package kcp

import "sync/atomic"

// Snmp defines network statistics indicator
type Snmp struct {
	BytesSent        uint64 // payload bytes sent
	BytesReceived    uint64
	MaxConn          uint64
	ActiveOpens      uint64
	PassiveOpens     uint64
	CurrEstab        uint64
	InErrs           uint64
	InCsumErrors     uint64 // checksum errors
	InSegs           uint64
	OutSegs          uint64
	OutBytes         uint64 // udp bytes sent
	RetransSegs      uint64
	FastRetransSegs  uint64
	EarlyRetransSegs uint64
	LostSegs         uint64
	RepeatSegs       uint64
	FECRecovered     uint64
	FECErrs          uint64
	FECSegs          uint64 // fec segments received
}

func newSnmp() *Snmp {
	return new(Snmp)
}

// Copy make a copy of current snmp snapshot
func (s *Snmp) Copy() *Snmp {
	d := newSnmp()
	d.BytesSent = atomic.LoadUint64(&s.BytesSent)
	d.BytesReceived = atomic.LoadUint64(&s.BytesReceived)
	d.MaxConn = atomic.LoadUint64(&s.MaxConn)
	d.ActiveOpens = atomic.LoadUint64(&s.ActiveOpens)
	d.PassiveOpens = atomic.LoadUint64(&s.PassiveOpens)
	d.CurrEstab = atomic.LoadUint64(&s.CurrEstab)
	d.InErrs = atomic.LoadUint64(&s.InErrs)
	d.InCsumErrors = atomic.LoadUint64(&s.InCsumErrors)
	d.InSegs = atomic.LoadUint64(&s.InSegs)
	d.OutSegs = atomic.LoadUint64(&s.OutSegs)
	d.OutBytes = atomic.LoadUint64(&s.OutBytes)
	d.RetransSegs = atomic.LoadUint64(&s.RetransSegs)
	d.FastRetransSegs = atomic.LoadUint64(&s.FastRetransSegs)
	d.EarlyRetransSegs = atomic.LoadUint64(&s.EarlyRetransSegs)
	d.LostSegs = atomic.LoadUint64(&s.LostSegs)
	d.RepeatSegs = atomic.LoadUint64(&s.RepeatSegs)
	d.FECSegs = atomic.LoadUint64(&s.FECSegs)
	d.FECErrs = atomic.LoadUint64(&s.FECErrs)
	d.FECRecovered = atomic.LoadUint64(&s.FECRecovered)
	return d
}

// DefaultSnmp is the global KCP connection statistics collector
var DefaultSnmp *Snmp

func init() {
	DefaultSnmp = newSnmp()
}