#include <stdio.h>
#include <stdbool.h>
#include <unistd.h>
#include <time.h>
#include <assert.h>
#include <signal.h>
#include <stdarg.h>

#ifndef WIIU
#define AUDIO_FREQUENCY 384000
#else
#define AUDIO_FREQUENCY 44100
#endif

#define FRAME_RATE (0x400000 / 70224.0)

#ifdef _WIN32
#include <direct.h>
#include <windows.h>
#define snprintf _snprintf
#endif

#include <Core/gb.h>
#include "libretro.h"

#ifdef _WIN32
static const char slash = '\\';
#else
static const char slash = '/';
#endif

#define VIDEO_WIDTH 160
#define VIDEO_HEIGHT 144
#define VIDEO_PIXELS (VIDEO_WIDTH * VIDEO_HEIGHT)

char battery_save_path[512];
char symbols_path[512];

enum model {
    MODEL_DMG,
    MODEL_CGB,
    MODEL_AGB,
    MODEL_AUTO
};

static enum model model = MODEL_AUTO;
static enum model auto_model = MODEL_CGB;
static uint32_t *frame_buf;

static uint32_t *frame_buf = NULL;
static struct retro_log_callback logging;
static retro_log_printf_t log_cb;

static retro_video_refresh_t video_cb;
static retro_audio_sample_batch_t audio_batch_cb;
static retro_input_poll_t input_poll_cb;
static retro_input_state_t input_state_cb;

signed short soundbuf[1024 * 2];

char retro_system_directory[4096];
char retro_save_directory[4096];
char retro_game_path[4096];

GB_gameboy_t gb1;
GB_gameboy_t gb2;
extern const unsigned char dmg_boot[], cgb_boot[], agb_boot[];
extern const unsigned dmg_boot_length, cgb_boot_length, agb_boot_length;
bool vblank1_occurred = false, vblank2_occurred = false;

static void fallback_log(enum retro_log_level level, const char *fmt, ...)
{
    (void)level;
    va_list va;
    va_start(va, fmt);
    vfprintf(stderr, fmt, va);
    va_end(va);
}

static struct retro_rumble_interface rumble;

static void GB_update_keys_status(GB_gameboy_t *gb, unsigned port)
{

    input_poll_cb();
    
    GB_set_key_state(gb, GB_KEY_RIGHT,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_RIGHT));
    GB_set_key_state(gb, GB_KEY_LEFT, input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_LEFT));
    GB_set_key_state(gb, GB_KEY_UP,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_UP) );
    GB_set_key_state(gb, GB_KEY_DOWN,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_DOWN));
    GB_set_key_state(gb, GB_KEY_A,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_A) );
    GB_set_key_state(gb, GB_KEY_B,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_B) );
    GB_set_key_state(gb, GB_KEY_SELECT,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_SELECT));
    GB_set_key_state(gb, GB_KEY_START,input_state_cb(port, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_START) );
    
    if (gb->rumble_state)
        rumble.set_rumble_state(port, RETRO_RUMBLE_STRONG, 65535);
    else
        rumble.set_rumble_state(port, RETRO_RUMBLE_STRONG, 0);
    
}


static void audio_callback(void *gb)
{
    size_t length = GB_apu_get_current_buffer_length(gb);

    while (length > sizeof(soundbuf) / 4)
    {
        GB_apu_copy_buffer(gb, (GB_sample_t *) soundbuf, 1024);
        audio_batch_cb(soundbuf, 1024);
        length -= 1024;
    }
    if (length) {
        GB_apu_copy_buffer(gb, (GB_sample_t *) soundbuf, length);
        audio_batch_cb(soundbuf, length);
    }
}


static void vblank1(GB_gameboy_t *gb)
{
    vblank1_occurred = true;
    GB_update_keys_status(gb, 0);
    audio_callback(gb);
}

static void vblank2(GB_gameboy_t *gb)
{
    vblank2_occurred = true;
    GB_update_keys_status(gb, 1);
    //audio_callback(gb);
}

static uint32_t rgb_encode(GB_gameboy_t *gb, uint8_t r, uint8_t g, uint8_t b)
{
    return r<<16|g<<8|b;
}

static retro_environment_t environ_cb;

void retro_init(void)
{
    frame_buf = (uint32_t*)malloc(2 * VIDEO_PIXELS * sizeof(uint32_t));
    const char *dir = NULL;

    if (environ_cb(RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY, &dir) && dir)
        snprintf(retro_system_directory, sizeof(retro_system_directory), "%s", dir);
    else
        snprintf(retro_system_directory, sizeof(retro_system_directory), "%s", ".");

    if (environ_cb(RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY, &dir) && dir)
        snprintf(retro_save_directory, sizeof(retro_save_directory), "%s", dir);
    else
        snprintf(retro_save_directory, sizeof(retro_save_directory), "%s", ".");
}

void retro_deinit(void)
{
    free(frame_buf);
    frame_buf = NULL;
}

unsigned retro_api_version(void)
{
    return RETRO_API_VERSION;
}

void retro_set_controller_port_device(unsigned port, unsigned device)
{
    log_cb(RETRO_LOG_INFO, "Plugging device %u into port %u.\n", device, port);
}

void retro_get_system_info(struct retro_system_info *info)
{
    memset(info, 0, sizeof(*info));
    info->library_name     = "SameBoy";
#ifdef GIT_VERSION
    info->library_version  = SAMEBOY_CORE_VERSION GIT_VERSION;
#else
    info->library_version  = SAMEBOY_CORE_VERSION;
#endif
    info->need_fullpath    = true;
    info->valid_extensions = "gb|gbc";
}

void retro_get_system_av_info(struct retro_system_av_info *info)
{
    struct retro_game_geometry geom = { VIDEO_WIDTH, VIDEO_HEIGHT * 2, VIDEO_WIDTH, VIDEO_HEIGHT * 2 ,160.0 / 288.0 };
    struct retro_system_timing timing = { FRAME_RATE, AUDIO_FREQUENCY };

    info->geometry = geom;
    info->timing   = timing;

}

void retro_set_environment(retro_environment_t cb)
{
    environ_cb = cb;

    if (cb(RETRO_ENVIRONMENT_GET_LOG_INTERFACE, &logging))
        log_cb = logging.log;
    else
        log_cb = fallback_log;

    static const struct retro_controller_description controllers[] = {
        { "Nintendo Gameboy", RETRO_DEVICE_SUBCLASS(RETRO_DEVICE_JOYPAD, 0) },
    };

    static const struct retro_controller_info ports[] = {
        { controllers, 1 },
        { NULL, 0 },
    };
    cb(RETRO_ENVIRONMENT_SET_CONTROLLER_INFO, (void*)ports);
}

void retro_set_audio_sample(retro_audio_sample_t 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;
}

void retro_reset(void)
{
    GB_reset(&gb1);
    GB_reset(&gb2);
}

static uint8_t byte_to_send1 = 0xFF, byte_to_send2 = 0xFF;

static void serial_start1(GB_gameboy_t *gb, uint8_t byte_received)
{
    byte_to_send1 = byte_received;
}

static uint8_t serial_end1(GB_gameboy_t *gb)
{
    uint8_t ret = GB_serial_get_data(&gb2);
    GB_serial_set_data(&gb2, byte_to_send1);
    return ret;
}

static void serial_start2(GB_gameboy_t *gb, uint8_t byte_received)
{
    byte_to_send2 = byte_received;
}

static uint8_t serial_end2(GB_gameboy_t *gb)
{
    uint8_t ret = GB_serial_get_data(&gb1);
    GB_serial_set_data(&gb1, byte_to_send2);
    return ret;
}

static void init_for_current_model(void)
{
    enum model effective_model = model;
    if (effective_model == MODEL_AUTO) {
        effective_model = auto_model;
    }
    if (GB_is_inited(&gb1)) {
        GB_switch_model_and_reset(&gb1, effective_model != MODEL_DMG);
    }
    else {
        if (effective_model == MODEL_DMG) {
            GB_init(&gb1);
        }
        else {
            GB_init_cgb(&gb1);
        }
    }
    if (GB_is_inited(&gb2)) {
        GB_switch_model_and_reset(&gb2, effective_model != MODEL_DMG);
    }
    else {
        if (effective_model == MODEL_DMG) {
            GB_init(&gb2);
        }
        else {
            GB_init_cgb(&gb2);
        }
    }

    const char *model_name = (const char *[]){"dmg", "cgb", "agb"}[effective_model];
    const unsigned char *boot_code = (const unsigned char *[]){dmg_boot, cgb_boot, agb_boot}[effective_model];
    unsigned boot_length = (unsigned []){dmg_boot_length, cgb_boot_length, agb_boot_length}[effective_model];

    char buf[256];
    snprintf(buf, sizeof(buf), "%s%c%s_boot.bin", retro_system_directory, slash, model_name);
    log_cb(RETRO_LOG_INFO, "Loading boot image: %s\n", buf);
    
    if (GB_load_boot_rom(&gb1, buf)) {
        GB_load_boot_rom_from_buffer(&gb1, boot_code, boot_length);
    }
    if (GB_load_boot_rom(&gb2, buf)) {
        GB_load_boot_rom_from_buffer(&gb2, boot_code, boot_length);
    }
    
    GB_set_vblank_callback(&gb1, (GB_vblank_callback_t) vblank1);
    GB_set_vblank_callback(&gb2, (GB_vblank_callback_t) vblank2);
    GB_set_user_data(&gb1, (void*)NULL);
    GB_set_user_data(&gb2, (void*)NULL);
    GB_set_pixels_output(&gb1,(unsigned int*)frame_buf);
    GB_set_rgb_encode_callback(&gb1, rgb_encode);
    GB_set_pixels_output(&gb2,(unsigned int*)(frame_buf + VIDEO_PIXELS));
    GB_set_rgb_encode_callback(&gb2, rgb_encode);
    GB_set_sample_rate(&gb1, AUDIO_FREQUENCY);
    GB_set_sample_rate(&gb2, AUDIO_FREQUENCY);
    GB_set_serial_transfer_start_callback(&gb1, serial_start1);
    GB_set_serial_transfer_end_callback(&gb1, serial_end1);
    GB_set_serial_transfer_start_callback(&gb2, serial_start2);
    GB_set_serial_transfer_end_callback(&gb2, serial_end2);

    struct retro_memory_descriptor descs[7];
    size_t size;
    uint16_t bank;

    memset(descs, 0, sizeof(descs));
    
    descs[0].ptr   = GB_get_direct_access(&gb1, GB_DIRECT_ACCESS_IE, &size, &bank);
    descs[0].start = 0xFFFF;
    descs[0].len   = 1;
    
    descs[1].ptr   = GB_get_direct_access(&gb1, GB_DIRECT_ACCESS_HRAM, &size, &bank);
    descs[1].start = 0xFF80;
    descs[1].len   = 0x0080;
    
    descs[2].ptr   = GB_get_direct_access(&gb1, GB_DIRECT_ACCESS_RAM, &size, &bank);
    descs[2].start = 0xC000;
    descs[2].len   = 0x2000;
    
    descs[3].ptr   = GB_get_direct_access(&gb1, GB_DIRECT_ACCESS_CART_RAM, &size, &bank);
    descs[3].start = 0xA000;
    descs[3].len   = 0x2000;
    
    descs[4].ptr   = GB_get_direct_access(&gb1, GB_DIRECT_ACCESS_VRAM, &size, &bank);
    descs[4].start = 0x8000;
    descs[4].len   = 0x2000;
    
    descs[5].ptr   = GB_get_direct_access(&gb1, GB_DIRECT_ACCESS_ROM, &size, &bank);
    descs[5].start = 0x0000;
    descs[5].len   = 0x4000;
    descs[5].flags = RETRO_MEMDESC_CONST;
    
    descs[6].ptr   = GB_get_direct_access(&gb1, GB_DIRECT_ACCESS_OAM, &size, &bank);
    descs[6].start = 0xFE00;
    descs[6].len   = 0x00A0;

    struct retro_memory_map mmaps;
    mmaps.descriptors = descs;
    mmaps.num_descriptors = sizeof(descs) / sizeof(descs[0]);
    environ_cb(RETRO_ENVIRONMENT_SET_MEMORY_MAPS, &mmaps);
}

static void check_variables(void)
{
    struct retro_variable var = {0};

    var.key = "sameboy_color_correction_mode";
    var.value = NULL;
    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value && GB_is_cgb(&gb1))
    {
        if (strcmp(var.value, "off") == 0)
        {
            GB_set_color_correction_mode(&gb1, GB_COLOR_CORRECTION_DISABLED);
            GB_set_color_correction_mode(&gb2, GB_COLOR_CORRECTION_DISABLED);
        }
        else if (strcmp(var.value, "correct curves") == 0)
        {
            GB_set_color_correction_mode(&gb1, GB_COLOR_CORRECTION_CORRECT_CURVES);
            GB_set_color_correction_mode(&gb2, GB_COLOR_CORRECTION_CORRECT_CURVES);
        }
        else if (strcmp(var.value, "emulate hardware") == 0)
        {
            GB_set_color_correction_mode(&gb1, GB_COLOR_CORRECTION_EMULATE_HARDWARE);
            GB_set_color_correction_mode(&gb2, GB_COLOR_CORRECTION_EMULATE_HARDWARE);
        }
        else if (strcmp(var.value, "preserve brightness") == 0)
        {
            GB_set_color_correction_mode(&gb1, GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS);
            GB_set_color_correction_mode(&gb2, GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS);
        }
    }

    var.key = "sameboy_high_pass_filter_mode";
    var.value = NULL;
    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
    {
        if (strcmp(var.value, "off") == 0)
        {
            GB_set_highpass_filter_mode(&gb1, GB_HIGHPASS_OFF);
            GB_set_highpass_filter_mode(&gb2, GB_HIGHPASS_OFF);
        }
        else if (strcmp(var.value, "accurate") == 0)
        {
            GB_set_highpass_filter_mode(&gb1, GB_HIGHPASS_ACCURATE);
            GB_set_highpass_filter_mode(&gb2, GB_HIGHPASS_ACCURATE);
        }
        else if (strcmp(var.value, "remove dc offset") == 0)
        {
            GB_set_highpass_filter_mode(&gb1, GB_HIGHPASS_REMOVE_DC_OFFSET);
            GB_set_highpass_filter_mode(&gb2, GB_HIGHPASS_REMOVE_DC_OFFSET);
        }
    }

    var.key = "sameboy_model";
    var.value = NULL;
    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
    {
        enum model new_model = model;
        if (strcmp(var.value, "Game Boy") == 0)
            new_model = MODEL_DMG;
        else if (strcmp(var.value, "Game Boy Color") == 0)
            new_model = MODEL_CGB;
        else if (strcmp(var.value, "Game Boy Advance") == 0)
            new_model = MODEL_AGB;
        else if (strcmp(var.value, "Auto") == 0)
            new_model = MODEL_AUTO;
        if (GB_is_inited(&gb1) && new_model != model) {
            model = new_model;
            init_for_current_model();
        }
        if (GB_is_inited(&gb2) && new_model != model) {
            model = new_model;
            init_for_current_model();
        }
        else {
            model = new_model;
        }
    }
}

int frames = 0;
void retro_run(void)
{
    bool updated = false;
    
    if (!frame_buf)
        return;
    
    if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE, &updated) && updated)
        check_variables();
    
    vblank1_occurred = vblank2_occurred = false;
    signed delta = 0;
    while (!vblank1_occurred || !vblank2_occurred) {
        if (delta >= 0) {
            delta -= GB_run(&gb1);
        }
        else {
            delta += GB_run(&gb2);
        }
    }
    
    video_cb(frame_buf, VIDEO_WIDTH, VIDEO_HEIGHT * 2, VIDEO_WIDTH * sizeof(uint32_t));
    
    frames++;
}

bool retro_load_game(const struct retro_game_info *info)
{
    struct retro_input_descriptor desc[] = {
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_LEFT,  "Left" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_UP,    "Up" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_DOWN,  "Down" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_RIGHT, "Right" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_B, "B" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_A, "A" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_SELECT, "Select" },
        { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_START, "Start" },
        { 0 },
    };

    environ_cb(RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS, desc);

    enum retro_pixel_format fmt = RETRO_PIXEL_FORMAT_XRGB8888;
    if (!environ_cb(RETRO_ENVIRONMENT_SET_PIXEL_FORMAT, &fmt))
    {
        log_cb(RETRO_LOG_INFO, "XRGB8888 is not supported.\n");
        return false;
    }

    snprintf(retro_game_path, sizeof(retro_game_path), "%s", info->path);

    auto_model = (info->path[strlen(info->path) - 1] & ~0x20) == 'C' ? MODEL_CGB : MODEL_DMG;
    init_for_current_model();
    
    if (GB_load_rom(&gb1,info->path)) {
        log_cb(RETRO_LOG_INFO, "Failed to load ROM\n");
        return false;
    }
    if (GB_load_rom(&gb2,info->path)) {
        log_cb(RETRO_LOG_INFO, "Failed to load ROM\n");
        return false;
    }
    bool yes = true;
    environ_cb(RETRO_ENVIRONMENT_SET_SUPPORT_ACHIEVEMENTS, &yes);

    if (environ_cb(RETRO_ENVIRONMENT_GET_RUMBLE_INTERFACE, &rumble))
        log_cb(RETRO_LOG_INFO, "Rumble environment supported.\n");
    else
        log_cb(RETRO_LOG_INFO, "Rumble environment not supported.\n");

    static const struct retro_variable vars[] = {
        { "sameboy_color_correction_mode", "Color Correction; off|correct curves|emulate hardware|preserve brightness" },
        { "sameboy_high_pass_filter_mode", "High Pass Filter; off|accurate|remove dc offset" },
        { "sameboy_model", "Emulated Model; Auto|Game Boy|Game Boy Color|Game Boy Advance" },
        { NULL }
    };

    environ_cb(RETRO_ENVIRONMENT_SET_VARIABLES, (void *)vars);
    check_variables();

    return true;
}

void retro_unload_game(void)
{
    GB_free(&gb1);
    GB_free(&gb2);
}

unsigned retro_get_region(void)
{
    return RETRO_REGION_NTSC;
}

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

size_t retro_serialize_size(void)
{
    return GB_get_save_state_size(&gb1);
}

bool retro_serialize(void *data, size_t size)
{
    GB_save_state_to_buffer(&gb1, (uint8_t*) data);
    if (data)
        return true;
    else
        return false;
}

bool retro_unserialize(const void *data, size_t size)
{
    if (GB_load_state_from_buffer(&gb1, (uint8_t*) data, size) == 0)
        return true;
    else
        return false;
}

void *retro_get_memory_data(unsigned type)
{
    void* data;
    switch(type)
    {
        case RETRO_MEMORY_SYSTEM_RAM:
            data = gb1.ram;
            break;
        case RETRO_MEMORY_SAVE_RAM:
            if (gb1.cartridge_type->has_battery && gb1.mbc_ram_size != 0)
            {
                data = gb1.mbc_ram;
                /* let's copy the save to gb2 so it can save independently */
                memcpy(gb2.mbc_ram, gb1.mbc_ram, gb1.mbc_ram_size);
            }
            else
                data = NULL;
            break;
        case RETRO_MEMORY_VIDEO_RAM:
            data = gb1.vram;
            break;
        case RETRO_MEMORY_RTC:
            if(gb1.cartridge_type->has_battery)
                data = &gb1.rtc_real;
            else
                data = NULL;
            break;
        default:
            data = NULL;
    }
    return data;
}

size_t retro_get_memory_size(unsigned type)
{
    size_t size;
    switch(type)
    {
        case RETRO_MEMORY_SYSTEM_RAM:
            size = gb1.ram_size;
            break;
        case RETRO_MEMORY_SAVE_RAM:
            if (gb1.cartridge_type->has_battery && gb1.mbc_ram_size != 0)
                size = gb1.mbc_ram_size;
            else
                size = 0;
            break;
        case RETRO_MEMORY_VIDEO_RAM:
            size = gb1.vram_size;
            break;
        case RETRO_MEMORY_RTC:
            if(gb1.cartridge_type->has_battery)
                size = sizeof (gb1.rtc_real);
            else
                size =  0;
            break;
        default:
            size = 0;
            break;
    }
    
    return size;
}

void retro_cheat_reset(void)
{}

void retro_cheat_set(unsigned index, bool enabled, const char *code)
{
    (void)index;
    (void)enabled;
    (void)code;
}