/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2018 Osimis S.A., Belgium
 *
 * 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.
 *
 * In addition, as a special exception, the copyright holders of this
 * program give permission to link the code of its release with the
 * OpenSSL project's "OpenSSL" library (or with modified versions of it
 * that use the same license as the "OpenSSL" library), and distribute
 * the linked executables. You must obey the GNU General Public License
 * in all respects for all of the code used other than "OpenSSL". If you
 * modify file(s) with this exception, you may extend this exception to
 * your version of the file(s), but you are not obligated to do so. If
 * you do not wish to do so, delete this exception statement from your
 * version. If you delete this exception statement from all source files
 * in the program, then also delete it here.
 * 
 * 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 "PrecompiledHeadersServer.h"

#if defined(_WIN32)
// "Please include winsock2.h before windows.h"
#  include <winsock2.h>
#endif

#include "OrthancInitialization.h"
#include "ServerContext.h"

#include "../Core/HttpClient.h"
#include "../Core/Logging.h"
#include "../Core/OrthancException.h"
#include "../Core/Toolbox.h"
#include "../Core/FileStorage/FilesystemStorage.h"

#include "ServerEnumerations.h"
#include "DatabaseWrapper.h"
#include "../Core/DicomParsing/FromDcmtkBridge.h"

#include <boost/lexical_cast.hpp>
#include <boost/filesystem.hpp>
#include <curl/curl.h>
#include <boost/thread/recursive_mutex.hpp>

#include <dcmtk/dcmnet/dul.h>   // For dcmDisableGethostbyaddr()



namespace Orthanc
{
  static boost::recursive_mutex globalMutex_;
  static Json::Value configuration_;
  static boost::filesystem::path defaultDirectory_;
  static std::string configurationAbsolutePath_;
  static FontRegistry fontRegistry_;
  static const char* configurationFileArg_ = NULL;


  static std::string GetGlobalStringParameterInternal(const std::string& parameter,
                                                      const std::string& defaultValue)
  {
    if (configuration_.isMember(parameter))
    {
      if (configuration_[parameter].type() != Json::stringValue)
      {
        LOG(ERROR) << "The configuration option \"" << parameter << "\" must be a string";
        throw OrthancException(ErrorCode_BadParameterType);
      }
      else
      {
        return configuration_[parameter].asString();
      }
    }
    else
    {
      return defaultValue;
    }
  }


  static bool GetGlobalBoolParameterInternal(const std::string& parameter,
                                             bool defaultValue)
  {
    if (configuration_.isMember(parameter))
    {
      if (configuration_[parameter].type() != Json::booleanValue)
      {
        LOG(ERROR) << "The configuration option \"" << parameter << "\" must be a Boolean (true or false)";
        throw OrthancException(ErrorCode_BadParameterType);
      }
      else
      {
        return configuration_[parameter].asBool();
      }
    }
    else
    {
      return defaultValue;
    }
  }



  static void AddFileToConfiguration(Json::Value& target,
                                     const boost::filesystem::path& path)
  {
    LOG(WARNING) << "Reading the configuration from: " << path;

    Json::Value config;

    {
      std::string content;
      SystemToolbox::ReadFile(content, path.string());

      Json::Value tmp;
      Json::Reader reader;
      if (!reader.parse(content, tmp) ||
          tmp.type() != Json::objectValue)
      {
        LOG(ERROR) << "The configuration file does not follow the JSON syntax: " << path;
        throw OrthancException(ErrorCode_BadJson);
      }

      Toolbox::CopyJsonWithoutComments(config, tmp);
    }

    if (target.size() == 0)
    {
      target = config;
    }
    else
    {
      Json::Value::Members members = config.getMemberNames();
      for (Json::Value::ArrayIndex i = 0; i < members.size(); i++)
      {
        if (target.isMember(members[i]))
        {
          LOG(ERROR) << "The configuration section \"" << members[i] << "\" is defined in 2 different configuration files";
          throw OrthancException(ErrorCode_BadFileFormat);          
        }
        else
        {
          target[members[i]] = config[members[i]];
        }
      }
    }
  }


  static void ScanFolderForConfiguration(Json::Value& target,
                                         const char* folder)
  {
    using namespace boost::filesystem;

    LOG(WARNING) << "Scanning folder \"" << folder << "\" for configuration files";

    directory_iterator end_it; // default construction yields past-the-end
    for (directory_iterator it(folder);
         it != end_it;
         ++it)
    {
      if (!is_directory(it->status()))
      {
        std::string extension = boost::filesystem::extension(it->path());
        Toolbox::ToLowerCase(extension);

        if (extension == ".json")
        {
          AddFileToConfiguration(target, it->path().string());
        }
      }
    }
  }


  static void ReadConfiguration(Json::Value& target,
                                const char* configurationFile)
  {
    target = Json::objectValue;

    if (configurationFile)
    {
      if (!boost::filesystem::exists(configurationFile))
      {
        LOG(ERROR) << "Inexistent path to configuration: " << configurationFile;
        throw OrthancException(ErrorCode_InexistentFile);
      }
      
      if (boost::filesystem::is_directory(configurationFile))
      {
        ScanFolderForConfiguration(target, configurationFile);
      }
      else
      {
        AddFileToConfiguration(target, configurationFile);
      }
    }
    else
    {
#if ORTHANC_STANDALONE == 1
      // No default path for the standalone configuration
      LOG(WARNING) << "Using the default Orthanc configuration";
      return;

#else
      // In a non-standalone build, we use the
      // "Resources/Configuration.json" from the Orthanc source code

      boost::filesystem::path p = ORTHANC_PATH;
      p /= "Resources";
      p /= "Configuration.json";

      AddFileToConfiguration(target, p);
#endif
    }
  }



  static void ReadGlobalConfiguration(const char* configurationFile)
  {
    // Read the content of the configuration
    configurationFileArg_ = configurationFile;
    ReadConfiguration(configuration_, configurationFile);

    // Adapt the paths to the configurations
    defaultDirectory_ = boost::filesystem::current_path();
    configurationAbsolutePath_ = "";

    if (configurationFile)
    {
      if (boost::filesystem::is_directory(configurationFile))
      {
        defaultDirectory_ = boost::filesystem::path(configurationFile);
        configurationAbsolutePath_ = boost::filesystem::absolute(configurationFile).parent_path().string();
      }
      else
      {
        defaultDirectory_ = boost::filesystem::path(configurationFile).parent_path();
        configurationAbsolutePath_ = boost::filesystem::absolute(configurationFile).string();
      }
    }
    else
    {
#if ORTHANC_STANDALONE != 1
      // In a non-standalone build, we use the
      // "Resources/Configuration.json" from the Orthanc source code

      boost::filesystem::path p = ORTHANC_PATH;
      p /= "Resources";
      p /= "Configuration.json";
      configurationAbsolutePath_ = boost::filesystem::absolute(p).string();
#endif
    }
  }


  static void ValidateGlobalConfiguration()
  {
    std::set<std::string> ids;

    Configuration::GetListOfOrthancPeers(ids);
    for (std::set<std::string>::const_iterator it = ids.begin(); it != ids.end(); ++it)
    {
      WebServiceParameters peer;
      Configuration::GetOrthancPeer(peer, *it);
      peer.CheckClientCertificate();
    }

    Configuration::GetListOfDicomModalities(ids);
    for (std::set<std::string>::const_iterator it = ids.begin(); it != ids.end(); ++it)
    {
      RemoteModalityParameters modality;
      Configuration::GetDicomModalityUsingSymbolicName(modality, *it);
    }
  }


  static void RegisterUserMetadata()
  {
    if (configuration_.isMember("UserMetadata"))
    {
      const Json::Value& parameter = configuration_["UserMetadata"];

      Json::Value::Members members = parameter.getMemberNames();
      for (size_t i = 0; i < members.size(); i++)
      {
        const std::string& name = members[i];

        if (!parameter[name].isInt())
        {
          LOG(ERROR) << "Not a number in this user-defined metadata: " << name;
          throw OrthancException(ErrorCode_BadParameterType);
        }

        int metadata = parameter[name].asInt();        

        LOG(INFO) << "Registering user-defined metadata: " << name << " (index " 
                  << metadata << ")";

        try
        {
          RegisterUserMetadata(metadata, name);
        }
        catch (OrthancException&)
        {
          LOG(ERROR) << "Cannot register this user-defined metadata: " << name;
          throw;
        }
      }
    }
  }


  static void RegisterUserContentType()
  {
    if (configuration_.isMember("UserContentType"))
    {
      const Json::Value& parameter = configuration_["UserContentType"];

      Json::Value::Members members = parameter.getMemberNames();
      for (size_t i = 0; i < members.size(); i++)
      {
        const std::string& name = members[i];
        std::string mime = "application/octet-stream";

        const Json::Value& value = parameter[name];
        int contentType;

        if (value.isArray() &&
            value.size() == 2 &&
            value[0].isInt() &&
            value[1].isString())
        {
          contentType = value[0].asInt();
          mime = value[1].asString();
        }
        else if (value.isInt())
        {
          contentType = value.asInt();
        }
        else
        {
          LOG(ERROR) << "Not a number in this user-defined attachment type: " << name;
          throw OrthancException(ErrorCode_BadParameterType);
        }

        LOG(INFO) << "Registering user-defined attachment type: " << name << " (index " 
                  << contentType << ") with MIME type \"" << mime << "\"";

        try
        {
          RegisterUserContentType(contentType, name, mime);
        }
        catch (OrthancException&)
        {
          throw;
        }
      }
    }
  }


  static void LoadCustomDictionary(const Json::Value& configuration)
  {
    if (configuration.type() != Json::objectValue ||
        !configuration.isMember("Dictionary") ||
        configuration["Dictionary"].type() != Json::objectValue)
    {
      return;
    }

    Json::Value::Members tags(configuration["Dictionary"].getMemberNames());

    for (Json::Value::ArrayIndex i = 0; i < tags.size(); i++)
    {
      const Json::Value& content = configuration["Dictionary"][tags[i]];
      if (content.type() != Json::arrayValue ||
          content.size() < 2 ||
          content.size() > 5 ||
          content[0].type() != Json::stringValue ||
          content[1].type() != Json::stringValue ||
          (content.size() >= 3 && content[2].type() != Json::intValue) ||
          (content.size() >= 4 && content[3].type() != Json::intValue) ||
          (content.size() >= 5 && content[4].type() != Json::stringValue))
      {
        throw OrthancException(ErrorCode_BadFileFormat);
      }

      DicomTag tag(FromDcmtkBridge::ParseTag(tags[i]));
      ValueRepresentation vr = StringToValueRepresentation(content[0].asString(), true);
      std::string name = content[1].asString();
      unsigned int minMultiplicity = (content.size() >= 2) ? content[2].asUInt() : 1;
      unsigned int maxMultiplicity = (content.size() >= 3) ? content[3].asUInt() : 1;
      std::string privateCreator = (content.size() >= 4) ? content[4].asString() : "";

      FromDcmtkBridge::RegisterDictionaryTag(tag, vr, name, minMultiplicity, maxMultiplicity, privateCreator);
    }
  }


  static void ConfigurePkcs11(const Json::Value& config)
  {
    if (config.type() != Json::objectValue ||
        !config.isMember("Module") ||
        config["Module"].type() != Json::stringValue)
    {
      LOG(ERROR) << "No path to the PKCS#11 module (DLL or .so) is provided for HTTPS client authentication";
      throw OrthancException(ErrorCode_BadFileFormat);
    }

    std::string pin;
    if (config.isMember("Pin"))
    {
      if (config["Pin"].type() == Json::stringValue)
      {
        pin = config["Pin"].asString();
      }
      else
      {
        LOG(ERROR) << "The PIN number in the PKCS#11 configuration must be a string";
        throw OrthancException(ErrorCode_BadFileFormat);
      }
    }

    bool verbose = false;
    if (config.isMember("Verbose"))
    {
      if (config["Verbose"].type() == Json::booleanValue)
      {
        verbose = config["Verbose"].asBool();
      }
      else
      {
        LOG(ERROR) << "The Verbose option in the PKCS#11 configuration must be a Boolean";
        throw OrthancException(ErrorCode_BadFileFormat);
      }
    }

    HttpClient::InitializePkcs11(config["Module"].asString(), pin, verbose);
  }



  void OrthancInitialize(const char* configurationFile)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);

    Toolbox::InitializeOpenSsl();

    InitializeServerEnumerations();

    // Read the user-provided configuration
    ReadGlobalConfiguration(configurationFile);
    ValidateGlobalConfiguration();

    if (configuration_.isMember("Locale"))
    {
      std::string locale = GetGlobalStringParameterInternal("Locale", "");
      Toolbox::InitializeGlobalLocale(configuration_["Locale"].asCString());
    }
    else
    {
      Toolbox::InitializeGlobalLocale(NULL);
    }

    if (configuration_.isMember("DefaultEncoding"))
    {
      std::string encoding = GetGlobalStringParameterInternal("DefaultEncoding", "");
      SetDefaultDicomEncoding(StringToEncoding(encoding.c_str()));
    }
    else
    {
      SetDefaultDicomEncoding(ORTHANC_DEFAULT_DICOM_ENCODING);
    }

    if (configuration_.isMember("Pkcs11"))
    {
      ConfigurePkcs11(configuration_["Pkcs11"]);
    }

    HttpClient::GlobalInitialize();

    RegisterUserMetadata();
    RegisterUserContentType();

    FromDcmtkBridge::InitializeDictionary(GetGlobalBoolParameterInternal("LoadPrivateDictionary", true));
    LoadCustomDictionary(configuration_);

    FromDcmtkBridge::InitializeCodecs();

    fontRegistry_.AddFromResource(EmbeddedResources::FONT_UBUNTU_MONO_BOLD_16);

    /* Disable "gethostbyaddr" (which results in memory leaks) and use raw IP addresses */
    dcmDisableGethostbyaddr.set(OFTrue);
  }



  void OrthancFinalize()
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);
    HttpClient::GlobalFinalize();
    FromDcmtkBridge::FinalizeCodecs();
    Toolbox::FinalizeOpenSsl();
    Toolbox::FinalizeGlobalLocale();
  }


  std::string Configuration::GetGlobalStringParameter(const std::string& parameter,
                                                      const std::string& defaultValue)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);
    return GetGlobalStringParameterInternal(parameter, defaultValue);
  }


  int Configuration::GetGlobalIntegerParameter(const std::string& parameter,
                                               int defaultValue)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);

    if (configuration_.isMember(parameter))
    {
      if (configuration_[parameter].type() != Json::intValue)
      {
        LOG(ERROR) << "The configuration option \"" << parameter << "\" must be an integer";
        throw OrthancException(ErrorCode_BadParameterType);
      }
      else
      {
        return configuration_[parameter].asInt();
      }
    }
    else
    {
      return defaultValue;
    }
  }


  unsigned int Configuration::GetGlobalUnsignedIntegerParameter(const std::string& parameter,
                                                                unsigned int defaultValue)
  {
    int v = GetGlobalIntegerParameter(parameter, defaultValue);

    if (v < 0)
    {
      LOG(ERROR) << "The configuration option \"" << parameter << "\" must be a positive integer";
      throw OrthancException(ErrorCode_ParameterOutOfRange);
    }
    else
    {
      return static_cast<unsigned int>(v);
    }
  }


  bool Configuration::GetGlobalBoolParameter(const std::string& parameter,
                                             bool defaultValue)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);
    return GetGlobalBoolParameterInternal(parameter, defaultValue);
  }


  void Configuration::GetDicomModalityUsingSymbolicName(RemoteModalityParameters& modality,
                                                        const std::string& name)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);

    if (!configuration_.isMember("DicomModalities"))
    {
      LOG(ERROR) << "No modality with symbolic name: " << name;
      throw OrthancException(ErrorCode_InexistentItem);
    }

    const Json::Value& modalities = configuration_["DicomModalities"];
    if (modalities.type() != Json::objectValue ||
        !modalities.isMember(name))
    {
      LOG(ERROR) << "No modality with symbolic name: " << name;
      throw OrthancException(ErrorCode_InexistentItem);
    }

    try
    {
      modality.Unserialize(modalities[name]);
    }
    catch (OrthancException&)
    {
      LOG(ERROR) << "Syntax error in the definition of DICOM modality \"" << name 
                 << "\". Please check your configuration file.";
      throw;
    }
  }


  bool Configuration::GetOrthancPeer(WebServiceParameters& peer,
                                     const std::string& name)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);

    if (!configuration_.isMember("OrthancPeers"))
    {
      return false;
    }

    try
    {
      const Json::Value& modalities = configuration_["OrthancPeers"];
      if (modalities.type() != Json::objectValue ||
          !modalities.isMember(name))
      {
        return false;
      }
      else
      {
        peer.Unserialize(modalities[name]);
        return true;
      }
    }
    catch (OrthancException&)
    {
      LOG(ERROR) << "Syntax error in the definition of peer \"" << name 
                 << "\". Please check your configuration file.";
      throw;
    }
  }


  static bool ReadKeys(std::set<std::string>& target,
                       const char* parameter,
                       bool onlyAlphanumeric)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);

    target.clear();
  
    if (!configuration_.isMember(parameter))
    {
      return true;
    }

    const Json::Value& modalities = configuration_[parameter];
    if (modalities.type() != Json::objectValue)
    {
      LOG(ERROR) << "Bad format of the \"DicomModalities\" configuration section";
      throw OrthancException(ErrorCode_BadFileFormat);
    }

    Json::Value::Members members = modalities.getMemberNames();
    for (size_t i = 0; i < members.size(); i++)
    {
      if (onlyAlphanumeric)
      {
        for (size_t j = 0; j < members[i].size(); j++)
        {
          if (!isalnum(members[i][j]) && members[i][j] != '-')
          {
            return false;
          }
        }
      }

      target.insert(members[i]);
    }

    return true;
  }


  void Configuration::GetListOfDicomModalities(std::set<std::string>& target)
  {
    target.clear();

    if (!ReadKeys(target, "DicomModalities", true))
    {
      LOG(ERROR) << "Only alphanumeric and dash characters are allowed in the names of the modalities";
      throw OrthancException(ErrorCode_BadFileFormat);
    }
  }


  void Configuration::GetListOfOrthancPeers(std::set<std::string>& target)
  {
    target.clear();

    if (!ReadKeys(target, "OrthancPeers", true))
    {
      LOG(ERROR) << "Only alphanumeric and dash characters are allowed in the names of Orthanc peers";
      throw OrthancException(ErrorCode_BadFileFormat);
    }
  }



  void Configuration::SetupRegisteredUsers(MongooseServer& httpServer)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);

    httpServer.ClearUsers();

    if (!configuration_.isMember("RegisteredUsers"))
    {
      return;
    }

    const Json::Value& users = configuration_["RegisteredUsers"];
    if (users.type() != Json::objectValue)
    {
      LOG(ERROR) << "Badly formatted list of users";
      throw OrthancException(ErrorCode_BadFileFormat);
    }

    Json::Value::Members usernames = users.getMemberNames();
    for (size_t i = 0; i < usernames.size(); i++)
    {
      const std::string& username = usernames[i];
      std::string password = users[username].asString();
      httpServer.RegisterUser(username.c_str(), password.c_str());
    }
  }


  std::string Configuration::InterpretRelativePath(const std::string& baseDirectory,
                                                   const std::string& relativePath)
  {
    boost::filesystem::path base(baseDirectory);
    boost::filesystem::path relative(relativePath);

    /**
       The following lines should be equivalent to this one: 

       return (base / relative).string();

       However, for some unknown reason, some versions of Boost do not
       make the proper path resolution when "baseDirectory" is an
       absolute path. So, a hack is used below.
    **/

    if (relative.is_absolute())
    {
      return relative.string();
    }
    else
    {
      return (base / relative).string();
    }
  }

  std::string Configuration::InterpretStringParameterAsPath(const std::string& parameter)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);
    return InterpretRelativePath(defaultDirectory_.string(), parameter);
  }


  void Configuration::GetGlobalListOfStringsParameter(std::list<std::string>& target,
                                                      const std::string& key)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);

    target.clear();
  
    if (!configuration_.isMember(key))
    {
      return;
    }

    const Json::Value& lst = configuration_[key];

    if (lst.type() != Json::arrayValue)
    {
      LOG(ERROR) << "Badly formatted list of strings";
      throw OrthancException(ErrorCode_BadFileFormat);
    }

    for (Json::Value::ArrayIndex i = 0; i < lst.size(); i++)
    {
      target.push_back(lst[i].asString());
    }    
  }


  bool Configuration::IsSameAETitle(const std::string& aet1,
                                    const std::string& aet2)
  {
    if (GetGlobalBoolParameter("StrictAetComparison", false))
    {
      // Case-sensitive matching
      return aet1 == aet2;
    }
    else
    {
      // Case-insensitive matching (default)
      std::string tmp1, tmp2;
      Toolbox::ToLowerCase(tmp1, aet1);
      Toolbox::ToLowerCase(tmp2, aet2);
      return tmp1 == tmp2;
    }
  }


  bool Configuration::LookupDicomModalityUsingAETitle(RemoteModalityParameters& modality,
                                                      const std::string& aet)
  {
    std::set<std::string> modalities;
    GetListOfDicomModalities(modalities);

    for (std::set<std::string>::const_iterator 
           it = modalities.begin(); it != modalities.end(); ++it)
    {
      try
      {
        GetDicomModalityUsingSymbolicName(modality, *it);

        if (IsSameAETitle(aet, modality.GetApplicationEntityTitle()))
        {
          return true;
        }
      }
      catch (OrthancException&)
      {
      }
    }

    return false;
  }


  bool Configuration::IsKnownAETitle(const std::string& aet,
                                     const std::string& ip)
  {
    RemoteModalityParameters modality;
    
    if (!LookupDicomModalityUsingAETitle(modality, aet))
    {
      LOG(WARNING) << "Modality \"" << aet
                   << "\" is not listed in the \"DicomModalities\" configuration option";
      return false;
    }
    else if (!Configuration::GetGlobalBoolParameter("DicomCheckModalityHost", false) ||
             ip == modality.GetHost())
    {
      return true;
    }
    else
    {
      LOG(WARNING) << "Forbidding access from AET \"" << aet
                   << "\" given its hostname (" << ip << ") does not match "
                   << "the \"DicomModalities\" configuration option ("
                   << modality.GetHost() << " was expected)";
      return false;
    }
  }


  RemoteModalityParameters Configuration::GetModalityUsingSymbolicName(const std::string& name)
  {
    RemoteModalityParameters modality;
    GetDicomModalityUsingSymbolicName(modality, name);

    return modality;
  }


  RemoteModalityParameters Configuration::GetModalityUsingAet(const std::string& aet)
  {
    RemoteModalityParameters modality;

    if (LookupDicomModalityUsingAETitle(modality, aet))
    {
      return modality;
    }
    else
    {
      LOG(ERROR) << "Unknown modality for AET: " << aet;
      throw OrthancException(ErrorCode_InexistentItem);
    }
  }


  void Configuration::UpdateModality(ServerContext& context,
                                     const std::string& symbolicName,
                                     const RemoteModalityParameters& modality)
  {
    {
      boost::recursive_mutex::scoped_lock lock(globalMutex_);

      if (!configuration_.isMember("DicomModalities"))
      {
        configuration_["DicomModalities"] = Json::objectValue;
      }

      Json::Value& modalities = configuration_["DicomModalities"];
      if (modalities.type() != Json::objectValue)
      {
        LOG(ERROR) << "Bad file format for modality: " << symbolicName;
        throw OrthancException(ErrorCode_BadFileFormat);
      }

      modalities.removeMember(symbolicName);

      Json::Value v;
      modality.Serialize(v, true /* force advanced format */);
      modalities[symbolicName] = v;
    }

#if ORTHANC_ENABLE_PLUGINS == 1
    if (context.HasPlugins())
    {
      context.GetPlugins().SignalUpdatedModalities();
    }
#endif
  }
  

  void Configuration::RemoveModality(ServerContext& context,
                                     const std::string& symbolicName)
  {
    {
      boost::recursive_mutex::scoped_lock lock(globalMutex_);

      if (!configuration_.isMember("DicomModalities"))
      {
        LOG(ERROR) << "No modality with symbolic name: " << symbolicName;
        throw OrthancException(ErrorCode_BadFileFormat);
      }

      Json::Value& modalities = configuration_["DicomModalities"];
      if (modalities.type() != Json::objectValue)
      {
        LOG(ERROR) << "Bad file format for the \"DicomModalities\" configuration section";
        throw OrthancException(ErrorCode_BadFileFormat);
      }

      modalities.removeMember(symbolicName.c_str());
    }

#if ORTHANC_ENABLE_PLUGINS == 1
    if (context.HasPlugins())
    {
      context.GetPlugins().SignalUpdatedModalities();
    }
#endif
  }


  void Configuration::UpdatePeer(ServerContext& context,
                                 const std::string& symbolicName,
                                 const WebServiceParameters& peer)
  {
    peer.CheckClientCertificate();

    {
      boost::recursive_mutex::scoped_lock lock(globalMutex_);

      if (!configuration_.isMember("OrthancPeers"))
      {
        LOG(ERROR) << "No peer with symbolic name: " << symbolicName;
        configuration_["OrthancPeers"] = Json::objectValue;
      }

      Json::Value& peers = configuration_["OrthancPeers"];
      if (peers.type() != Json::objectValue)
      {
        LOG(ERROR) << "Bad file format for the \"OrthancPeers\" configuration section";
        throw OrthancException(ErrorCode_BadFileFormat);
      }

      peers.removeMember(symbolicName);

      Json::Value v;
      peer.Serialize(v, 
                     false /* use simple format if possible */, 
                     true  /* include passwords */);
      peers[symbolicName] = v;
    }

#if ORTHANC_ENABLE_PLUGINS == 1
    if (context.HasPlugins())
    {
      context.GetPlugins().SignalUpdatedPeers();
    }
#endif
  }
  

  void Configuration::RemovePeer(ServerContext& context,
                                 const std::string& symbolicName)
  {
    {
      boost::recursive_mutex::scoped_lock lock(globalMutex_);

      if (!configuration_.isMember("OrthancPeers"))
      {
        LOG(ERROR) << "No peer with symbolic name: " << symbolicName;
        throw OrthancException(ErrorCode_BadFileFormat);
      }

      Json::Value& peers = configuration_["OrthancPeers"];
      if (peers.type() != Json::objectValue)
      {
        LOG(ERROR) << "Bad file format for the \"OrthancPeers\" configuration section";
        throw OrthancException(ErrorCode_BadFileFormat);
      }

      peers.removeMember(symbolicName.c_str());
    }

#if ORTHANC_ENABLE_PLUGINS == 1
    if (context.HasPlugins())
    {
      context.GetPlugins().SignalUpdatedPeers();
    }
#endif
  }


  
  const std::string& Configuration::GetConfigurationAbsolutePath()
  {
    return configurationAbsolutePath_;
  }


  static IDatabaseWrapper* CreateSQLiteWrapper()
  {
    std::string storageDirectoryStr = Configuration::GetGlobalStringParameter("StorageDirectory", "OrthancStorage");

    // Open the database
    boost::filesystem::path indexDirectory = Configuration::InterpretStringParameterAsPath(
      Configuration::GetGlobalStringParameter("IndexDirectory", storageDirectoryStr));

    LOG(WARNING) << "SQLite index directory: " << indexDirectory;

    try
    {
      boost::filesystem::create_directories(indexDirectory);
    }
    catch (boost::filesystem::filesystem_error&)
    {
    }

    return new DatabaseWrapper(indexDirectory.string() + "/index");
  }


  namespace
  {
    // Anonymous namespace to avoid clashes between compilation modules

    class FilesystemStorageWithoutDicom : public IStorageArea
    {
    private:
      FilesystemStorage storage_;

    public:
      FilesystemStorageWithoutDicom(const std::string& path) : storage_(path)
      {
      }

      virtual void Create(const std::string& uuid,
                          const void* content, 
                          size_t size,
                          FileContentType type)
      {
        if (type != FileContentType_Dicom)
        {
          storage_.Create(uuid, content, size, type);
        }
      }

      virtual void Read(std::string& content,
                        const std::string& uuid,
                        FileContentType type)
      {
        if (type != FileContentType_Dicom)
        {
          storage_.Read(content, uuid, type);
        }
        else
        {
          throw OrthancException(ErrorCode_UnknownResource);
        }
      }

      virtual void Remove(const std::string& uuid,
                          FileContentType type) 
      {
        if (type != FileContentType_Dicom)
        {
          storage_.Remove(uuid, type);
        }
      }
    };
  }


  static IStorageArea* CreateFilesystemStorage()
  {
    std::string storageDirectoryStr = Configuration::GetGlobalStringParameter("StorageDirectory", "OrthancStorage");

    boost::filesystem::path storageDirectory = Configuration::InterpretStringParameterAsPath(storageDirectoryStr);
    LOG(WARNING) << "Storage directory: " << storageDirectory;

    if (Configuration::GetGlobalBoolParameter("StoreDicom", true))
    {
      return new FilesystemStorage(storageDirectory.string());
    }
    else
    {
      LOG(WARNING) << "The DICOM files will not be stored, Orthanc running in index-only mode";
      return new FilesystemStorageWithoutDicom(storageDirectory.string());
    }
  }


  IDatabaseWrapper* Configuration::CreateDatabaseWrapper()
  {
    return CreateSQLiteWrapper();
  }


  IStorageArea* Configuration::CreateStorageArea()
  {
    return CreateFilesystemStorage();
  }  


  void Configuration::GetConfiguration(Json::Value& result)
  {
    boost::recursive_mutex::scoped_lock lock(globalMutex_);
    result = configuration_;
  }


  void Configuration::FormatConfiguration(std::string& result)
  {
    Json::Value config;
    GetConfiguration(config);

    Json::StyledWriter w;
    result = w.write(config);
  }


  const FontRegistry& Configuration::GetFontRegistry()
  {
    return fontRegistry_;
  }


  void Configuration::SetDefaultEncoding(Encoding encoding)
  {
    SetDefaultDicomEncoding(encoding);

    {
      // Propagate the encoding to the configuration file that is
      // stored in memory
      boost::recursive_mutex::scoped_lock lock(globalMutex_);
      configuration_["DefaultEncoding"] = EnumerationToString(encoding);
    }
  }


  bool Configuration::HasConfigurationChanged()
  {
    Json::Value starting;
    GetConfiguration(starting);

    Json::Value current;
    ReadConfiguration(current, configurationFileArg_);

    Json::FastWriter writer;
    std::string a = writer.write(starting);
    std::string b = writer.write(current);

    return a != b;
  }
}