#ifndef BOOST_NETWORK_PROTOCOL_HTTP_SERVER_CONNECTION_HPP_20101027
#define BOOST_NETWORK_PROTOCOL_HTTP_SERVER_CONNECTION_HPP_20101027

// Copyright 2010 Dean Michael Berris.
// 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)

#include <boost/throw_exception.hpp>
#include <boost/scope_exit.hpp>
#include <boost/network/protocol/http/algorithms/linearize.hpp>
#include <boost/network/utils/thread_pool.hpp>
#include <boost/range/adaptor/sliced.hpp>
#include <boost/range/algorithm/transform.hpp>
#include <boost/range/algorithm/copy.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/streambuf.hpp>
#include <boost/asio/strand.hpp>
#include <boost/asio/buffer.hpp>
#include <boost/make_shared.hpp>
#include <boost/network/protocol/http/server/request_parser.hpp>
#include <boost/range/iterator_range.hpp>
#include <boost/optional.hpp>
#include <boost/utility/typed_in_place_factory.hpp>
#include <boost/thread/locks.hpp>
#include <boost/thread/recursive_mutex.hpp>
#include <boost/utility/enable_if.hpp>
#include <list>
#include <vector>
#include <iterator>
#ifdef BOOST_NETWORK_NO_LIB
#include <boost/network/protocol/http/server/impl/parsers.ipp>
#endif

#ifndef BOOST_NETWORK_HTTP_SERVER_CONNECTION_HEADER_BUFFER_MAX_SIZE
/** Here we define a page's worth of header connection buffer data.
 *  This can be tuned to reduce the memory cost of connections, but this 
 *  default size is set to be friendly to typical service applications.
 *  This is the maximum size though and Boost.Asio's internal representation
 *  of a streambuf would make appropriate decisions on how big a buffer
 *  is to begin with.
 *
 *  This kinda assumes that a page is by default 4096. Since we're using
 *  the default allocator with the static buffers, it's not guaranteed that
 *  the static buffers will be page-aligned when they are allocated.
 */
#define BOOST_NETWORK_HTTP_SERVER_CONNECTION_HEADER_BUFFER_MAX_SIZE 4096
#endif /* BOOST_NETWORK_HTTP_SERVER_CONNECTION_HEADER_BUFFER_MAX_SIZE */

namespace boost { namespace network { namespace http {

#ifndef BOOST_NETWORK_NO_LIB
    extern void parse_version(std::string const & partial_parsed, fusion::tuple<uint8_t,uint8_t> & version_pair);
    extern void parse_headers(std::string const & input, std::vector<request_header_narrow> & container);
#endif

    template <class Tag, class Handler>
    struct async_connection : boost::enable_shared_from_this<async_connection<Tag,Handler> > {

        enum status_t {
            ok = 200
            , created = 201
            , accepted = 202
            , no_content = 204
            , partial_content = 206
            , multiple_choices = 300
            , moved_permanently = 301
            , moved_temporarily = 302
            , not_modified = 304
            , bad_request = 400
            , unauthorized = 401
            , forbidden = 403
            , not_found = 404
            , not_supported = 405
            , not_acceptable = 406
            , request_timeout = 408
            , precondition_failed = 412
            , unsatisfiable_range = 416
            , internal_server_error = 500
            , not_implemented = 501
            , bad_gateway = 502
            , service_unavailable = 503
            , space_unavailable = 507
        };

        typedef typename string<Tag>::type string_type;
        typedef basic_request<Tag> request;
        typedef shared_ptr<async_connection> connection_ptr;

    private:
        static char const * status_message(status_t status) {
            static char const 
                ok_[]                       = "OK"
                , created_[]                = "Created"
                , accepted_[]               = "Accepted"
                , no_content_[]             = "No Content"
                , multiple_choices_[]       = "Multiple Choices"
                , moved_permanently_[]      = "Moved Permanently"
                , moved_temporarily_[]      = "Moved Temporarily"
                , not_modified_[]           = "Not Modified"
                , bad_request_[]            = "Bad Request"
                , unauthorized_[]           = "Unauthorized"
                , forbidden_[]              = "Fobidden"
                , not_found_[]              = "Not Found"
                , not_supported_[]          = "Not Supported"
                , not_acceptable_[]         = "Not Acceptable"
                , internal_server_error_[]  = "Internal Server Error"
                , not_implemented_[]        = "Not Implemented"
                , bad_gateway_[]            = "Bad Gateway"
                , service_unavailable_[]    = "Service Unavailable"
                , unknown_[]                = "Unknown"
                , partial_content_[]        = "Partial Content"
                , request_timeout_[]        = "Request Timeout"
                , precondition_failed_[]    = "Precondition Failed"
                , unsatisfiable_range_[]    = "Requested Range Not Satisfiable"
                , space_unavailable_[]      = "Insufficient Space to Store Resource"
                ;
            switch(status) {
                case ok:                    return ok_;
                case created:               return created_;
                case accepted:              return accepted_;
                case no_content:            return no_content_;
                case multiple_choices:      return multiple_choices_;
                case moved_permanently:     return moved_permanently_;
                case moved_temporarily:     return moved_temporarily_;
                case not_modified:          return not_modified_;
                case bad_request:           return bad_request_;
                case unauthorized:          return unauthorized_;
                case forbidden:             return forbidden_;
                case not_found:             return not_found_;
                case not_supported:         return not_supported_;
                case not_acceptable:        return not_acceptable_;
                case internal_server_error: return internal_server_error_;
                case not_implemented:       return not_implemented_;
                case bad_gateway:           return bad_gateway_;
                case service_unavailable:   return service_unavailable_;
                case partial_content:       return partial_content_;
                case request_timeout:       return request_timeout_;
                case precondition_failed:   return precondition_failed_;
                case unsatisfiable_range:   return unsatisfiable_range_;
                case space_unavailable:     return space_unavailable_;
                default:                    return unknown_;
            }
        }

    public:

        async_connection(
            asio::io_service & io_service
            , Handler & handler
            , utils::thread_pool & thread_pool
            )
        : socket_(io_service)
        , strand(io_service)
        , handler(handler)
        , thread_pool_(thread_pool)
        , headers_already_sent(false)
        , headers_in_progress(false)
        , headers_buffer(BOOST_NETWORK_HTTP_SERVER_CONNECTION_HEADER_BUFFER_MAX_SIZE)
        {
            new_start = read_buffer_.begin();
        }

        ~async_connection() throw () {
            boost::system::error_code ignored;
            socket_.shutdown(asio::ip::tcp::socket::shutdown_receive, ignored);
        }

        /** Function: template <class Range> set_headers(Range headers)
         *  Precondition: headers have not been sent yet
         *  Postcondition: headers have been linearized to a buffer, 
         *                 and assumed to have been sent already when the function exits
         *  Throws: std::logic_error in case the headers have already been sent. 
         *
         *  A call to set_headers takes a Range where each element models the
         *  Header concept. This Range will be linearized onto a buffer, which is
         *  then sent as soon as the first call to `write` or `flush` commences.
         */
        template <class Range>
        void set_headers(Range headers) {
            lock_guard lock(headers_mutex);
            if (headers_in_progress || headers_already_sent) 
                boost::throw_exception(std::logic_error("Headers have already been sent."));

            if (error_encountered)
                boost::throw_exception(boost::system::system_error(*error_encountered));

            typedef constants<Tag> consts;
            {
                std::ostream stream(&headers_buffer);
                stream
                    << consts::http_slash() << 1<< consts::dot() << 1 << consts::space()
                    << status << consts::space() << status_message(status)
                    << consts::crlf();
                if (!boost::empty(headers)) {
                    typedef typename Range::const_iterator iterator;
                    typedef typename string<Tag>::type string_type;
                    boost::transform(headers, 
                        std::ostream_iterator<string_type>(stream),
                        linearize_header<Tag>());
                } else {
                    stream << consts::crlf();
                }
                stream << consts::crlf();
            }

            write_headers_only(
                boost::bind(
                    &async_connection<Tag,Handler>::do_nothing
                    , async_connection<Tag,Handler>::shared_from_this()
                ));
        }

        void set_status(status_t new_status) {
            lock_guard lock(headers_mutex);
            if (headers_already_sent) boost::throw_exception(std::logic_error("Headers have already been sent, cannot reset status."));
            if (error_encountered) boost::throw_exception(boost::system::system_error(*error_encountered));

            status = new_status;
        }

        template <class Range>
        void write(Range const & range) {
            lock_guard lock(headers_mutex);
            if (error_encountered) boost::throw_exception(boost::system::system_error(*error_encountered));

            boost::function<void(boost::system::error_code)> f = 
                boost::bind(
                    &async_connection<Tag,Handler>::default_error
                    , async_connection<Tag,Handler>::shared_from_this()
                    , _1);

            write_impl(
                boost::make_iterator_range(range)
                , f
                );
        }

        template <class Range, class Callback>
        typename disable_if<is_base_of<asio::const_buffer, typename Range::value_type>, void>::type
        write(Range const & range, Callback const & callback) {
            lock_guard lock(headers_mutex);
            if (error_encountered) boost::throw_exception(boost::system::system_error(*error_encountered));
            write_impl(boost::make_iterator_range(range), callback);
        }

        template <class ConstBufferSeq, class Callback>
        typename enable_if<is_base_of<asio::const_buffer, typename ConstBufferSeq::value_type>, void>::type
        write(ConstBufferSeq const & seq, Callback const & callback)
        {
            write_vec_impl(seq, callback, shared_array_list(), shared_buffers());
        }

    private:
        typedef boost::array<char, BOOST_NETWORK_HTTP_SERVER_CONNECTION_BUFFER_SIZE> buffer_type;

    public:
        typedef iterator_range<buffer_type::const_iterator> input_range;
        typedef boost::function<void(input_range, boost::system::error_code, std::size_t, connection_ptr)> read_callback_function;

        void read(read_callback_function callback) {
            if (error_encountered) boost::throw_exception(boost::system::system_error(*error_encountered));
            if (new_start != read_buffer_.begin())
            {
                input_range input = boost::make_iterator_range(new_start, read_buffer_.end());
                thread_pool().post(
                    boost::bind(
                        callback
                        , input
                        , boost::system::error_code()
                        , std::distance(new_start, data_end)
                        , async_connection<Tag,Handler>::shared_from_this())
                );
                new_start = read_buffer_.begin();
                return;
            }

            socket().async_read_some(
                asio::buffer(read_buffer_)
                , strand.wrap(
                    boost::bind(
                        &async_connection<Tag,Handler>::wrap_read_handler
                        , async_connection<Tag,Handler>::shared_from_this()
                        , callback
                        , asio::placeholders::error, asio::placeholders::bytes_transferred)));
        }

        asio::ip::tcp::socket & socket()    { return socket_;               }
        utils::thread_pool & thread_pool()  { return thread_pool_;          }
        bool has_error()                    { return (!!error_encountered); }
        optional<boost::system::system_error> error()
                                            { return error_encountered;     }

    private:

        void wrap_read_handler(read_callback_function callback, boost::system::error_code const & ec, std::size_t bytes_transferred) {
            if (ec) error_encountered = in_place<boost::system::system_error>(ec);
            buffer_type::const_iterator data_start = read_buffer_.begin()
                                       ,data_end   = read_buffer_.begin();
            std::advance(data_end, bytes_transferred);
            thread_pool().post(
                boost::bind(
                    callback
                    , boost::make_iterator_range(data_start, data_end)
                    , ec
                    , bytes_transferred
                    , async_connection<Tag,Handler>::shared_from_this()));
        }

        void default_error(boost::system::error_code const & ec) {
            error_encountered = in_place<boost::system::system_error>(ec);
        }

        typedef boost::array<char, BOOST_NETWORK_HTTP_SERVER_CONNECTION_BUFFER_SIZE> array;
        typedef std::list<shared_ptr<array> > array_list;
        typedef boost::shared_ptr<array_list> shared_array_list;
        typedef boost::shared_ptr<std::vector<asio::const_buffer> > shared_buffers;
        typedef request_parser<Tag> request_parser_type;
        typedef boost::lock_guard<boost::recursive_mutex> lock_guard;
        typedef std::list<boost::function<void()> > pending_actions_list;

        asio::ip::tcp::socket socket_;
        asio::io_service::strand strand;
        Handler & handler;
        utils::thread_pool & thread_pool_;
        volatile bool headers_already_sent, headers_in_progress;
        asio::streambuf headers_buffer;

        boost::recursive_mutex headers_mutex;
        buffer_type read_buffer_;
        status_t status;
        request_parser_type parser;
        request request_;
        buffer_type::iterator new_start, data_end;
        string_type partial_parsed;
        optional<boost::system::system_error> error_encountered;
        pending_actions_list pending_actions;

        template <class, class> friend struct async_server_base;

        enum state_t {
            method, uri, version, headers
        };

        void start() {
            typename ostringstream<Tag>::type ip_stream;
            ip_stream << socket_.remote_endpoint().address().to_v4().to_string() << ':'
                << socket_.remote_endpoint().port();
            request_.source = ip_stream.str();
            read_more(method);
        }

        void read_more(state_t state) {
            socket_.async_read_some(
                asio::buffer(read_buffer_)
                , strand.wrap(
                    boost::bind(
                        &async_connection<Tag,Handler>::handle_read_data,
                        async_connection<Tag,Handler>::shared_from_this(),
                        state,
                        boost::asio::placeholders::error,
                        boost::asio::placeholders::bytes_transferred
                        )
                    )
                );
        }

        void handle_read_data(state_t state, boost::system::error_code const & ec, std::size_t bytes_transferred) {
            if (!ec) {
                logic::tribool parsed_ok;
                iterator_range<buffer_type::iterator> result_range, input_range;
                data_end = read_buffer_.begin();
                std::advance(data_end, bytes_transferred);
                switch (state) {
                    case method:
                        input_range = boost::make_iterator_range(
                            new_start, data_end);
                        fusion::tie(parsed_ok, result_range) = parser.parse_until(
                            request_parser_type::method_done, input_range);
                        if (!parsed_ok) { 
                            client_error();
                            break;
                        } else if (parsed_ok == true) {
                            swap(partial_parsed, request_.method);
                            request_.method.append(
                                boost::begin(result_range),
                                boost::end(result_range));
                            trim(request_.method);
                            new_start = boost::end(result_range);
                        } else {
                            partial_parsed.append(
                                boost::begin(result_range),
                                boost::end(result_range));
                            new_start = read_buffer_.begin();
                            read_more(method);
                            break;
                        }
                    case uri:
                        input_range = boost::make_iterator_range(
                            new_start, data_end);
                        fusion::tie(parsed_ok, result_range) = parser.parse_until(
                            request_parser_type::uri_done,
                            input_range);
                        if (!parsed_ok) {
                            client_error();
                            break;
                        } else if (parsed_ok == true) {
                            swap(partial_parsed, request_.destination);
                            request_.destination.append(
                                boost::begin(result_range),
                                boost::end(result_range));
                            trim(request_.destination);
                            new_start = boost::end(result_range);
                        } else {
                            partial_parsed.append(
                                boost::begin(result_range),
                                boost::end(result_range));
                            new_start = read_buffer_.begin();
                            read_more(uri);
                            break;
                        }
                    case version:
                        input_range = boost::make_iterator_range(
                            new_start, data_end);
                        fusion::tie(parsed_ok, result_range) = parser.parse_until(
                            request_parser_type::version_done,
                            input_range);
                        if (!parsed_ok) {
                            client_error();
                            break;
                        } else if (parsed_ok == true) {
                            fusion::tuple<uint8_t, uint8_t> version_pair;
                            partial_parsed.append(boost::begin(result_range), boost::end(result_range));
                            parse_version(partial_parsed, version_pair);
                            request_.http_version_major = fusion::get<0>(version_pair);
                            request_.http_version_minor = fusion::get<1>(version_pair);
                            new_start = boost::end(result_range);
                            partial_parsed.clear();
                        } else {
                            partial_parsed.append(
                                boost::begin(result_range),
                                boost::end(result_range));
                            new_start = read_buffer_.begin();
                            read_more(version);
                            break;
                        }
                    case headers:
                        input_range = boost::make_iterator_range(
                            new_start, data_end);
                        fusion::tie(parsed_ok, result_range) = parser.parse_until(
                            request_parser_type::headers_done,
                            input_range);
                        if (!parsed_ok) {
                            client_error();
                            break;
                        } else if (parsed_ok == true) {
                            partial_parsed.append(
                                boost::begin(result_range),
                                boost::end(result_range));
                            parse_headers(partial_parsed, request_.headers);
                            new_start = boost::end(result_range);
                            thread_pool().post(
                                boost::bind(
                                    &Handler::operator(),
                                    &handler,
                                    cref(request_),
                                    async_connection<Tag,Handler>::shared_from_this()));
                            return;
                        } else {
                            partial_parsed.append(
                                boost::begin(result_range),
                                boost::end(result_range));
                            new_start = read_buffer_.begin();
                            read_more(headers);
                            break;
                        }
                    default:
                        BOOST_ASSERT(false && "This is a bug, report to the cpp-netlib devel mailing list!");
                        std::abort();
                }
            } else {
                error_encountered = in_place<boost::system::system_error>(ec);
            }
        }

        void client_error() {
            static char const * bad_request = 
                "HTTP/1.0 400 Bad Request\r\nConnection: close\r\nContent-Type: text/plain\r\nContent-Length: 12\r\n\r\nBad Request.";

            asio::async_write(
                socket()
                , asio::buffer(bad_request, strlen(bad_request))
                , strand.wrap(
                    boost::bind(
                        &async_connection<Tag,Handler>::client_error_sent
                        , async_connection<Tag,Handler>::shared_from_this()
                        , asio::placeholders::error
                        , asio::placeholders::bytes_transferred)));
        }

        void client_error_sent(boost::system::error_code const & ec, std::size_t bytes_transferred) {
            if (!ec) {
                boost::system::error_code ignored;
                socket().shutdown(asio::ip::tcp::socket::shutdown_both, ignored);
                socket().close(ignored);
            } else {
                error_encountered = in_place<boost::system::system_error>(ec);
            }
        }

        void do_nothing() {}

        void write_headers_only(boost::function<void()> callback) {
            if (headers_in_progress) return;
            headers_in_progress = true;
            asio::async_write(
                socket()
                , headers_buffer
                , strand.wrap(
                    boost::bind(
                        &async_connection<Tag,Handler>::handle_write_headers
                        , async_connection<Tag,Handler>::shared_from_this()
                        , callback
                        , asio::placeholders::error
                        , asio::placeholders::bytes_transferred)));
        }

        void handle_write_headers(boost::function<void()> callback, boost::system::error_code const & ec, std::size_t bytes_transferred) {
            lock_guard lock(headers_mutex);
            if (!ec) {
                headers_buffer.consume(headers_buffer.size());
                headers_already_sent = true;
                thread_pool().post(callback);
                pending_actions_list::iterator start = pending_actions.begin()
                    , end = pending_actions.end();
                while (start != end) {
                    thread_pool().post(*start++);
                }
                pending_actions_list().swap(pending_actions);
            } else {
                error_encountered = in_place<boost::system::system_error>(ec);
            }
        }

        void handle_write(
            boost::function<void(boost::system::error_code const &)> callback
            , shared_array_list temporaries
            , shared_buffers buffers
            , boost::system::error_code const & ec
            , std::size_t bytes_transferred
        ) {
            // we want to forget the temporaries and buffers
            thread_pool().post(boost::bind(callback, ec));
        }

        template <class Range>
        void write_impl(Range range, boost::function<void(boost::system::error_code)> callback) {
            // linearize the whole range into a vector
            // of fixed-sized buffers, then schedule an asynchronous
            // write of these buffers -- make sure they are live
            // by making these linearized buffers shared and made
            // part of the completion handler.
            //
            // once the range has been linearized and sent, schedule
            // a wrapper to be called in the io_service's thread, that
            // will re-schedule the given callback into the thread pool
            // referred to here so that the io_service's thread can concentrate
            // on doing I/O.
            //

            static std::size_t const connection_buffer_size =
                BOOST_NETWORK_HTTP_SERVER_CONNECTION_BUFFER_SIZE;
            shared_array_list temporaries = 
                boost::make_shared<array_list>();
            shared_buffers buffers = 
                boost::make_shared<std::vector<asio::const_buffer> >(0);

            std::size_t range_size = boost::distance(range);
            buffers->reserve(
                (range_size / connection_buffer_size)
                + ((range_size % connection_buffer_size)?1:0)
                );
            std::size_t slice_size = 
                std::min(range_size,connection_buffer_size);
            typename boost::range_iterator<Range>::type
                start = boost::begin(range)
                , end  = boost::end(range);
            while (slice_size != 0) {
                using boost::adaptors::sliced;
                shared_ptr<array> new_array = make_shared<array>();
                boost::copy(
                    range | sliced(0,slice_size)
                    , new_array->begin()
                    );
                temporaries->push_back(new_array);
                buffers->push_back(asio::buffer(new_array->data(), slice_size));
                std::advance(start, slice_size);
                range = boost::make_iterator_range(start, end);
                range_size = boost::distance(range);
                slice_size = std::min(range_size, connection_buffer_size);
            }

            if (!buffers->empty()) {
                write_vec_impl(*buffers, callback, temporaries, buffers);
            }
        }

        template <class ConstBufferSeq, class Callback>
        void write_vec_impl(ConstBufferSeq const & seq
                           ,Callback const & callback
                           ,shared_array_list temporaries
                           ,shared_buffers buffers)
        {
            lock_guard lock(headers_mutex);
            if (error_encountered)
                boost::throw_exception(boost::system::system_error(*error_encountered));

            boost::function<void(boost::system::error_code)> callback_function =
                    callback;

            boost::function<void()> continuation = boost::bind(
                &async_connection<Tag,Handler>::template write_vec_impl<ConstBufferSeq, boost::function<void(boost::system::error_code)> >
                ,async_connection<Tag,Handler>::shared_from_this()
                ,seq, callback_function, temporaries, buffers
            );

            if (!headers_already_sent && !headers_in_progress) {
                write_headers_only(continuation);
                return;
            } else if (headers_in_progress && !headers_already_sent) {
                pending_actions.push_back(continuation);
                return;
            }

            asio::async_write(
                 socket_
                ,seq
                ,boost::bind(
                    &async_connection<Tag,Handler>::handle_write
                    ,async_connection<Tag,Handler>::shared_from_this()
                    ,callback_function
                    ,temporaries
                    ,buffers
                    ,asio::placeholders::error
                    ,asio::placeholders::bytes_transferred)
            );
        }
    };
    
} /* http */
    
} /* network */
    
} /* boost */

#endif /* BOOST_NETWORK_PROTOCOL_HTTP_SERVER_CONNECTION_HPP_20101027 */

