#ifndef INCLUDED_OS_TIMEWHEEL_H
#define INCLUDED_OS_TIMEWHEEL_H

#ifndef INCLUDED_OS_TYPES_H
#include <os_types.h>
#endif /*INCLUDED_OS_TYPES_H*/

#ifndef INCLUDED_OS_TIMER_H
#include <os_timer.h>
#endif /*INCLUDED_OS_TIMER_H*/

#ifndef INCLUDED_OS_MACROS_H
#include <os_macros.h>
#endif /*INCLUDED_OS_MACROS_H*/


/* -------------------------------------------------------------------------------------------------------------- */
/*  */

#define OS_TIMEWHEEL_TICK_OK             0
#define OS_TIMEWHEEL_TICK_NEED_SCHEDULE  201


/* -------------------------------------------------------------------------------------------------------------- */
/* |------|------|------|------|--------|
 *     6      6      6      6     8(R)
 *     N3     N2     N1     N0
 */

#define TWR_BITS        8
#define TWN_BITS        6

#define TWN_MASK        0x3F

#define TWR_SIZE        (1<<TWR_BITS)
#define TWN_SIZE        (1<<TWN_BITS)

#define TWR_MAX         (0xFFu)
#define TWN0_MAX        (0x3FFFu)               /*11 1111 1111 1111*/
#define TWN1_MAX        (0xFFFFFu)              /*1111 1111 1111 1111 1111*/
#define TWN2_MAX        (0x3FFFFFFu)            /*11 1111 1111 1111 1111 1111 1111*/
#define TWN3_MAX        (0xFFFFFFFu)            /*1111 1111 1111 1111 1111 1111 1111 1111*/

#define TWN_IDX(T, N)      (((T)>>(TWR_BITS + (N)*TWN_BITS)) & TWN_MASK)

/* -------------------------------------------------------------------------------------------------------------- */
/*  */

extern volatile os_tick_t os_timewheel__tick;
extern os_list_t os_timewheel__R[TWR_SIZE];
extern os_list_t os_timewheel__N0[TWN_SIZE];
extern os_list_t os_timewheel__N1[TWN_SIZE];
extern os_list_t os_timewheel__N2[TWN_SIZE];
extern os_list_t os_timewheel__N3[TWN_SIZE];

OS_STATIC_FORCE_INLINE
void os_timewheel_init(void) {
    os_timewheel__tick = 0;

    for (os_size_t i=0; i<OS_ARRAY_SIZE(os_timewheel__R); i++) {
        os_list_init(&os_timewheel__R[i]);
    }
    for (os_size_t i=0; i<OS_ARRAY_SIZE(os_timewheel__N0); i++) {
        os_list_init(&os_timewheel__N0[i]);
    }
    for (os_size_t i=0; i<OS_ARRAY_SIZE(os_timewheel__N1); i++) {
        os_list_init(&os_timewheel__N1[i]);
    }
    for (os_size_t i=0; i<OS_ARRAY_SIZE(os_timewheel__N2); i++) {
        os_list_init(&os_timewheel__N2[i]);
    }
    for (os_size_t i=0; i<OS_ARRAY_SIZE(os_timewheel__N3); i++) {
        os_list_init(&os_timewheel__N3[i]);
    }
}

OS_STATIC_FORCE_INLINE
os_list_t* os_timewheel_find(os_tick_t tick) {
    if (tick<=TWR_MAX) {
        return &os_timewheel__R[tick];
    }else if (tick<=TWN0_MAX) {
        return &os_timewheel__N0[TWN_IDX(tick, 0)];
    }else if (tick<=TWN1_MAX) {
        return &os_timewheel__N1[TWN_IDX(tick, 1)];
    }else if (tick<=TWN2_MAX) {
        return &os_timewheel__N2[TWN_IDX(tick, 2)];
    }else if (tick<=TWN3_MAX) {
        return &os_timewheel__N3[TWN_IDX(tick, 3)];
    }else {
        return NULL;
    }
}


OS_STATIC_FORCE_INLINE
void os_timewheel_add_timer(os_timer_t* timer, os_timer_function_t function, void* userdata, os_tick_t ticks, int flags) {
    os_list_remove(&timer->node);
    os_timer_init(timer, function, userdata, ticks, flags);
    timer->expire_tick = os_timewheel__tick + ticks;
    os_list_t* wheel = os_timewheel_find(timer->expire_tick);
    os_list_insert_before(wheel, &timer->node);
}

OS_STATIC_FORCE_INLINE
void os_timewheel_add_until_timer(os_timer_t* timer, os_timer_function_t function, void* userdata, os_tick_t ticks, int flags) {
    os_timer_init(timer, function, userdata, ticks, flags);
    timer->expire_tick = ticks;
    os_list_t* wheel = os_timewheel_find(timer->expire_tick);
    os_list_insert_before(wheel, &timer->node);
}


os_err_t os_timewheel_tick(void);


/* ------------------------------------------------------------------------------------------------------------------ */
/*  */

#define OS_AddTimer         os_timewheel_add_timer
#define OS_AddUntilTimer    os_timewheel_add_until_timer
#define OS_TimerTick        os_timewheel_tick

#endif /*INCLUDED_OS_TIMEWHEEL_H*/