/*
 * Copyright (c) 2020-2022, Liav A. <liavalb@hotmail.co.il>
 * Copyright (c) 2022, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Platform.h>
#include <AK/Singleton.h>
#include <AK/StringView.h>
#include <AK/UUID.h>
#include <Kernel/API/DeviceFileTypes.h>
#include <Kernel/Boot/CommandLine.h>
#include <Kernel/Bus/PCI/API.h>
#include <Kernel/Bus/PCI/Access.h>
#include <Kernel/Bus/PCI/Controller/VolumeManagementDevice.h>
#include <Kernel/Devices/BlockDevice.h>
#include <Kernel/Devices/Device.h>
#include <Kernel/Devices/Storage/AHCI/Controller.h>
#include <Kernel/Devices/Storage/NVMe/NVMeController.h>
#include <Kernel/Devices/Storage/SD/PCISDHostController.h>
#include <Kernel/Devices/Storage/SD/SDHostController.h>
#include <Kernel/Devices/Storage/StorageManagement.h>
#include <Kernel/Devices/Storage/VirtIO/VirtIOBlockController.h>
#include <Kernel/FileSystem/Ext2FS/FileSystem.h>
#include <Kernel/FileSystem/MountFile.h>
#include <Kernel/FileSystem/VirtualFileSystem.h>
#include <Kernel/Library/Panic.h>
#include <LibPartition/EBRPartitionTable.h>
#include <LibPartition/GUIDPartitionTable.h>
#include <LibPartition/MBRPartitionTable.h>

namespace Kernel {

static Singleton<StorageManagement> s_the;
static Atomic<u32> s_storage_device_minor_number;
static Atomic<u32> s_partition_device_minor_number;
static Atomic<u32> s_controller_id;

static Atomic<u32> s_relative_ahci_controller_id;
static Atomic<u32> s_relative_nvme_controller_id;
static Atomic<u32> s_relative_sd_controller_id;

static constexpr int root_mount_flags = 0;

static constexpr StringView partition_uuid_prefix = "PARTUUID:"sv;

static constexpr StringView partition_number_prefix = "part"sv;
static constexpr StringView block_device_prefix = "block"sv;

static constexpr StringView ahci_device_prefix = "ahci"sv;
static constexpr StringView nvme_device_prefix = "nvme"sv;
static constexpr StringView logical_unit_number_device_prefix = "lun"sv;
static constexpr StringView sd_device_prefix = "sd"sv;

UNMAP_AFTER_INIT StorageManagement::StorageManagement()
{
}

u32 StorageManagement::generate_relative_nvme_controller_id(Badge<NVMeController>)
{
    auto controller_id = s_relative_nvme_controller_id.load();
    s_relative_nvme_controller_id++;
    return controller_id;
}

u32 StorageManagement::generate_relative_ahci_controller_id(Badge<AHCIController>)
{
    auto controller_id = s_relative_ahci_controller_id.load();
    s_relative_ahci_controller_id++;
    return controller_id;
}

u32 StorageManagement::generate_relative_sd_controller_id(Badge<SDHostController>)
{
    auto controller_id = s_relative_sd_controller_id.load();
    s_relative_sd_controller_id++;
    return controller_id;
}

ErrorOr<void> StorageManagement::add_controller(StorageController& controller)
{
    TRY(m_controllers.try_append(controller));
    return {};
}

void StorageManagement::add_device(StorageDevice& device)
{
    m_storage_devices.append(device);
    // FIXME: Maybe handle this error in some way shape or form
    (void)enumerate_device_partitions(device);
}

void StorageManagement::remove_device(StorageDevice& device)
{
    m_storage_devices.remove(device);
}

UNMAP_AFTER_INIT void StorageManagement::enumerate_pci_controllers(bool nvme_poll)
{
    if (!kernel_command_line().disable_physical_storage()) {
        // NOTE: Search for VMD devices before actually searching for storage controllers
        // because the VMD device is only a bridge to such (NVMe) controllers.
        MUST(PCI::enumerate([&](PCI::DeviceIdentifier const& device_identifier) -> void {
            constexpr PCI::HardwareID vmd_device = { 0x8086, 0x9a0b };
            if (device_identifier.hardware_id() == vmd_device) {
                auto controller = PCI::VolumeManagementDevice::must_create(device_identifier);
                MUST(PCI::Access::the().add_host_controller_and_scan_for_devices(move(controller)));
            }
        }));

        RefPtr<VirtIOBlockController> virtio_controller;

        auto const& handle_mass_storage_device = [&](PCI::DeviceIdentifier const& device_identifier) {
            using SubclassID = PCI::MassStorage::SubclassID;

            auto subclass_code = static_cast<SubclassID>(device_identifier.subclass_code().value());
            if (subclass_code == SubclassID::SATAController
                && device_identifier.prog_if() == PCI::MassStorage::SATAProgIF::AHCI) {
                if (auto ahci_controller_or_error = AHCIController::initialize(device_identifier); !ahci_controller_or_error.is_error())
                    m_controllers.append(ahci_controller_or_error.value());
                else
                    dmesgln("Unable to initialize AHCI controller: {}", ahci_controller_or_error.error());
            }
            if (subclass_code == SubclassID::NVMeController) {
                auto controller = NVMeController::try_initialize(device_identifier, nvme_poll);
                if (controller.is_error()) {
                    dmesgln("Unable to initialize NVMe controller: {}", controller.error());
                } else {
                    m_controllers.append(controller.release_value());
                }
            }
            if (VirtIOBlockController::is_handled(device_identifier)) {
                if (virtio_controller.is_null()) {
                    auto controller = make_ref_counted<VirtIOBlockController>();
                    m_controllers.append(controller);
                    virtio_controller = controller;
                }
                if (auto res = virtio_controller->add_device(device_identifier); res.is_error()) {
                    dmesgln("Unable to initialize VirtIO block device: {}", res.error());
                }
            }
        };

        auto const& handle_base_device = [&](PCI::DeviceIdentifier const& device_identifier) {
            using SubclassID = PCI::Base::SubclassID;

            auto subclass_code = static_cast<SubclassID>(device_identifier.subclass_code().value());
            if (subclass_code == SubclassID::SDHostController) {

                auto sdhc_or_error = PCISDHostController::try_initialize(device_identifier);
                if (sdhc_or_error.is_error()) {
                    dmesgln("PCI: Failed to initialize SD Host Controller ({} - {}): {}", device_identifier.address(), device_identifier.hardware_id(), sdhc_or_error.error());
                } else {
                    m_controllers.append(sdhc_or_error.release_value());
                }
            }
        };

        MUST(PCI::enumerate([&](PCI::DeviceIdentifier const& device_identifier) -> void {
            auto class_code = device_identifier.class_code();
            if (class_code == PCI::ClassID::MassStorage) {
                handle_mass_storage_device(device_identifier);
            } else if (class_code == PCI::ClassID::Base) {
                handle_base_device(device_identifier);
            }
        }));
    }
}

UNMAP_AFTER_INIT void StorageManagement::enumerate_storage_devices()
{
    for (auto& controller : m_controllers) {
        for (size_t device_index = 0; device_index < controller->devices_count(); device_index++) {
            auto device = controller->device(device_index);
            if (device.is_null())
                continue;
            m_storage_devices.append(device.release_nonnull());
        }
    }
}

UNMAP_AFTER_INIT void StorageManagement::dump_storage_devices_and_partitions() const
{
    critical_dmesgln("StorageManagement: Detected {} storage devices", m_storage_devices.size_slow());
    for (auto const& storage_device : m_storage_devices) {
        auto const& partitions = storage_device.partitions();
        if (partitions.is_empty()) {
            critical_dmesgln("  Device: block{}:{} ({}, no partitions)", storage_device.major(), storage_device.minor(), storage_device.command_set_to_string_view());
        } else {
            critical_dmesgln("  Device: block{}:{} ({}, {} partitions)", storage_device.major(), storage_device.minor(), storage_device.command_set_to_string_view(), partitions.size());
            unsigned partition_number = 1;
            for (auto const& partition : partitions) {
                critical_dmesgln("    Partition: {}, block{}:{} (UUID {})", partition_number, partition->major(), partition->minor(), partition->metadata().unique_guid().to_string());
                partition_number++;
            }
        }
    }
}

ErrorOr<NonnullOwnPtr<Partition::PartitionTable>> StorageManagement::try_to_initialize_partition_table(StorageDevice& device) const
{
    auto mbr_table_or_error = Partition::MBRPartitionTable::try_to_initialize(device);
    if (!mbr_table_or_error.is_error())
        return mbr_table_or_error.release_value();
    auto ebr_table_or_error = Partition::EBRPartitionTable::try_to_initialize(device);
    if (!ebr_table_or_error.is_error()) {
        return ebr_table_or_error.release_value();
    }
    return TRY(Partition::GUIDPartitionTable::try_to_initialize(device));
}

ErrorOr<void> StorageManagement::enumerate_device_partitions(StorageDevice& device)
{
    auto partition_table = TRY(try_to_initialize_partition_table(device));
    for (auto partition_metadata : partition_table->partitions()) {
        auto disk_partition = TRY(StorageDevicePartition::create(device, generate_partition_minor_number(), partition_metadata));
        device.add_partition(disk_partition);
    }

    return {};
}

UNMAP_AFTER_INIT void StorageManagement::enumerate_disk_partitions()
{
    for (auto& device : m_storage_devices) {
        // FIXME: Maybe handle this error in some way shape or form
        (void)enumerate_device_partitions(device);
    }
}

UNMAP_AFTER_INIT Optional<unsigned> StorageManagement::extract_boot_device_partition_number_parameter(StringView device_prefix)
{
    VERIFY(m_boot_argument.starts_with(device_prefix));
    VERIFY(!m_boot_argument.starts_with(partition_uuid_prefix));
    auto storage_device_relative_address_view = m_boot_argument.substring_view(device_prefix.length());
    auto parameter_view = storage_device_relative_address_view.find_last_split_view(';');
    if (parameter_view == storage_device_relative_address_view)
        return {};
    if (!parameter_view.starts_with(partition_number_prefix)) {
        PANIC("StorageManagement: Invalid root boot parameter.");
    }

    auto parameter_number = parameter_view.substring_view(partition_number_prefix.length()).to_number<unsigned>();
    if (!parameter_number.has_value()) {
        PANIC("StorageManagement: Invalid root boot parameter.");
    }

    return parameter_number.value();
}

UNMAP_AFTER_INIT Array<unsigned, 3> StorageManagement::extract_boot_device_address_parameters(StringView device_prefix)
{
    VERIFY(!m_boot_argument.starts_with(partition_uuid_prefix));
    Array<unsigned, 3> address_parameters;
    auto parameters_view = m_boot_argument.substring_view(device_prefix.length()).find_first_split_view(';');
    size_t parts_count = 0;
    bool parse_failure = false;
    parameters_view.for_each_split_view(':', SplitBehavior::Nothing, [&](StringView parameter_view) {
        if (parse_failure)
            return;
        if (parts_count > 2)
            return;
        auto parameter_number = parameter_view.to_number<unsigned>();
        if (!parameter_number.has_value()) {
            parse_failure = true;
            return;
        }
        address_parameters[parts_count] = parameter_number.value();
        parts_count++;
    });

    if (parts_count > 3) {
        dbgln("StorageManagement: Detected {} parts in boot device parameter.", parts_count);
        PANIC("StorageManagement: Invalid root boot parameter.");
    }
    if (parse_failure) {
        PANIC("StorageManagement: Invalid root boot parameter.");
    }

    return address_parameters;
}

UNMAP_AFTER_INIT void StorageManagement::resolve_partition_from_boot_device_parameter(StorageDevice const& chosen_storage_device, StringView boot_device_prefix)
{
    auto possible_partition_number = extract_boot_device_partition_number_parameter(boot_device_prefix);
    if (!possible_partition_number.has_value())
        return;

    auto partition_number = possible_partition_number.value();
    if (chosen_storage_device.partitions().size() <= partition_number)
        PANIC("StorageManagement: Invalid partition number parameter.");
    m_boot_block_device = *chosen_storage_device.partitions()[partition_number];
}

UNMAP_AFTER_INIT void StorageManagement::determine_hardware_relative_boot_device(StringView relative_hardware_prefix, Function<bool(StorageDevice const&)> filter_device_callback)
{
    VERIFY(m_boot_argument.starts_with(relative_hardware_prefix));
    auto address_parameters = extract_boot_device_address_parameters(relative_hardware_prefix);

    RefPtr<StorageDevice> chosen_storage_device;

    for (auto& storage_device : m_storage_devices) {
        if (!filter_device_callback(storage_device))
            continue;
        auto storage_device_lun = storage_device.logical_unit_number_address();
        if (storage_device.parent_controller_hardware_relative_id() == address_parameters[0]
            && storage_device_lun.target_id == address_parameters[1]
            && storage_device_lun.disk_id == address_parameters[2]) {
            m_boot_block_device = storage_device;
            chosen_storage_device = storage_device;
            break;
        }
    }

    if (chosen_storage_device)
        resolve_partition_from_boot_device_parameter(*chosen_storage_device, relative_hardware_prefix);
}

UNMAP_AFTER_INIT void StorageManagement::determine_ata_boot_device()
{
    determine_hardware_relative_boot_device(ahci_device_prefix, [](StorageDevice const& device) -> bool {
        return device.command_set() == StorageDevice::CommandSet::ATA;
    });
}

UNMAP_AFTER_INIT void StorageManagement::determine_nvme_boot_device()
{
    determine_hardware_relative_boot_device(nvme_device_prefix, [](StorageDevice const& device) -> bool {
        return device.command_set() == StorageDevice::CommandSet::NVMe;
    });
}

UNMAP_AFTER_INIT void StorageManagement::determine_sd_boot_device()
{
    determine_hardware_relative_boot_device(sd_device_prefix, [](StorageDevice const& device) -> bool {
        return device.command_set() == StorageDevice::CommandSet::SD;
    });
}

UNMAP_AFTER_INIT void StorageManagement::determine_block_boot_device()
{
    VERIFY(m_boot_argument.starts_with(block_device_prefix));
    auto parameters_view = extract_boot_device_address_parameters(block_device_prefix);

    // Note: We simply fetch the corresponding BlockDevice with the major and minor parameters.
    // We don't try to accept and resolve a partition number as it will make this code much more
    // complicated. This rule is also explained in the boot_device_addressing(7) manual page.
    Device::run_by_type_and_major_minor_numbers(DeviceNodeType::Block, parameters_view[0], parameters_view[1], [&](RefPtr<Device> device) {
        if (device && device->is_block_device())
            m_boot_block_device = *static_ptr_cast<BlockDevice>(device);
    });
}

UNMAP_AFTER_INIT void StorageManagement::determine_boot_device_with_logical_unit_number()
{
    VERIFY(m_boot_argument.starts_with(logical_unit_number_device_prefix));
    auto address_parameters = extract_boot_device_address_parameters(logical_unit_number_device_prefix);

    RefPtr<StorageDevice> chosen_storage_device;

    for (auto& storage_device : m_storage_devices) {
        auto storage_device_lun = storage_device.logical_unit_number_address();
        if (storage_device_lun.controller_id == address_parameters[0]
            && storage_device_lun.target_id == address_parameters[1]
            && storage_device_lun.disk_id == address_parameters[2]) {
            m_boot_block_device = storage_device;
            chosen_storage_device = storage_device;
            break;
        }
    }

    if (chosen_storage_device)
        resolve_partition_from_boot_device_parameter(*chosen_storage_device, logical_unit_number_device_prefix);
}

UNMAP_AFTER_INIT bool StorageManagement::determine_boot_device(StringView boot_argument)
{
    m_boot_argument = boot_argument;

    if (m_boot_argument.starts_with(block_device_prefix)) {
        determine_block_boot_device();
        return m_boot_block_device;
    }

    if (m_boot_argument.starts_with(partition_uuid_prefix)) {
        determine_boot_device_with_partition_uuid();
        return m_boot_block_device;
    }

    if (m_boot_argument.starts_with(logical_unit_number_device_prefix)) {
        determine_boot_device_with_logical_unit_number();
        return m_boot_block_device;
    }

    if (m_boot_argument.starts_with(ahci_device_prefix)) {
        determine_ata_boot_device();
        return m_boot_block_device;
    }

    if (m_boot_argument.starts_with(nvme_device_prefix)) {
        determine_nvme_boot_device();
        return m_boot_block_device;
    }

    if (m_boot_argument.starts_with(sd_device_prefix)) {
        determine_sd_boot_device();
        return m_boot_block_device;
    }
    PANIC("StorageManagement: Invalid root boot parameter.");
}

UNMAP_AFTER_INIT void StorageManagement::determine_boot_device_with_partition_uuid()
{
    VERIFY(m_boot_argument.starts_with(partition_uuid_prefix));

    auto partition_uuid = UUID(m_boot_argument.substring_view(partition_uuid_prefix.length()), UUID::Endianness::Mixed);

    for (auto& storage_device : m_storage_devices) {
        for (auto& partition : storage_device.partitions()) {
            if (partition->metadata().unique_guid().is_zero())
                continue;
            if (partition->metadata().unique_guid() == partition_uuid) {
                m_boot_block_device = *partition;
                break;
            }
        }
    }
}

RefPtr<BlockDevice> StorageManagement::boot_block_device() const
{
    auto device = m_boot_block_device.strong_ref();
    if (!device)
        return nullptr;
    return *device;
}

MinorNumber StorageManagement::generate_storage_minor_number()
{
    return s_storage_device_minor_number.fetch_add(1);
}

MinorNumber StorageManagement::generate_partition_minor_number()
{
    return s_partition_device_minor_number.fetch_add(1);
}

u32 StorageManagement::generate_controller_id()
{
    return s_controller_id.fetch_add(1);
}

ErrorOr<NonnullRefPtr<VFSRootContext>> StorageManagement::create_first_vfs_root_context() const
{
    auto vfs_root_context = TRY(VFSRootContext::create_with_empty_ramfs());

    auto const* fs_type_initializer = TRY(VirtualFileSystem::find_filesystem_type_initializer("ext2"sv));
    VERIFY(fs_type_initializer);
    auto mount_file = TRY(MountFile::create(*fs_type_initializer, root_mount_flags));

    auto boot_device_description = boot_block_device();
    if (!boot_device_description) {
        dump_storage_devices_and_partitions();
        PANIC("StorageManagement: Couldn't find a suitable device to boot from");
    }
    auto description = TRY(OpenFileDescription::try_create(boot_device_description.release_nonnull()));

    auto fs = TRY(FileBackedFileSystem::create_and_append_filesystems_list_from_mount_file_and_description(mount_file, description));

    // NOTE: Fake a mounted count of 1 so the called VirtualFileSystem function in the
    // next pivot_root logic block thinks everything is OK.
    fs->mounted_count().with([](auto& mounted_count) {
        mounted_count++;
    });

    TRY(VirtualFileSystem::pivot_root_by_copying_mounted_fs_instance(*vfs_root_context, *fs, root_mount_flags));
    // NOTE: Return the mounted count to normal now we have it really mounted.
    fs->mounted_count().with([](auto& mounted_count) {
        mounted_count--;
    });
    return vfs_root_context;
}

UNMAP_AFTER_INIT void StorageManagement::initialize(bool poll)
{
    if (!PCI::Access::is_disabled()) {
        enumerate_pci_controllers(poll);
    }

    enumerate_storage_devices();
    enumerate_disk_partitions();
}

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