#ifndef CLIENT_HTTP_HPP
#define	CLIENT_HTTP_HPP

#include <boost/asio.hpp>
#include <boost/utility/string_ref.hpp>
#include <boost/algorithm/string/predicate.hpp>
#include <boost/functional/hash.hpp>

#include <unordered_map>
#include <map>
#include <random>
#include <mutex>
#include <type_traits>

class case_insensitive_equals {
public:
	bool operator()( const std::string &key1, const std::string &key2 ) const {
		return boost::algorithm::iequals( key1, key2 );
	}
};
class case_insensitive_hash {
public:
	size_t operator()( const std::string &key ) const {
		std::size_t seed = 0;
		for( auto &c : key )
			boost::hash_combine( seed, std::tolower( c ) );
		return seed;
	}
};

namespace SimpleWeb {
	template <class socket_type>
	class Client;

	template <class socket_type>
	class ClientBase {
	public:
		virtual ~ClientBase() {}

		class Response {
			friend class ClientBase<socket_type>;
			friend class Client<socket_type>;
		public:
			std::string http_version, status_code;

			std::istream content;

			std::unordered_multimap<std::string, std::string, case_insensitive_hash, case_insensitive_equals> header;

		private:
			boost::asio::streambuf content_buffer;

			Response() : content( &content_buffer ) {}
		};

		class Config {
			friend class ClientBase<socket_type>;
		private:
			Config() {}
		public:
			/// Set timeout on requests in seconds. Default value: 0 (no timeout). 
			size_t timeout = 0;
			/// Set proxy server (server:port)
			std::string proxy_server;
		};

		/// Set before calling request
		Config config;

		std::shared_ptr<Response> request( const std::string& request_type, const std::string& path = "/", boost::string_ref content = "",
			const std::map<std::string, std::string>& header = std::map<std::string, std::string>() ) {
			auto corrected_path = path;
			if( corrected_path == "" )
				corrected_path = "/";
			if( !config.proxy_server.empty() && std::is_same<socket_type, boost::asio::ip::tcp::socket>::value )
				corrected_path = "http://" + host + ':' + std::to_string( port ) + corrected_path;

			boost::asio::streambuf write_buffer;
			std::ostream write_stream( &write_buffer );
			write_stream << request_type << " " << corrected_path << " HTTP/1.1\r\n";
			write_stream << "Host: " << host << "\r\n";
			for( auto& h : header ) {
				write_stream << h.first << ": " << h.second << "\r\n";
			}
			if( content.size()>0 )
				write_stream << "Content-Length: " << content.size() << "\r\n";
			write_stream << "\r\n";

			connect();

			auto timer = get_timeout_timer();
			boost::asio::async_write( *socket, write_buffer,
				[this, &content, timer]( const boost::system::error_code &ec, size_t /*bytes_transferred*/ ) {
				if( timer )
					timer->cancel();
				if( !ec ) {
					if( !content.empty() ) {
						auto timer = get_timeout_timer();
						boost::asio::async_write( *socket, boost::asio::buffer( content.data(), content.size() ),
							[this, timer]( const boost::system::error_code &ec, size_t /*bytes_transferred*/ ) {
							if( timer )
								timer->cancel();
							if( ec ) {
								std::lock_guard<std::mutex> lock( socket_mutex );
								this->socket = nullptr;
								throw boost::system::system_error( ec );
							}
						} );
					}
				}
				else {
					std::lock_guard<std::mutex> lock( socket_mutex );
					socket = nullptr;
					throw boost::system::system_error( ec );
				}
			} );
			io_service.reset();
			io_service.run();

			return request_read();
		}

		std::shared_ptr<Response> request( const std::string& request_type, const std::string& path, std::iostream& content,
			const std::map<std::string, std::string>& header = std::map<std::string, std::string>() ) {
			auto corrected_path = path;
			if( corrected_path == "" )
				corrected_path = "/";
			if( !config.proxy_server.empty() && std::is_same<socket_type, boost::asio::ip::tcp::socket>::value )
				corrected_path = "http://" + host + ':' + std::to_string( port ) + corrected_path;

			content.seekp( 0, std::ios::end );
			auto content_length = content.tellp();
			content.seekp( 0, std::ios::beg );

			boost::asio::streambuf write_buffer;
			std::ostream write_stream( &write_buffer );
			write_stream << request_type << " " << corrected_path << " HTTP/1.1\r\n";
			write_stream << "Host: " << host << "\r\n";
			for( auto& h : header ) {
				write_stream << h.first << ": " << h.second << "\r\n";
			}
			if( content_length>0 )
				write_stream << "Content-Length: " << content_length << "\r\n";
			write_stream << "\r\n";
			if( content_length>0 )
				write_stream << content.rdbuf();

			connect();

			auto timer = get_timeout_timer();
			boost::asio::async_write( *socket, write_buffer,
				[this, timer]( const boost::system::error_code &ec, size_t /*bytes_transferred*/ ) {
				if( timer )
					timer->cancel();
				if( ec ) {
					std::lock_guard<std::mutex> lock( socket_mutex );
					socket = nullptr;
					throw boost::system::system_error( ec );
				}
			} );
			io_service.reset();
			io_service.run();

			return request_read();
		}

		void close() {
			std::lock_guard<std::mutex> lock( socket_mutex );
			if( socket ) {
				boost::system::error_code ec;
				socket->lowest_layer().shutdown( boost::asio::ip::tcp::socket::shutdown_both, ec );
				socket->lowest_layer().close();
			}
		}

	protected:
		boost::asio::io_service io_service;
		boost::asio::ip::tcp::resolver resolver;

		std::unique_ptr<socket_type> socket;
		std::mutex socket_mutex;

		std::string host;
		unsigned short port;

		ClientBase( const std::string& host_port, unsigned short default_port ) : resolver( io_service ) {
			auto parsed_host_port = parse_host_port( host_port, default_port );
			host = parsed_host_port.first;
			port = parsed_host_port.second;
		}

		std::pair<std::string, unsigned short> parse_host_port( const std::string &host_port, unsigned short default_port ) {
			std::pair<std::string, unsigned short> parsed_host_port;
			size_t host_end = host_port.find( ':' );
			if( host_end == std::string::npos ) {
				parsed_host_port.first = host_port;
				parsed_host_port.second = default_port;
			}
			else {
				parsed_host_port.first = host_port.substr( 0, host_end );
				parsed_host_port.second = static_cast<unsigned short>( stoul( host_port.substr( host_end + 1 ) ) );
			}
			return parsed_host_port;
		}

		virtual void connect() = 0;

		std::shared_ptr<boost::asio::deadline_timer> get_timeout_timer() {
			if( config.timeout == 0 )
				return nullptr;

			auto timer = std::make_shared<boost::asio::deadline_timer>( io_service );
			timer->expires_from_now( boost::posix_time::seconds( config.timeout ) );
			timer->async_wait( [this]( const boost::system::error_code& ec ) {
				if( !ec ) {
					close();
				}
			} );
			return timer;
		}

		void parse_response_header( const std::shared_ptr<Response> &response ) const {
			std::string line;
			getline( response->content, line );
			size_t version_end = line.find( ' ' );
			if( version_end != std::string::npos ) {
				if( 5<line.size() )
					response->http_version = line.substr( 5, version_end - 5 );
				if( ( version_end + 1 )<line.size() )
					response->status_code = line.substr( version_end + 1, line.size() - ( version_end + 1 ) - 1 );

				getline( response->content, line );
				size_t param_end;
				while( ( param_end = line.find( ':' ) ) != std::string::npos ) {
					size_t value_start = param_end + 1;
					if( ( value_start )<line.size() ) {
						if( line[value_start] == ' ' )
							value_start++;
						if( value_start<line.size() )
							response->header.insert( std::make_pair( line.substr( 0, param_end ), line.substr( value_start, line.size() - value_start - 1 ) ) );
					}

					getline( response->content, line );
				}
			}
		}

		std::shared_ptr<Response> request_read() {
			std::shared_ptr<Response> response( new Response() );

			boost::asio::streambuf chunked_streambuf;

			auto timer = get_timeout_timer();
			boost::asio::async_read_until( *socket, response->content_buffer, "\r\n\r\n",
				[this, &response, &chunked_streambuf, timer]( const boost::system::error_code& ec, size_t bytes_transferred ) {
				if( timer )
					timer->cancel();
				if( !ec ) {
					size_t num_additional_bytes = response->content_buffer.size() - bytes_transferred;

					parse_response_header( response );

					auto header_it = response->header.find( "Content-Length" );
					if( header_it != response->header.end() ) {
						auto content_length = stoull( header_it->second );
						if( content_length>num_additional_bytes ) {
							auto timer = get_timeout_timer();
							boost::asio::async_read( *socket, response->content_buffer,
								boost::asio::transfer_exactly( static_cast< size_t >( content_length - num_additional_bytes ) ),
								[this, timer]( const boost::system::error_code& ec, size_t /*bytes_transferred*/ ) {
								if( timer )
									timer->cancel();
								if( ec ) {
									std::lock_guard<std::mutex> lock( socket_mutex );
									this->socket = nullptr;
									throw boost::system::system_error( ec );
								}
							} );
						}
					}
					else if( ( header_it = response->header.find( "Transfer-Encoding" ) ) != response->header.end() && header_it->second == "chunked" ) {
						request_read_chunked( response, chunked_streambuf );
					}
				}
				else {
					std::lock_guard<std::mutex> lock( socket_mutex );
					socket = nullptr;
					throw boost::system::system_error( ec );
				}
			} );
			io_service.reset();
			io_service.run();

			return response;
		}

		void request_read_chunked( const std::shared_ptr<Response> &response, boost::asio::streambuf &streambuf ) {
			auto timer = get_timeout_timer();
			boost::asio::async_read_until( *socket, response->content_buffer, "\r\n",
				[this, &response, &streambuf, timer]( const boost::system::error_code& ec, size_t bytes_transferred ) {
				if( timer )
					timer->cancel();
				if( !ec ) {
					std::string line;
					getline( response->content, line );
					bytes_transferred -= line.size() + 1;
					line.pop_back();
					std::streamsize length = stol( line, 0, 16 );

					auto num_additional_bytes = response->content_buffer.size() - bytes_transferred;

					auto post_process = [this, &response, &streambuf, length] {
						std::ostream stream( &streambuf );
						if( length>0 ) {
							std::vector<char> buffer( static_cast<size_t>( length ) );
							response->content.read( &buffer[0], length );
							stream.write( &buffer[0], length );
						}

						//Remove "\r\n"
						response->content.get();
						response->content.get();

						if( length>0 )
							request_read_chunked( response, streambuf );
						else {
							std::ostream response_stream( &response->content_buffer );
							response_stream << stream.rdbuf();
						}
					};

					if( ( 2 + length )>num_additional_bytes ) {
						auto timer = get_timeout_timer();
						boost::asio::async_read( *socket, response->content_buffer,
							boost::asio::transfer_exactly( static_cast< size_t >( 2 + length - num_additional_bytes ) ),
							[this, post_process, timer]( const boost::system::error_code& ec, size_t /*bytes_transferred*/ ) {
							if( timer )
								timer->cancel();
							if( !ec ) {
								post_process();
							}
							else {
								std::lock_guard<std::mutex> lock( socket_mutex );
								this->socket = nullptr;
								throw boost::system::system_error( ec );
							}
						} );
					}
					else
						post_process();
				}
				else {
					std::lock_guard<std::mutex> lock( socket_mutex );
					socket = nullptr;
					throw boost::system::system_error( ec );
				}
			} );
		}
	};

	template<class socket_type>
	class Client : public ClientBase<socket_type> {};

	typedef boost::asio::ip::tcp::socket HTTP;

	template<>
	class Client<HTTP> : public ClientBase<HTTP> {
	public:
		Client( const std::string& server_port_path ) : ClientBase<HTTP>::ClientBase( server_port_path, 80 ) {}

	protected:
		void connect() {
			if( !socket || !socket->is_open() ) {
				std::unique_ptr<boost::asio::ip::tcp::resolver::query> query;
				if( config.proxy_server.empty() )
					query = std::unique_ptr<boost::asio::ip::tcp::resolver::query>( new boost::asio::ip::tcp::resolver::query( host, std::to_string( port ) ) );
				else {
					auto proxy_host_port = parse_host_port( config.proxy_server, 8080 );
					query = std::unique_ptr<boost::asio::ip::tcp::resolver::query>( new boost::asio::ip::tcp::resolver::query( proxy_host_port.first, std::to_string( proxy_host_port.second ) ) );
				}
				resolver.async_resolve( *query, [this]( const boost::system::error_code &ec,
					boost::asio::ip::tcp::resolver::iterator it ) {
					if( !ec ) {
						{
							std::lock_guard<std::mutex> lock( socket_mutex );
							socket = std::unique_ptr<HTTP>( new HTTP( io_service ) );
						}

						auto timer = get_timeout_timer();
						boost::asio::async_connect( *socket, it, [this, timer]
						( const boost::system::error_code &ec, boost::asio::ip::tcp::resolver::iterator /*it*/ ) {
							if( timer )
								timer->cancel();
							if( !ec ) {
								boost::asio::ip::tcp::no_delay option( true );
								this->socket->set_option( option );
							}
							else {
								std::lock_guard<std::mutex> lock( socket_mutex );
								this->socket = nullptr;
								throw boost::system::system_error( ec );
							}
						} );
					}
					else {
						std::lock_guard<std::mutex> lock( socket_mutex );
						socket = nullptr;
						throw boost::system::system_error( ec );
					}
				} );
				io_service.reset();
				io_service.run();
			}
		}
	};
}

#endif	/* CLIENT_HTTP_HPP */