#include <cstdlib>
#include <string>
#include <algorithm>
#include <cctype>
#include <functional>
#include <fstream>
#include <set>
#include <boost/asio.hpp>
#include <boost/filesystem.hpp>
#include <boost/filesystem/fstream.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/program_options/detail/config_file.hpp>
#include <boost/program_options/parsers.hpp>
#include <boost/algorithm/string.hpp>
#include "util.h"
#include "Log.h"

#if defined(__linux__) || defined(__FreeBSD_kernel__)
#include <sys/types.h>
#include <ifaddrs.h>
#elif defined(WIN32)
#include <stdlib.h>
#include <string.h>
#include <stdio.h>    
#include <winsock2.h>
#include <ws2tcpip.h>
#include <iphlpapi.h>
#include <shlobj.h>

#pragma comment(lib, "IPHLPAPI.lib")

#define MALLOC(x) HeapAlloc(GetProcessHeap(), 0, (x))
#define FREE(x) HeapFree(GetProcessHeap(), 0, (x))

int inet_pton(int af, const char *src, void *dst)
{ /* This function was written by Petar Korponai?. See
http://stackoverflow.com/questions/15660203/inet-pton-identifier-not-found */
    struct sockaddr_storage ss;
    int size = sizeof (ss);
    char src_copy[INET6_ADDRSTRLEN + 1];

    ZeroMemory (&ss, sizeof (ss));
    strncpy_s (src_copy, src, INET6_ADDRSTRLEN + 1);
    src_copy[INET6_ADDRSTRLEN] = 0;

    if (WSAStringToAddress (src_copy, af, NULL, (struct sockaddr *)&ss, &size) == 0)
    {
        switch (af)
        {
            case AF_INET:
                *(struct in_addr *)dst = ((struct sockaddr_in *)&ss)->sin_addr;
                return 1;
            case AF_INET6:
                *(struct in6_addr *)dst = ((struct sockaddr_in6 *)&ss)->sin6_addr;
                return 1;
        }
    }
    return 0;
}
#endif

namespace i2p {
namespace util {

namespace config {
    std::map<std::string, std::string> mapArgs;
    std::map<std::string, std::vector<std::string> > mapMultiArgs;

    void OptionParser(int argc, const char* const argv[])
    {
        mapArgs.clear();
        mapMultiArgs.clear();
        for(int i = 1; i < argc; ++i) {
            std::string strKey (argv[i]);
            std::string strValue;
            size_t has_data = strKey.find('=');
            if(has_data != std::string::npos) {
                strValue = strKey.substr(has_data+1);
                strKey = strKey.substr(0, has_data);
            }

#ifdef WIN32
            boost::to_lower(strKey);
            if(boost::algorithm::starts_with(strKey, "/"))
                strKey = "-" + strKey.substr(1);
#endif
            if(strKey[0] != '-')
                break;

            mapArgs[strKey] = strValue;
            mapMultiArgs[strKey].push_back(strValue);
        }

        for(auto& entry : mapArgs) {
            std::string name = entry.first;

            //  interpret --foo as -foo (as long as both are not set)
            if (name.find("--") == 0) {
                std::string singleDash(name.begin()+1, name.end());
                if (mapArgs.count(singleDash) == 0)
                    mapArgs[singleDash] = entry.second;
                name = singleDash;
            }
        }
    }

    const char* GetCharArg(const std::string& strArg, const std::string& nDefault)
    {
        if(mapArgs.count(strArg))
            return mapArgs[strArg].c_str();
        return nDefault.c_str();
    }

    std::string GetArg(const std::string& strArg, const std::string& strDefault)
    {
        if(mapArgs.count(strArg))
            return mapArgs[strArg];
        return strDefault;
    }

    int GetArg(const std::string& strArg, int nDefault)
    {
        if(mapArgs.count(strArg))
            return stoi(mapArgs[strArg]);
        return nDefault;
    }

}

namespace filesystem
{
    std::string appName("i2pd");

    void SetAppName(const std::string& name)
    {
        appName = name;
    }

    std::string GetAppName()
    {
        return appName;
    }

    const boost::filesystem::path& GetDataDir()
    {
        static boost::filesystem::path path;

        // TODO: datadir parameter is useless because GetDataDir is called before OptionParser
        // and mapArgs is not initialized yet
        /*if (i2p::util::config::mapArgs.count("-datadir")) 
            path = boost::filesystem::system_complete(i2p::util::config::mapArgs["-datadir"]);
        else */
        path = GetDefaultDataDir();

        if(!boost::filesystem::exists(path)) {
            // Create data directory
            if(!boost::filesystem::create_directory(path)) {
                LogPrint("Failed to create data directory!");
                path = "";
                return path;
            }
        }
        if(!boost::filesystem::is_directory(path)) 
            path = GetDefaultDataDir();
        return path;
    }

    std::string GetFullPath(const std::string& filename)
    {
        std::string fullPath = GetDataDir().string();
#ifndef _WIN32
        fullPath.append("/");
#else
        fullPath.append("\\");
#endif
        fullPath.append(filename);
        return fullPath;
    }       

    boost::filesystem::path GetConfigFile()
    {
        boost::filesystem::path pathConfigFile(i2p::util::config::GetArg("-conf", "i2p.conf"));
        if(!pathConfigFile.is_complete())
            pathConfigFile = GetDataDir() / pathConfigFile;
        return pathConfigFile;
    }

    boost::filesystem::path GetDefaultDataDir()
    {
        // Windows < Vista: C:\Documents and Settings\Username\Application Data\i2pd
        // Windows >= Vista: C:\Users\Username\AppData\Roaming\i2pd
        // Mac: ~/Library/Application Support/i2pd
        // Unix: ~/.i2pd or /var/lib/i2pd is system=1

#ifdef WIN32
        // Windows
        char localAppData[MAX_PATH];
        SHGetFolderPath(NULL, CSIDL_APPDATA, 0, NULL, localAppData);
        return boost::filesystem::path(std::string(localAppData) + "\\" + appName);
#else
        if(i2p::util::config::GetArg("-service", 0)) // use system folder
            return boost::filesystem::path(std::string ("/var/lib/") + appName);
        boost::filesystem::path pathRet;
        char* pszHome = getenv("HOME");
        if(pszHome == NULL || strlen(pszHome) == 0)
            pathRet = boost::filesystem::path("/");
        else
            pathRet = boost::filesystem::path(pszHome);
#ifdef MAC_OSX
        // Mac
        pathRet /= "Library/Application Support";
        boost::filesystem::create_directory(pathRet);
        return pathRet / appName;
#else
        // Unix
        return pathRet / (std::string (".") + appName);
#endif
#endif
    }

    void ReadConfigFile(std::map<std::string, std::string>& mapSettingsRet,
                        std::map<std::string, std::vector<std::string> >& mapMultiSettingsRet)
    {
        boost::filesystem::ifstream streamConfig(GetConfigFile());
        if(!streamConfig.good())
            return; // No i2pd.conf file is OK

        std::set<std::string> setOptions;
        setOptions.insert("*");

        for(boost::program_options::detail::config_file_iterator it(streamConfig, setOptions), end;
          it != end; ++it) {
            // Don't overwrite existing settings so command line settings override i2pd.conf
            std::string strKey = std::string("-") + it->string_key;
            if(mapSettingsRet.count(strKey) == 0) {
                mapSettingsRet[strKey] = it->value[0];
            }
            mapMultiSettingsRet[strKey].push_back(it->value[0]);
        }
    }

    boost::filesystem::path GetCertificatesDir()
    {
        return GetDataDir () / "certificates";
    }
}

namespace http
{
    std::string httpRequest(const std::string& address)
    {
        try {
            i2p::util::http::url u(address);
            boost::asio::ip::tcp::iostream site;
            // please don't uncomment following line because it's not compatible with boost 1.46
            // 1.46 is default boost for Ubuntu 12.04 LTS
            //site.expires_from_now (boost::posix_time::seconds(30));
            if(u.port_ == 80)
                site.connect(u.host_, "http");
            else {
                std::stringstream ss; ss << u.port_;
                site.connect(u.host_, ss.str());
            }
            if(site) {
                // User-Agent is needed to get the server list routerInfo files.
                site << "GET " << u.path_ << " HTTP/1.1\r\nHost: " << u.host_
                     << "\r\nAccept: */*\r\n" << "User-Agent: Wget/1.11.4\r\n"
                     << "Connection: close\r\n\r\n";
                // read response and extract content                
                return GetHttpContent(site);
            } else {
                LogPrint("Can't connect to ", address);
                return "";
            }
        } catch(const std::exception& ex) {
            LogPrint("Failed to download ", address, " : ", ex.what());
            return "";
        }
    }

    std::string GetHttpContent (std::istream& response)
    {
        std::string version, statusMessage;
        response >> version; // HTTP version
        int status;
        response >> status; // status
        std::getline (response, statusMessage);
        if(status == 200) { // OK
            bool isChunked = false;
            std::string header;
            while(!response.eof() && header != "\r") {
                std::getline(response, header);
                auto colon = header.find (':');
                if(colon != std::string::npos) {
                    std::string field = header.substr (0, colon);
                    if(field == i2p::util::http::TRANSFER_ENCODING)
                        isChunked = (header.find("chunked", colon + 1) != std::string::npos);
                }
            }

            std::stringstream ss;
            if(isChunked)
                MergeChunkedResponse(response, ss);
            else    
                ss << response.rdbuf();

            return ss.str();
        } else {
            LogPrint("HTTP response ", status);
            return "";
        }
    }

    void MergeChunkedResponse(std::istream& response, std::ostream& merged)
    {
        while(!response.eof()) {   
            std::string hexLen;
            int len;
            std::getline(response, hexLen);
            std::istringstream iss(hexLen);
            iss >> std::hex >> len;
            if(!len)
                break;
            char* buf = new char[len];
            response.read(buf, len);
            merged.write(buf, len);
            delete[] buf;
            std::getline(response, hexLen); // read \r\n after chunk
        }
    }   
    
    int httpRequestViaI2pProxy(const std::string& address, std::string &content)
    {
        content = "";
        try {
            boost::asio::ip::tcp::iostream site;
            // please don't uncomment following line because it's not compatible with boost 1.46
            // 1.46 is default boost for Ubuntu 12.04 LTS
            //site.expires_from_now (boost::posix_time::seconds(30));
            {
                std::stringstream ss; ss << i2p::util::config::GetArg("-httpproxyport", 4446);
                site.connect("127.0.0.1", ss.str());
            }
            if(site) {
                i2p::util::http::url u(address);
                std::stringstream ss;
                ss << "GET " << address << " HTTP/1.0" << std::endl;
                ss << "Host: " << u.host_ << std::endl;
                ss << "Accept: */*" << std::endl;
                ss << "User - Agent: Wget / 1.11.4" << std::endl;
                ss << "Connection: close" << std::endl;
                ss << std::endl;
                site << ss.str();

                // read response
                std::string version, statusMessage;
                site >> version; // HTTP version
                int status;
                site >> status; // status
                std::getline(site, statusMessage);
                if(status == 200) { // OK
                    std::string header;
                    while(std::getline(site, header) && header != "\r"){}
                    std::stringstream ss;
                    ss << site.rdbuf();
                    content = ss.str();
                    return status;
                } else {
                    LogPrint("HTTP response ", status);
                    return status;
                }
            } else {
                LogPrint("Can't connect to proxy");
                return 408;
            }
        } catch (std::exception& ex) {
            LogPrint("Failed to download ", address, " : ", ex.what());
            return 408;
        }
    }
    
    url::url(const std::string& url_s)
    {
        portstr_ = "80";
        port_ = 80;
        user_ = "";
        pass_ = "";

        parse(url_s);
    }


    void url::parse(const std::string& url_s)
    {
        const std::string prot_end("://");
        std::string::const_iterator prot_i = search(
            url_s.begin(), url_s.end(), prot_end.begin(), prot_end.end()
        );
        protocol_.reserve(distance(url_s.begin(), prot_i));
        // Make portocol lowercase
        transform(
            url_s.begin(), prot_i, back_inserter(protocol_), std::ptr_fun<int, int>(std::tolower)
        ); 
        if(prot_i == url_s.end())
            return;
        advance(prot_i, prot_end.length());
        std::string::const_iterator path_i = find(prot_i, url_s.end(), '/');
        host_.reserve(distance(prot_i, path_i));
        // Make host lowerase
        transform(prot_i, path_i, back_inserter(host_), std::ptr_fun<int, int>(std::tolower));

        // parse user/password
        auto user_pass_i = find(host_.begin(), host_.end(), '@');
        if(user_pass_i != host_.end()) {
            std::string user_pass = std::string(host_.begin(), user_pass_i);
            auto pass_i = find(user_pass.begin(), user_pass.end(), ':');
            if (pass_i != user_pass.end()) {
                user_ = std::string(user_pass.begin(), pass_i);
                pass_ = std::string(pass_i + 1, user_pass.end());
            } else
                user_ = user_pass;

            host_.assign(user_pass_i + 1, host_.end());
        }

        // parse port
        auto port_i = find(host_.begin(), host_.end(), ':');
        if(port_i != host_.end()) {
            portstr_ = std::string(port_i + 1, host_.end());
            host_.assign(host_.begin(), port_i);
            try {
                port_ = boost::lexical_cast<decltype(port_)>(portstr_);
            } catch(const std::exception& e) {
                port_ = 80;
            }
        }

        std::string::const_iterator query_i = find(path_i, url_s.end(), '?');
        path_.assign(path_i, query_i);
        if( query_i != url_s.end() )
            ++query_i;
        query_.assign(query_i, url_s.end());
    }

    std::string urlDecode(const std::string& data)
    {
        std::string res(data);
        for(size_t pos = res.find('%'); pos != std::string::npos; pos = res.find('%', pos + 1)) {
            const char c = strtol(res.substr(pos + 1, 2).c_str(), NULL, 16);
            res.replace(pos, 3, 1, c);
        }
        return res;
    }
} 

namespace net {

#if defined(__linux__) || defined(__FreeBSD_kernel__)   
    
    int GetMTUUnix(const boost::asio::ip::address& localAddress, int fallback)
    {
        ifaddrs* ifaddr, *ifa = nullptr;
        if(getifaddrs(&ifaddr) == -1) {
            LogPrint(eLogError, "Can't excute getifaddrs");
            return fallback;
        }

        int family = 0;
        // look for interface matching local address   
        for(ifa = ifaddr; ifa != nullptr; ifa = ifa->ifa_next) {
            if(!ifa->ifa_addr)
                continue;

            family = ifa->ifa_addr->sa_family;
            if(family == AF_INET && localAddress.is_v4()) {
                sockaddr_in* sa = (sockaddr_in*) ifa->ifa_addr;
                if(!memcmp(&sa->sin_addr, localAddress.to_v4().to_bytes().data(), 4))
                    break; // address matches
            } else if(family == AF_INET6 && localAddress.is_v6()) {
                sockaddr_in6* sa = (sockaddr_in6*) ifa->ifa_addr;
                if(!memcmp(&sa->sin6_addr, localAddress.to_v6().to_bytes().data(), 16))
                    break; // address matches
            }
        }
        int mtu = fallback;
        if(ifa && family) { // interface found?
            int fd = socket(family, SOCK_DGRAM, 0);
            if(fd > 0) {
                ifreq ifr;
                strncpy(ifr.ifr_name, ifa->ifa_name, IFNAMSIZ); // set interface for query
                if(ioctl(fd, SIOCGIFMTU, &ifr) >= 0)  
                    mtu = ifr.ifr_mtu; // MTU
                else
                    LogPrint (eLogError, "Failed to run ioctl");            
                close(fd);
            } else
                LogPrint(eLogError, "Failed to create datagram socket");   
        } else {
            LogPrint(
                eLogWarning, "Interface for local address",
                localAddress.to_string(), " not found"
            );
        }

        freeifaddrs(ifaddr);

        return mtu;
    }

#elif defined(WIN32)
    int GetMTUWindowsIpv4(sockaddr_in inputAddress, int fallback)
    {
        ULONG outBufLen = 0;
        PIP_ADAPTER_ADDRESSES pAddresses = nullptr;
        PIP_ADAPTER_ADDRESSES pCurrAddresses = nullptr;
        PIP_ADAPTER_UNICAST_ADDRESS pUnicast = nullptr;


        if(GetAdaptersAddresses(AF_INET, GAA_FLAG_INCLUDE_PREFIX, nullptr, pAddresses, &outBufLen)
          == ERROR_BUFFER_OVERFLOW) {
            FREE(pAddresses);
            pAddresses = (IP_ADAPTER_ADDRESSES*) MALLOC(outBufLen);
        }

        DWORD dwRetVal = GetAdaptersAddresses(
            AF_INET, GAA_FLAG_INCLUDE_PREFIX, nullptr, pAddresses, &outBufLen
        );

        if(dwRetVal != NO_ERROR) {
            LogPrint(
                eLogError, "GetMTU() has failed: enclosed GetAdaptersAddresses() call has failed"
            );
            FREE(pAddresses);
            return fallback;
        }

        pCurrAddresses = pAddresses;
        while(pCurrAddresses) {
            PIP_ADAPTER_UNICAST_ADDRESS firstUnicastAddress = pCurrAddresses->FirstUnicastAddress;

            pUnicast = pCurrAddresses->FirstUnicastAddress;
            if(pUnicast == nullptr) {
                LogPrint(
                    eLogError, "GetMTU() has failed: not a unicast ipv4 address, this is not supported"
                );
            }
            for(int i = 0; pUnicast != nullptr; ++i) {
                LPSOCKADDR lpAddr = pUnicast->Address.lpSockaddr;
                sockaddr_in* localInterfaceAddress = (sockaddr_in*) lpAddr;
                if(localInterfaceAddress->sin_addr.S_un.S_addr == inputAddress.sin_addr.S_un.S_addr) {
                    result = pAddresses->Mtu;
                    FREE(pAddresses);
                    return result;
                }
                pUnicast = pUnicast->Next;
            }
            pCurrAddresses = pCurrAddresses->Next;
        }

        LogPrint(eLogError, "GetMTU() error: no usable unicast ipv4 addresses found");
        FREE(pAddresses);
        return fallback;
    }

    int GetMTUWindowsIpv6(sockaddr_in6 inputAddress, int fallback)
    {
        ULONG outBufLen = 0;
        PIP_ADAPTER_ADDRESSES pAddresses = nullptr;
        PIP_ADAPTER_ADDRESSES pCurrAddresses = nullptr;
        PIP_ADAPTER_UNICAST_ADDRESS pUnicast = nullptr;

        if(GetAdaptersAddresses(AF_INET6, GAA_FLAG_INCLUDE_PREFIX, nullptr, pAddresses, &outBufLen)
          == ERROR_BUFFER_OVERFLOW) {
            FREE(pAddresses);
            pAddresses = (IP_ADAPTER_ADDRESSES*) MALLOC(outBufLen);
        }

        DWORD dwRetVal = GetAdaptersAddresses(
            AF_INET6, GAA_FLAG_INCLUDE_PREFIX, nullptr, pAddresses, &outBufLen
        );

        if(dwRetVal != NO_ERROR) {
            LogPrint(
                eLogError,
                "GetMTU() has failed: enclosed GetAdaptersAddresses() call has failed"
            );
            FREE(pAddresses);
            return fallback;
        }

        bool found_address = false;
        pCurrAddresses = pAddresses;
        while(pCurrAddresses) {
            PIP_ADAPTER_UNICAST_ADDRESS firstUnicastAddress = pCurrAddresses->FirstUnicastAddress;
            pUnicast = pCurrAddresses->FirstUnicastAddress;
            if(pUnicast == nullptr) {
                LogPrint(
                    eLogError,
                    "GetMTU() has failed: not a unicast ipv6 address, this is not supported"
                );
            }
            for(int i = 0; pUnicast != nullptr; ++i) {
                LPSOCKADDR lpAddr = pUnicast->Address.lpSockaddr;
                sockaddr_in6 *localInterfaceAddress = (sockaddr_in6*) lpAddr;

                for (int j = 0; j != 8; ++j) {
                    if (localInterfaceAddress->sin6_addr.u.Word[j] != inputAddress.sin6_addr.u.Word[j]) {
                        break;
                    } else {
                        found_address = true;
                    }
                } if (found_address) {
                    result = pAddresses->Mtu;
                    FREE(pAddresses);
                    pAddresses = nullptr;
                    return result;
                }
                pUnicast = pUnicast->Next;
            }

            pCurrAddresses = pCurrAddresses->Next;
        }

        LogPrint(eLogError, "GetMTU() error: no usable unicast ipv6 addresses found");
        FREE(pAddresses);
        return fallback;
    }

    int GetMTUWindows(const boost::asio::ip::address& localAddress, int fallback)
    { 
#ifdef UNICODE
        string localAddress_temporary = localAddress.to_string();
        wstring localAddressUniversal(localAddress_temporary.begin(), localAddress_temporary.end());
#else
        std::string localAddressUniversal = localAddress.to_string();
#endif

        if(localAddress.is_v4()) {
            sockaddr_in inputAddress;
            inet_pton(AF_INET, localAddressUniversal.c_str(), &(inputAddress.sin_addr));
            return GetMTUWindowsIpv4(inputAddress, fallback);
        } else if(localAddress.is_v6()) {
            sockaddr_in6 inputAddress;
            inet_pton(AF_INET6, localAddressUniversal.c_str(), &(inputAddress.sin6_addr)); 
            return GetMTUWindowsIpv6(inputAddress, fallback);
        } else {
            LogPrint(eLogError, "GetMTU() has failed: address family is not supported");
            return fallback;
        }

    }
#endif // WIN32

    int GetMTU(const boost::asio::ip::address& localAddress)
    {
        const int fallback = 576; // fallback MTU

#if defined(__linux__) || defined(__FreeBSD_kernel__)
        return GetMTUUnix(localAddress, fallback);
#elif defined(WIN32)
        return GetMTUWindows(localAddress, fallback);
#endif
    }
} 

} // util
} // i2p