/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, Belgium
 * Copyright (C) 2017-2019 Osimis S.A., Belgium
 *
 * This program is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero 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
 * Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 **/


#include "Configuration.h"

#include "DicomWebServers.h"

#include <Plugins/Samples/Common/OrthancPluginCppWrapper.h>
#include <Core/Toolbox.h>

#include <fstream>
#include <json/reader.h>
#include <boost/regex.hpp>
#include <boost/lexical_cast.hpp>
#include <boost/algorithm/string/predicate.hpp>


namespace OrthancPlugins
{
  bool LookupHttpHeader(std::string& value,
                        const OrthancPluginHttpRequest* request,
                        const std::string& header)
  {
    value.clear();

    for (uint32_t i = 0; i < request->headersCount; i++)
    {
      std::string s = request->headersKeys[i];
      Orthanc::Toolbox::ToLowerCase(s);
      if (s == header)
      {
        value = request->headersValues[i];
        return true;
      }
    }

    return false;
  }


  void ParseContentType(std::string& application,
                        std::map<std::string, std::string>& attributes,
                        const std::string& header)
  {
    application.clear();
    attributes.clear();

    std::vector<std::string> tokens;
    Orthanc::Toolbox::TokenizeString(tokens, header, ';');

    assert(tokens.size() > 0);
    application = tokens[0];
    Orthanc::Toolbox::StripSpaces(application);
    Orthanc::Toolbox::ToLowerCase(application);

    boost::regex pattern("\\s*([^=]+)\\s*=\\s*(([^=\"]+)|\"([^=\"]+)\")\\s*");
    
    for (size_t i = 1; i < tokens.size(); i++)
    {
      boost::cmatch what;
      if (boost::regex_match(tokens[i].c_str(), what, pattern))
      {
        std::string key(what[1]);
        std::string value(what.length(3) != 0 ? what[3] : what[4]);
        Orthanc::Toolbox::ToLowerCase(key);
        attributes[key] = value;
      }
    }
  }


  void ParseAssociativeArray(std::map<std::string, std::string>& target,
                             const Json::Value& value)
  {
    if (value.type() != Json::objectValue)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat,
                                      "The JSON object is not a JSON associative array as expected");
    }

    Json::Value::Members names = value.getMemberNames();

    for (size_t i = 0; i < names.size(); i++)
    {
      if (value[names[i]].type() != Json::stringValue)
      {
        throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat,
                                        "Value \"" + names[i] + "\" in the associative array "
                                        "is not a string as expected");
      }
      else
      {
        target[names[i]] = value[names[i]].asString();
      }
    }
  }
  

  void ParseAssociativeArray(std::map<std::string, std::string>& target,
                             const Json::Value& value,
                             const std::string& key)
  {
    if (value.type() != Json::objectValue)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat,
                                      "This is not a JSON object");
    }

    if (value.isMember(key))
    {
      ParseAssociativeArray(target, value[key]);
    }
    else
    {
      target.clear();
    }
  }


  bool ParseTag(Orthanc::DicomTag& target,
                const std::string& name)
  {
    OrthancPluginDictionaryEntry entry;
    
    if (OrthancPluginLookupDictionary(OrthancPlugins::GetGlobalContext(), &entry, name.c_str()) == OrthancPluginErrorCode_Success)
    {
      target = Orthanc::DicomTag(entry.group, entry.element);
      return true;
    }
    else
    {
      return false;
    }
  }


  void ParseJsonBody(Json::Value& target,
                     const OrthancPluginHttpRequest* request)
  {
    Json::Reader reader;
    if (!reader.parse(reinterpret_cast<const char*>(request->body),
                      reinterpret_cast<const char*>(request->body) + request->bodySize, target))
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat,
                                      "A JSON file was expected");
    }
  }


  std::string RemoveMultipleSlashes(const std::string& source)
  {
    std::string target;
    target.reserve(source.size());

    size_t prefix = 0;
  
    if (boost::starts_with(source, "https://"))
    {
      prefix = 8;
    }
    else if (boost::starts_with(source, "http://"))
    {
      prefix = 7;
    }

    for (size_t i = 0; i < prefix; i++)
    {
      target.push_back(source[i]);
    }

    bool isLastSlash = false;

    for (size_t i = prefix; i < source.size(); i++)
    {
      if (source[i] == '/')
      {
        if (!isLastSlash)
        {
          target.push_back('/');
          isLastSlash = true;
        }
      }
      else
      {
        target.push_back(source[i]);
        isLastSlash = false;
      }
    }

    return target;
  }


  bool LookupStringValue(std::string& target,
                         const Json::Value& json,
                         const std::string& key)
  {
    if (json.type() != Json::objectValue)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat);
    }
    else if (!json.isMember(key))
    {
      return false;
    }
    else if (json[key].type() != Json::stringValue)
    {
      throw Orthanc::OrthancException(
        Orthanc::ErrorCode_BadFileFormat,
        "The field \"" + key + "\" in a JSON object should be a string");
    }
    else
    {
      target = json[key].asString();
      return true;
    }
  }


  bool LookupIntegerValue(int& target,
                          const Json::Value& json,
                          const std::string& key)
  {
    if (json.type() != Json::objectValue)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat);
    }
    else if (!json.isMember(key))
    {
      return false;
    }
    else if (json[key].type() != Json::intValue &&
             json[key].type() != Json::uintValue)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat);      
    }
    else
    {
      target = json[key].asInt();
      return true;
    }
  }


  bool LookupBooleanValue(bool& target,
                          const Json::Value& json,
                          const std::string& key)
  {
    if (json.type() != Json::objectValue)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat);
    }
    else if (!json.isMember(key))
    {
      return false;
    }
    else if (json[key].type() != Json::booleanValue)
    {
      throw Orthanc::OrthancException(Orthanc::ErrorCode_BadFileFormat);      
    }
    else
    {
      target = json[key].asBool();
      return true;
    }
  }


  namespace Configuration
  {
    // Assume Latin-1 encoding by default (as in the Orthanc core)
    static Orthanc::Encoding defaultEncoding_ = Orthanc::Encoding_Latin1;
    static std::auto_ptr<OrthancConfiguration> configuration_;


    void Initialize()
    {
      configuration_.reset(new OrthancConfiguration);
      
      OrthancPlugins::OrthancConfiguration global;
      global.GetSection(*configuration_, "DicomWeb");

      std::string s;
      if (global.LookupStringValue(s, "DefaultEncoding"))
      {
        defaultEncoding_ = Orthanc::StringToEncoding(s.c_str());
      }

      OrthancPlugins::OrthancConfiguration servers;
      configuration_->GetSection(servers, "Servers");
      OrthancPlugins::DicomWebServers::GetInstance().Load(servers.GetJson());
    }


    std::string GetStringValue(const std::string& key,
                               const std::string& defaultValue)
    {
      assert(configuration_.get() != NULL);
      return configuration_->GetStringValue(key, defaultValue);
    }


    bool GetBooleanValue(const std::string& key,
                         bool defaultValue)
    {
      assert(configuration_.get() != NULL);
      return configuration_->GetBooleanValue(key, defaultValue);
    }


    unsigned int GetUnsignedIntegerValue(const std::string& key,
                                         unsigned int defaultValue)
    {
      assert(configuration_.get() != NULL);
      return configuration_->GetUnsignedIntegerValue(key, defaultValue);
    }


    std::string GetDicomWebRoot()
    {
      assert(configuration_.get() != NULL);
      std::string root = configuration_->GetStringValue("Root", "/dicom-web/");

      // Make sure the root URI starts and ends with a slash
      if (root.size() == 0 ||
          root[0] != '/')
      {
        root = "/" + root;
      }
    
      if (root[root.length() - 1] != '/')
      {
        root += "/";
      }

      return root;
    }

    
    std::string GetOrthancApiRoot()
    {
      std::string root = OrthancPlugins::Configuration::GetDicomWebRoot();
      std::vector<std::string> tokens;
      Orthanc::Toolbox::TokenizeString(tokens, root, '/');

      int depth = 0;
      for (size_t i = 0; i < tokens.size(); i++)
      {
        if (tokens[i].empty() ||
            tokens[i] == ".")
        {
          // Don't change the depth
        }
        else if (tokens[i] == "..")
        {
          depth--;
        }
        else
        {
          depth++;
        }
      }

      std::string orthancRoot = "./";
      for (int i = 0; i < depth; i++)
      {
        orthancRoot += "../";
      }

      return orthancRoot;
    }


    std::string GetWadoRoot()
    {
      assert(configuration_.get() != NULL);
      std::string root = configuration_->GetStringValue("WadoRoot", "/wado/");

      // Make sure the root URI starts with a slash
      if (root.size() == 0 ||
          root[0] != '/')
      {
        root = "/" + root;
      }

      // Remove the trailing slash, if any
      if (root[root.length() - 1] == '/')
      {
        root = root.substr(0, root.length() - 1);
      }

      return root;
    }


    static bool IsHttpsProto(const std::string& proto,
                             bool defaultValue)
    {
      if (proto == "http")
      {
        return false;
      }
      else if (proto == "https")
      {
        return true;
      }
      else
      {
        return defaultValue;
      }
    }


    static bool LookupHttpHeader2(std::string& value,
                                  const OrthancPlugins::HttpClient::HttpHeaders& headers,
                                  const std::string& name)
    {
      for (OrthancPlugins::HttpClient::HttpHeaders::const_iterator
             it = headers.begin(); it != headers.end(); ++it)
      {
        if (boost::iequals(it->first, name))
        {
          value = it->second;
          return false;
        }
      }

      return false;
    }


    std::string GetBaseUrl(const OrthancPlugins::HttpClient::HttpHeaders& headers)
    {
      assert(configuration_.get() != NULL);
      std::string host = configuration_->GetStringValue("Host", "");
      bool https = configuration_->GetBooleanValue("Ssl", false);

      std::string forwarded;
      if (host.empty() &&
          LookupHttpHeader2(forwarded, headers, "forwarded"))
      {
        // There is a "Forwarded" HTTP header in the query
        // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Forwarded
        
        std::vector<std::string> forwarders;
        Orthanc::Toolbox::TokenizeString(forwarders, forwarded, ',');

        // Only consider the first forwarder, if any
        if (!forwarders.empty())
        {
          std::vector<std::string> tokens;
          Orthanc::Toolbox::TokenizeString(tokens, forwarders[0], ';');

          for (size_t j = 0; j < tokens.size(); j++)
          {
            std::vector<std::string> args;
            Orthanc::Toolbox::TokenizeString(args, tokens[j], '=');
            
            if (args.size() == 2)
            {
              std::string key = Orthanc::Toolbox::StripSpaces(args[0]);
              std::string value = Orthanc::Toolbox::StripSpaces(args[1]);

              Orthanc::Toolbox::ToLowerCase(key);
              if (key == "host")
              {
                host = value;
              }
              else if (key == "proto")
              {
                https = IsHttpsProto(value, https);
              }
            }
          }
        }
      }

      if (host.empty() &&
          !LookupHttpHeader2(host, headers, "host"))
      {
        // Should never happen: The "host" header should always be present
        // in HTTP requests. Provide a default value anyway.
        host = "localhost:8042";
      }

      return (https ? "https://" : "http://") + host + GetDicomWebRoot();
    }


    std::string GetBaseUrl(const OrthancPluginHttpRequest* request)
    {
      OrthancPlugins::HttpClient::HttpHeaders headers;

      std::string value;
      if (LookupHttpHeader(value, request, "forwarded"))
      {
        headers["Forwarded"] = value;
      }

      if (LookupHttpHeader(value, request, "host"))
      {
        headers["Host"] = value;
      }

      return GetBaseUrl(headers);
    }


    std::string GetWadoUrl(const std::string& wadoBase,
                           const std::string& studyInstanceUid,
                           const std::string& seriesInstanceUid,
                           const std::string& sopInstanceUid)
    {
      if (studyInstanceUid.empty() ||
          seriesInstanceUid.empty() ||
          sopInstanceUid.empty())
      {
        return "";
      }
      else
      {
        return (wadoBase + 
                "studies/" + studyInstanceUid + 
                "/series/" + seriesInstanceUid + 
                "/instances/" + sopInstanceUid + "/");
      }
    }


    Orthanc::Encoding GetDefaultEncoding()
    {
      return defaultEncoding_;
    }


    static bool IsXmlExpected(const std::string& acceptHeader)
    {
      std::string accept;
      Orthanc::Toolbox::ToLowerCase(accept, acceptHeader);
  
      if (accept == "application/dicom+json" ||
          accept == "application/json" ||
          accept == "*/*")
      {
        return false;
      }
      else if (accept == "application/dicom+xml" ||
               accept == "application/xml" ||
               accept == "text/xml")
      {
        return true;
      }
      else
      {
        OrthancPlugins::LogError("Unsupported return MIME type: " + accept +
                                 ", will return DICOM+JSON");
        return false;
      }
    }


    bool IsXmlExpected(const std::map<std::string, std::string>& headers)
    {
      std::map<std::string, std::string>::const_iterator found = headers.find("accept");

      if (found == headers.end())
      {
        return false;   // By default, return DICOM+JSON
      }
      else
      {
        return IsXmlExpected(found->second);
      }
    }


    bool IsXmlExpected(const OrthancPluginHttpRequest* request)
    {
      std::string accept;

      if (OrthancPlugins::LookupHttpHeader(accept, request, "accept"))
      {
        return IsXmlExpected(accept);
      }
      else
      {
        return false;   // By default, return DICOM+JSON
      }
    }
  }
}
