/*
 * ActionQueue.hpp
 *
 *  Created on: Aug 16, 2013
 *      Author: heber
 */

#ifndef ACTIONQUEUE_HPP_
#define ACTIONQUEUE_HPP_

// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "CodePatterns/Singleton.hpp"

#include "CodePatterns/Observer/Channels.hpp"
#include "CodePatterns/Observer/Observable.hpp"

#ifdef HAVE_ACTION_THREAD
#include <boost/thread.hpp>
#endif
#include <vector>

#include "Actions/Action.hpp"
#include "Actions/ActionState.hpp"
#include "Actions/ActionStatusList.hpp"

#ifdef HAVE_ACTION_THREAD
void stopQueue();
void waitQueue();
#endif

class CommandLineParser;

namespace MoleCuilder {

class ActionHistory;
class ActionRegistry;
class ActionTrait;
class DryRunAdvocate;

namespace Queuedetail {
  template <class T> const T* lastChanged()
  {
    ASSERT(0, "Queuedetail::lastChanged() - only specializations may be used.");
    return NULL;
  }
}

/** This class combines the whole handling of Actions into a single class.
 *
 * It spawns new Actions by its internal ActionRegistry. Spawned Actions are
 * automatically queued and placed into a History after execution.
 */
class ActionQueue : public Singleton<ActionQueue>, public Observable
{
  friend class Singleton<ActionQueue>;
public:
  typedef std::vector<std::string> ActionTokens_t;
  typedef std::vector< Action * > ActionQueue_t;

  //!> channels for this observable
  enum NotificationType {
    ActionQueued,  // new action was queued
    NotificationType_MAX  // denotes the maximum of available notification types
  };

  //>! access to last changed element (atom or molecule)
  template <class T> const T* lastChanged() const
  { return Queuedetail::lastChanged<T>(); }

  /** Queues the Action with \a name to be called.
   *
   * \param name token of Action to actionqueue
   * \param state whether Actions needs to be filled via a Dialog or not
   */
  void queueAction(const std::string &name, enum Action::QueryOptions state = Action::Interactive);

  /** Returns the spawned action by token \a name.
   *
   * Action is checked into internal actionqueue.
   *
   * \return ref to newly spawned action
   */
  const Action& getActionByName(const std::string &name);

  /** Checks whether the Action is known by the given \a name.
   *
   * \param name token of action to check
   * \return true - token is known, false - else
   */
  bool isActionKnownByName(const std::string &name) const;

  /** Register an Action with the ActionRegistry.
   *
   * \param _action action to add
   */
  void registerAction(Action *_action);

  /** Returns the vector with the tokens of all currently known Actions.
   *
   * \return list of all tokens
   */
  const ActionTokens_t getListOfActions() const;

  /** Returns the trait to an Action.
   *
   * \param name name of Action
   * \return const ref to its default Trait.
   */
  const ActionTrait& getActionsTrait(const std::string &name) const;

  /** Print the current contents of the actionqueue as CLI instantiated list of Actions.
   *
   * This is useful for storing the current session.
   *
   * \param output output stream to print to
   */
  void outputAsCLI(std::ostream &output) const;

  /** Print the current contents of the actionqueue as Python instantiated list of Actions.
   *
   * This is useful for storing the current session.
   *
   * \param output output stream to print to
   */
  void outputAsPython(std::ostream &output) const;

  /** Undoes last called Acfriend void ::cleanUp();tion.
   *
   */
  void undoLast();

  /** Redoes last undone Action.
   *
   */
  void redoLast();

  /** Checks whether there is one completed Action stored in ActionHistory in the past.
   *
   * @return true - at least one Action to undo present, false - else
   */
  bool canUndo() const;

  /** Checks whether there is one completed Action stored in ActionHistory in the future.
   *
   * @return true - at least one Action to redo present, false - else
   */
  bool canRedo() const;

  /** Return status of last executed action.
   *
   * \return true - action executed correctly, false - else
   */
  bool getLastActionOk() const
  {  return lastActionOk; }

  /** Getter to ref to list of status messages.
   *
   * This is meant for UIs to registers as Observables.
   *
   * \return ref to StatusList variable
   */
  ActionStatusList& getStatusList()
  { return StatusList; }

  /** Getter for isDryRun state flag.
   *
   * \return true - ActionQueue does not execute Actions but skips, false - else
   */
  bool getDryRun() const
  { return dryrun_flag; }

  /** States whether the ActionQueue is currently executing Actions or done executing.
   *
   * \return true - ActionQueue is done executing Actions.
   */
  bool isIdle() const;

private:
  //!> grant Action access to internal history functions.
  friend class Action;
  //!> grant CommandLineParser access to stop and clearQueue()
  friend class ::CommandLineParser;
  //!> grant Advocate access to setting dryrun
  friend class DryRunAdvocate;

  /** Queues the Action with \a name to be called.
   *
   * \param _action action to add
   * \param state whether Actions needs to be filled via a Dialog or not
   */
  void queueAction(const Action * const _action, enum Action::QueryOptions state = Action::Interactive);

  /** Wrapper function to add state to ActionHistory.
   *
   * \param _Action Action whose state to add
   * \param _state state to add
   */
  void addElement(Action* _Action, ActionState::ptr _state);

  /** Advocate function to add status message to the list.
   *
   */
  void pushStatus(const std::string &_msg)
  { StatusList.pushMessage(_msg); }

  /** Wrapper function to clear ActionHistory.
   *
   */
  void clear();

  /** Clears all actions present in the actionqueues from \a _fromAction.
   *
   * @param _fromAction 0 if all Actions to clear or else
   */
  void clearQueue(const size_t _fromAction = 0);

#ifdef HAVE_ACTION_THREAD
  boost::thread &getRunThread()
  { return run_thread; }

  /** Clears the temporary queue.
   *
   */
  void clearTempQueue();

  /** Sets the run_thread_isIdle flag.
   *
   * @param _flag state to set to
   */
  void setRunThreadIdle(const bool _flag);

  /** Runs the ActionQueue.
   *
   */
  void run();

  friend void ::stopQueue();

  /** Stops the internal thread.
   *
   */
  void stop();

  friend void ::waitQueue();

  /** Wait till all currently queued actions are processed.
   *
   */
  void wait();

  /** Moves all action from tempqueue into real queue.
   *
   */
  void insertTempQueue();

#endif

  /** Insert an action after CurrentAction.
   *
   * This is implemented only to allow action's COMMAND to work. If we
   * were to use queueAction, actions would come after all other already
   * present actions.
   */
  void insertAction(Action *_action, enum Action::QueryOptions state);

  /** Sets the current state of the \a isDryRun flag.
   *
   * \param _dryrun true - Actions will not get executed anymore, false - else
   */
  void setDryRun(const bool _dryrun)
  { dryrun_flag = _dryrun; }

  /** Checks whether next Action should be skipped or not.
   *
   * \param _nextaction next action to execute to inspect whether it unsets dryrun_flag
   * \return true - dryrun_flag set and \a _nextaction is not unsetting dry run
   */
  bool isDryRun(const Action *_nextaction) const;

private:
  /** Private cstor for ActionQueue.
   *
   * Must be private as is singleton.
   *
   */
  ActionQueue();

  /** Dstor for ActionQueue.
   *
   */
  ~ActionQueue();

private:
  friend const Action *Queuedetail::lastChanged<Action>();
  static const Action *_lastchangedaction;

  //!> ActionRegistry to spawn new actions
  ActionRegistry *AR;

  //!> ActionHistory is for undoing and redoing actions, requires ActionRegistry fully initialized
  ActionHistory *history;

  //!> internal actionqueue of actions
  ActionQueue_t actionqueue;

  //!> indicates that the last action has failed
  bool lastActionOk;

  //!> point to current action in actionqueue
  size_t CurrentAction;

#ifdef HAVE_ACTION_THREAD
  //!> internal temporary actionqueue of actions used by insertAction()
  ActionQueue_t tempqueue;

  //!> internal thread to call Actions
  boost::thread run_thread;

  //!> internal mutex to synchronize access to queue
  mutable boost::mutex mtx_queue;

  //!> conditional variable notifying when run_thread is idling
  boost::condition_variable cond_idle;

  //!> flag indicating whether run_thread is idle or not
  bool run_thread_isIdle;

  //!> internal mutex to synchronize access to run_thread_isIdle
  mutable boost::mutex mtx_idle;
#endif

  //!> internal list of status messages from Actions for UIs to display
  ActionStatusList StatusList;

  //!> internal flag whether to call or skip actions (i.e. do a dry run)
  bool dryrun_flag;
};
namespace Queuedetail {
  template <>       inline  const Action* lastChanged<Action>() { return ActionQueue::_lastchangedaction; }
}

};

#endif /* ACTIONQUEUE_HPP_ */