#ifndef ETHERLIB_TIMER_H
#define ETHERLIB_TIMER_H

#include <stdint.h>
#include <stdbool.h>

/**
 * A single point in time
 */
typedef struct {
    uint32_t s; ///< Seconds
    uint32_t us; ///< Microseconds
} TimePoint;

/**
 * Convert TimePoint to microseconds.
 * @param t time
 * @return time in microseconds
 */
int64_t time_to_us(const TimePoint * t);

/**
 * Convert microseconds to TimePoint.
 * @param t pointer to TimePoint structure
 * @param us time in microseconds
 */
void time_from_us(TimePoint * t, int64_t us);

/**
 * Add microseconds to TimePoint.
 * @param t pointer to TimePoint structure
 * @param us time in microseconds
 */
void time_add_us(TimePoint * t, int64_t us);

#define TIMER_SCHED_FAILED (-1)

struct Timer_;

/**
 * Alarm user data.
 */
typedef struct {
    void * ptr;
    uint32_t u;
} AlarmUserData;

typedef void (*TimerAlarmCb)(struct Timer_ * timer, AlarmUserData user);

/**
 * Alarm assignment.
 */
typedef struct {
    uint32_t id; ///< Timing ID
    TimePoint time; ///< Alarm time
    TimerAlarmCb cb; ///< Pointer to callback function
    AlarmUserData params; ///< User data passed to callback function
} AlarmAssignment;

/**
 * Timer class
 */
typedef struct Timer_ {
    TimePoint time; ///< Absolute time
    AlarmAssignment * nextAlarm; ///< Nearest alarm
    uint32_t maxSched; ///< Maximum number of scheduled alarms
    uint32_t nSched; ///< Number of scheduled alarms
    AlarmAssignment alarms[]; ///< Alarm assigment pool
} Timer;

/**
 * Create new timer
 * @param maxSched number of maximum alarms to be scheduled
 * @return pointer to new instance OR NULL on error
 */
Timer * timer_new(uint32_t maxSched);

/**
 * Schedule new alarm.
 * @param tmr pointer to Timer instance
 * @param t alarm time
 * @param cb alarm callback function
 * @param params user-defined params passed to callback function
 * @return ID of new schedule OR TIMER_SCHED_FAILED
 */
uint32_t timer_sched(Timer * tmr, const TimePoint * t, TimerAlarmCb cb, AlarmUserData params);

/**
 * Schedule new alarm by specifying time relatively from the current time point.
 * @param tmr pointer to Timer instance
 * @param us relative alarm time
 * @param cb alarm callback function
 * @param params user-defined params passed to callback function
 * @return ID of new schedule OR TIMER_SCHED_FAILED
 */
uint32_t timer_sched_rel(Timer * tmr, int64_t us, TimerAlarmCb cb, AlarmUserData params);

/**
 * Unschedule alarm.
 * @param tmr pointer to Timer instance
 * @param id schedule ID returned by timer_sched() or timer_sched_rel()
 */
void timer_unsched(Timer * tmr, uint32_t id);

/**
 * Set time.
 * @param tmr pointer to Timer instance
 * @param t time
 */
void timer_set_time(Timer * tmr, const TimePoint * t);

/**
 * Get current time in microseconds.
 * @param tmr pointer to Timer instance
 * @return current time in microseconds
 */
int64_t timer_get_time_us(const Timer * tmr);

/**
 * Get current time.
 * @param tmr pointer to Timer instance
 * @return current time
 */
TimePoint timer_get_time(const Timer * tmr);

/**
 * Advance timer.
 * @param tmr pointer to Timer instance
 * @param us time advancement in microseconds
 */
void timer_tick(Timer * tmr, int64_t us);

/**
 * Print Timer report.
 * @param tmr pointer to Timer instance
 */
void timer_report(const Timer * tmr);

#endif //ETHERLIB_TIMER_H