/******************************************************************************
 *
 * Project:  OpenCPN
 *
 ***************************************************************************
 *   Copyright (C) 2019 Alec Leamas                                        *
 *                                                                         *
 *   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 2 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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,  USA.         *
 ***************************************************************************
 */

/**
 * Plugin catalog management: Check for available versions and branches,
 * download as required.
 */

#ifndef CATALOG_HANDLER_H__
#define CATALOG_HANDLER_H__

#include <string>
#include <memory>
#include <ostream>
#include <vector>

#include "catalog_parser.h"

/**
 * A local proxy for the catalog server. The server has a number
 * of branches, some of which containing a plugin catalog.
 *
 * Backend code for channel management (which catalog to get) and
 * the important download function.
 *
 * Also: CatalogData handling, basically version and date for
 * various ocpn-plugins.xml.
 */
class CatalogHandler {
public:
  enum class ServerStatus {
    UNKNOWN,
    OK,
    OK_MSG,
    CURL_ERROR,
    JSON_ERROR,
    XML_ERROR,
    OS_ERROR
  };

  static CatalogHandler* getInstance();

  /** Download channel json data, possibly return error code. */
  ServerStatus LoadChannels(std::ostream* json);

  /** Parse and store json channel data, possibly return error code. */
  ServerStatus LoadChannels(const std::string& json);

  /** Get the downloaded list of channels, empty on errors. */
  std::vector<std::string> GetChannels();

  /** Set the active channel used when downloading catalog. */
  bool SetActiveChannel(const char* channel);

  /** Get the branch (a. k. a. channel) used to download. */
  std::string GetActiveChannel();

  /** Set a custom url, overrides also channel settings. */
  void SetCustomUrl(const char* url);

  /** Set a custom url, overrides also channel settings. */
  std::string GetCustomUrl();

  /** Get the default URL, with actual channel included */
  std::string GetDefaultUrl();

  /** Download the latest catalog to given stream. */
  ServerStatus DownloadCatalog(std::ostream* stream);

  /** Download the latest catalog to local path. */
  ServerStatus DownloadCatalog(std::string& path);

  /** Download the specified catalog to given stream. */
  ServerStatus DownloadCatalog(std::ostream* stream, std::string url);

  /** Download the specified catalog to local path. */
  ServerStatus DownloadCatalog(std::string& filePath, std::string url);

  /** Parse XML contents, save as latest data if latest is true. */
  ServerStatus ParseCatalog(const std::string xml, bool latest = false);

  /** Data for default version, installed with main opencpn. */
  CatalogData DefaultCatalogData();

  /** Data for user catalog which overrides the default one. */
  CatalogData UserCatalogData();

  /** Data for latest parsed data marked as latest. */
  CatalogData LatestCatalogData();

  /** Invalidate *CatalogData caches */
  void ClearCatalogData();

  /** Last error message, free format. */
  std::string LastErrorMsg();

  ServerStatus DoParseCatalog(const std::string xml, catalog_ctx* ctx);

protected:
  /** Initiate the handler. */
  CatalogHandler();

  void LoadCatalogData(const std::string& path, CatalogData& data);

  const char* const GET_BRANCHES_PATH = "/repos/OpenCPN/plugins/branches";
  const char* const GITHUB_API = "https://api.github.com";

  const char* const REPO_URL = "https://raw.githubusercontent.com";
  const char* const REPO_PATH = "/OpenCPN/plugins/@branch@/ocpn-plugins.xml";

  const char* const DEFAULT_CHANNEL = "master";

private:
  std::vector<std::string> channels;
  ServerStatus status;
  std::ostream* stream;
  std::string error_msg;
  CatalogData latest_data;
  CatalogData default_data;
  CatalogData user_data;
};

typedef CatalogHandler::ServerStatus catalog_status;

#endif  // CATALOG_HANDLER_H__
