Plugin.h

/*
 * 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 Library 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.
 *
 * Plugin.h
 * Header file for plugin class - plugins inherit from this.
 * Copyright (C) 2005-2008 Simon Newton
 */

#ifndef INCLUDE_OLAD_PLUGIN_H_
#define INCLUDE_OLAD_PLUGIN_H_

#include <ola/plugin_id.h>

#include <set>
#include <string>
#include <functional>

namespace ola {

using std::string;
class PluginAdaptor;

/*
 * The interface for a plugin
 */
class AbstractPlugin {
  public :
    AbstractPlugin() {}
    virtual ~AbstractPlugin() {}

    // load the preferences for a plugin
    virtual bool LoadPreferences() = 0;
    // The location for preferences. This can be anything really but should
    // indicate to the user how how the preferences were loaded.
    virtual string PreferenceSource() const = 0;
    // true if this plugin is enabled
    virtual bool IsEnabled() const = 0;
    // start the plugin
    virtual bool Start() = 0;
    // stop the plugin
    virtual bool Stop() = 0;
    // return the plugin_id of this plugin
    virtual ola_plugin_id Id() const = 0;
    // return the name of this plugin
    virtual string Name() const = 0;
    // return the description of this plugin
    virtual string Description() const = 0;

    virtual void ConflictsWith(std::set<ola_plugin_id> *conflict_set) = 0;

    // used to sort plugins
    virtual bool operator<(const AbstractPlugin &other) const = 0;
};


struct PluginLessThan: public std::binary_function<AbstractPlugin*,
                                                   AbstractPlugin*, bool> {
  bool operator()(AbstractPlugin *x, AbstractPlugin *y) {
    return x->Id() < y->Id();
  }
};


class Plugin: public AbstractPlugin {
  public :
    explicit Plugin(PluginAdaptor *plugin_adaptor):
      AbstractPlugin(),
      m_plugin_adaptor(plugin_adaptor),
      m_preferences(NULL),
      m_enabled(false) {
    }
    virtual ~Plugin() {}

    bool LoadPreferences();
    string PreferenceSource() const;
    bool IsEnabled() const;
    virtual bool Start();
    virtual bool Stop();
    // return true if this plugin is enabled by default
    virtual bool DefaultMode() const { return true; }
    virtual ola_plugin_id Id() const = 0;

    // return the prefix used to identify this plugin
    virtual string PluginPrefix() const = 0;

    // by default we don't conflict with any other plugins
    virtual void ConflictsWith(std::set<ola_plugin_id>*) {}

    bool operator<(const AbstractPlugin &other) const {
      return Id() < other.Id();
    }

  protected:
    virtual bool StartHook() { return 0; }
    virtual bool StopHook() { return 0; }
    virtual bool SetDefaultPreferences() { return true; }

    PluginAdaptor *m_plugin_adaptor;
    class Preferences *m_preferences;  // preferences container
    static const char ENABLED_KEY[];

  private:
    bool m_enabled;  // are we running
    Plugin(const Plugin&);
    Plugin& operator=(const Plugin&);
};
}  // namespace ola

// interface functions
typedef ola::AbstractPlugin* create_t(ola::PluginAdaptor *plugin_adaptor);

#endif  // INCLUDE_OLAD_PLUGIN_H_