//
// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BEAST_HTTP_IMPL_MESSAGE_IPP
#define BEAST_HTTP_IMPL_MESSAGE_IPP

#include <beast/core/error.hpp>
#include <beast/core/string_view.hpp>
#include <beast/http/type_traits.hpp>
#include <beast/http/rfc7230.hpp>
#include <beast/core/detail/ci_char_traits.hpp>
#include <beast/core/detail/type_traits.hpp>
#include <boost/assert.hpp>
#include <boost/optional.hpp>
#include <boost/throw_exception.hpp>
#include <stdexcept>

namespace beast {
namespace http {

template<class Fields>
template<class>
string_view
header<true, Fields>::
get_method_string() const
{
    if(method_ != verb::unknown)
        return to_string(method_);
    return fields.method_impl();
}

template<class Fields>
template<class>
void
header<true, Fields>::
set_method(verb v)
{
    if(v == verb::unknown)
        BOOST_THROW_EXCEPTION(
            std::invalid_argument{"unknown verb"});
    method_ = v;
    fields.method_impl({});
}

template<class Fields>
template<class>
void
header<true, Fields>::
set_method(string_view s)
{
    method_ = string_to_verb(s);
    if(method_ != verb::unknown)
        fields.method_impl({});
    else
        fields.method_impl(s);
}

template<class Fields>
template<class>
string_view
header<false, Fields>::
get_reason() const
{
    auto const s = fields.reason_impl();
    if(! s.empty())
        return s;
    return obsolete_reason(result_);
}

template<class Fields>
void
swap(
    header<true, Fields>& m1,
    header<true, Fields>& m2)
{
    using std::swap;
    swap(m1.version, m2.version);
    swap(m1.fields, m2.fields);
    swap(m1.method_, m2.method_);
}

template<class Fields>
void
swap(
    header<false, Fields>& a,
    header<false, Fields>& b)
{
    using std::swap;
    swap(a.version, b.version);
    swap(a.fields, b.fields);
    swap(a.result_, b.result_);
}

template<bool isRequest, class Body, class Fields>
void
swap(
    message<isRequest, Body, Fields>& m1,
    message<isRequest, Body, Fields>& m2)
{
    using std::swap;
    swap(m1.base(), m2.base());
    swap(m1.body, m2.body);
}

template<bool isRequest, class Fields>
bool
is_keep_alive(header<isRequest, Fields> const& msg)
{
    BOOST_ASSERT(msg.version == 10 || msg.version == 11);
    if(msg.version == 11)
    {
        if(token_list{msg.fields["Connection"]}.exists("close"))
            return false;
        return true;
    }
    if(token_list{msg.fields["Connection"]}.exists("keep-alive"))
        return true;
    return false;
}

template<bool isRequest, class Fields>
bool
is_upgrade(header<isRequest, Fields> const& msg)
{
    BOOST_ASSERT(msg.version == 10 || msg.version == 11);
    if(msg.version == 10)
        return false;
    if(token_list{msg.fields["Connection"]}.exists("upgrade"))
        return true;
    return false;
}

namespace detail {

struct prepare_info
{
    boost::optional<connection> connection_value;
    boost::optional<std::uint64_t> content_length;
};

template<bool isRequest, class Body, class Fields>
inline
void
prepare_options(prepare_info& pi,
    message<isRequest, Body, Fields>& msg)
{
    beast::detail::ignore_unused(pi, msg);
}

template<bool isRequest, class Body, class Fields>
void
prepare_option(prepare_info& pi,
    message<isRequest, Body, Fields>& msg,
        connection value)
{
    beast::detail::ignore_unused(msg);
    pi.connection_value = value;
}

template<
    bool isRequest, class Body, class Fields,
    class Opt, class... Opts>
void
prepare_options(prepare_info& pi,
    message<isRequest, Body, Fields>& msg,
        Opt&& opt, Opts&&... opts)
{
    prepare_option(pi, msg, opt);
    prepare_options(pi, msg,
        std::forward<Opts>(opts)...);
}

template<bool isRequest, class Body, class Fields>
void
prepare_content_length(prepare_info& pi,
    message<isRequest, Body, Fields> const& msg,
        std::true_type)
{
    typename Body::reader w{msg};
    // VFALCO This is a design problem!
    error_code ec;
    w.init(ec);
    if(ec)
        BOOST_THROW_EXCEPTION(system_error{ec});
    pi.content_length = w.content_length();
}

template<bool isRequest, class Body, class Fields>
void
prepare_content_length(prepare_info& pi,
    message<isRequest, Body, Fields> const& msg,
        std::false_type)
{
    beast::detail::ignore_unused(msg);
    pi.content_length = boost::none;
}

} // detail

template<
    bool isRequest, class Body, class Fields,
    class... Options>
void
prepare(message<isRequest, Body, Fields>& msg,
    Options&&... options)
{
    // VFALCO TODO
    static_assert(is_body<Body>::value,
        "Body requirements not met");
    static_assert(is_body_reader<Body>::value,
        "BodyReader requirements not met");
    detail::prepare_info pi;
    detail::prepare_content_length(pi, msg,
        detail::has_content_length<typename Body::reader>{});
    detail::prepare_options(pi, msg,
        std::forward<Options>(options)...);

    if(msg.fields.exists("Connection"))
        BOOST_THROW_EXCEPTION(std::invalid_argument{
            "prepare called with Connection field set"});

    if(msg.fields.exists("Content-Length"))
        BOOST_THROW_EXCEPTION(std::invalid_argument{
            "prepare called with Content-Length field set"});

    if(token_list{msg.fields["Transfer-Encoding"]}.exists("chunked"))
        BOOST_THROW_EXCEPTION(std::invalid_argument{
            "prepare called with Transfer-Encoding: chunked set"});

    if(pi.connection_value != connection::upgrade)
    {
        if(pi.content_length)
        {
            struct set_field
            {
                void
                operator()(message<true, Body, Fields>& msg,
                    detail::prepare_info const& pi) const
                {
                    using beast::detail::ci_equal;
                    if(*pi.content_length > 0 ||
                        msg.method() == verb::post)
                    {
                        msg.fields.insert(
                            "Content-Length", *pi.content_length);
                    }
                }

                void
                operator()(message<false, Body, Fields>& msg,
                    detail::prepare_info const& pi) const
                {
                    if(to_status_class(msg.result()) != status_class::informational &&
                        msg.result() != status::no_content &&
                        msg.result() != status::not_modified)
                    {
                        msg.fields.insert(
                            "Content-Length", *pi.content_length);
                    }
                }
            };
            set_field{}(msg, pi);
        }
        else if(msg.version >= 11)
        {
            msg.fields.insert("Transfer-Encoding", "chunked");
        }
    }

    auto const content_length =
        msg.fields.exists("Content-Length");

    if(pi.connection_value)
    {
        switch(*pi.connection_value)
        {
        case connection::upgrade:
            msg.fields.insert("Connection", "upgrade");
            break;

        case connection::keep_alive:
            if(msg.version < 11)
            {
                if(content_length)
                    msg.fields.insert("Connection", "keep-alive");
            }
            break;

        case connection::close:
            if(msg.version >= 11)
                msg.fields.insert("Connection", "close");
            break;
        }
    }

    // rfc7230 6.7.
    if(msg.version < 11 && token_list{
            msg.fields["Connection"]}.exists("upgrade"))
        BOOST_THROW_EXCEPTION(std::invalid_argument{
            "invalid version for Connection: upgrade"});
}

} // http
} // beast

#endif