/*
    Copyright 2016-2023 melonDS team

    This file is part of melonDS.

    melonDS 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 Foundation, either version 3 of the License, or (at your option)
    any later version.

    melonDS 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 melonDS. If not, see http://www.gnu.org/licenses/.
*/

#ifndef MELONDS_SPI_FIRMWARE_H
#define MELONDS_SPI_FIRMWARE_H

#include <array>
#include <string_view>
#include "types.h"
#include "Platform.h"

u16 CRC16(const u8* data, u32 len, u32 start);



using MacAddress = std::array<u8, 6>;
using IpAddress = std::array<u8, 4>;

constexpr unsigned DEFAULT_FIRMWARE_LENGTH = 0x20000;
constexpr MacAddress DEFAULT_MAC = {0x00, 0x09, 0xBF, 0x11, 0x22, 0x33};
constexpr unsigned MAX_SSID_LENGTH = 32;
constexpr std::u16string_view  DEFAULT_USERNAME = u"melonDS";
constexpr const char* const DEFAULT_SSID = "melonAP";

/**
 * The position of the first extended Wi-fi settings block in the DSi firmware,
 * relative to the position of the first user settings block.
 * The generated firmware also uses this offset.
 */
constexpr int EXTENDED_WIFI_SETTINGS_OFFSET = -0xA00;

using FirmwareIdentifier = std::array<u8, 4>;

constexpr FirmwareIdentifier GENERATED_FIRMWARE_IDENTIFIER = {'M', 'E', 'L', 'N'};


class Firmware
{
public:

    enum class WepMode : u8
    {
        None = 0,
        Hex5 = 1,
        Hex13 = 2,
        Hex16 = 3,
        Ascii5 = 5,
        Ascii13 = 6,
        Ascii16 = 7,
    };

    enum class WpaMode : u8
    {
        Normal = 0,
        WPA_WPA2 = 0x10,
        WPS_WPA = 0x13,
        Unused = 0xff,
    };

    enum class WpaSecurity : u8
    {
        None = 0,
        WPA_TKIP = 4,
        WPA2_TKIP = 5,
        WPA_AES = 6,
        WPA2_AES = 7,
    };

    enum class AccessPointStatus : u8
    {
        Normal = 0,
        Aoss = 1,
        NotConfigured = 0xff
    };

    /**
     * @see https://problemkaputt.de/gbatek.htm#dsfirmwarewifiinternetaccesspoints
     */
    union WifiAccessPoint
    {
        /**
         * Constructs an unconfigured access point.
         */
        WifiAccessPoint();

        /**
         * Constructs an access point configured with melonDS's defaults.
         */
        explicit WifiAccessPoint(int consoletype);
        void UpdateChecksum();
        u8 Bytes[256];
        struct
        {
            char ProxyUsername[32];
            char ProxyPassword[32];
            char SSID[32];
            char SSIDWEP64[32];
            u8 WEPKey1[16];
            u8 WEPKey2[16];
            u8 WEPKey3[16];
            u8 WEPKey4[16];
            IpAddress Address;
            IpAddress Gateway;
            IpAddress PrimaryDns;
            IpAddress SecondaryDns;
            u8 SubnetMask;
            u8 Unknown0[21];
            enum WepMode WepMode;
            AccessPointStatus Status;
            u8 SSIDLength;
            u8 Unknown1;
            u16 Mtu;
            u8 Unknown2[3];
            u8 ConnectionConfigured;
            u8 NintendoWFCID[6];
            u8 Unknown3[8];
            u16 Checksum;
        };
    };

    static_assert(sizeof(WifiAccessPoint) == 256, "WifiAccessPoint should be 256 bytes");

    union ExtendedWifiAccessPoint
    {
        ExtendedWifiAccessPoint();
        void UpdateChecksum();
        u8 Bytes[512];
        struct
        {
            WifiAccessPoint Base;

            // DSi-specific entries now
            u8 PrecomputedPSK[32];
            char WPAPassword[64];
            char Unused0[33];
            WpaSecurity Security;
            bool ProxyEnabled;
            bool ProxyAuthentication;
            char ProxyName[48];
            u8 Unused1[52];
            u16 ProxyPort;
            u8 Unused2[20];
            u16 ExtendedChecksum;
        } Data;
    };

    static_assert(sizeof(ExtendedWifiAccessPoint) == 512, "WifiAccessPoint should be 512 bytes");


    enum class FirmwareConsoleType : u8
    {
        DS = 0xFF,
        DSLite = 0x20,
        DSi = 0x57,
        iQueDS = 0x43,
        iQueDSLite = 0x63,
    };

    enum class WifiVersion : u8
    {
        V1_4 = 0,
        V5 = 3,
        V6_7 = 5,
        W006 = 6,
        W015 = 15,
        W024 = 24,
        N3DS = 34,
    };

    enum RFChipType : u8
    {
        Type2 = 0x2,
        Type3 = 0x3,
    };

    enum class WifiBoard : u8
    {
        W015 = 0x1,
        W024 = 0x2,
        W028 = 0x3,
        Unused = 0xff,
    };

    enum Language : u8
    {
        Japanese = 0,
        English = 1,
        French = 2,
        German = 3,
        Italian = 4,
        Spanish = 5,
        Chinese = 6,
        Reserved = 7,
    };

    enum GBAScreen : u8
    {
        Upper = 0,
        Lower = (1 << 3),
    };

    enum BacklightLevel : u8
    {
        Low = 0,
        Medium = 1 << 4,
        High = 2 << 4,
        Max = 3 << 4
    };

    enum BootMenu : u8
    {
        Manual = 0,
        Autostart = 1 << 6,
    };

    /**
     * @note GBATek says the header is actually 511 bytes;
     * this header struct is 512 bytes due to padding,
     * but the last byte is just the first byte of the firmware's code.
     * It doesn't affect the offset of any of the fields,
     * so leaving that last byte in there is harmless.
     * @see https://problemkaputt.de/gbatek.htm#dsfirmwareheader
     * @see https://problemkaputt.de/gbatek.htm#dsfirmwarewificalibrationdata
    */
    union FirmwareHeader
    {
        explicit FirmwareHeader(int consoletype);
        void UpdateChecksum();
        u8 Bytes[512];
        struct
        {
            u16 ARM9GUICodeOffset;
            u16 ARM7WifiCodeOffset;
            u16 GUIWifiCodeChecksum;
            u16 BootCodeChecksum;

            FirmwareIdentifier Identifier;

            u16 ARM9BootCodeROMAddress;
            u16 ARM9BootCodeRAMAddress;
            u16 ARM7BootCodeRAMAddress;
            u16 ARM7BootCodeROMAddress;
            u16 ShiftAmounts;
            u16 DataGfxRomAddress;

            u8 BuildMinute;
            u8 BuildHour;
            u8 BuildDay;
            u8 BuildMonth;
            u8 BuildYear;

            FirmwareConsoleType ConsoleType;

            u8 Unused0[2];

            u16 UserSettingsOffset;
            u8 Unknown0[2];
            u8 Unknown1[2];
            u16 DataGfxChecksum;
            u8 Unused2[2];

            // Begin wi-fi settings
            u16 WifiConfigChecksum;
            u16 WifiConfigLength;
            u8 Unused1;
            enum WifiVersion WifiVersion;

            u8 Unused3[6];

            MacAddress MacAddr;

            u16 EnabledChannels;

            u8 Unknown2[2];

            enum RFChipType RFChipType;
            u8 RFBitsPerEntry;
            u8 RFEntries;
            u8 Unknown3;

            u8 InitialValues[32];
            u8 InitialBBValues[105];
            u8 Unused4;
            union
            {
                struct
                {
                    u8 InitialRFValues[36];
                    u8 InitialRF56Values[84];
                    u8 InitialBB1EValues[14];
                    u8 InitialRf9Values[14];
                } Type2Config;

                struct
                {
                    u8 InitialRFValues[41];
                    u8 BBIndicesPerChannel;
                    u8 BBIndex1;
                    u8 BBData1[14];
                    u8 BBIndex2;
                    u8 BBData2[14];
                    u8 RFIndex1;
                    u8 RFData1[14];
                    u8 RFIndex2;
                    u8 RFData2[14];
                    u8 Unused0[46];
                } Type3Config;
            };

            u8 Unknown4;
            u8 Unused5;
            u8 Unused6[153];
            enum WifiBoard WifiBoard;
            u8 WifiFlash;
            u8 Unused7;
        };
    };

    static_assert(sizeof(FirmwareHeader) == 512, "FirmwareHeader should be 512 bytes");

    struct ExtendedUserSettings
    {
        char ID[8];
        u16 Checksum;
        u16 ChecksumLength;
        u8 Version;
        u8 UpdateCount;
        u8 BootMenuFlags;
        u8 GBABorder;
        u16 TemperatureCalibration0;
        u16 TemperatureCalibration1;
        u16 TemperatureCalibrationDegrees;
        u8 TemperatureFlags;
        u8 BacklightIntensity;
        u32 DateCenturyOffset;
        u8 DateMonthRecovery;
        u8 DateDayRecovery;
        u8 DateYearRecovery;
        u8 DateTimeFlags;
        char DateSeparator;
        char TimeSeparator;
        char DecimalSeparator;
        char ThousandsSeparator;
        u8 DaylightSavingsTimeNth;
        u8 DaylightSavingsTimeDay;
        u8 DaylightSavingsTimeOfMonth;
        u8 DaylightSavingsTimeFlags;
    };

    static_assert(sizeof(ExtendedUserSettings) == 0x28, "ExtendedUserSettings should be 40 bytes");

    union UserData
    {
        UserData();
        void UpdateChecksum();
        [[nodiscard]] bool ChecksumValid() const
        {
            bool baseChecksumOk = Checksum == CRC16(Bytes, 0x70, 0xFFFF);
            bool extendedChecksumOk = Bytes[0x74] != 1 || ExtendedSettings.Checksum == CRC16(Bytes + 0x74, 0x8A, 0xFFFF);
            // For our purposes, the extended checksum is OK if we're not using extended data

            return baseChecksumOk && extendedChecksumOk;
        }

        u8 Bytes[256];
        struct
        {
            u16 Version;
            u8 FavoriteColor;
            u8 BirthdayMonth;
            u8 BirthdayDay;
            u8 Unused0;
            char16_t Nickname[10];
            u16 NameLength;
            char16_t Message[26];
            u16 MessageLength;
            u8 AlarmHour;
            u8 AlarmMinute;
            u8 Unknown0[2];
            u8 AlarmFlags;
            u8 Unused1;
            u16 TouchCalibrationADC1[2];
            u8 TouchCalibrationPixel1[2];
            u16 TouchCalibrationADC2[2];
            u8 TouchCalibrationPixel2[2];
            u16 Settings;
            u8 Year;
            u8 RTCClockAdjust;
            u32 RTCOffset;
            u8 Unused2[4];
            u16 UpdateCounter;
            u16 Checksum;
            union
            {
                u8 Unused3[0x8C];
                struct
                {
                    u8 Unknown0;
                    Language ExtendedLanguage; // padded
                    u16 SupportedLanguageMask;
                    u8 Unused0[0x86];
                    u16 Checksum;
                } ExtendedSettings;
            };
        };
    };
    static_assert(sizeof(UserData) == 256, "UserData should be 256 bytes");

    /**
     * Constructs a default firmware blob
     * filled with data necessary for booting and configuring NDS games.
     * The Wi-fi section has one access point configured with melonDS's defaults.
     * Will not contain executable code.
     * @param consoletype Console type to use. 1 for DSi, 0 for NDS.
     */
    explicit Firmware(int consoletype);

    /**
     * Loads a firmware blob from the given file.
     * Will rewind the file's stream offset to its initial position when finished.
     */
    explicit Firmware(Platform::FileHandle* file);

    /**
     * Constructs a firmware blob from a copy of the given data.
     * @param data Buffer containing the firmware data.
     * @param length Length of the buffer in bytes.
     * If too short, the firmware will be padded with zeroes.
     * If too long, the extra data will be ignored.
     */
    Firmware(const u8* data, u32 length);
    Firmware(const Firmware& other);
    Firmware(Firmware&& other) noexcept;
    Firmware& operator=(const Firmware& other);
    Firmware& operator=(Firmware&& other) noexcept;
    ~Firmware();

    [[nodiscard]] FirmwareHeader& GetHeader() { return *reinterpret_cast<FirmwareHeader*>(FirmwareBuffer); }
    [[nodiscard]] const FirmwareHeader& GetHeader() const { return *reinterpret_cast<const FirmwareHeader*>(FirmwareBuffer); }

    /// @return The offset of the first basic Wi-fi settings block in the firmware
    /// (not the extended Wi-fi settings block used by the DSi).
    /// @see WifiAccessPointPosition
    [[nodiscard]] u32 GetWifiAccessPointOffset() const { return GetUserDataOffset() - 0x400; }

    /// @return The address of the first basic Wi-fi settings block in the firmware.
    [[nodiscard]] u8* GetWifiAccessPointPosition() { return FirmwareBuffer + GetWifiAccessPointOffset(); }
    [[nodiscard]] const u8* GetWifiAccessPointPosition() const { return FirmwareBuffer + GetWifiAccessPointOffset(); }

    [[nodiscard]] const std::array<WifiAccessPoint, 3>& GetAccessPoints() const
    {
        // An std::array is a wrapper around a C array, so this cast is fine.
        return *reinterpret_cast<const std::array<WifiAccessPoint, 3>*>(GetWifiAccessPointPosition());
    }

    [[nodiscard]] std::array<WifiAccessPoint, 3>& GetAccessPoints()
    {
        // An std::array is a wrapper around a C array, so this cast is fine.
        return *reinterpret_cast<std::array<WifiAccessPoint, 3>*>(GetWifiAccessPointPosition());
    }

    /// @returns \c true if this firmware image contains bootable code.
    /// @note Non-bootable firmware can still be valid;
    /// DSi firmware is non-bootable for instance.
    /// If this firmware is not bootable, then melonDS should use direct-boot mode.
    [[nodiscard]] bool IsBootable() const;

    /// @return The address of the first extended Wi-fi settings block in the firmware.
    /// @warning Only meaningful if this is DSi firmware.
    [[nodiscard]] u32 GetExtendedAccessPointOffset() const { return GetUserDataOffset() + EXTENDED_WIFI_SETTINGS_OFFSET; }
    [[nodiscard]] u8* GetExtendedAccessPointPosition() { return FirmwareBuffer + GetExtendedAccessPointOffset(); }
    [[nodiscard]] const u8* GetExtendedAccessPointPosition() const { return FirmwareBuffer + GetExtendedAccessPointOffset(); }

    [[nodiscard]] const std::array<ExtendedWifiAccessPoint, 3>& GetExtendedAccessPoints() const
    {
        // An std::array is a wrapper around a C array, so this cast is fine.
        return *reinterpret_cast<const std::array<ExtendedWifiAccessPoint, 3>*>(GetExtendedAccessPointPosition());
    }

    [[nodiscard]] std::array<ExtendedWifiAccessPoint, 3>& GetExtendedAccessPoints()
    {
        // An std::array is a wrapper around a C array, so this cast is fine.
        return *reinterpret_cast<std::array<ExtendedWifiAccessPoint, 3>*>(GetExtendedAccessPointPosition());
    }

    /// @return The pointer to the firmware buffer,
    /// or \c nullptr if this object is invalid
    /// (e.g. it was moved from, or its constructor failed).
    [[nodiscard]] u8* Buffer() { return FirmwareBuffer; }
    [[nodiscard]] const u8* Buffer() const { return FirmwareBuffer; }

    [[nodiscard]] u32 Length() const { return FirmwareBufferLength; }
    [[nodiscard]] u32 Mask() const { return FirmwareMask; }

    /// @return The offset of the first user data section in the firmware.
    /// @see UserDataPosition
    [[nodiscard]] u32 GetUserDataOffset() const { return GetHeader().UserSettingsOffset << 3; }

    /// @return The address of the first user data section in the firmware.
    /// @see UserDataOffset
    [[nodiscard]] u8* GetUserDataPosition() { return FirmwareBuffer + GetUserDataOffset(); }
    [[nodiscard]] const u8* GetUserDataPosition() const { return FirmwareBuffer + GetUserDataOffset(); }


     /// @return Reference to the two user data sections.
     /// @note Either \c UserData object could be the "effective" one,
     /// so prefer using \c EffectiveUserData() if you're not modifying both.
    [[nodiscard]] const std::array<union UserData, 2>& GetUserData() const
    {
        // An std::array is a wrapper around a C array, so this cast is fine.
        return *reinterpret_cast<const std::array<union UserData, 2>*>(GetUserDataPosition());
    };

    /**
     * @return Reference to the two user data sections.
     * @note Either \c UserData object could be the "effective" one,
     * so prefer using \c EffectiveUserData() if you're not modifying both.
     * @warning Remember to call UserData::UpdateChecksum() after modifying any of its fields.
     */
    [[nodiscard]] std::array<union UserData, 2>& GetUserData()
    {
        // An std::array is a wrapper around a C array, so this cast is fine.
        return *reinterpret_cast<std::array<union UserData, 2>*>(GetUserDataPosition());
    }

    /**
     * @return Reference to whichever of the two user data sections
     * will be used by the firmware.
     * Specifically, the firmware will use whichever one has the valid checksum
     * (or the newer one if they're both valid).
     */
    [[nodiscard]] const union UserData& GetEffectiveUserData() const;

    /**
     * @return Reference to whichever of the two user data sections
     * has the highest update counter.
     */
    [[nodiscard]] union UserData& GetEffectiveUserData();

    /// Fix the given firmware length to an acceptable length
    u32 FixFirmwareLength(u32 originalLength);

    /// Updates the checksums of all used sections of the firmware.
    void UpdateChecksums();
private:
    u8* FirmwareBuffer;
    u32 FirmwareBufferLength;
    u32 FirmwareMask;
};

#endif //MELONDS_SPI_FIRMWARE_H