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

#include <AK/StringBuilder.h>
#include <AK/StringView.h>
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Net/IPv4Socket.h>
#include <Kernel/Net/LocalSocket.h>
#include <Kernel/Net/Socket.h>
#include <Kernel/Process.h>
#include <Kernel/UnixTypes.h>
#include <LibC/errno_numbers.h>

namespace Kernel {

KResultOr<NonnullRefPtr<Socket>> Socket::create(int domain, int type, int protocol)
{
    switch (domain) {
    case AF_LOCAL:
        return LocalSocket::create(type & SOCK_TYPE_MASK);
    case AF_INET:
        return IPv4Socket::create(type & SOCK_TYPE_MASK, protocol);
    default:
        return EAFNOSUPPORT;
    }
}

Socket::Socket(int domain, int type, int protocol)
    : m_domain(domain)
    , m_type(type)
    , m_protocol(protocol)
{
    auto& process = *Process::current();
    m_origin = { process.pid().value(), process.uid(), process.gid() };
}

Socket::~Socket()
{
}

void Socket::set_setup_state(SetupState new_setup_state)
{
    dbgln_if(SOCKET_DEBUG, "Socket({}) setup state moving from {} to {}", this, to_string(m_setup_state), to_string(new_setup_state));
    m_setup_state = new_setup_state;
    evaluate_block_conditions();
}

RefPtr<Socket> Socket::accept()
{
    Locker locker(m_lock);
    if (m_pending.is_empty())
        return nullptr;
    dbgln_if(SOCKET_DEBUG, "Socket({}) de-queueing connection", this);
    auto client = m_pending.take_first();
    VERIFY(!client->is_connected());
    auto& process = *Process::current();
    client->m_acceptor = { process.pid().value(), process.uid(), process.gid() };
    client->m_connected = true;
    client->m_role = Role::Accepted;
    if (!m_pending.is_empty())
        evaluate_block_conditions();
    return client;
}

KResult Socket::queue_connection_from(NonnullRefPtr<Socket> peer)
{
    dbgln_if(SOCKET_DEBUG, "Socket({}) queueing connection", this);
    Locker locker(m_lock);
    if (m_pending.size() >= m_backlog)
        return ECONNREFUSED;
    m_pending.append(peer);
    evaluate_block_conditions();
    return KSuccess;
}

KResult Socket::setsockopt(int level, int option, Userspace<const void*> user_value, socklen_t user_value_size)
{
    if (level != SOL_SOCKET)
        return ENOPROTOOPT;
    VERIFY(level == SOL_SOCKET);
    switch (option) {
    case SO_SNDTIMEO:
        if (user_value_size != sizeof(timeval))
            return EINVAL;
        {
            auto timeout = copy_time_from_user(static_ptr_cast<const timeval*>(user_value));
            if (!timeout.has_value())
                return EFAULT;
            m_send_timeout = timeout.value();
        }
        return KSuccess;
    case SO_RCVTIMEO:
        if (user_value_size != sizeof(timeval))
            return EINVAL;
        {
            auto timeout = copy_time_from_user(static_ptr_cast<const timeval*>(user_value));
            if (!timeout.has_value())
                return EFAULT;
            m_receive_timeout = timeout.value();
        }
        return KSuccess;
    case SO_BINDTODEVICE: {
        if (user_value_size != IFNAMSIZ)
            return EINVAL;
        auto user_string = static_ptr_cast<const char*>(user_value);
        auto ifname = copy_string_from_user(user_string, user_value_size);
        if (ifname.is_null())
            return EFAULT;
        auto device = NetworkAdapter::lookup_by_name(ifname);
        if (!device)
            return ENODEV;
        m_bound_interface = device;
        return KSuccess;
    }
    case SO_KEEPALIVE:
        // FIXME: Obviously, this is not a real keepalive.
        return KSuccess;
    case SO_TIMESTAMP:
        if (user_value_size != sizeof(int))
            return EINVAL;
        {
            int timestamp;
            if (!copy_from_user(&timestamp, static_ptr_cast<const int*>(user_value)))
                return EFAULT;
            m_timestamp = timestamp;
        }
        if (m_timestamp && (domain() != AF_INET || type() == SOCK_STREAM)) {
            // FIXME: Support SO_TIMESTAMP for more protocols?
            m_timestamp = 0;
            return ENOTSUP;
        }
        return KSuccess;
    default:
        dbgln("setsockopt({}) at SOL_SOCKET not implemented.", option);
        return ENOPROTOOPT;
    }
}

KResult Socket::getsockopt(FileDescription&, int level, int option, Userspace<void*> value, Userspace<socklen_t*> value_size)
{
    socklen_t size;
    if (!copy_from_user(&size, value_size.unsafe_userspace_ptr()))
        return EFAULT;

    // FIXME: Add TCP_NODELAY, IPPROTO_TCP and IPPROTO_IP (used in OpenSSH)
    if (level != SOL_SOCKET) {
        // Not sure if this is the correct error code, but it's only temporary until other levels are implemented.
        return ENOPROTOOPT;
    }

    switch (option) {
    case SO_SNDTIMEO:
        if (size < sizeof(timeval))
            return EINVAL;
        {
            timeval tv = m_send_timeout.to_timeval();
            if (!copy_to_user(static_ptr_cast<timeval*>(value), &tv))
                return EFAULT;
        }
        size = sizeof(timeval);
        if (!copy_to_user(value_size, &size))
            return EFAULT;
        return KSuccess;
    case SO_RCVTIMEO:
        if (size < sizeof(timeval))
            return EINVAL;
        {
            timeval tv = m_send_timeout.to_timeval();
            if (!copy_to_user(static_ptr_cast<timeval*>(value), &tv))
                return EFAULT;
        }
        size = sizeof(timeval);
        if (!copy_to_user(value_size, &size))
            return EFAULT;
        return KSuccess;
    case SO_ERROR: {
        if (size < sizeof(int))
            return EINVAL;
        dbgln("getsockopt(SO_ERROR): FIXME!");
        int errno = 0;
        if (!copy_to_user(static_ptr_cast<int*>(value), &errno))
            return EFAULT;
        size = sizeof(int);
        if (!copy_to_user(value_size, &size))
            return EFAULT;
        return KSuccess;
    }
    case SO_BINDTODEVICE:
        if (size < IFNAMSIZ)
            return EINVAL;
        if (m_bound_interface) {
            const auto& name = m_bound_interface->name();
            auto length = name.length() + 1;
            if (!copy_to_user(static_ptr_cast<char*>(value), name.characters(), length))
                return EFAULT;
            size = length;
            if (!copy_to_user(value_size, &size))
                return EFAULT;
            return KSuccess;
        } else {
            size = 0;
            if (!copy_to_user(value_size, &size))
                return EFAULT;

            return EFAULT;
        }
    case SO_TIMESTAMP:
        if (size < sizeof(int))
            return EINVAL;
        if (!copy_to_user(static_ptr_cast<int*>(value), &m_timestamp))
            return EFAULT;
        size = sizeof(int);
        if (!copy_to_user(value_size, &size))
            return EFAULT;
        return KSuccess;
    default:
        dbgln("setsockopt({}) at SOL_SOCKET not implemented.", option);
        return ENOPROTOOPT;
    }
}

KResultOr<size_t> Socket::read(FileDescription& description, u64, UserOrKernelBuffer& buffer, size_t size)
{
    if (is_shut_down_for_reading())
        return 0;
    Time t {};
    return recvfrom(description, buffer, size, 0, {}, 0, t);
}

KResultOr<size_t> Socket::write(FileDescription& description, u64, const UserOrKernelBuffer& data, size_t size)
{
    if (is_shut_down_for_writing())
        return EPIPE;
    return sendto(description, data, size, 0, {}, 0);
}

KResult Socket::shutdown(int how)
{
    Locker locker(lock());
    if (type() == SOCK_STREAM && !is_connected())
        return ENOTCONN;
    if (m_role == Role::Listener)
        return ENOTCONN;
    if (!m_shut_down_for_writing && (how & SHUT_WR))
        shut_down_for_writing();
    if (!m_shut_down_for_reading && (how & SHUT_RD))
        shut_down_for_reading();
    m_shut_down_for_reading |= (how & SHUT_RD) != 0;
    m_shut_down_for_writing |= (how & SHUT_WR) != 0;
    return KSuccess;
}

KResult Socket::stat(::stat& st) const
{
    memset(&st, 0, sizeof(st));
    st.st_mode = S_IFSOCK;
    return KSuccess;
}

void Socket::set_connected(bool connected)
{
    Locker locker(lock());
    if (m_connected == connected)
        return;
    m_connected = connected;
    evaluate_block_conditions();
}

}