// ------------------------------------------------------------------------
//   Project atila
//   Active Thing (activething.com) git.activething.com/go
//
//   File name  rkey.go
//   Created by DEV
//   Modified   05/02/2024
//
//   Copyright 2024 activething.com
// ------------------------------------------------------------------------
// 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.
// ------------------------------------------------------------------------

package times

import (
	"sync/atomic"
	"time"


)

type (


	Expiration 	struct {
		timer 	*time.Timer
		times 	Chrono

		state    uint32
		source   uint32
		timeout  int64
		deadline int64

		expireFn func()
	}
)


func NewExpiration(duration time.Duration, expirer func()) *Expiration {
	ex := &Expiration{
		times:    *NewChrono(false),
		state:    uint32(TimerStateCreated),
		source:   uint32(ExpirationSourceSelf),
		timeout:  int64(duration),
		expireFn: expirer,
	}
	if duration > 0 {
		atomic.StoreUint32(&ex.source,uint32(ExpirationSourceTimer))
	}
	return ex
}



func (e *Expiration) Reset() {
	e.times.Reset()
	atomic.StoreUint32(&e.state ,uint32(TimerStateCreated))
	atomic.StoreUint32(&e.source,uint32(ExpirationSourceSelf))
	atomic.StoreInt64 (&e.timeout ,0)
	atomic.StoreInt64 (&e.deadline,0)
	if e.timer != nil {
		if !e.timer.Stop() {
			select {
			case <- e.timer.C:
			default:
			}
		}
	}
}



func (e *Expiration) State() TimerState {
	return TimerState(atomic.LoadUint32(&e.state)) }



func (e *Expiration) Chono() Chronometer {
	return &e.times }


func (e *Expiration) Source() ExpirationSource {
	return ExpirationSource(atomic.LoadUint32(&e.source)) }



func (e *Expiration) Timeout() time.Duration {
	return time.Duration(atomic.LoadInt64(&e.timeout)) }


func (e *Expiration) Deadline() time.Time {
	return time.Unix(0,atomic.LoadInt64(&e.deadline)) }



func (e *Expiration) Start(expirer Expirer) error {
	if !atomic.CompareAndSwapUint32(&e.state,uint32(TimerStateCreated),uint32(TimerStateStarted)) {
		return G.ErrAlreadyStarted
	}

	st := e.times.Start()
	to := time.Duration(atomic.LoadInt64(&e.timeout))
	dl := st.Add(to)

	if expirer != nil {
		pd, ph := expirer.Deadline()
		if ph {
			if pd.Before(st) {
				atomic.StoreUint32(&e.state ,uint32(TimerStateExpired))
				atomic.StoreUint32(&e.source,uint32(ExpirationSourceParent))
				return G.ErrExpired
			}
			if pd.Before(dl) {
				atomic.StoreInt64 (&e.deadline,pd.UnixNano())
				atomic.StoreUint32(&e.source  ,uint32(ExpirationSourceParent))
				return nil
			}
		}
	}

	if atomic.LoadUint32(&e.source)  == uint32(ExpirationSourceTimer) {
		atomic.StoreInt64 (&e.deadline,dl.UnixNano())
		if e.timer == nil {
			e.timer = time.NewTimer(to)
		} else {
			e.timer.Reset(to)
		}
		go func(ex *Expiration) {
			select {
			case <-ex.timer.C:
				atomic.StoreUint32(&ex.state,uint32(TimerStateExpired))
				ex.times.Stop()
				if ex.expireFn != nil {
					ex.expireFn()
				}
				return
			}
		}(e)


	}

	return nil
}


func (e *Expiration) Stop() error {
	if !atomic.CompareAndSwapUint32(&e.state,uint32(TimerStateStarted), uint32(TimerStateStopped)) {
		return G.ErrNotStarted
	}
	e.times.Stop()
	if e.timer != nil && !e.timer.Stop() {
		select {
		case <-e.timer.C:
		}
	}
	return nil
}

/*
   ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

   I HAVE NO DESIRE TO WALK ON WATER," SAID SIDDHARTA.
   "LET THE OLD SHRAMANAS SATISFY THEMSELVES WITH SUCH SKILLS.

   SIDDHARTA
   - HERMANN HESSE -

   :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

*/