/*
 * Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
 * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <Kernel/API/DeviceFileTypes.h>
#include <Kernel/API/MajorNumberAllocation.h>
#include <Kernel/Devices/Device.h>
#include <Kernel/Devices/TTY/SlavePTY.h>
#include <Kernel/FileSystem/DevPtsFS/FileSystem.h>
#include <Kernel/FileSystem/DevPtsFS/Inode.h>
#include <Kernel/Time/TimeManagement.h>

namespace Kernel {

ErrorOr<NonnullRefPtr<FileSystem>> DevPtsFS::try_create(FileSystemSpecificOptions const&)
{
    return TRY(adopt_nonnull_ref_or_enomem(new (nothrow) DevPtsFS));
}

DevPtsFS::DevPtsFS() = default;
DevPtsFS::~DevPtsFS() = default;

ErrorOr<void> DevPtsFS::initialize()
{
    m_root_inode = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) DevPtsFSInode(*this)));
    m_root_inode->m_metadata.inode = { fsid(), 1 };
    m_root_inode->m_metadata.mode = 0040555;
    m_root_inode->m_metadata.uid = 0;
    m_root_inode->m_metadata.gid = 0;
    m_root_inode->m_metadata.size = 0;
    m_root_inode->m_metadata.mtime = TimeManagement::boot_time();
    return {};
}

static unsigned inode_index_to_pty_index(InodeIndex inode_index)
{
    VERIFY(inode_index > 1);
    return inode_index.value() - 2;
}

Inode& DevPtsFS::root_inode()
{
    return *m_root_inode;
}

ErrorOr<void> DevPtsFS::rename(Inode&, StringView, Inode&, StringView)
{
    return EROFS;
}

u8 DevPtsFS::internal_file_type_to_directory_entry_type(DirectoryEntryView const& entry) const
{
    return ram_backed_file_type_to_directory_entry_type(entry);
}

ErrorOr<NonnullRefPtr<Inode>> DevPtsFS::get_inode(InodeIdentifier inode_id) const
{
    if (inode_id.index() == 1)
        return *m_root_inode;

    unsigned pty_index = inode_index_to_pty_index(inode_id.index());

    UserID pty_uid;
    GroupID pty_gid;
    LockRefPtr<SlavePTY> device;

    Device::run_by_type_and_major_minor_numbers(DeviceNodeType::Character, to_underlying(MajorAllocation::CharacterDeviceFamily::SlavePTY), pty_index, [&](RefPtr<Device> found_device) {
        if (!found_device)
            return;
        auto& pty = static_cast<SlavePTY&>(*found_device);
        pty_uid = pty.uid();
        pty_gid = pty.gid();
        device = pty;
    });

    if (!device)
        return ENOENT;

    auto inode = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) DevPtsFSInode(const_cast<DevPtsFS&>(*this), inode_id.index(), device)));
    inode->m_metadata.inode = inode_id;
    inode->m_metadata.size = 0;
    inode->m_metadata.uid = pty_uid;
    inode->m_metadata.gid = pty_gid;
    inode->m_metadata.mode = 0020600;
    inode->m_metadata.major_device = to_underlying(MajorAllocation::CharacterDeviceFamily::SlavePTY);
    inode->m_metadata.minor_device = pty_index;
    inode->m_metadata.mtime = TimeManagement::boot_time();
    return inode;
}

}