#include <pci.h>
#include <io.h>

#include "../../../Kernel/DAPI.hpp"
#include "../../../Kernel/Fex.hpp"

extern "C" int DriverEntry(void *Data);
int CallbackHandler(KernelCallback *Data);

HEAD(FexFormatType_Driver, FexOSType_Fennix, DriverEntry);

#pragma GCC diagnostic ignored "-Wmissing-field-initializers"

__attribute__((section(".extended"))) FexExtended ExtendedHeader = {
    .Driver = {
        .Name = "VMware Virtual Mouse Driver",
        .Type = FexDriverType_Input,
        .Callback = CallbackHandler,
        .Bind = {
            .Type = BIND_INTERRUPT,
            .Interrupt = {
                .Vector = {0xC}, // IRQ12
            }}}};

KernelAPI *KAPI;

#define print(msg) KAPI->Util.DebugPrint((char *)(msg), KAPI->Info.DriverUID)

/* --------------------------------------------------------------------------------------------------------- */

/* https://wiki.osdev.org/VMware_tools */

typedef struct
{
    union
    {
        uint32_t ax;
        uint32_t magic;
    };
    union
    {
        uint32_t bx;
        size_t size;
    };
    union
    {
        uint32_t cx;
        uint16_t command;
    };
    union
    {
        uint32_t dx;
        uint16_t port;
    };
    uint32_t si;
    uint32_t di;
} VMwareCommand;

#define VMWARE_MAGIC 0x564D5868 /* hXMV */
#define VMWARE_PORT 0x5658

#define CMD_GETVERSION 0xA
#define CMD_ABSPOINTER_DATA 0x27
#define CMD_ABSPOINTER_STATUS 0x28
#define CMD_ABSPOINTER_COMMAND 0x29

#define ABSPOINTER_ENABLE 0x45414552 /* Q E A E */
#define ABSPOINTER_RELATIVE 0xF5
#define ABSPOINTER_ABSOLUTE 0x53424152 /* R A B S */

void CommandSend(VMwareCommand *cmd)
{
    cmd->magic = VMWARE_MAGIC;
    cmd->port = VMWARE_PORT;
    asm volatile("in %%dx, %0"
                 : "+a"(cmd->ax), "+b"(cmd->bx), "+c"(cmd->cx), "+d"(cmd->dx), "+S"(cmd->si), "+D"(cmd->di));
}

bool IsVMwareBackdoorAvailable(void)
{
    VMwareCommand cmd;
    cmd.bx = ~VMWARE_MAGIC;
    cmd.command = CMD_GETVERSION;
    CommandSend(&cmd);
    if (cmd.bx != VMWARE_MAGIC || cmd.ax == 0xFFFFFFFF)
        return false;
    return true;
}

int DriverEntry(void *Data)
{
    /* There's a bug somewhere in driver or kernel and it's just crashing. */
    return NOT_IMPLEMENTED;

    if (!Data)
        return INVALID_KERNEL_API;
    KAPI = (KernelAPI *)Data;
    if (KAPI->Version.Major < 0 || KAPI->Version.Minor < 0 || KAPI->Version.Patch < 0)
        return KERNEL_API_VERSION_NOT_SUPPORTED;

    if (!IsVMwareBackdoorAvailable())
        return SYSTEM_NOT_SUPPORTED;

    return OK;
}

void Absolute(void)
{
    VMwareCommand cmd;

    /* Enable */
    cmd.bx = ABSPOINTER_ENABLE;
    cmd.command = CMD_ABSPOINTER_COMMAND;
    CommandSend(&cmd);

    /* Status */
    cmd.bx = 0;
    cmd.command = CMD_ABSPOINTER_STATUS;
    CommandSend(&cmd);

    /* Read data (1) */
    cmd.bx = 1;
    cmd.command = CMD_ABSPOINTER_DATA;
    CommandSend(&cmd);

    /* Enable absolute */
    cmd.bx = ABSPOINTER_ABSOLUTE;
    cmd.command = CMD_ABSPOINTER_COMMAND;
    CommandSend(&cmd);
}

void Relative(void)
{
    VMwareCommand cmd;
    cmd.bx = ABSPOINTER_RELATIVE;
    cmd.command = CMD_ABSPOINTER_COMMAND;
    CommandSend(&cmd);
}

enum Config
{
    READ_CONFIG = 0x20,
    WRITE_CONFIG = 0x60
};

enum Ports
{
    DATA = 0x60,
    STATUS = 0x64,
    COMMAND = 0x64,
};

enum State
{
    OUTPUT_FULL = (1 << 0),
    INPUT_FULL = (1 << 1),
    MOUSE_BYTE = (1 << 5)
};

void WaitRead()
{
    uint64_t Timeout = 100000;
    while (Timeout--)
        if (inb(Ports::STATUS) & State::OUTPUT_FULL)
            return;
}

void WaitWrite()
{
    uint64_t Timeout = 100000;
    while (Timeout--)
        if ((inb(Ports::STATUS) & State::INPUT_FULL) == 0)
            return;
}

void Write(uint16_t Port, uint8_t Value)
{
    WaitWrite();
    outb(Port, Value);
}

uint8_t Read()
{
    WaitRead();
    return inb(Ports::DATA);
}

int MouseX = 0, MouseY = 0, MouseZ = 0;
int MouseButton = 0;

int CallbackHandler(KernelCallback *Data)
{
    switch (Data->Reason)
    {
    case AcknowledgeReason:
    {
        print("Kernel acknowledged the driver.");
        break;
    }
    case ConfigurationReason:
    {
        outb(COMMAND, 0xA8);
        Write(COMMAND, READ_CONFIG);
        uint8_t Status = Read();
        Status |= 0b10;
        Write(COMMAND, WRITE_CONFIG);
        Write(DATA, Status);
        Write(COMMAND, 0xD4);
        Write(DATA, 0xF6);
        Read();
        Write(COMMAND, 0xD4);
        Write(DATA, 0xF4);
        Read();
        Absolute();
        print("VMware mouse configured.");
        break;
    }
    case FetchReason:
    {
        Data->InputCallback.Mouse.X = MouseX;
        Data->InputCallback.Mouse.Y = MouseY;
        Data->InputCallback.Mouse.Z = MouseZ;
        Data->InputCallback.Mouse.Buttons.Left = MouseButton & 0x20;
        Data->InputCallback.Mouse.Buttons.Right = MouseButton & 0x10;
        Data->InputCallback.Mouse.Buttons.Middle = MouseButton & 0x08;
        break;
    }
    case StopReason:
    {
        Relative();
        // TODO: UNTESTED!!!
        outb(COMMAND, 0xA8);
        Write(COMMAND, READ_CONFIG);
        uint8_t Status = Read();
        Status &= ~0b10;
        Write(COMMAND, WRITE_CONFIG);
        Write(DATA, Status);
        Write(COMMAND, 0xD4);
        Write(DATA, 0xF5);
        Read();
        print("Driver stopped.");
        break;
    }
    case InterruptReason:
    {
        uint8_t Data = inb(0x60);
        (void)Data;
        VMwareCommand cmd;
        cmd.bx = 0;
        cmd.command = CMD_ABSPOINTER_STATUS;
        CommandSend(&cmd);

        if (cmd.ax == 0xFFFF0000)
        {
            print("VMware mouse is not connected?");
            Relative();
            Absolute();
            return ERROR;
        }
        if ((cmd.ax & 0xFFFF) < 4)
            return ERROR;

        cmd.bx = 4;
        cmd.command = CMD_ABSPOINTER_DATA;
        CommandSend(&cmd);

        int flags = (cmd.ax & 0xFFFF0000) >> 16; /* Not important */
        (void)flags;
        MouseButton = (cmd.ax & 0xFFFF); /* 0x10 = Right, 0x20 = Left, 0x08 = Middle */
        MouseX = cmd.bx;                 /* Both X and Y are scaled from 0 to 0xFFFF */
        MouseY = cmd.cx;                 /* You should map these somewhere to the actual resolution. */
        MouseZ = (int8_t)cmd.dx;         /* Z is a single signed byte indicating scroll direction. */
        break;
    }

    default:
    {
        print("Unknown reason.");
        break;
    }
    }
    return OK;
}