/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include <AK/Endian.h>
#include <AK/LogStream.h>
#include <AK/Optional.h>
#include <AK/String.h>
#include <AK/StringView.h>
#include <AK/Vector.h>

namespace AK {

class [[gnu::packed]] IPv4Address {
    enum class SubnetClass : int {
        A = 0,
        B,
        C,
        D
    };

public:
    using in_addr_t = u32;

    constexpr IPv4Address() = default;

    constexpr IPv4Address(u32 a, u32 b, u32 c, u32 d)
    {
        m_data = (d << 24) | (c << 16) | (b << 8) | a;
    }

    constexpr IPv4Address(const u8 data[4])
    {
        m_data = (u32(data[3]) << 24) | (u32(data[2]) << 16) | (u32(data[1]) << 8) | u32(data[0]);
    }

    constexpr IPv4Address(NetworkOrdered<u32> address)
        : m_data(address)
    {
    }

    constexpr u8 operator[](int i) const
    {
        ASSERT(i >= 0 && i < 4);
        return octet(SubnetClass(i));
    }

    String to_string() const
    {
        return String::formatted("{}.{}.{}.{}",
            octet(SubnetClass::A),
            octet(SubnetClass::B),
            octet(SubnetClass::C),
            octet(SubnetClass::D));
    }

    static Optional<IPv4Address> from_string(const StringView& string)
    {
        if (string.is_null())
            return {};

        const auto parts = string.split_view('.');

        u32 a {};
        u32 b {};
        u32 c {};
        u32 d {};

        if (parts.size() == 1) {
            d = parts[0].to_uint().value_or(256);
        } else if (parts.size() == 2) {
            a = parts[0].to_uint().value_or(256);
            d = parts[1].to_uint().value_or(256);
        } else if (parts.size() == 3) {
            a = parts[0].to_uint().value_or(256);
            b = parts[1].to_uint().value_or(256);
            d = parts[2].to_uint().value_or(256);
        } else if (parts.size() == 4) {
            a = parts[0].to_uint().value_or(256);
            b = parts[1].to_uint().value_or(256);
            c = parts[2].to_uint().value_or(256);
            d = parts[3].to_uint().value_or(256);
        } else {
            return {};
        }

        if (a > 255 || b > 255 || c > 255 || d > 255)
            return {};
        return IPv4Address(a, b, c, d);
    }

    constexpr in_addr_t to_in_addr_t() const { return m_data; }
    constexpr u32 to_u32() const { return m_data; }

    constexpr bool operator==(const IPv4Address& other) const = default;
    constexpr bool operator!=(const IPv4Address& other) const = default;

    constexpr bool is_zero() const
    {
        return m_data == 0u;
    }

private:
    constexpr u32 octet(const SubnetClass subnet) const
    {
        NetworkOrdered<u32> address(m_data);
        constexpr auto bits_per_byte = 8;
        const auto bits_to_shift = bits_per_byte * int(subnet);
        return (m_data >> bits_to_shift) & 0x0000'00FF;
    }

    u32 m_data {};
};

static_assert(sizeof(IPv4Address) == 4);

template<>
struct Traits<IPv4Address> : public GenericTraits<IPv4Address> {
    static constexpr unsigned hash(const IPv4Address& address) { return int_hash(address.to_u32()); }
};

inline const LogStream& operator<<(const LogStream& stream, const IPv4Address& value)
{
    return stream << value.to_string();
}

template<>
struct Formatter<IPv4Address> : Formatter<String> {
    void format(FormatBuilder& builder, IPv4Address value)
    {
        return Formatter<String>::format(builder, value.to_string());
    }
};

}

using AK::IPv4Address;