//
// 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_WEBSOCKET_IMPL_ACCEPT_IPP
#define BEAST_WEBSOCKET_IMPL_ACCEPT_IPP

#include <beast/http/message.hpp>
#include <beast/http/header_parser.hpp>
#include <beast/http/read.hpp>
#include <beast/http/string_body.hpp>
#include <beast/http/write.hpp>
#include <beast/core/handler_helpers.hpp>
#include <beast/core/handler_ptr.hpp>
#include <beast/core/prepare_buffers.hpp>
#include <beast/core/detail/type_traits.hpp>
#include <boost/assert.hpp>
#include <memory>
#include <type_traits>

namespace beast {
namespace websocket {

//------------------------------------------------------------------------------

// Respond to an upgrade HTTP request
template<class NextLayer>
template<class Handler>
class stream<NextLayer>::response_op
{
    struct data
    {
        bool cont;
        stream<NextLayer>& ws;
        http::response_header res;
        error_code final_ec;
        int state = 0;

        template<class Fields>
        data(Handler&, stream<NextLayer>& ws_,
            http::header<true, Fields> const& req,
                bool cont_)
            : cont(cont_)
            , ws(ws_)
            , res(ws_.build_response(req))
        {
            // can't call stream::reset() here
            // otherwise accept_op will malfunction
            //
            if(res.status != 101)
                final_ec = error::handshake_failed;
        }
    };

    handler_ptr<data, Handler> d_;

public:
    response_op(response_op&&) = default;
    response_op(response_op const&) = default;

    template<class DeducedHandler, class... Args>
    response_op(DeducedHandler&& h,
            stream<NextLayer>& ws, Args&&... args)
        : d_(std::forward<DeducedHandler>(h),
            ws, std::forward<Args>(args)...)
    {
        (*this)(error_code{}, false);
    }

    void operator()(
        error_code ec, bool again = true);

    friend
    void* asio_handler_allocate(
        std::size_t size, response_op* op)
    {
        return beast_asio_helpers::
            allocate(size, op->d_.handler());
    }

    friend
    void asio_handler_deallocate(
        void* p, std::size_t size, response_op* op)
    {
        return beast_asio_helpers::
            deallocate(p, size, op->d_.handler());
    }

    friend
    bool asio_handler_is_continuation(response_op* op)
    {
        return op->d_->cont;
    }

    template<class Function>
    friend
    void asio_handler_invoke(Function&& f, response_op* op)
    {
        return beast_asio_helpers::
            invoke(f, op->d_.handler());
    }
};

template<class NextLayer>
template<class Handler>
void
stream<NextLayer>::response_op<Handler>::
operator()(error_code ec, bool again)
{
    auto& d = *d_;
    d.cont = d.cont || again;
    while(! ec && d.state != 99)
    {
        switch(d.state)
        {
        case 0:
            // send response
            d.state = 1;
            http::async_write(d.ws.next_layer(),
                d.res, std::move(*this));
            return;

        // sent response
        case 1:
            d.state = 99;
            ec = d.final_ec;
            if(! ec)
            {
                pmd_read(
                    d.ws.pmd_config_, d.res.fields);
                d.ws.open(detail::role_type::server);
            }
            break;
        }
    }
    d_.invoke(ec);
}

//------------------------------------------------------------------------------

// read and respond to an upgrade request
//
template<class NextLayer>
template<class Handler>
class stream<NextLayer>::accept_op
{
    struct data
    {
        bool cont;
        stream<NextLayer>& ws;
        http::header_parser<true, http::fields> p;
        int state = 0;

        template<class Buffers>
        data(Handler& handler, stream<NextLayer>& ws_,
                Buffers const& buffers)
            : cont(beast_asio_helpers::
                is_continuation(handler))
            , ws(ws_)
        {
            using boost::asio::buffer_copy;
            using boost::asio::buffer_size;
            ws.reset();
            ws.stream_.buffer().commit(buffer_copy(
                ws.stream_.buffer().prepare(
                    buffer_size(buffers)), buffers));
        }
    };

    handler_ptr<data, Handler> d_;

public:
    accept_op(accept_op&&) = default;
    accept_op(accept_op const&) = default;

    template<class DeducedHandler, class... Args>
    accept_op(DeducedHandler&& h,
            stream<NextLayer>& ws, Args&&... args)
        : d_(std::forward<DeducedHandler>(h),
            ws, std::forward<Args>(args)...)
    {
        (*this)(error_code{}, 0, false);
    }

    void operator()(error_code const& ec)
    {
        (*this)(ec, 0);
    }

    void operator()(error_code ec,
        std::size_t bytes_used, bool again = true);

    friend
    void* asio_handler_allocate(
        std::size_t size, accept_op* op)
    {
        return beast_asio_helpers::
            allocate(size, op->d_.handler());
    }

    friend
    void asio_handler_deallocate(
        void* p, std::size_t size, accept_op* op)
    {
        return beast_asio_helpers::
            deallocate(p, size, op->d_.handler());
    }

    friend
    bool asio_handler_is_continuation(accept_op* op)
    {
        return op->d_->cont;
    }

    template<class Function>
    friend
    void asio_handler_invoke(Function&& f, accept_op* op)
    {
        return beast_asio_helpers::
            invoke(f, op->d_.handler());
    }
};

template<class NextLayer>
template<class Handler>
void
stream<NextLayer>::accept_op<Handler>::
operator()(error_code ec,
    std::size_t bytes_used, bool again)
{
    auto& d = *d_;
    d.cont = d.cont || again;
    if(ec)
        goto upcall;
    switch(d.state)
    {
    case 0:
        // read message
        d.state = 1;
        http::async_read_some(d.ws.next_layer(),
            d.ws.stream_.buffer(), d.p,
                std::move(*this));
        return;

    case 1:
    {
        BOOST_ASSERT(d.p.got_header());
        d.ws.stream_.buffer().consume(bytes_used);
        // Arguments from our state must be
        // moved to the stack before releasing
        // the handler.
        auto& ws = d.ws;
        auto m = d.p.release();
        response_op<Handler>{
            d_.release_handler(),
                ws, std::move(m), true};
        return;
    }
    }
upcall:
    d_.invoke(ec);
}

template<class NextLayer>
template<class AcceptHandler>
typename async_completion<
    AcceptHandler, void(error_code)>::result_type
stream<NextLayer>::
async_accept(AcceptHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements requirements not met");
    return async_accept(boost::asio::null_buffers{},
        std::forward<AcceptHandler>(handler));
}

template<class NextLayer>
template<class ConstBufferSequence, class AcceptHandler>
typename async_completion<
    AcceptHandler, void(error_code)>::result_type
stream<NextLayer>::
async_accept(ConstBufferSequence const& bs, AcceptHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements requirements not met");
    static_assert(beast::is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    beast::async_completion<
        AcceptHandler, void(error_code)
            > completion{handler};
    accept_op<decltype(completion.handler)>{
        completion.handler, *this, bs};
    return completion.result.get();
}

template<class NextLayer>
template<class Fields, class AcceptHandler>
typename async_completion<
    AcceptHandler, void(error_code)>::result_type
stream<NextLayer>::
async_accept(http::header<true, Fields> const& req,
    AcceptHandler&& handler)
{
    static_assert(is_AsyncStream<next_layer_type>::value,
        "AsyncStream requirements requirements not met");
    beast::async_completion<
        AcceptHandler, void(error_code)
            > completion{handler};
    reset();
    response_op<decltype(completion.handler)>{
        completion.handler, *this, req,
            beast_asio_helpers::
                is_continuation(completion.handler)};
    return completion.result.get();
}

template<class NextLayer>
void
stream<NextLayer>::
accept()
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    accept(boost::asio::null_buffers{}, ec);
    if(ec)
        throw system_error{ec};
}

template<class NextLayer>
void
stream<NextLayer>::
accept(error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    accept(boost::asio::null_buffers{}, ec);
}

template<class NextLayer>
template<class ConstBufferSequence>
void
stream<NextLayer>::
accept(ConstBufferSequence const& buffers)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    static_assert(is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    error_code ec;
    accept(buffers, ec);
    if(ec)
        throw system_error{ec};
}

template<class NextLayer>
template<class ConstBufferSequence>
void
stream<NextLayer>::
accept(ConstBufferSequence const& buffers, error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    static_assert(beast::is_ConstBufferSequence<
        ConstBufferSequence>::value,
            "ConstBufferSequence requirements not met");
    using boost::asio::buffer_copy;
    using boost::asio::buffer_size;
    reset();
    stream_.buffer().commit(buffer_copy(
        stream_.buffer().prepare(
            buffer_size(buffers)), buffers));
    http::header_parser<true, http::fields> p;
    auto const bytes_used = http::read_some(
        next_layer(), stream_.buffer(), p, ec);
    if(ec)
        return;
    BOOST_ASSERT(p.got_header());
    stream_.buffer().consume(bytes_used);
    accept(p.get(), ec);
}

template<class NextLayer>
template<class Fields>
void
stream<NextLayer>::
accept(http::header<true, Fields> const& request)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    error_code ec;
    accept(request, ec);
    if(ec)
        throw system_error{ec};
}

template<class NextLayer>
template<class Fields>
void
stream<NextLayer>::
accept(http::header<true, Fields> const& req,
    error_code& ec)
{
    static_assert(is_SyncStream<next_layer_type>::value,
        "SyncStream requirements not met");
    reset();
    auto const res = build_response(req);
    http::write(stream_, res, ec);
    if(ec)
        return;
    if(res.status != 101)
    {
        ec = error::handshake_failed;
        // VFALCO TODO Respect keep alive setting, perform
        //             teardown if Connection: close.
        return;
    }
    pmd_read(pmd_config_, req.fields);
    open(detail::role_type::server);
}

} // websocket
} // beast

#endif