#ifndef __TIMER_WRAP__
#define __TIMER_WRAP__

#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>

typedef enum {

	TIMER_INIT,
	TIMER_DELETED,
	TIMER_PAUSED,
	TIMER_CANCELLED,
	TIMER_RESUMED,
	TIMER_RUNNING,
} TIMER_STATE_T;

typedef struct Timer_ {

	/* Timer config */
	timer_t* posix_timer;
	void* user_arg;
	unsigned long exp_timer;		/* in milli-sec */
	unsigned long sec_exp_timer;	/* in milli-sec */
	uint32_t thresdhold;			/* No of times to invoke the timer callback */
	void (*cb)(struct Timer_*, void*); /* Timer Callback  */
	bool exponential_backoff;

	/* place holder value to store
	 * dynamic attributes of timer */
	unsigned long time_remaining;	/* Time left for paused timer for next expiration */
	uint32_t invocation_counter;
	struct itimerspec ts;
	unsigned long exp_back_off_time;
	TIMER_STATE_T timer_state;
} Timer_t;

/* Returns NULL in timer creation fails, else
 * return a pointer to Timer object*/
Timer_t*
setup_timer(
	void (*timer_cb)(Timer_t*, void*), /*  Timer Callback with user data*/
	unsigned long exp_timer,         	/*  First expiration time interval in msec */
	unsigned long sec_exp_timer,        /*  Subsequent expiration time interval in msec */
	uint32_t threshold,					/*  Max no of expirations, 0 for infinite*/
	void* user_arg,                  	/*  Arg to timer callback */
	bool exponential_backoff);

static inline void
timer_delete_user_data(Timer_t* timer) {

	if (timer->user_arg) {
		free(timer->user_arg);
		timer->user_arg = NULL;
	}
}

static inline TIMER_STATE_T
timer_get_current_state(Timer_t* timer) {

	return timer->timer_state;
}

static inline void
timer_set_state(Timer_t* timer, TIMER_STATE_T timer_state) {

	timer->timer_state = timer_state;
}

void
resurrect_timer(Timer_t* timer);

void
start_timer(Timer_t* timer);

void
delete_timer(Timer_t* timer);

void
cancel_timer(Timer_t* timer);

void
pause_timer(Timer_t* timer);

void
resume_timer(Timer_t* timer);

int
execute_timer(Timer_t* timer, TIMER_STATE_T action);

/* get remaining time in msec */
unsigned long
timer_get_time_remaining_in_mill_sec(Timer_t* timer);

void
restart_timer(Timer_t* timer);

void
reschedule_timer(Timer_t* timer,
	unsigned long exp_ti,
	unsigned long sec_exp_ti);

void
print_timer(Timer_t* timer);

unsigned long
timespec_to_millisec(
	struct timespec* time);

void
timer_fill_itimerspec(struct timespec* ts,
	unsigned long msec);

bool
is_timer_running(Timer_t* timer);

#endif /* __TIMER_WRAP__  */