package peer

import (
	"errors"
	"log"
	"net/netip"
	"syscall"
	"time"

	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
)

// devRetry calls fn up to 6 times with exponential backoff, retrying on EBUSY
// (transient netlink contention during WireGuard handshake/rekey). Fatal on
// any other error.
func devRetry(vpnIP netip.Addr, op string, fn func() error) {
	const attempts = 6
	timeout := 10 * time.Millisecond
	for i := range attempts {
		err := fn()
		if err == nil {
			return
		}
		if errors.Is(err, syscall.EBUSY) && i < attempts-1 {
			time.Sleep(timeout)
			timeout *= 2
			continue
		}
		log.Fatalf("%s %v: %v", op, vpnIP, err)
	}
}

func (a *App) devPeers() []wgtypes.Peer {
	peers, err := a.dev.Peers()
	if err != nil {
		log.Fatalf("Failed to get peers %v: %v", a.vpnIP, err)
	}
	return peers
}

func (a *App) devAddPeer(p *Peer) {
	log.Printf("RELAYED: %s - %s ", p.Name, p.VPNIP.String())
	devRetry(p.VPNIP, "AddPeer", func() error { return a.dev.AddPeer(p.PubKey()) })
	p.State = StateRelayed
}

func (a *App) devAddDirect(p *Peer, endpoint netip.AddrPort) {
	log.Printf("DIRECT: %s - %s @ %s", p.Name, p.VPNIP.String(), endpoint.String())
	devRetry(p.VPNIP, "AddDirect", func() error { return a.dev.AddDirect(p.PubKey(), endpoint, p.VPNIP) })
	p.State = StateDirect
}

func (a *App) devSetRelay(p *Peer, endpoint netip.AddrPort) {
	log.Printf("RELAY: %s - %s @ %s", p.Name, p.VPNIP.String(), endpoint.String())
	devRetry(p.VPNIP, "SetRelay", func() error { return a.dev.SetRelay(p.PubKey(), endpoint, a.vpnNet) })
	p.State = StateDirect // Direct connection. The app marks peer as relay.
}

func (a *App) devPromote(p *Peer) {
	ep := p.WGEndpoint()
	if ep.IsValid() {
		log.Printf("PROMOTED: %s - %s @ %s", p.Name, p.VPNIP.String(), p.WGEndpoint().String())
	} else {
		log.Printf("PROMOTED: %s - %s (no IP)", p.Name, p.VPNIP.String())
	}
	devRetry(p.VPNIP, "Promote", func() error { return a.dev.Promote(p.PubKey(), p.VPNIP) })
	p.State = StateDirect
}

func (a *App) devAddProbe(p *Peer, endpoint netip.AddrPort) {
	log.Printf("PROBE: %s - %s @ %s", p.Name, p.VPNIP.String(), endpoint.String())
	devRetry(p.VPNIP, "AddProbe", func() error { return a.dev.AddProbe(p.PubKey(), endpoint) })
	p.State = StateProbing
}

func (a *App) devRemove(p *Peer) {
	log.Printf("REMOVED: %s - %s", p.Name, p.VPNIP.String())
	devRetry(p.VPNIP, "RemovePeer", func() error { return a.dev.RemovePeer(p.PubKey()) })
}