS; ControllerIndex++) {
                        game_controller_input *OldController = GetController(OldInput, ControllerIndex+1);
                        game_controller_input *NewController = GetController(NewInput, ControllerIndex+1);

                        if(ControllerHandles[ControllerIndex] != 0 && SDL_GameControllerGetAttached(ControllerHandles[ControllerIndex])) {
                            NewController->IsAnalog = OldController->IsAnalog;
                            NewController->IsConnected = TRUE;

                            S16 StickX = SDL_GameControllerGetAxis(ControllerHandles[ControllerIndex], SDL_CONTROLLER_AXIS_LEFTX);
                            S16 StickY = SDL_GameControllerGetAxis(ControllerHandles[ControllerIndex], SDL_CONTROLLER_AXIS_LEFTY);

                            NewController->IsAnalog = TRUE;
                            NewController->StickAverageX = SDLProcessInputStickValue((F32)StickX, CONTROLLER_LEFT_THUMB_DEADZONE);
                            NewController->StickAverageY = SDLProcessInputStickValue((F32)StickY, CONTROLLER_LEFT_THUMB_DEADZONE);

                            if((NewController->StickAverageX != 0.0f) || (NewController->StickAverageY != 0.0f)) {
                                NewController->IsAnalog = TRUE;
                            }

                            if(SDL_GameControllerGetButton(ControllerHandles[ControllerIndex], SDL_CONTROLLER_BUTTON_DPAD_UP)) {
                                NewController->StickAverageY = -1.0f;
                                NewController->IsAnalog = FALSE;
                            }

                            if(SDL_GameControllerGetButton(ControllerHandles[ControllerIndex], SDL_CONTROLLER_BUTTON_DPAD_DOWN)) {
                                NewController->StickAverageY = 1.0f;
                                NewController->IsAnalog = FALSE;
                            }

                            if(SDL_GameControllerGetButton(ControllerHandles[ControllerIndex], SDL_CONTROLLER_BUTTON_DPAD_LEFT)) {
                                NewController->StickAverageX = -1.0f;
                                NewController->IsAnalog = FALSE;
                            }

                            if(SDL_GameControllerGetButton(ControllerHandles[ControllerIndex], SDL_CONTROLLER_BUTTON_DPAD_RIGHT)) {
                                NewController->StickAverageX = 1.0f;
                                NewController->IsAnalog = FALSE;
                            }

                            F32 Threshold = 0.5f;
                            SDLProcessInputDigitalButton(ControllerHandles[(NewController->StickAverageY < -Threshold) ? 1 : 0], &OldController->MoveUp, SDL_CONTROLLER_BUTTON_A, &NewController->MoveUp);
                            SDLProcessInputDigitalButton(ControllerHandles[(NewController->StickAverageY > Threshold) ? 1 : 0], &OldController->MoveDown, SDL_CONTROLLER_BUTTON_A, &NewController->MoveDown);
                            SDLProcessInputDigitalButton(ControllerHandles[(NewController->StickAverageX < -Threshold) ? 1 : 0], &OldController->MoveLeft, SDL_CONTROLLER_BUTTON_A, &NewController->MoveLeft);
                            SDLProcessInputDigitalButton(ControllerHandles[(NewController->StickAverageX > Threshold) ? 1 : 0], &OldController->MoveRight, SDL_CONTROLLER_BUTTON_A, &NewController->MoveRight);

                            SDLProcessInputDigitalButton(ControllerHandles[ControllerIndex], &OldController->ActionDown, SDL_CONTROLLER_BUTTON_A, &NewController->ActionDown);
                            SDLProcessInputDigitalButton(ControllerHandles[ControllerIndex], &OldController->ActionRight, SDL_CONTROLLER_BUTTON_B, &NewController->ActionRight);
                            SDLProcessInputDigitalButton(ControllerHandles[ControllerIndex], &OldController->ActionLeft, SDL_CONTROLLER_BUTTON_X, &NewController->ActionLeft);
                            SDLProcessInputDigitalButton(ControllerHandles[ControllerIndex], &OldController->ActionUp, SDL_CONTROLLER_BUTTON_Y, &NewController->ActionUp);
                            SDLProcessInputDigitalButton(ControllerHandles[ControllerIndex], &OldController->LeftShoulder, SDL_CONTROLLER_BUTTON_LEFTSHOULDER, &NewController->LeftShoulder);
                            SDLProcessInputDigitalButton( ControllerHandles[ControllerIndex], &OldController->RightShoulder, SDL_CONTROLLER_BUTTON_RIGHTSHOULDER, &NewController->RightShoulder);

                            SDLProcessInputDigitalButton(ControllerHandles[ControllerIndex], &OldController->Start, SDL_CONTROLLER_BUTTON_START, &NewController->Start);
                            SDLProcessInputDigitalButton( ControllerHandles[ControllerIndex], &OldController->Back, SDL_CONTROLLER_BUTTON_BACK, &NewController->Back);
                        } else {
                            /* NOTE: This controller is not plugged in. */
                            NewController->IsConnected = FALSE;
                        }
                    }

                    S32 TargetQueueBytes = SoundOutput.LatencySampleCount *
                                               SoundOutput.BytesPerSample;
                    S32 BytesToWrite =
                        TargetQueueBytes - SDL_GetQueuedAudioSize(1);
                    game_sound_output_buffer SoundBuffer;
                    SoundBuffer.SamplesPerSecond =
                        SoundOutput.SamplesPerSecond;
                    SoundBuffer.SampleCount =
                        BytesToWrite / SoundOutput.BytesPerSample;
                    SoundBuffer.Samples = (short *)SoundOutput.Samples;

                    thread_context Context;
                    memset(&Context, 0, sizeof(Context));

                    game_offscreen_buffer Buffer;
                    Buffer.Memory = GlobalBackbuffer.Memory;
                    Buffer.Width = GlobalBackbuffer.Width;
                    Buffer.Height = GlobalBackbuffer.Height;
                    Buffer.BytesPerPixel = 4;
                    Buffer.Pitch = GlobalBackbuffer.Pitch;

                    if(Game.UpdateAndRender) {
                        Game.UpdateAndRender(&Context, &GameMemory,
                                             NewInput, &Buffer,
                                             &SoundBuffer);
                    }

                    SDLFillSoundBuffer(&SoundOutput, BytesToWrite);

                    U64 WorkCounter = SDLGetWallClock();
                    F32 WorkSecondsElapsed =
                        SDLGetSecondsElapsed(LastCounter, WorkCounter);

                    F32 SecondsElapsedForFrame = WorkSecondsElapsed;
                    if(SecondsElapsedForFrame < TargetSecondsPerFrame) {
                        while(SecondsElapsedForFrame < TargetSecondsPerFrame) {
                            SecondsElapsedForFrame =
                                SDLGetSecondsElapsed(LastCounter,
                                                     SDLGetWallClock());
                            SDL_Delay((U32)((TargetSecondsPerFrame -
                                        SecondsElapsedForFrame) * 1000.0));
                        }
                    } else {
                        /* TODO: Missed frame rate! */
                        /* TODO: Logging. */
                    }

                    U64 EndCounter = SDLGetWallClock();

                    SDLDisplayBufferInWindow(GlobalBackbuffer, Window,
                                             Renderer);

                    F64 MSPerFrame = 1000.0 *
                        SDLGetSecondsElapsed(LastCounter, EndCounter);
                    F64 FPS = 0.0;

                    LastCounter = EndCounter;

#if 0
                    U64 EndCycleCount = __rdtsc();
                    U64 CyclesElapsed = EndCycleCount - LastCycleCount;
                    F64 MCPF = ((double)CyclesElapsed / (1000.0 * 1000.0));
                    fprintf(stderr, "%.02f ms/f, %.02f/s, %.02f mc/f\n",
                            MSPerFrame, FPS, MCPF);
                    LastCycleCount = EndCycleCount;
#endif

                    SWAP(game_input *, NewInput, OldInput);
                }
            } else {
                /* TODO: Failed to allocate Samples and Sound memory . . . */
            }
        } else {
            /* TODO: This didn't work . . . */
        }
    } else {
        /* TODO: This didn't work . . . */
    }

    /* NOTE: Let the OS clean things up. */
    /* NOTE: This, however, might need to be closed? Is there maybe some
     *       clean up state that close communicates to the controller? */
    /* SDLDeinitControllers(); */
    /* SDL_CloseAudio(); */
    /* SDL_DestroyRenderer(Renderer); */
    /* SDL_DestroyWindow(Window); */
    /* SDL_Quit(); */

    return 0;
}