#include <cstring>
#include <cassert>
#include <boost/lexical_cast.hpp>
#include <string>
#include <atomic>
#include <memory>
#include <set>
#include <boost/asio.hpp>
#include <mutex>

#include "I2PService.h"
#include "Destination.h"
#include "HTTPProxy.h"
#include "util.h"
#include "Identity.h"
#include "Streaming.h"
#include "Destination.h"
#include "ClientContext.h"
#include "I2PEndian.h"
#include "I2PTunnel.h"
#include "Config.h"
#include "HTTP.h"

namespace i2p
{
namespace proxy
{
	static const size_t http_buffer_size = 8192;
	class HTTPProxyHandler: public i2p::client::I2PServiceHandler, public std::enable_shared_from_this<HTTPProxyHandler> 
	{
		private:
			enum state 
			{
				GET_METHOD,
				GET_HOSTNAME,
				GET_HTTPV,
				GET_HTTPVNL, //TODO: fallback to finding HOst: header if needed
				DONE
			};

			void EnterState(state nstate);
			bool HandleData(uint8_t *http_buff, std::size_t len);
			void HandleSockRecv(const boost::system::error_code & ecode, std::size_t bytes_transfered);
			void Terminate();
			void AsyncSockRead();
			void HTTPRequestFailed(const char *message);
			void RedirectToJumpService();
			void ExtractRequest();
			bool IsI2PAddress();
			bool ValidateHTTPRequest();
			void HandleJumpServices();
			bool CreateHTTPRequest(uint8_t *http_buff, std::size_t len);
			void SentHTTPFailed(const boost::system::error_code & ecode);
			void HandleStreamRequestComplete (std::shared_ptr<i2p::stream::Stream> stream);

			uint8_t m_http_buff[http_buffer_size];
			std::shared_ptr<boost::asio::ip::tcp::socket> m_sock;
			std::string m_request; //Data left to be sent
			std::string m_url; //URL
			std::string m_method; //Method
			std::string m_version; //HTTP version
			std::string m_address; //Address
			std::string m_path; //Path
			int m_port; //Port
			state m_state;//Parsing state

		public:

			HTTPProxyHandler(HTTPProxyServer * parent, std::shared_ptr<boost::asio::ip::tcp::socket> sock) : 
				I2PServiceHandler(parent), m_sock(sock)
				{ EnterState(GET_METHOD); }
			~HTTPProxyHandler() { Terminate(); }
			void Handle () { AsyncSockRead(); }
	};

	void HTTPProxyHandler::AsyncSockRead()
	{
		LogPrint(eLogDebug, "HTTPProxy: async sock read");
		if(m_sock) {
			m_sock->async_receive(boost::asio::buffer(m_http_buff, http_buffer_size),
						std::bind(&HTTPProxyHandler::HandleSockRecv, shared_from_this(),
								std::placeholders::_1, std::placeholders::_2));
		} else {
			LogPrint(eLogError, "HTTPProxy: no socket for read");
		}
	}

	void HTTPProxyHandler::Terminate() {
		if (Kill()) return;
		if (m_sock) 
		{
			LogPrint(eLogDebug, "HTTPProxy: close sock");
			m_sock->close();
			m_sock = nullptr;
		}
		Done(shared_from_this());
	}

	/* All hope is lost beyond this point */
	//TODO: handle this apropriately
	void HTTPProxyHandler::HTTPRequestFailed(const char *message)
	{
		std::size_t size = std::strlen(message);
		std::stringstream ss;
		ss << "HTTP/1.0 500 Internal Server Error\r\n"
		   << "Content-Type: text/plain\r\n";
		ss << "Content-Length: " << std::to_string(size + 2) << "\r\n"
		   << "\r\n"; /* end of headers */
		ss << message << "\r\n";
		std::string response = ss.str();
		boost::asio::async_write(*m_sock, boost::asio::buffer(response),
					 std::bind(&HTTPProxyHandler::SentHTTPFailed, shared_from_this(), std::placeholders::_1));
	}

	void HTTPProxyHandler::RedirectToJumpService(/*HTTPProxyHandler::errTypes error*/)
	{
		std::stringstream response;
		std::string httpAddr; i2p::config::GetOption("http.address", httpAddr);
		uint16_t    httpPort; i2p::config::GetOption("http.port", httpPort);

		response << "HTTP/1.1 302 Found\r\nLocation: http://" << httpAddr << ":" << httpPort << "/?page=jumpservices&address=" << m_address << "\r\n\r\n";
		boost::asio::async_write(*m_sock, boost::asio::buffer(response.str (),response.str ().length ()),
					 std::bind(&HTTPProxyHandler::SentHTTPFailed, shared_from_this(), std::placeholders::_1));
	}

	void HTTPProxyHandler::EnterState(HTTPProxyHandler::state nstate) 
	{
		m_state = nstate;
	}

	void HTTPProxyHandler::ExtractRequest()
	{
		LogPrint(eLogDebug, "HTTPProxy: request: ", m_method, " ", m_url);
		i2p::http::URL url;
		url.parse (m_url);
		m_address = url.host;
		m_port = url.port;
		m_path = url.path;
		if (url.query.length () > 0) m_path += "?" + url.query;
		if (!m_port) m_port = 80;
		LogPrint(eLogDebug, "HTTPProxy: server: ", m_address, ", port: ", m_port, ", path: ", m_path);
	}

	bool HTTPProxyHandler::ValidateHTTPRequest() 
	{
		if ( m_version != "HTTP/1.0" && m_version != "HTTP/1.1" ) 
		{
			LogPrint(eLogError, "HTTPProxy: unsupported version: ", m_version);
			HTTPRequestFailed("unsupported HTTP version");
			return false;
		}
		return true;
	}

	void HTTPProxyHandler::HandleJumpServices() 
	{
		static const char * helpermark1 = "?i2paddresshelper=";
		static const char * helpermark2 = "&i2paddresshelper=";
		size_t addressHelperPos1 = m_path.rfind (helpermark1);
		size_t addressHelperPos2 = m_path.rfind (helpermark2);
		size_t addressHelperPos;
		if (addressHelperPos1 == std::string::npos)
		{
			if (addressHelperPos2 == std::string::npos)
				return; //Not a jump service
			else
				addressHelperPos = addressHelperPos2;
		}
		else
		{
			if (addressHelperPos2 == std::string::npos)
				addressHelperPos = addressHelperPos1;
			else if ( addressHelperPos1 > addressHelperPos2 )
				addressHelperPos = addressHelperPos1;
			else
				addressHelperPos = addressHelperPos2;
		}
		auto base64 = m_path.substr (addressHelperPos + strlen(helpermark1));
		base64 = i2p::util::http::urlDecode(base64); //Some of the symbols may be urlencoded
		LogPrint (eLogInfo, "HTTPProxy: jump service for ", m_address, ", inserting to address book");
		//TODO: this is very dangerous and broken. We should ask the user before doing anything see http://pastethis.i2p/raw/pn5fL4YNJL7OSWj3Sc6N/
		//TODO: we could redirect the user again to avoid dirtiness in the browser
		i2p::client::context.GetAddressBook ().InsertAddress (m_address, base64);
		m_path.erase(addressHelperPos);
	}

	bool HTTPProxyHandler::IsI2PAddress()
	{
		auto pos = m_address.rfind (".i2p");
		if (pos != std::string::npos && (pos+4) == m_address.length ())
		{
			return true;
		}
		return false;
	}

	bool HTTPProxyHandler::CreateHTTPRequest(uint8_t *http_buff, std::size_t len) 
	{
		ExtractRequest(); //TODO: parse earlier
		if (!ValidateHTTPRequest()) return false;
		HandleJumpServices();

		i2p::data::IdentHash identHash;
		if (IsI2PAddress ())
		{
			if (!i2p::client::context.GetAddressBook ().GetIdentHash (m_address, identHash)){
				RedirectToJumpService();
				return false;
			}
		}
		

		m_request = m_method;
		m_request.push_back(' ');
		m_request += m_path;
		m_request.push_back(' ');
		m_request += m_version;
		m_request.push_back('\r');
		m_request.push_back('\n');
		m_request.append("Connection: close\r\n");
		// TODO: temporary shortcut. Must be implemented properly
		uint8_t * eol = nullptr;
		bool isEndOfHeader = false;
		while (!isEndOfHeader && len && (eol = (uint8_t *)memchr (http_buff, '\r', len)))
		{
			if (eol)
			{
				*eol = 0; eol++;			
				if (strncmp ((const char *)http_buff, "Referer", 7) && strncmp ((const char *)http_buff, "Connection", 10)) // strip out referer and connection
				{
					if (!strncmp ((const char *)http_buff, "User-Agent", 10)) // replace UserAgent
						m_request.append("User-Agent: MYOB/6.66 (AN/ON)");
					else
						m_request.append ((const char *)http_buff);
					m_request.append ("\r\n");
				}
				isEndOfHeader = !http_buff[0];
				auto l = eol - http_buff;
				http_buff = eol;
				len -= l;
				if (len > 0) // \r
				{
					http_buff++;
					len--;
				}	
			}
		}	
		m_request.append(reinterpret_cast<const char *>(http_buff),len);	
		return true;
	}

	bool HTTPProxyHandler::HandleData(uint8_t *http_buff, std::size_t len)
	{
		while (len > 0) 
		{
			//TODO: fallback to finding HOst: header if needed
			switch (m_state) 
			{
				case GET_METHOD:
					switch (*http_buff) 
					{
						case ' ': EnterState(GET_HOSTNAME); break;
						default: m_method.push_back(*http_buff); break;
					}
				break;
				case GET_HOSTNAME:
					switch (*http_buff) 
					{
						case ' ': EnterState(GET_HTTPV); break;
						default: m_url.push_back(*http_buff); break;
					}
				break;
				case GET_HTTPV:
					switch (*http_buff) 
					{
						case '\r': EnterState(GET_HTTPVNL); break;
						default: m_version.push_back(*http_buff); break;
					}
				break;
				case GET_HTTPVNL:
					switch (*http_buff) 
					{
						case '\n': EnterState(DONE); break;
						default:
							LogPrint(eLogError, "HTTPProxy: rejected invalid request ending with: ", ((int)*http_buff));
							HTTPRequestFailed("rejected invalid request");
							return false;
					}
				break;
				default:
					LogPrint(eLogError, "HTTPProxy: invalid state: ", m_state);
					HTTPRequestFailed("invalid parser state");
					return false;
			}
			http_buff++;
			len--;
			if (m_state == DONE)
				return CreateHTTPRequest(http_buff,len);
		}
		return true;
	}

	void HTTPProxyHandler::HandleSockRecv(const boost::system::error_code & ecode, std::size_t len)
	{
		LogPrint(eLogDebug, "HTTPProxy: sock recv: ", len, " bytes");
		if(ecode) 
		{
			LogPrint(eLogWarning, "HTTPProxy: sock recv got error: ", ecode);
			Terminate();
			return;
		}

		if (HandleData(m_http_buff, len)) 
		{
			if (m_state == DONE) 
			{
				LogPrint(eLogDebug, "HTTPProxy: requested: ", m_url);
				GetOwner()->CreateStream (std::bind (&HTTPProxyHandler::HandleStreamRequestComplete,
						shared_from_this(), std::placeholders::_1), m_address, m_port);
			} 
			else 
				AsyncSockRead();
		}

	}

	void HTTPProxyHandler::SentHTTPFailed(const boost::system::error_code & ecode)
	{
		if (ecode)
			LogPrint (eLogError, "HTTPProxy: Closing socket after sending failure because: ", ecode.message ());
		Terminate();
	}

	void HTTPProxyHandler::HandleStreamRequestComplete (std::shared_ptr<i2p::stream::Stream> stream)
	{
		if (stream) 
		{
			if (Kill()) return;
			LogPrint (eLogInfo, "HTTPProxy: New I2PTunnel connection");
			auto connection = std::make_shared<i2p::client::I2PTunnelConnection>(GetOwner(), m_sock, stream);
			GetOwner()->AddHandler (connection);
			connection->I2PConnect (reinterpret_cast<const uint8_t*>(m_request.data()), m_request.size());
			Done(shared_from_this());
		} 
		else 
		{
			LogPrint (eLogError, "HTTPProxy: error when creating the stream, check the previous warnings for more info");
			HTTPRequestFailed("error when creating the stream, check logs");
		}
	}

	HTTPProxyServer::HTTPProxyServer(const std::string& address, int port, std::shared_ptr<i2p::client::ClientDestination> localDestination): 
		TCPIPAcceptor(address, port, localDestination ? localDestination : i2p::client::context.GetSharedLocalDestination ()) 
	{
	}
	
	std::shared_ptr<i2p::client::I2PServiceHandler> HTTPProxyServer::CreateHandler(std::shared_ptr<boost::asio::ip::tcp::socket> socket)
	{
		return std::make_shared<HTTPProxyHandler> (this, socket);
	}
}
}