/**
 * Orthanc - A Lightweight, RESTful DICOM Store
 * Copyright (C) 2012-2015 Sebastien Jodogne, Medical Physics
 * Department, University Hospital of Liege, 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.
 * 
 * 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 <orthanc/OrthancCPlugin.h>

#include <json/reader.h>
#include <json/value.h>
#include <string.h>
#include <stdio.h>
#include <fstream>
#include <algorithm>
#include <sys/stat.h>

static OrthancPluginContext* context_ = NULL;
static std::map<std::string, std::string> folders_;
static const char* INDEX_URI = "/app/plugin-serve-folders.html";


static const char* GetMimeType(const std::string& path)
{
  size_t dot = path.find_last_of('.');

  std::string extension = (dot == std::string::npos) ? "" : path.substr(dot);
  std::transform(extension.begin(), extension.end(), extension.begin(), tolower);

  if (extension == ".html")
  {
    return "text/html";
  }
  else if (extension == ".css")
  {
    return "text/css";
  }
  else if (extension == ".js")
  {
    return "application/javascript";
  }
  else if (extension == ".gif")
  {
    return "image/gif";
  }
  else if (extension == ".svg")
  {
    return "image/svg+xml";
  }
  else if (extension == ".json")
  {
    return "application/json";
  }
  else if (extension == ".xml")
  {
    return "application/xml";
  }
  else if (extension == ".png")
  {
    return "image/png";
  }
  else if (extension == ".jpg" || extension == ".jpeg")
  {
    return "image/jpeg";
  }
  else if (extension == ".woff")
  {
    return "application/x-font-woff";
  }
  else
  {
    std::string s = "Unknown MIME type for extension: " + extension;
    OrthancPluginLogWarning(context_, s.c_str());
    return "application/octet-stream";
  }
}



static bool ReadFile(std::string& content,
                     const std::string& path)
{
  struct stat s;
  if (stat(path.c_str(), &s) != 0 ||
      !(s.st_mode & S_IFREG))
  {
    // Either the path does not exist, or it is not a regular file
    return false;
  }

  FILE* fp = fopen(path.c_str(), "rb");
  if (fp == NULL)
  {
    return false;
  }

  long size;

  if (fseek(fp, 0, SEEK_END) == -1 ||
      (size = ftell(fp)) < 0)
  {
    fclose(fp);
    return false;
  }

  content.resize(size);
      
  if (fseek(fp, 0, SEEK_SET) == -1)
  {
    fclose(fp);
    return false;
  }

  bool ok = true;

  if (size > 0 &&
      fread(&content[0], size, 1, fp) != 1)
  {
    ok = false;
  }

  fclose(fp);

  return ok;
}


static bool ReadConfiguration(Json::Value& configuration,
                              OrthancPluginContext* context)
{
  std::string s;

  {
    char* tmp = OrthancPluginGetConfiguration(context);
    if (tmp == NULL)
    {
      OrthancPluginLogError(context, "Error while retrieving the configuration from Orthanc");
      return false;
    }

    s.assign(tmp);
    OrthancPluginFreeString(context, tmp);      
  }

  Json::Reader reader;
  if (reader.parse(s, configuration))
  {
    return true;
  }
  else
  {
    OrthancPluginLogError(context, "Unable to parse the configuration");
    return false;
  }
}


static int32_t FolderCallback(OrthancPluginRestOutput* output,
                              const char* url,
                              const OrthancPluginHttpRequest* request)
{
  if (request->method != OrthancPluginHttpMethod_Get)
  {
    OrthancPluginSendMethodNotAllowed(context_, output, "GET");
    return 0;
  }

  const std::string uri = request->groups[0];
  const std::string item = request->groups[1];

  std::map<std::string, std::string>::const_iterator found = folders_.find(uri);
  if (found == folders_.end())
  {
    std::string s = "Unknown URI in plugin server-folders: " + uri;
    OrthancPluginLogError(context_, s.c_str());
    OrthancPluginSendHttpStatusCode(context_, output, 404);
    return 0;
  }

  std::string path = found->second + "/" + item;
  const char* mime = GetMimeType(path);

  std::string s;
  if (ReadFile(s, path))
  {
    const char* resource = s.size() ? s.c_str() : NULL;
    OrthancPluginAnswerBuffer(context_, output, resource, s.size(), mime);
  }
  else
  {
    std::string s = "Inexistent file in served folder: " + path;
    OrthancPluginLogError(context_, s.c_str());
    OrthancPluginSendHttpStatusCode(context_, output, 404);
  }

  return 0;
}


static int32_t IndexCallback(OrthancPluginRestOutput* output,
                             const char* url,
                             const OrthancPluginHttpRequest* request)
{
  if (request->method != OrthancPluginHttpMethod_Get)
  {
    OrthancPluginSendMethodNotAllowed(context_, output, "GET");
    return 0;
  }

  std::string s = "<html><body><h1>Additional folders served by Orthanc</h1>\n";

  if (folders_.empty())
  {
    s += "<p>Empty section <tt>ServeFolders</tt> in your configuration file: No additional folder is served.</p>\n";
  }
  else
  {
    s += "<ul>\n";
    for (std::map<std::string, std::string>::const_iterator
           it = folders_.begin(); it != folders_.end(); ++it)
    {
      s += "<li><a href=\"" + it->first + "/index.html\">" + it->first + "</li>\n";
    }
    
    s += "</ul>\n";
  }

  s += "</body></html>\n";

  OrthancPluginAnswerBuffer(context_, output, s.c_str(), s.size(), "text/html");

  return 0;
}



extern "C"
{
  ORTHANC_PLUGINS_API int32_t OrthancPluginInitialize(OrthancPluginContext* context)
  {
    context_ = context;

    /* Check the version of the Orthanc core */
    if (OrthancPluginCheckVersion(context_) == 0)
    {
      char info[1024];
      sprintf(info, "Your version of Orthanc (%s) must be above %d.%d.%d to run this plugin",
              context_->orthancVersion,
              ORTHANC_PLUGINS_MINIMAL_MAJOR_NUMBER,
              ORTHANC_PLUGINS_MINIMAL_MINOR_NUMBER,
              ORTHANC_PLUGINS_MINIMAL_REVISION_NUMBER);
      OrthancPluginLogError(context_, info);
      return -1;
    }

    OrthancPluginSetDescription(context_, "Serve additional folders with the HTTP server of Orthanc.");

    Json::Value configuration;
    if (!ReadConfiguration(configuration, context_))
    {
      return -1;
    }

    if (configuration.isMember("ServeFolders"))
    {
      if (configuration["ServeFolders"].type() != Json::objectValue)
      {
        OrthancPluginLogError(context_, "The \"ServeFolders\" configuration section is badly formatted (must be a JSON object)");
        return -1;
      }
    }
    else
    {
      OrthancPluginLogWarning(context_, "No section \"ServeFolders\" in your configuration file: "
                              "No additional folder will be served!");
      configuration["ServeFolders"] = Json::objectValue;
    }


    Json::Value::Members members = configuration["ServeFolders"].getMemberNames();

    // Register the callback for each base URI
    for (Json::Value::Members::const_iterator 
           it = members.begin(); it != members.end(); ++it)
    {
      const std::string& baseUri = *it;
      const std::string path = configuration["ServeFolders"][*it].asString();
      const std::string regex = "(" + baseUri + ")/(.*)";

      if (baseUri.empty() ||
          *baseUri.rbegin() == '/')
      {
        std::string message = "The URI of a folder to be server cannot be empty or end with a '/': " + *it;
        OrthancPluginLogWarning(context_, message.c_str());
        return -1;
      }

      OrthancPluginRegisterRestCallback(context, regex.c_str(), FolderCallback);
      folders_[baseUri] = path;
    }

    OrthancPluginRegisterRestCallback(context, INDEX_URI, IndexCallback);
    OrthancPluginSetRootUri(context, INDEX_URI);

    return 0;
  }


  ORTHANC_PLUGINS_API void OrthancPluginFinalize()
  {
  }


  ORTHANC_PLUGINS_API const char* OrthancPluginGetName()
  {
    return "serve-folders";
  }


  ORTHANC_PLUGINS_API const char* OrthancPluginGetVersion()
  {
    return SERVE_FOLDERS_VERSION;
  }
}