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

#pragma once

#include <AK/HashMap.h>
#include <AK/SetOnce.h>
#include <AK/SinglyLinkedList.h>
#include <Kernel/Library/DoubleBuffer.h>
#include <Kernel/Library/KBuffer.h>
#include <Kernel/Locking/MutexProtected.h>
#include <Kernel/Net/IP/IPv4.h>
#include <Kernel/Net/IP/SocketTuple.h>
#include <Kernel/Net/Socket.h>

namespace Kernel {

class NetworkAdapter;
class TCPPacket;
class TCPSocket;

class IPv4Socket : public Socket {
public:
    static ErrorOr<NonnullRefPtr<Socket>> create(int type, int protocol);
    virtual ~IPv4Socket() override;

    virtual ErrorOr<void> close() override;
    virtual ErrorOr<void> bind(Credentials const&, Userspace<sockaddr const*>, socklen_t) override;
    virtual ErrorOr<void> connect(Credentials const&, OpenFileDescription&, Userspace<sockaddr const*>, socklen_t) override;
    virtual ErrorOr<void> listen(size_t) override;
    virtual void get_local_address(sockaddr*, socklen_t*) override;
    virtual void get_peer_address(sockaddr*, socklen_t*) override;
    virtual bool can_read(OpenFileDescription const&, u64) const override;
    virtual bool can_write(OpenFileDescription const&, u64) const override;
    virtual ErrorOr<size_t> sendto(OpenFileDescription&, UserOrKernelBuffer const&, size_t, int, Userspace<sockaddr const*>, socklen_t) override;
    virtual ErrorOr<size_t> recvfrom(OpenFileDescription&, UserOrKernelBuffer&, size_t, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, UnixDateTime&, bool blocking) override;
    virtual ErrorOr<void> setsockopt(int level, int option, Userspace<void const*>, socklen_t) override;
    virtual ErrorOr<void> getsockopt(OpenFileDescription&, int level, int option, Userspace<void*>, Userspace<socklen_t*>) override;

    virtual ErrorOr<void> ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg) override;

    bool did_receive(IPv4Address const& peer_address, u16 peer_port, ReadonlyBytes, UnixDateTime const&);

    IPv4Address const& local_address() const { return m_local_address; }
    u16 local_port() const { return m_local_port; }
    void set_local_port(u16 port) { m_local_port = port; }
    bool has_specific_local_address() { return m_local_address.to_u32() != 0; }

    IPv4Address const& peer_address() const { return m_peer_address; }
    u16 peer_port() const { return m_peer_port; }
    void set_peer_port(u16 port) { m_peer_port = port; }

    Vector<IPv4Address> const& multicast_memberships() const { return m_multicast_memberships; }

    IPv4SocketTuple tuple() const { return IPv4SocketTuple(m_local_address, m_local_port, m_peer_address, m_peer_port); }

    ErrorOr<NonnullOwnPtr<KString>> pseudo_path(OpenFileDescription const& description) const override;

    u8 type_of_service() const { return m_type_of_service; }
    u8 ttl() const { return m_ttl; }

    enum class BufferMode {
        Packets,
        Bytes,
    };
    BufferMode buffer_mode() const { return m_buffer_mode; }

protected:
    static constexpr size_t receive_buffer_size = 256 * KiB;

    IPv4Socket(int type, int protocol, NonnullOwnPtr<DoubleBuffer> receive_buffer, OwnPtr<KBuffer> optional_scratch_buffer);
    virtual StringView class_name() const override { return "IPv4Socket"sv; }

    void set_bound() { m_bound.set(); }
    ErrorOr<void> ensure_bound();

    virtual ErrorOr<void> protocol_bind() { return {}; }
    virtual ErrorOr<void> protocol_listen() { return {}; }
    virtual ErrorOr<size_t> protocol_receive(ReadonlyBytes /* raw_ipv4_packet */, UserOrKernelBuffer&, size_t, int) { return ENOTIMPL; }
    virtual ErrorOr<size_t> protocol_send(UserOrKernelBuffer const&, size_t) { return ENOTIMPL; }
    virtual ErrorOr<void> protocol_connect(OpenFileDescription&) { return {}; }
    virtual ErrorOr<size_t> protocol_size(ReadonlyBytes /* raw_ipv4_packet */) { return ENOTIMPL; }
    virtual bool protocol_is_disconnected() const { return false; }

    virtual void shut_down_for_reading() override;

    void set_local_address(IPv4Address address) { m_local_address = address; }
    void set_peer_address(IPv4Address address) { m_peer_address = address; }

    static ErrorOr<NonnullOwnPtr<DoubleBuffer>> try_create_receive_buffer();
    void drop_receive_buffer();

    size_t available_space_in_receive_buffer() const { return m_receive_buffer ? m_receive_buffer->space_for_writing() : 0; }

private:
    virtual bool is_ipv4() const override { return true; }

    ErrorOr<size_t> receive_byte_buffered(OpenFileDescription&, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, bool blocking);
    ErrorOr<size_t> receive_packet_buffered(OpenFileDescription&, UserOrKernelBuffer& buffer, size_t buffer_length, int flags, Userspace<sockaddr*>, Userspace<socklen_t*>, UnixDateTime&, bool blocking);

    void set_can_read(bool);

    IPv4Address m_local_address;
    IPv4Address m_peer_address;

    Vector<IPv4Address> m_multicast_memberships;
    bool m_multicast_loop { true };
    SetOnce m_bound;

    struct ReceivedPacket {
        IPv4Address peer_address;
        u16 peer_port;
        UnixDateTime timestamp;
        OwnPtr<KBuffer> data;
    };

    SinglyLinkedList<ReceivedPacket, CountingSizeCalculationPolicy> m_receive_queue;

    OwnPtr<DoubleBuffer> m_receive_buffer;

    u16 m_local_port { 0 };
    u16 m_peer_port { 0 };

    u32 m_bytes_received { 0 };

    u8 m_type_of_service { IPTOS_LOWDELAY };
    u8 m_ttl { 64 };

    bool m_can_read { false };

    BufferMode m_buffer_mode { BufferMode::Packets };

    OwnPtr<KBuffer> m_scratch_buffer;

    IntrusiveListNode<IPv4Socket> m_list_node;

public:
    using List = IntrusiveList<&IPv4Socket::m_list_node>;

    static MutexProtected<IPv4Socket::List>& all_sockets();
};

}