/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 *    Copyright 2017, 2018, 2021 (c) Fraunhofer IOSB (Author: Julius Pfrommer)
 *    Copyright 2017 (c) Stefan Profanter, fortiss GmbH
 */

#ifndef UA_TIMER_H_
#define UA_TIMER_H_

#include <open62541/types.h>
#include <open62541/plugin/eventloop.h>
#include "ziptree.h"

_UA_BEGIN_DECLS

/* The timer is protected by its own mutex. The mutex is released before calling
 * into the callbacks. So the timer can be modified from the callbacks it is
 * executing. Also, the timer mutex can never lead to locking. Because the timer
 * mutex will be left without acquiring another mutex.
 *
 * Obviously, the timer must not be deleted from within one of its
 * callbacks. */

/* Callback where the application is either a client or a server */
typedef void (*UA_ApplicationCallback)(void *application, void *data);

typedef struct UA_TimerEntry {
    ZIP_ENTRY(UA_TimerEntry) treeEntry;
    UA_TimerPolicy timerPolicy;      /* Timer policy to handle cycle misses */
    UA_DateTime nextTime;            /* The next time when the callback is to be
                                      * executed */
    UA_UInt64 interval;              /* Interval in 100ns resolution. If the
                                      * interval is zero, the callback is not
                                      * repeated and removed after execution. */
    UA_ApplicationCallback callback; /* This is also a sentinel value. If the
                                      * callback is NULL, then the entry is
                                      * marked for deletion. */
    void *application;
    void *data;

    ZIP_ENTRY(UA_TimerEntry) idTreeEntry;
    UA_UInt64 id;                            /* Id of the entry */
} UA_TimerEntry;

typedef ZIP_HEAD(UA_TimerTree, UA_TimerEntry) UA_TimerTree;
typedef ZIP_HEAD(UA_TimerIdTree, UA_TimerEntry) UA_TimerIdTree;

typedef struct {
    UA_TimerTree tree;     /* The root of the time-sorted tree */
    UA_TimerIdTree idTree; /* The root of the id-sorted tree */
    UA_UInt64 idCounter;   /* Generate unique identifiers. Identifiers are
                            * always above zero. */
#if UA_MULTITHREADING >= 100
    UA_Lock timerMutex;
#endif

    UA_TimerTree processTree; /* When the timer is processed, all entries that
                               * need processing now are moved to processTree.
                               * Then we iterate over that tree. */
} UA_Timer;

void
UA_Timer_init(UA_Timer *t);

UA_DateTime
UA_Timer_nextRepeatedTime(UA_Timer *t);

UA_StatusCode
UA_Timer_addTimedCallback(UA_Timer *t, UA_ApplicationCallback callback,
                          void *application, void *data, UA_DateTime date,
                          UA_UInt64 *callbackId);

UA_StatusCode
UA_Timer_addRepeatedCallback(UA_Timer *t, UA_ApplicationCallback callback,
                             void *application, void *data, UA_Double interval_ms,
                             UA_DateTime *baseTime, UA_TimerPolicy timerPolicy,
                             UA_UInt64 *callbackId);

UA_StatusCode
UA_Timer_changeRepeatedCallback(UA_Timer *t, UA_UInt64 callbackId,
                                UA_Double interval_ms, UA_DateTime *baseTime,
                                UA_TimerPolicy timerPolicy);

void
UA_Timer_removeCallback(UA_Timer *t, UA_UInt64 callbackId);

UA_DateTime
UA_Timer_process(UA_Timer *t, UA_DateTime nowMonotonic);

void
UA_Timer_clear(UA_Timer *t);

_UA_END_DECLS

#endif /* UA_TIMER_H_ */