/*
   Copyright 2015 CoreOS, Inc.

   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 wait

import (
	"sync"
	"time"
)

type WaitTime interface {
	// Wait returns a chan that waits on the given deadline.
	// The chan will be triggered when Trigger is called with a
	// deadline that is later than the one it is waiting for.
	// The given deadline MUST be unique. The deadline should be
	// retrived by calling time.Now() in most cases.
	Wait(deadline time.Time) <-chan struct{}
	// Trigger triggers all the waiting chans with an earlier deadline.
	Trigger(deadline time.Time)
}

type timeList struct {
	l sync.Mutex
	m map[int64]chan struct{}
}

func NewTimeList() *timeList {
	return &timeList{m: make(map[int64]chan struct{})}
}

func (tl *timeList) Wait(deadline time.Time) <-chan struct{} {
	tl.l.Lock()
	defer tl.l.Unlock()
	ch := make(chan struct{}, 1)
	// The given deadline SHOULD be unique.
	tl.m[deadline.UnixNano()] = ch
	return ch
}

func (tl *timeList) Trigger(deadline time.Time) {
	tl.l.Lock()
	defer tl.l.Unlock()
	for t, ch := range tl.m {
		if t < deadline.UnixNano() {
			delete(tl.m, t)
			close(ch)
		}
	}
}