package main

import (
	"crypto/cipher"
	"sync"
	"time"
)

type KeyPair struct {
	receive     cipher.AEAD
	send        cipher.AEAD
	sendNonce   uint64
	isInitiator bool
	created     time.Time
	localIndex  uint32
	remoteIndex uint32
}

type KeyPairs struct {
	mutex    sync.RWMutex
	current  *KeyPair
	previous *KeyPair
	next     *KeyPair // not yet "confirmed by transport"
}

/* Called during recieving to confirm the handshake
 * was completed correctly
 */
func (kp *KeyPairs) Used(key *KeyPair) {
	if key == kp.next {
		kp.mutex.Lock()
		kp.previous = kp.current
		kp.current = key
		kp.next = nil
		kp.mutex.Unlock()
	}
}

func (kp *KeyPairs) Current() *KeyPair {
	kp.mutex.RLock()
	defer kp.mutex.RUnlock()
	return kp.current
}