/*
 * Copyright (C) 2012-2014 Arctium Emulation <http://arctium.org>
 * Copyright (C) 2008-2017 TrinityCore <http://www.trinitycore.org/>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "Helper.hpp"

namespace Connection_Patcher
{
    namespace Helper
    {
        // adapted from http://stackoverflow.com/questions/8593608/how-can-i-copy-a-directory-using-boost-filesystem
        void CopyDir(boost::filesystem::path const & source, boost::filesystem::path const & destination)
        {
            namespace fs = boost::filesystem;
            if (!fs::exists(source) || !fs::is_directory(source))
                throw std::invalid_argument("Source directory " + source.string() + " does not exist or is not a directory.");

            if (fs::exists(destination))
                throw std::invalid_argument("Destination directory " + destination.string() + " already exists.");

            if (!fs::create_directory(destination))
                throw std::runtime_error("Unable to create destination directory" + destination.string());

            for (fs::directory_iterator file(source); file != fs::directory_iterator(); ++file)
            {
                fs::path current(file->path());
                if (fs::is_directory(current))
                    CopyDir(current, destination / current.filename());
                else
                    fs::copy_file(current, destination / current.filename());
            }
        }

        // adapted from http://stackoverflow.com/questions/21422094/boostasio-download-image-file-from-server
        void DownloadFile(const std::string& serverName, int port, const std::string& getCommand, std::ostream& out)
        {
            using namespace boost::asio;
            using boost::asio::ip::tcp;

            io_service io_service;

            // Get a list of endpoints corresponding to the server name.
            tcp::resolver resolver(io_service);
            tcp::resolver::query query(serverName, std::to_string(port));
            tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
            tcp::resolver::iterator end;

            // Try each endpoint until we successfully establish a connection.
            tcp::socket socket(io_service);
            boost::system::error_code error = boost::asio::error::host_not_found;
            while (error && endpoint_iterator != end)
            {
                socket.close();
                socket.connect(*endpoint_iterator++, error);
            }

            boost::asio::streambuf request;
            std::ostream request_stream(&request);

            request_stream << "GET " << getCommand << " HTTP/1.0\r\n";
            request_stream << "Host: " << serverName << ':' << port << "\r\n";
            request_stream << "Accept: */*\r\n";
            request_stream << "Connection: close\r\n\r\n";

            // Send the request.
            boost::asio::write(socket, request);

            // Read the response status line.
            boost::asio::streambuf response;
            boost::asio::read_until(socket, response, "\r\n");

            // Check that response is OK.
            std::istream response_stream(&response);
            std::string http_version;
            response_stream >> http_version;
            unsigned int status_code;
            response_stream >> status_code;
            std::string status_message;
            std::getline(response_stream, status_message);

            // Read the response headers, which are terminated by a blank line.
            boost::asio::read_until(socket, response, "\r\n\r\n");

            // Process the response headers.
            std::string header;
            while (std::getline(response_stream, header) && header != "\r")
            { }

            // Write whatever content we already have to output.
            if (response.size() > 0)
                out << &response;

            // Read until EOF, writing data to output as we go.
            while (boost::asio::read(socket, response, boost::asio::transfer_at_least(1), error))
                out << &response;
        }

        Constants::BinaryTypes GetBinaryType(std::vector<unsigned char> const& data)
        {
            // Check MS-DOS magic
            if (*reinterpret_cast<uint16_t const*>(data.data()) == 0x5A4D)
            {
                uint32_t const peOffset(*reinterpret_cast<uint32_t const*>(data.data() + 0x3C));

                // Check PE magic
                if (*reinterpret_cast<uint32_t const*>(data.data() + peOffset) != 0x4550)
                    throw std::invalid_argument("Not a PE file!");

                return Constants::BinaryTypes(*reinterpret_cast<uint16_t const*>(data.data() + peOffset + 4));
            }
            else
                return Constants::BinaryTypes(*reinterpret_cast<uint32_t const*>(data.data()));
        }

        std::string GetFileChecksum(std::vector<unsigned char> const& data)
        {
            SHA256Hash h;
            h.UpdateData(data.data(), data.size());
            h.Finalize();

            return ByteArrayToHexStr(h.GetDigest(), h.GetLength());
        }

        std::set<size_t> SearchOffset(std::vector<unsigned char> const& binary, std::vector<unsigned char> const& pattern)
        {
            std::set<size_t> offsets;
            for (size_t i = 0; (i + pattern.size()) < binary.size(); i++)
            {
                size_t matches = 0;

                for (size_t j = 0; j < pattern.size(); j++)
                {
                    if (pattern[j] == 0)
                    {
                        matches++;
                        continue;
                    }

                    if (binary[i + j] != pattern[j])
                        break;

                    matches++;
                }

                if (matches == pattern.size())
                {
                    offsets.insert(i);
                    i += matches;
                }
            }

            return offsets.empty() ? throw std::runtime_error("unable to find pattern") : offsets;
        }

        uint32_t GetBuildNumber(std::vector<unsigned char> const& binary)
        {
            std::set<size_t> offsets = SearchOffset(binary, Patterns::Common::BinaryVersion());

            if (!offsets.empty())
            {
                size_t const verOffset = (*offsets.begin());
                std::string ver(&binary[verOffset + 16], &binary[verOffset + 21]);

                return std::stoi(ver);
            }
            return 0;
        }
    }
}