/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <AK/Memory.h>
#include <AK/Singleton.h>
#include <Kernel/Devices/PS2MouseDevice.h>
#include <Kernel/Devices/VMWareBackdoor.h>
#include <Kernel/IO.h>

namespace Kernel {

#define IRQ_MOUSE 12
#define I8042_BUFFER 0x60
#define I8042_STATUS 0x64
#define I8042_ACK 0xFA
#define I8042_BUFFER_FULL 0x01
#define I8042_WHICH_BUFFER 0x20
#define I8042_MOUSE_BUFFER 0x20
#define I8042_KEYBOARD_BUFFER 0x00

#define PS2MOUSE_SET_RESOLUTION 0xE8
#define PS2MOUSE_STATUS_REQUEST 0xE9
#define PS2MOUSE_REQUEST_SINGLE_PACKET 0xEB
#define PS2MOUSE_GET_DEVICE_ID 0xF2
#define PS2MOUSE_SET_SAMPLE_RATE 0xF3
#define PS2MOUSE_ENABLE_PACKET_STREAMING 0xF4
#define PS2MOUSE_DISABLE_PACKET_STREAMING 0xF5
#define PS2MOUSE_SET_DEFAULTS 0xF6
#define PS2MOUSE_RESEND 0xFE
#define PS2MOUSE_RESET 0xFF

#define PS2MOUSE_INTELLIMOUSE_ID 0x03
#define PS2MOUSE_INTELLIMOUSE_EXPLORER_ID 0x04

//#define PS2MOUSE_DEBUG

static AK::Singleton<PS2MouseDevice> s_the;

PS2MouseDevice::PS2MouseDevice()
    : IRQHandler(IRQ_MOUSE)
    , CharacterDevice(10, 1)
{
    initialize();
}

PS2MouseDevice::~PS2MouseDevice()
{
}

void PS2MouseDevice::create()
{
    s_the.ensure_instance();
}

PS2MouseDevice& PS2MouseDevice::the()
{
    return *s_the;
}

void PS2MouseDevice::handle_irq(const RegisterState&)
{
    if (auto* backdoor = VMWareBackdoor::the()) {
        if (backdoor->vmmouse_is_absolute()) {
            IO::in8(I8042_BUFFER);
            auto packet = backdoor->receive_mouse_packet();
            m_entropy_source.add_random_event(packet);
            if (packet.has_value())
                m_queue.enqueue(packet.value());
            return;
        }
    }
    for (;;) {
        u8 status = IO::in8(I8042_STATUS);
        if (!(((status & I8042_WHICH_BUFFER) == I8042_MOUSE_BUFFER) && (status & I8042_BUFFER_FULL)))
            return;

        u8 data = IO::in8(I8042_BUFFER);
        m_data[m_data_state] = data;

        auto commit_packet = [&] {
            m_data_state = 0;
#ifdef PS2MOUSE_DEBUG
            dbg() << "PS2Mouse: " << m_data[1] << ", " << m_data[2] << " " << ((m_data[0] & 1) ? "Left" : "") << " " << ((m_data[0] & 2) ? "Right" : "") << " (buffered: " << m_queue.size() << ")";
#endif
            m_entropy_source.add_random_event(*(u32*)m_data);

            parse_data_packet();
        };

        switch (m_data_state) {
        case 0:
            if (!(data & 0x08)) {
                dbg() << "PS2Mouse: Stream out of sync.";
                break;
            }
            ++m_data_state;
            break;
        case 1:
            ++m_data_state;
            break;
        case 2:
            if (m_has_wheel) {
                ++m_data_state;
                break;
            }
            commit_packet();
            break;
        case 3:
            ASSERT(m_has_wheel);
            commit_packet();
            break;
        }
    }
}

void PS2MouseDevice::parse_data_packet()
{
    int x = m_data[1];
    int y = m_data[2];
    int z = 0;
    if (m_has_wheel) {
        // FIXME: For non-Intellimouse, this is a full byte.
        //        However, for now, m_has_wheel is only set for Intellimouse.
        z = (char)(m_data[3] & 0x0f);

        // -1 in 4 bits
        if (z == 15)
            z = -1;
    }
    bool x_overflow = m_data[0] & 0x40;
    bool y_overflow = m_data[0] & 0x80;
    bool x_sign = m_data[0] & 0x10;
    bool y_sign = m_data[0] & 0x20;
    if (x && x_sign)
        x -= 0x100;
    if (y && y_sign)
        y -= 0x100;
    if (x_overflow || y_overflow) {
        x = 0;
        y = 0;
    }
    MousePacket packet;
    packet.x = x;
    packet.y = y;
    packet.z = z;
    packet.buttons = m_data[0] & 0x07;

    if (m_has_five_buttons) {
        if (m_data[3] & 0x10)
            packet.buttons |= MousePacket::BackButton;
        if (m_data[3] & 0x20)
            packet.buttons |= MousePacket::ForwardButton;
    }

    packet.is_relative = true;
#ifdef PS2MOUSE_DEBUG
    dbg() << "PS2 Relative Mouse: Buttons " << String::format("%x", packet.buttons);
    dbg() << "Mouse: X " << packet.x << ", Y " << packet.y << ", Z " << packet.z;
#endif
    m_queue.enqueue(packet);
}

void PS2MouseDevice::wait_then_write(u8 port, u8 data)
{
    prepare_for_output();
    IO::out8(port, data);
}

u8 PS2MouseDevice::wait_then_read(u8 port)
{
    prepare_for_input();
    return IO::in8(port);
}

void PS2MouseDevice::initialize()
{
    // Enable PS aux port
    wait_then_write(I8042_STATUS, 0xa8);

    check_device_presence();

    if (m_device_present)
        initialize_device();
}

void PS2MouseDevice::check_device_presence()
{
    mouse_write(PS2MOUSE_REQUEST_SINGLE_PACKET);
    u8 maybe_ack = mouse_read();
    if (maybe_ack == I8042_ACK) {
        m_device_present = true;
        klog() << "PS2MouseDevice: Device detected";

        // the mouse will send a packet of data, since that's what we asked
        // for. we don't care about the content.
        mouse_read();
        mouse_read();
        mouse_read();
    } else {
        m_device_present = false;
        klog() << "PS2MouseDevice: Device not detected";
    }
}

u8 PS2MouseDevice::get_device_id()
{
    mouse_write(PS2MOUSE_GET_DEVICE_ID);
    expect_ack();
    return mouse_read();
}

void PS2MouseDevice::set_sample_rate(u8 rate)
{
    mouse_write(PS2MOUSE_SET_SAMPLE_RATE);
    expect_ack();
    mouse_write(rate);
    expect_ack();
}

void PS2MouseDevice::initialize_device()
{
    if (!m_device_present)
        return;

    // Enable interrupts
    wait_then_write(I8042_STATUS, 0x20);

    // Enable the PS/2 mouse IRQ (12).
    // NOTE: The keyboard uses IRQ 1 (and is enabled by bit 0 in this register).
    u8 status = wait_then_read(I8042_BUFFER) | 2;
    wait_then_write(I8042_STATUS, 0x60);
    wait_then_write(I8042_BUFFER, status);

    // Set default settings.
    mouse_write(PS2MOUSE_SET_DEFAULTS);
    expect_ack();

    // Enable.
    mouse_write(PS2MOUSE_ENABLE_PACKET_STREAMING);
    expect_ack();

    u8 device_id = get_device_id();

    if (device_id != PS2MOUSE_INTELLIMOUSE_ID) {
        // Send magical wheel initiation sequence.
        set_sample_rate(200);
        set_sample_rate(100);
        set_sample_rate(80);
        device_id = get_device_id();
    }

    if (device_id == PS2MOUSE_INTELLIMOUSE_ID) {
        m_has_wheel = true;
        klog() << "PS2MouseDevice: Mouse wheel enabled!";
    } else {
        klog() << "PS2MouseDevice: No mouse wheel detected!";
    }

    if (device_id == PS2MOUSE_INTELLIMOUSE_ID) {
        // Try to enable 5 buttons as well!
        set_sample_rate(200);
        set_sample_rate(200);
        set_sample_rate(80);
        device_id = get_device_id();
    }

    if (device_id == PS2MOUSE_INTELLIMOUSE_EXPLORER_ID) {
        m_has_five_buttons = true;
        klog() << "PS2MouseDevice: 5 buttons enabled!";
    }

    enable_irq();
}

void PS2MouseDevice::expect_ack()
{
    u8 data = mouse_read();
    ASSERT(data == I8042_ACK);
}

void PS2MouseDevice::prepare_for_input()
{
    for (;;) {
        if (IO::in8(I8042_STATUS) & 1)
            return;
    }
}

void PS2MouseDevice::prepare_for_output()
{
    for (;;) {
        if (!(IO::in8(I8042_STATUS) & 2))
            return;
    }
}

void PS2MouseDevice::mouse_write(u8 data)
{
    prepare_for_output();
    IO::out8(I8042_STATUS, 0xd4);
    prepare_for_output();
    IO::out8(I8042_BUFFER, data);
}

u8 PS2MouseDevice::mouse_read()
{
    prepare_for_input();
    return IO::in8(I8042_BUFFER);
}

bool PS2MouseDevice::can_read(const FileDescription&, size_t) const
{
    return !m_queue.is_empty();
}

KResultOr<size_t> PS2MouseDevice::read(FileDescription&, size_t, UserOrKernelBuffer& buffer, size_t size)
{
    ASSERT(size > 0);
    size_t nread = 0;
    size_t remaining_space_in_buffer = static_cast<size_t>(size) - nread;
    while (!m_queue.is_empty() && remaining_space_in_buffer) {
        auto packet = m_queue.dequeue();
#ifdef PS2MOUSE_DEBUG
        dbg() << "PS2 Mouse Read: Buttons " << String::format("%x", packet.buttons);
        dbg() << "PS2 Mouse: X " << packet.x << ", Y " << packet.y << ", Z " << packet.z << " Relative " << packet.buttons;
        dbg() << "PS2 Mouse Read: Filter packets";
#endif
        size_t bytes_read_from_packet = min(remaining_space_in_buffer, sizeof(MousePacket));
        if (!buffer.write(&packet, nread, bytes_read_from_packet))
            return KResult(-EFAULT);
        nread += bytes_read_from_packet;
        remaining_space_in_buffer -= bytes_read_from_packet;
    }
    return nread;
}

KResultOr<size_t> PS2MouseDevice::write(FileDescription&, size_t, const UserOrKernelBuffer&, size_t)
{
    return 0;
}

}