/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Checked.h>
#include <AK/Format.h>
#include <AK/Singleton.h>
#include <Kernel/Debug.h>
#include <Kernel/Devices/BXVGADevice.h>
#include <Kernel/IO.h>
#include <Kernel/PCI/Access.h>
#include <Kernel/Process.h>
#include <Kernel/VM/AnonymousVMObject.h>
#include <Kernel/VM/MemoryManager.h>
#include <LibC/errno_numbers.h>
#include <LibC/sys/ioctl_numbers.h>

namespace Kernel {

#define MAX_RESOLUTION_WIDTH 4096
#define MAX_RESOLUTION_HEIGHT 2160

#define VBE_DISPI_IOPORT_INDEX 0x01CE
#define VBE_DISPI_IOPORT_DATA 0x01CF

#define VBE_DISPI_INDEX_ID 0x0
#define VBE_DISPI_INDEX_XRES 0x1
#define VBE_DISPI_INDEX_YRES 0x2
#define VBE_DISPI_INDEX_BPP 0x3
#define VBE_DISPI_INDEX_ENABLE 0x4
#define VBE_DISPI_INDEX_BANK 0x5
#define VBE_DISPI_INDEX_VIRT_WIDTH 0x6
#define VBE_DISPI_INDEX_VIRT_HEIGHT 0x7
#define VBE_DISPI_INDEX_X_OFFSET 0x8
#define VBE_DISPI_INDEX_Y_OFFSET 0x9
#define VBE_DISPI_DISABLED 0x00
#define VBE_DISPI_ENABLED 0x01
#define VBE_DISPI_LFB_ENABLED 0x40

static AK::Singleton<BXVGADevice> s_the;

UNMAP_AFTER_INIT void BXVGADevice::initialize()
{
    s_the.ensure_instance();
}

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

UNMAP_AFTER_INIT BXVGADevice::BXVGADevice()
    : BlockDevice(29, 0)

{
    m_framebuffer_address = PhysicalAddress(find_framebuffer_address());
    set_safe_resolution();
}

void BXVGADevice::set_safe_resolution()
{
    m_framebuffer_width = 1024;
    m_framebuffer_height = 768;
    m_framebuffer_pitch = m_framebuffer_width * sizeof(u32);
    set_resolution(m_framebuffer_width, m_framebuffer_height);
}

void BXVGADevice::set_register(u16 index, u16 data)
{
    IO::out16(VBE_DISPI_IOPORT_INDEX, index);
    IO::out16(VBE_DISPI_IOPORT_DATA, data);
}

u16 BXVGADevice::get_register(u16 index)
{
    IO::out16(VBE_DISPI_IOPORT_INDEX, index);
    return IO::in16(VBE_DISPI_IOPORT_DATA);
}

void BXVGADevice::revert_resolution()
{
    set_resolution_registers(m_framebuffer_width, m_framebuffer_height);
    VERIFY(validate_setup_resolution(m_framebuffer_width, m_framebuffer_height));
}

void BXVGADevice::set_resolution_registers(size_t width, size_t height)
{
    dbgln_if(BXVGA_DEBUG, "BXVGADevice resolution registers set to - {}x{}", width, height);
    set_register(VBE_DISPI_INDEX_ENABLE, VBE_DISPI_DISABLED);
    set_register(VBE_DISPI_INDEX_XRES, (u16)width);
    set_register(VBE_DISPI_INDEX_YRES, (u16)height);
    set_register(VBE_DISPI_INDEX_VIRT_WIDTH, (u16)width);
    set_register(VBE_DISPI_INDEX_VIRT_HEIGHT, (u16)height * 2);
    set_register(VBE_DISPI_INDEX_BPP, 32);
    set_register(VBE_DISPI_INDEX_ENABLE, VBE_DISPI_ENABLED | VBE_DISPI_LFB_ENABLED);
    set_register(VBE_DISPI_INDEX_BANK, 0);
}

bool BXVGADevice::test_resolution(size_t width, size_t height)
{
    dbgln_if(BXVGA_DEBUG, "BXVGADevice resolution test - {}x{}", width, height);
    set_resolution_registers(width, height);
    bool resolution_changed = validate_setup_resolution(width, height);
    revert_resolution();
    return resolution_changed;
}
bool BXVGADevice::set_resolution(size_t width, size_t height)
{
    if (Checked<size_t>::multiplication_would_overflow(width, height, sizeof(u32)))
        return false;

    if (!test_resolution(width, height))
        return false;

    set_resolution_registers(width, height);
    dbgln("BXVGADevice resolution set to {}x{} (pitch={})", width, height, m_framebuffer_pitch);

    m_framebuffer_width = width;
    m_framebuffer_height = height;
    m_framebuffer_pitch = width * sizeof(u32);
    return true;
}

bool BXVGADevice::validate_setup_resolution(size_t width, size_t height)
{
    if ((u16)width != get_register(VBE_DISPI_INDEX_XRES) || (u16)height != get_register(VBE_DISPI_INDEX_YRES)) {
        return false;
    }
    return true;
}

void BXVGADevice::set_y_offset(size_t y_offset)
{
    VERIFY(y_offset == 0 || y_offset == m_framebuffer_height);
    m_y_offset = y_offset;
    set_register(VBE_DISPI_INDEX_Y_OFFSET, (u16)y_offset);
}

UNMAP_AFTER_INIT u32 BXVGADevice::find_framebuffer_address()
{
    // NOTE: The QEMU card has the same PCI ID as the Bochs one.
    static const PCI::ID bochs_vga_id = { 0x1234, 0x1111 };
    static const PCI::ID virtualbox_vga_id = { 0x80ee, 0xbeef };
    u32 framebuffer_address = 0;
    PCI::enumerate([&framebuffer_address](const PCI::Address& address, PCI::ID id) {
        if (id == bochs_vga_id || id == virtualbox_vga_id) {
            framebuffer_address = PCI::get_BAR0(address) & 0xfffffff0;
            dbgln("BXVGA: framebuffer @ {}", PhysicalAddress(framebuffer_address));
        }
    });
    return framebuffer_address;
}

KResultOr<Region*> BXVGADevice::mmap(Process& process, FileDescription&, const Range& range, u64 offset, int prot, bool shared)
{
    REQUIRE_PROMISE(video);
    if (!shared)
        return ENODEV;
    if (offset != 0)
        return ENXIO;
    if (range.size() != page_round_up(framebuffer_size_in_bytes()))
        return EOVERFLOW;

    auto vmobject = AnonymousVMObject::create_for_physical_range(m_framebuffer_address, framebuffer_size_in_bytes());
    if (!vmobject)
        return ENOMEM;
    return process.space().allocate_region_with_vmobject(
        range,
        vmobject.release_nonnull(),
        0,
        "BXVGA Framebuffer",
        prot,
        shared);
}

String BXVGADevice::device_name() const
{
    return String::formatted("fb{}", minor());
}

int BXVGADevice::ioctl(FileDescription&, unsigned request, FlatPtr arg)
{
    REQUIRE_PROMISE(video);
    switch (request) {
    case FB_IOCTL_GET_SIZE_IN_BYTES: {
        auto* out = (size_t*)arg;
        size_t value = framebuffer_size_in_bytes();
        if (!copy_to_user(out, &value))
            return -EFAULT;
        return 0;
    }
    case FB_IOCTL_GET_BUFFER: {
        auto* index = (int*)arg;
        int value = m_y_offset == 0 ? 0 : 1;
        if (!copy_to_user(index, &value))
            return -EFAULT;
        return 0;
    }
    case FB_IOCTL_SET_BUFFER: {
        if (arg != 0 && arg != 1)
            return -EINVAL;
        set_y_offset(arg == 0 ? 0 : m_framebuffer_height);
        return 0;
    }
    case FB_IOCTL_GET_RESOLUTION: {
        auto* user_resolution = (FBResolution*)arg;
        FBResolution resolution;
        resolution.pitch = m_framebuffer_pitch;
        resolution.width = m_framebuffer_width;
        resolution.height = m_framebuffer_height;
        if (!copy_to_user(user_resolution, &resolution))
            return -EFAULT;
        return 0;
    }
    case FB_IOCTL_SET_RESOLUTION: {
        auto* user_resolution = (FBResolution*)arg;
        FBResolution resolution;
        if (!copy_from_user(&resolution, user_resolution))
            return -EFAULT;
        if (resolution.width > MAX_RESOLUTION_WIDTH || resolution.height > MAX_RESOLUTION_HEIGHT)
            return -EINVAL;
        if (!set_resolution(resolution.width, resolution.height)) {
            dbgln_if(BXVGA_DEBUG, "Reverting resolution: [{}x{}]", m_framebuffer_width, m_framebuffer_height);
            resolution.pitch = m_framebuffer_pitch;
            resolution.width = m_framebuffer_width;
            resolution.height = m_framebuffer_height;
            if (!copy_to_user(user_resolution, &resolution))
                return -EFAULT;
            return -EINVAL;
        }
        dbgln_if(BXVGA_DEBUG, "New resolution: [{}x{}]", m_framebuffer_width, m_framebuffer_height);
        resolution.pitch = m_framebuffer_pitch;
        resolution.width = m_framebuffer_width;
        resolution.height = m_framebuffer_height;
        if (!copy_to_user(user_resolution, &resolution))
            return -EFAULT;
        return 0;
    }
    default:
        return -EINVAL;
    };
}

}