#include "Log.h"
#include "api/Mouse.h"
#include "arch/CPU.h"
#include "arch/x86_64/IO.h"
#include "fs/devices/MouseDevice.h"
#include "thread/Thread.h"

extern Thread* g_io_thread;

static u8 g_mouse_packet[3];
static int g_index = 0;

#define PS2_MOUSE_Y_OVERFLOW 0x80
#define PS2_MOUSE_X_OVERFLOW 0x40
#define PS2_MOUSE_Y_SIGN 0x20
#define PS2_MOUSE_X_SIGN 0x10
#define PS2_MOUSE_ALWAYS_1 0x08
#define PS2_MOUSE_MIDDLE_BTN 0x04
#define PS2_MOUSE_RIGHT_BTN 0x02
#define PS2_MOUSE_LEFT_BTN 0x01

extern CircularQueue<moon::MousePacket, 20> mouse_queue;

static void process_mouse_event(u8 data)
{
    if (g_index == 0)
    {
        // NOTE: https://wiki.osdev.org/Mouse_Input#PS2_Mouse says to discard the packet if X or Y overflow is 1, but
        // https://wiki.osdev.org/PS2_Mouse uses it. Discard for now.
        if (data & PS2_MOUSE_X_OVERFLOW) return;
        if (data & PS2_MOUSE_Y_OVERFLOW) return;

        if ((data & PS2_MOUSE_ALWAYS_1) == 0) return;
    }

    g_mouse_packet[g_index++] = data;
    if (g_index < 3) return;
    g_index = 0;

    moon::MousePacket packet;
    packet.xdelta = g_mouse_packet[1];
    packet.ydelta = g_mouse_packet[2];
    packet.buttons = 0;

    u8 flags = g_mouse_packet[0];
    if (flags & PS2_MOUSE_X_SIGN) packet.xdelta = -(256 - packet.xdelta);
    if (flags & PS2_MOUSE_Y_SIGN) packet.ydelta = -(256 - packet.ydelta);

    if (flags & PS2_MOUSE_MIDDLE_BTN) packet.buttons |= moon::MouseButton::Middle;
    if (flags & PS2_MOUSE_RIGHT_BTN) packet.buttons |= moon::MouseButton::Right;
    if (flags & PS2_MOUSE_LEFT_BTN) packet.buttons |= moon::MouseButton::Left;

    MouseDevice::add_mouse_event(packet);
}

static void mouse_interrupt(Registers*, void*)
{
    const u8 data = IO::inb(0x60);
    process_mouse_event(data);
}

#define PS2_MOUSE_TIMEOUT 100000

static void mouse_wait()
{
    int timeout = PS2_MOUSE_TIMEOUT;
    while (--timeout)
    {
        if ((IO::inb(0x64) & 0b10) == 0) return;
        CPU::pause();
    }
}

static void mouse_wait_for_input()
{
    int timeout = PS2_MOUSE_TIMEOUT;
    while (--timeout)
    {
        if (IO::inb(0x64) & 0b1) return;
        CPU::pause();
    }
}

static void mouse_write_data(u8 byte)
{
    mouse_wait();
    IO::outb(0x64, 0xD4);
    mouse_wait();
    IO::outb(0x60, byte);
}

void init_mouse()
{
    CPU::register_interrupt(12, mouse_interrupt, nullptr);

    IO::outb(0x64, 0xA8); // Enable PS/2 auxiliary port

    mouse_wait();
    IO::outb(0x64, 0x20); // Get Compaq status byte
    mouse_wait_for_input();
    u8 status = IO::inb(0x60);
    status |= 0x02;  // Enable IRQ12
    status &= ~0x20; // Disable Mouse Clock
    mouse_wait();
    IO::outb(0x64, 0x60); // Set Compaq status byte
    mouse_wait();
    IO::outb(0x60, status);

    mouse_write_data(0xF6); // Reset defaults
    mouse_wait();
    IO::inb(0x60);

    mouse_write_data(0xF4); // Send automatic packets when the mouse moves or is clicked
    mouse_wait();
    IO::inb(0x60);

    g_index = 0;
}