// Copyright (c) 2018-2022, The Monero Project

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#include "parse.h"

#include <type_traits>
#include "hex.h"
#include "net/socks.h"
#include "net/tor_address.h"
#include "net/i2p_address.h"
#include "string_tools.h"
#include "string_tools_lexical.h"

namespace net
{
    namespace
    {
        bool percent_decoding(std::string& out)
        {
            auto pos = out.find('%');
            while (pos != std::string::npos)
            {
                if (out.size() - pos < 3)
                    return false;
                if (!epee::from_hex::to_buffer(epee::as_mut_byte_span(out[pos]), {out.data() + pos + 1, 2}))
                    return false;
                out.erase(pos + 1, 2);
                pos = out.find('%', pos + 1);
            }

            return true;
        }
    } // anonymous

    scheme_and_authority::scheme_and_authority(boost::string_ref uri)
      : scheme(), authority()
    {
        static_assert(std::is_same<std::string::size_type, boost::string_ref::size_type>());

        // Stop at scheme end or path begin. URN not supported
        const auto split = uri.find_first_of(":/");
        if (split != boost::string_ref::npos && uri.substr(split).starts_with("://"))
        {
            scheme.assign(uri.data(), split);
            uri = uri.substr(split + 3);
        }

        uri = uri.substr(0, uri.find('/'));
        authority.assign(uri.data(), uri.size());
    }

    userinfo_and_hostport::userinfo_and_hostport(boost::string_ref authority)
      : userinfo(), hostport()
    {
        static_assert(std::is_same<std::string::size_type, boost::string_ref::size_type>());

        const auto split = authority.find('@');
        if (split != boost::string_ref::npos)
        {
            userinfo.assign(authority.data(), split);
            authority = authority.substr(split + 1);
        }

        hostport.assign(authority.data(), authority.size());
    }

    boost::optional<user_and_pass> user_and_pass::get(boost::string_ref userinfo)
    {
        static_assert(std::is_same<std::string::size_type, boost::string_ref::size_type>());
        boost::optional<user_and_pass> out = user_and_pass{};

        const auto split = userinfo.find(':');
        if (split != boost::string_ref::npos)
        {
            out->user.assign(userinfo.data(), split);
            userinfo = userinfo.substr(split + 1);
        }
        else
        {
            out->user.assign(userinfo.data(), userinfo.size());
            userinfo = {};
        }

        out->pass.assign(userinfo.data(), userinfo.size());
        if (percent_decoding(out->user) && percent_decoding(out->pass))
            return out;
        return boost::none;
    }

    boost::optional<uri_components> uri_components::get(const boost::string_ref uri)
    {
        scheme_and_authority result1{uri};
        userinfo_and_hostport result2{result1.authority};
        auto result3 = user_and_pass::get(result2.userinfo);
        if (!result3)
            return boost::none;

        boost::optional<uri_components> out = uri_components{};
        out->scheme = std::move(result1.scheme);
        out->userinfo = std::move(*result3);
        out->hostport = std::move(result2.hostport);
        return out;
    }

    void get_network_address_host_and_port(const std::string& address, std::string& host, std::string& port)
    {
        // If IPv6 address format with port "[addr:addr:addr:...:addr]:port"
        if (address.find(']') != std::string::npos)
        {
            host = address.substr(1, address.rfind(']') - 1);
            if ((host.size() + 2) < address.size())
            {
                port = address.substr(address.rfind(':') + 1);
            }
        }
        // Else if IPv6 address format without port e.g. "addr:addr:addr:...:addr"
        else if (std::count(address.begin(), address.end(), ':') >= 2)
        {
            host = address;
        }
        // Else IPv4, Tor, I2P address or hostname
        else
        {
            host = address.substr(0, address.rfind(':'));
            if (host.size() < address.size())
            {
                port = address.substr(host.size() + 1);
            }
        }
    }

    expect<epee::net_utils::network_address>
    get_network_address(const boost::string_ref address, const std::uint16_t default_port)
    {
        std::string host_str = "";
        std::string port_str = "";

        bool ipv6 = false;

        get_network_address_host_and_port(std::string(address), host_str, port_str);

        boost::string_ref host_str_ref(host_str);
        boost::string_ref port_str_ref(port_str);

        if (host_str.empty())
            return make_error_code(net::error::invalid_host);
        if (host_str_ref.ends_with(".onion"))
            return tor_address::make(address, default_port);
        if (host_str_ref.ends_with(".i2p"))
            return i2p_address::make(address);

        boost::system::error_code ec;
        boost::asio::ip::address_v6 v6 = boost::asio::ip::make_address_v6(host_str, ec);
        ipv6 = !ec;

        std::uint16_t port = default_port;
        if (port_str.size())
        {
            if (!epee::string_tools::get_xtype_from_string(port, port_str))
                return make_error_code(net::error::invalid_port);
        }

        if (ipv6)
        {
            return {epee::net_utils::ipv6_network_address{v6, port}};
        }
        else
        {
            std::uint32_t ip = 0;
            if (epee::string_tools::get_ip_int32_from_string(ip, host_str))
                return {epee::net_utils::ipv4_network_address{ip, port}};
        }
        return make_error_code(net::error::unsupported_address);
    }

    expect<epee::net_utils::ipv4_network_subnet>
    get_ipv4_subnet_address(const boost::string_ref address, bool allow_implicit_32)
    {
        uint32_t mask = 32;
        const boost::string_ref::size_type slash = address.find_first_of('/');
        if (slash != boost::string_ref::npos)
        {
            if (!epee::string_tools::get_xtype_from_string(mask, std::string{address.substr(slash + 1)}))
                return make_error_code(net::error::invalid_mask);
            if (mask > 32)
                return make_error_code(net::error::invalid_mask);
        }
        else if (!allow_implicit_32)
            return make_error_code(net::error::invalid_mask);

        std::uint32_t ip = 0;
        boost::string_ref S(address.data(), slash != boost::string_ref::npos ? slash : address.size());
        if (!epee::string_tools::get_ip_int32_from_string(ip, std::string(S)))
            return make_error_code(net::error::invalid_host);

        return {epee::net_utils::ipv4_network_subnet{ip, (uint8_t)mask}};
    }

    expect<boost::asio::ip::tcp::endpoint> get_tcp_endpoint(const boost::string_ref address)
    {
        uint16_t port = 0;
        expect<epee::net_utils::network_address> parsed = get_network_address(address, port);
        if (!parsed)
        {
            return parsed.error();
        }

        boost::asio::ip::tcp::endpoint result;
        switch (parsed->get_type_id())
        {
            case epee::net_utils::ipv4_network_address::get_type_id():
            {
                const auto &ipv4 = parsed->as<epee::net_utils::ipv4_network_address>();
                result = boost::asio::ip::tcp::endpoint(boost::asio::ip::address_v4(SWAP32BE(ipv4.ip())), ipv4.port());
                break;
            }
            case epee::net_utils::ipv6_network_address::get_type_id():
            {
                const auto &ipv6 = parsed->as<epee::net_utils::ipv6_network_address>();
                result = boost::asio::ip::tcp::endpoint(ipv6.ip(), ipv6.port());
                break;
            }
            default:
                return make_error_code(net::error::unsupported_address);
        }
        if (result.port() == 0)
        {
            return make_error_code(net::error::invalid_port);
        }

        return result;
    }

    namespace socks
    {
        endpoint::endpoint()
          : endpoint(boost::asio::ip::tcp::endpoint{})
        {}

        endpoint::endpoint(const boost::asio::ip::tcp::endpoint& address)
          : address(address), userinfo(), ver(version::v4a)
        {}

        expect<endpoint> endpoint::get(const boost::string_ref uri)
        {
            auto components = uri_components::get(uri);
            if (!components)
                return {net::error::invalid_encoding};
            auto tcp_endpoint = get_tcp_endpoint(components->hostport);
            if (!tcp_endpoint)
                return tcp_endpoint.error();

            endpoint out{};
            if (components->scheme.empty() || components->scheme == "socks" || components->scheme == "socks4a")
                out.ver = version::v4a;
            else if (components->scheme == "socks4")
                out.ver = version::v4;
            else if (components->scheme == "socks5")
                out.ver = version::v5;
            else
                return {net::error::invalid_scheme};

            // Only version 5 supports user/pass authentication
            if (!components->userinfo.user.empty() || !components->userinfo.pass.empty())
            {
                if (out.ver != version::v5)
                    return {net::error::unexpected_userinfo};
            }

            out.address = std::move(*tcp_endpoint);
            out.userinfo = std::move(components->userinfo);
            return out;
        }
    }
}