// libTorrent - BitTorrent library
// Copyright (C) 2005-2011, Jari Sundell
//
// 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// In addition, as a special exception, the copyright holders give
// permission to link the code of portions of this program with the
// OpenSSL library under certain conditions as described in each
// individual source file, and distribute linked combinations
// including the two.
//
// 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.
//
// Contact:  Jari Sundell <jaris@ifi.uio.no>
//
//           Skomakerveien 33
//           3185 Skoppum, NORWAY

#ifndef LIBTORRENT_PEER_RESOURCE_MANAGER_H
#define LIBTORRENT_PEER_RESOURCE_MANAGER_H

#include <string>
#include <vector>
#include <cinttypes>
#include <torrent/common.h>

namespace torrent {

// This class will handle the division of various resources like
// uploads. For now the weight is equal to the value of the priority.
//
// Although the ConnectionManager class keeps a tally of open sockets,
// we still need to balance them across the different downloads so
// ResourceManager will also keep track of those.
//
// Add unlimited handling later.

class choke_group;
class DownloadMain;
class Rate;
class ResourceManager;

class LIBTORRENT_EXPORT resource_manager_entry {
public:
  friend class ResourceManager;

  resource_manager_entry(DownloadMain* d = NULL, uint16_t pri = 0, uint16_t grp = 0) :
    m_download(d), m_priority(pri), m_group(grp) {}

  DownloadMain*       download()         { return m_download; }
  const DownloadMain* c_download() const { return m_download; }

  uint16_t            priority() const   { return m_priority; }
  uint16_t            group() const      { return m_group; }

  const Rate*         up_rate() const;
  const Rate*         down_rate() const;

protected:
  void                set_priority(uint16_t pri) { m_priority = pri; }
  void                set_group(uint16_t grp)    { m_group = grp; }

private:
  DownloadMain*       m_download;

  uint16_t            m_priority;
  uint16_t            m_group;
};


class LIBTORRENT_EXPORT ResourceManager :
    private std::vector<resource_manager_entry>,
    private std::vector<choke_group*> {
public:
  using base_type       = std::vector<resource_manager_entry>;
  using choke_base_type = std::vector<choke_group*>;
  using value_type      = base_type::value_type;
  using iterator        = base_type::iterator;

  using group_iterator = choke_base_type::iterator;

  using base_type::begin;
  using base_type::end;
  using base_type::size;
  using base_type::capacity;

  ResourceManager() = default;
  ~ResourceManager();

  void                insert(DownloadMain* d, uint16_t priority) { insert(value_type(d, priority)); }
  void                erase(DownloadMain* d);

  void                push_group(const std::string& name);

  iterator            find(const DownloadMain* d);
  iterator            find_throw(const DownloadMain* d);
  iterator            find_group_end(uint16_t group);

  unsigned int            group_size() const                    { return choke_base_type::size(); }
  choke_group*            group_back()                          { return choke_base_type::back(); }

  choke_group*            group_at(uint16_t grp);
  choke_group*            group_at_name(const std::string& name);

  int                     group_index_of(const std::string& name);

  group_iterator          group_begin() { return choke_base_type::begin(); }
  group_iterator          group_end()   { return choke_base_type::end(); }

  resource_manager_entry& entry_at(const DownloadMain* d) { return *find_throw(d); }

  static void         set_priority(iterator itr, uint16_t pri);
  void                set_group(iterator itr, uint16_t grp);

  // When setting this, make sure you choke peers, else change
  // receive_can_unchoke.
  unsigned int        currently_upload_unchoked() const         { return m_currentlyUploadUnchoked; }
  unsigned int        currently_download_unchoked() const       { return m_currentlyDownloadUnchoked; }

  unsigned int        max_upload_unchoked() const               { return m_maxUploadUnchoked; }
  unsigned int        max_download_unchoked() const             { return m_maxDownloadUnchoked; }

  void                set_max_upload_unchoked(unsigned int m);
  void                set_max_download_unchoked(unsigned int m);

  void                receive_upload_unchoke(int num);
  void                receive_download_unchoke(int num);

  int                 retrieve_upload_can_unchoke() const;
  int                 retrieve_download_can_unchoke() const;

  void                receive_tick();

private:
  ResourceManager(const ResourceManager&) = delete;
  ResourceManager& operator=(const ResourceManager&) = delete;

  iterator            insert(const resource_manager_entry& entry);

  void                update_group_iterators();
  void                validate_group_iterators();

  unsigned int        total_weight() const;

  int                 balance_unchoked(unsigned int weight, unsigned int max_unchoked, bool is_up);

  unsigned int        m_currentlyUploadUnchoked{0};
  unsigned int        m_currentlyDownloadUnchoked{0};

  unsigned int        m_maxUploadUnchoked{0};
  unsigned int        m_maxDownloadUnchoked{0};
};

} // namespace torrent

#endif