/*
 * Copyright (c) 2017 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @file parc_EventScheduler.h
 * @ingroup events
 * @brief Event scheduler
 *
 * Provides a facade implementing many regularly available event functions.
 * This is an interface that software implementors may use to substitute
 * different kinds of underlying implementations of these event management functions.
 * Notable examples are libevent and libev.
 *
 */
#ifndef libparc_parc_EventScheduler_h
#define libparc_parc_EventScheduler_h

#include <stdlib.h>
#include <stdint.h>

/*
 * Currently implemented using libevent
 */

#include <parc/algol/parc_Memory.h>
#include <parc/logging/parc_Log.h>

/**
 * @typedef PARCEventScheduler
 * @brief A structure containing private event state
 */
struct PARCEventScheduler;
typedef struct PARCEventScheduler PARCEventScheduler;

typedef enum {
    PARCEventSchedulerDispatchType_Blocking = 0x00,
    PARCEventSchedulerDispatchType_LoopOnce = 0x01,
    PARCEventSchedulerDispatchType_NonBlocking = 0x02,
} PARCEventSchedulerDispatchType;

/**
 * Create a new parcEventScheduler instance.
 *
 * A new parcEventScheduler instance is returned.
 *
 * @returns A pointer to the a PARCEvent instance.
 *
 * Example:
 * @code
 * {
 *     PARCEvent *parcEventScheduler = parcEvent_Create();
 * }
 * @endcode
 *
 */
PARCEventScheduler *parcEventScheduler_Create(void);

/**
 * Start the event eventScheduler
 *
 * @param [in] parcEventScheduler - The parcEventScheduler instance to start.
 * @param type - The mode of dispatch for this `PARCEventScheduler` instance.
 * @returns 0 on success, -1 on failure
 *
 * Example:
 * @code
 * {
 *     result = parcEventScheduler_Start(parcEventScheduler, PARCEventScheduler_Blocking);
 * }
 * @endcode
 *
 */
int parcEventScheduler_Start(PARCEventScheduler *parcEventScheduler, PARCEventSchedulerDispatchType type);

/**
 * Dispatch the event scheduler to process any pending events, blocking until
 * some events have been triggered and then processed.
 *
 * @param [in] parcEventScheduler - The parcEventScheduler instance to run.
 * @returns 0 on success, -1 on failure
 *
 * Example:
 * @code
 * {
 *     result = parcEventScheduler_DispatchBlocking(parcEventScheduler, PARCEventScheduler_Blocking);
 * }
 * @endcode
 */
int parcEventScheduler_DispatchBlocking(PARCEventScheduler *parcEventScheduler);

/**
 * Dispatch the event scheduler to process any pending events.
 *
 * If there are no pending events then the function will immediately return.
 *
 * @param [in] parcEventScheduler - The parcEventScheduler instance to run.
 * @returns 0 on success, -1 on failure
 *
 * Example:
 * @code
 * {
 *     result = parcEventScheduler_DispatchNonBlocking(parcEventScheduler, PARCEventScheduler_Blocking);
 * }
 * @endcode
 *
 */
int parcEventScheduler_DispatchNonBlocking(PARCEventScheduler *parcEventScheduler);

/**
 * Stop the event parcEventScheduler
 *
 * @param [in] parcEventScheduler instance to stop scheduling.
 * @param [in] delay time to wait before stopping, 0 for stop now
 * @returns 0 on success, -1 on failure
 *
 * Example:
 * @code
 * {
 *     result = parcEventScheduler_Stop(parcEventScheduler, timeout);
 * }
 * @endcode
 *
 */
int parcEventScheduler_Stop(PARCEventScheduler *parcEventScheduler, struct timeval *delay);

/**
 * Immediately abort the event parcEventScheduler
 *
 * @param [in] parcEventScheduler instance to abort scheduling.
 * @returns 0 on success, -1 on failure
 *
 * Example:
 * @code
 * {
 *     result = parcEventScheduler_Abort(parcEventScheduler);
 * }
 * @endcode
 *
 */
int parcEventScheduler_Abort(PARCEventScheduler *parcEventScheduler);

/**
 * Destroy a parcEventScheduler instance.
 *
 * The address of the parcEventScheduler instance is passed in.
 *
 * @param [in] parcEventScheduler address of instance to destroy.
 *
 * Example:
 * @code
 * {
 *     parcEventScheduler_Destroy(&parcEventScheduler);
 * }
 * @endcode
 *
 */
void parcEventScheduler_Destroy(PARCEventScheduler **parcEventScheduler);

/**
 * Turn on debugging flags and messages
 *
 * Example:
 * @code
 * {
 *     parcEventScheduler_EnableDebug();
 * }
 * @endcode
 *
 */
void parcEventScheduler_EnableDebug(void);

/**
 * Turn off debugging flags and messages
 *
 * Example:
 * @code
 * {
 *     parcEventScheduler_DisableDebug();
 * }
 * @endcode
 *
 */
void parcEventScheduler_DisableDebug(void);

/**
 * Internal libevent data accessor function.
 *
 * THIS IS FOR INTERNAL USE ONLY. USE WITH CAUTION.
 *
 * Example:
 * @code
 * {
 *     parcEventScheduler_GetEvBase(parcEventScheduler);
 * }
 * @endcode
 *
 */
void *parcEventScheduler_GetEvBase(PARCEventScheduler *parcEventScheduler);

/**
 * Logger accessor function
 *
 * Example:
 * @code
 * {
 *     PARCLog *logger = parcEventScheduler_GetLogger(parcEventScheduler);
 * }
 * @endcode
 *
 */
PARCLog *parcEventScheduler_GetLogger(PARCEventScheduler *parcEventScheduler);
#endif // libparc_parc_EventScheduler_h