/*
 * Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Singleton.h>
#include <Kernel/Arch/x86/IO.h>
#include <Kernel/Bus/PCI/API.h>
#include <Kernel/Bus/PCI/IDs.h>
#include <Kernel/CommandLine.h>
#include <Kernel/Graphics/Bochs/GraphicsAdapter.h>
#include <Kernel/Graphics/Console/BootFramebufferConsole.h>
#include <Kernel/Graphics/GraphicsManagement.h>
#include <Kernel/Graphics/Intel/NativeGraphicsAdapter.h>
#include <Kernel/Graphics/VGA/ISAAdapter.h>
#include <Kernel/Graphics/VGA/PCIAdapter.h>
#include <Kernel/Graphics/VGA/VGACompatibleAdapter.h>
#include <Kernel/Graphics/VirtIOGPU/GraphicsAdapter.h>
#include <Kernel/Memory/AnonymousVMObject.h>
#include <Kernel/Multiboot.h>
#include <Kernel/Sections.h>

namespace Kernel {

static Singleton<GraphicsManagement> s_the;

extern Atomic<Graphics::Console*> g_boot_console;

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

bool GraphicsManagement::is_initialized()
{
    return s_the.is_initialized();
}

UNMAP_AFTER_INIT GraphicsManagement::GraphicsManagement()
{
}

void GraphicsManagement::disable_vga_emulation_access_permanently()
{
    SpinlockLocker locker(m_main_vga_lock);
    disable_vga_text_mode_console_cursor();
    IO::out8(0x3c4, 1);
    u8 sr1 = IO::in8(0x3c5);
    IO::out8(0x3c5, sr1 | 1 << 5);
    IO::delay(1000);
    m_vga_access_is_disabled = true;
}

void GraphicsManagement::enable_vga_text_mode_console_cursor()
{
    SpinlockLocker locker(m_main_vga_lock);
    if (m_vga_access_is_disabled)
        return;
    IO::out8(0x3D4, 0xA);
    IO::out8(0x3D5, 0);
}

void GraphicsManagement::disable_vga_text_mode_console_cursor()
{
    SpinlockLocker locker(m_main_vga_lock);
    if (m_vga_access_is_disabled)
        return;
    IO::out8(0x3D4, 0xA);
    IO::out8(0x3D5, 0x20);
}

void GraphicsManagement::set_vga_text_mode_cursor(size_t console_width, size_t x, size_t y)
{
    SpinlockLocker locker(m_main_vga_lock);
    if (m_vga_access_is_disabled)
        return;
    enable_vga_text_mode_console_cursor();
    u16 value = y * console_width + x;
    IO::out8(0x3d4, 0x0e);
    IO::out8(0x3d5, MSB(value));
    IO::out8(0x3d4, 0x0f);
    IO::out8(0x3d5, LSB(value));
}

void GraphicsManagement::deactivate_graphical_mode()
{
    // FIXME: Remove this once we don't support Framebuffer devices anymore.
    for (auto& graphics_device : m_graphics_devices) {
        graphics_device.enable_consoles();
    }

    for (auto& connector : m_display_connector_nodes) {
        connector.set_display_mode({}, DisplayConnector::DisplayMode::Console);
    }
}
void GraphicsManagement::activate_graphical_mode()
{
    // FIXME: Remove this once we don't support Framebuffer devices anymore.
    for (auto& graphics_device : m_graphics_devices) {
        graphics_device.disable_consoles();
    }

    for (auto& connector : m_display_connector_nodes) {
        connector.set_display_mode({}, DisplayConnector::DisplayMode::Graphical);
    }
}

void GraphicsManagement::attach_new_display_connector(Badge<DisplayConnector>, DisplayConnector& connector)
{
    m_display_connector_nodes.append(connector);
}
void GraphicsManagement::detach_display_connector(Badge<DisplayConnector>, DisplayConnector& connector)
{
    m_display_connector_nodes.remove(connector);
}

static inline bool is_vga_compatible_pci_device(PCI::DeviceIdentifier const& device_identifier)
{
    // Note: Check for Display Controller, VGA Compatible Controller or
    // Unclassified, VGA-Compatible Unclassified Device
    auto is_display_controller_vga_compatible = device_identifier.class_code().value() == 0x3 && device_identifier.subclass_code().value() == 0x0;
    auto is_general_pci_vga_compatible = device_identifier.class_code().value() == 0x0 && device_identifier.subclass_code().value() == 0x1;
    return is_display_controller_vga_compatible || is_general_pci_vga_compatible;
}

static inline bool is_display_controller_pci_device(PCI::DeviceIdentifier const& device_identifier)
{
    return device_identifier.class_code().value() == 0x3;
}

UNMAP_AFTER_INIT bool GraphicsManagement::determine_and_initialize_isa_graphics_device()
{
    dmesgln("Graphics: Using a ISA VGA compatible generic adapter");
    auto adapter = ISAVGAAdapter::initialize();
    m_graphics_devices.append(*adapter);
    adapter->enable_consoles();
    m_vga_adapter = adapter;
    return true;
}

UNMAP_AFTER_INIT bool GraphicsManagement::determine_and_initialize_graphics_device(PCI::DeviceIdentifier const& device_identifier)
{
    VERIFY(is_vga_compatible_pci_device(device_identifier) || is_display_controller_pci_device(device_identifier));
    auto add_and_configure_adapter = [&](GenericGraphicsAdapter& graphics_device) {
        m_graphics_devices.append(graphics_device);
        graphics_device.enable_consoles();
        graphics_device.initialize_framebuffer_devices();
    };
    RefPtr<GenericGraphicsAdapter> adapter;

    auto create_bootloader_framebuffer_device = [&]() {
        if (multiboot_framebuffer_addr.is_null()) {
            // Prekernel sets the framebuffer address to 0 if MULTIBOOT_INFO_FRAMEBUFFER_INFO
            // is not present, as there is likely never a valid framebuffer at this physical address.
            dmesgln("Graphics: Bootloader did not set up a framebuffer");
        } else if (multiboot_framebuffer_type != MULTIBOOT_FRAMEBUFFER_TYPE_RGB) {
            dmesgln("Graphics: The framebuffer set up by the bootloader is not RGB");
        } else {
            dmesgln("Graphics: Using a preset resolution from the bootloader");
            adapter = PCIVGACompatibleAdapter::initialize_with_preset_resolution(device_identifier,
                multiboot_framebuffer_addr,
                multiboot_framebuffer_width,
                multiboot_framebuffer_height,
                multiboot_framebuffer_pitch);
        }
    };

    if (!adapter) {
        switch (device_identifier.hardware_id().vendor_id) {
        case PCI::VendorID::QEMUOld:
            if (device_identifier.hardware_id().device_id == 0x1111)
                adapter = BochsGraphicsAdapter::initialize(device_identifier);
            break;
        case PCI::VendorID::VirtualBox:
            if (device_identifier.hardware_id().device_id == 0xbeef)
                adapter = BochsGraphicsAdapter::initialize(device_identifier);
            break;
        case PCI::VendorID::Intel:
            adapter = IntelNativeGraphicsAdapter::initialize(device_identifier);
            break;
        case PCI::VendorID::VirtIO:
            dmesgln("Graphics: Using VirtIO console");
            adapter = VirtIOGraphicsAdapter::initialize(device_identifier);
            break;
        default:
            if (!is_vga_compatible_pci_device(device_identifier))
                break;
            //  Note: Although technically possible that a system has a
            //  non-compatible VGA graphics device that was initialized by the
            //  Multiboot bootloader to provide a framebuffer, in practice we
            //  probably want to support these devices natively instead of
            //  initializing them as some sort of a generic GenericGraphicsAdapter. For now,
            //  the only known example of this sort of device is qxl in QEMU. For VGA
            //  compatible devices we don't have a special driver for (e.g. ati-vga,
            //  qxl-vga, cirrus-vga, vmware-svga in QEMU), it's much more likely that
            //  these devices will be supported by the Multiboot loader that will
            //  utilize VESA BIOS extensions (that we don't currently) of these cards
            //  support, so we want to utilize the provided framebuffer of these
            //  devices, if possible.
            if (!m_vga_adapter && PCI::is_io_space_enabled(device_identifier.address())) {
                create_bootloader_framebuffer_device();
            } else {
                dmesgln("Graphics: Using a PCI VGA compatible generic adapter");
                adapter = PCIVGACompatibleAdapter::initialize(device_identifier);
            }
            break;
        }
    }

    if (!adapter)
        return false;
    add_and_configure_adapter(*adapter);

    // Note: If IO space is enabled, this VGA adapter is operating in VGA mode.
    // Note: If no other VGA adapter is attached as m_vga_adapter, we should attach it then.
    if (!m_vga_adapter && PCI::is_io_space_enabled(device_identifier.address()) && adapter->vga_compatible()) {
        dbgln("Graphics adapter @ {} is operating in VGA mode", device_identifier.address());
        m_vga_adapter = static_ptr_cast<VGACompatibleAdapter>(adapter);
    }
    return true;
}

UNMAP_AFTER_INIT bool GraphicsManagement::initialize()
{

    /* Explanation on the flow when not requesting to force not creating any
     * framebuffer devices:
     * If the user wants to use a Console instead of the graphical environment,
     * they doesn't need to request text mode.
     * Graphical mode might not be accessible on bare-metal hardware because
     * the bootloader didn't set a framebuffer and we don't have a native driver
     * to set a framebuffer for it. We don't have VBE modesetting capabilities
     * in the kernel yet, so what will happen is one of the following situations:
     * 1. The bootloader didn't specify settings of a pre-set framebuffer. The
     * kernel has a native driver for a detected display adapter, therefore
     * the kernel can still set a framebuffer.
     * 2. The bootloader specified settings of a pre-set framebuffer, and the
     * kernel has a native driver for a detected display adapter, therefore
     * the kernel can still set a framebuffer and change the settings of it.
     * In that situation, the kernel will simply ignore the Multiboot pre-set
     * framebuffer.
     * 2. The bootloader specified settings of a pre-set framebuffer, and the
     * kernel does not have a native driver for a detected display adapter,
     * therefore the kernel will use the pre-set framebuffer. Modesetting is not
     * available in this situation.
     * 3. The bootloader didn't specify settings of a pre-set framebuffer, and
     * the kernel does not have a native driver for a detected display adapter,
     * therefore the kernel will try to initialize a VGA text mode console.
     * In that situation, the kernel will assume that VGA text mode was already
     * initialized, but will still try to modeset it. No switching to graphical
     * environment is allowed in this case.
     *
     * By default, the kernel assumes that no framebuffer was created until it
     * was proven that there's an existing framebuffer or we can modeset the
     * screen resolution to create a framebuffer.
     *
     * Special cases:
     * 1. If the user disabled PCI access, the kernel behaves like it's running
     * on a pure ISA PC machine and therefore the kernel will try to initialize
     * a variant that is suitable for ISA VGA handling, and not PCI adapters.
     *
     * If the user requests to force no initialization of framebuffer devices
     * the same flow above will happen, except that no framebuffer device will
     * be created, so SystemServer will not try to initialize WindowServer.
     */

    auto graphics_subsystem_mode = kernel_command_line().graphics_subsystem_mode();
    if (graphics_subsystem_mode == CommandLine::GraphicsSubsystemMode::Disabled)
        return true;

    if (graphics_subsystem_mode == CommandLine::GraphicsSubsystemMode::Limited && !multiboot_framebuffer_addr.is_null() && multiboot_framebuffer_type != MULTIBOOT_FRAMEBUFFER_TYPE_RGB) {
        dmesgln("Graphics: Using a preset resolution from the bootloader, without knowing the PCI device");
        m_preset_resolution_generic_display_connector = GenericDisplayConnector::must_create_with_preset_resolution(
            multiboot_framebuffer_addr,
            multiboot_framebuffer_width,
            multiboot_framebuffer_height,
            multiboot_framebuffer_pitch);
        return true;
    }

    if (PCI::Access::is_disabled()) {
        determine_and_initialize_isa_graphics_device();
        return true;
    }

    MUST(PCI::enumerate([&](PCI::DeviceIdentifier const& device_identifier) {
        // Note: Each graphics controller will try to set its native screen resolution
        // upon creation. Later on, if we don't want to have framebuffer devices, a
        // framebuffer console will take the control instead.
        if (!is_vga_compatible_pci_device(device_identifier) && !is_display_controller_pci_device(device_identifier))
            return;
        determine_and_initialize_graphics_device(device_identifier);
    }));

    if (!m_console) {
        // If no graphics driver was instantiated and we had a bootloader provided
        // framebuffer console we can simply re-use it.
        if (auto* boot_console = g_boot_console.load()) {
            m_console = *boot_console;
            boot_console->unref(); // Drop the leaked reference from Kernel::init()
        }
    }

    if (m_graphics_devices.is_empty()) {
        dbgln("No graphics adapter was initialized.");
        return false;
    }
    return true;
}

void GraphicsManagement::set_console(Graphics::Console& console)
{
    m_console = console;

    if (auto* boot_console = g_boot_console.exchange(nullptr)) {
        // Disable the initial boot framebuffer console permanently
        boot_console->disable();
        // TODO: Even though we swapped the pointer and disabled the console
        // we technically can't safely destroy it as other CPUs might still
        // try to use it. Once we solve this problem we can drop the reference
        // that we intentionally leaked in Kernel::init().
    }
}

}