/*! \file
 *  \brief \ref Bellringer that manages and activates time-triggered activities.
 */

#pragma once
#include "../object/queue.h"
#include "../types.h"

struct Vault;
struct Bell;

/*! \brief Manages and activates time-triggered activities.
 *  \ingroup ipc
 *
 *  The Bellringer is regularly activated and checks whether any of the bells
 * should ring. The bells are stored in a Queue<Bell> that is managed by the
 * Bellringer. A clever implementation avoids iterating through the whole list
 * for every iteration by keeping the bells sorted and storing delta times. This
 * approach leads to a complexity of O(1) for the method called by the timer
 * interrupt in case no bells need to be rung.
 */
class Bellringer {
  // Prevent copies and assignments
  Bellringer(const Bellringer&) = delete;
  Bellringer& operator=(const Bellringer&) = delete;

  /*! \brief List of bells currently managed.
   *
   * This list contains non-expired bells enqueued by job().
   * These bells will be checked on every call to check().
   *
   * All elements that should be inserted into a Queue instance
   * are required to be derived from Queue<Bell>::Node.
   */
  Queue<Bell> bells;

  //! Link pointer for bells
  static Bell** bell_link(Bell& obj, unsigned link_index);

 public:
  // constructor
  Bellringer() : bells(0, bell_link) {}

  /*! \brief Checks whether there are bells to be rung.
   *
   *  Every call to check elapses a tick. Once such a tick reduces a bells
   *  remaining time to zero, the bell will be rung.
   *
   *  \todo(16) Implement Method
   */
  void check(Vault& vault);

  /*! \brief Passes a `bell` to the bellringer to be rung after `ms`
   *  milliseconds.
   *  \param bell Bell that should be rung after `ms` milliseconds
   *  \param ms number of milliseconds that should be waited before
   *  ringing the bell
   *
   *  \todo(16) Implement Method
   */
  void sleep(Vault& vault, unsigned int ms);

  /*! \brief Checks whether there are enqueued bells.
   *  \return true if there are enqueued bells, false otherwise
   *
   *  \todo(16) Implement Method
   */
  bool bellPending() const;
};