package peer

import (
	"net/netip"
	"testing"

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

	"vppn/m"
)

func testPoller(t *testing.T) (*HubPoller, chan HubPeer, chan wgtypes.Key) {
	t.Helper()
	addCh := make(chan HubPeer, 8)
	removeCh := make(chan wgtypes.Key, 8)
	hp := &HubPoller{
		selfVPNIP: netip.MustParseAddr("10.0.0.1"),
		vpnNet:    netip.MustParsePrefix("10.0.0.0/24"),
		addCh:     addCh,
		removeCh:  removeCh,
		known:     make(map[wgtypes.Key]int64),
	}
	return hp, addCh, removeCh
}

func stateWith(key wgtypes.Key, peerIP byte, version int64) m.NetworkState {
	var s m.NetworkState
	s.Peers[peerIP] = &m.Peer{
		PeerIP:     peerIP,
		Version:    version,
		WGPubKey:   key[:],
		SignPubKey: make([]byte, 32),
	}
	return s
}

func TestApply_EmitsAddsAndReportsChange(t *testing.T) {
	hp, addCh, _ := testPoller(t)
	key := mustKey(t)

	if changed := hp.apply(stateWith(key, 2, 1)); !changed {
		t.Fatal("expected changed=true on first apply")
	}
	if len(addCh) != 1 {
		t.Fatalf("expected 1 add, got %d", len(addCh))
	}
	if got := <-addCh; got.PubKey != key {
		t.Errorf("add pubkey mismatch")
	}
}

func TestApply_NoChangeWhenVersionSame(t *testing.T) {
	hp, addCh, _ := testPoller(t)
	key := mustKey(t)

	hp.apply(stateWith(key, 2, 1))
	<-addCh // drain initial add

	if changed := hp.apply(stateWith(key, 2, 1)); changed {
		t.Fatal("expected changed=false when version unchanged")
	}
	if len(addCh) != 0 {
		t.Fatalf("expected no re-emit, got %d adds", len(addCh))
	}
}

func TestApply_ReEmitsOnVersionBump(t *testing.T) {
	hp, addCh, _ := testPoller(t)
	key := mustKey(t)

	hp.apply(stateWith(key, 2, 1))
	<-addCh

	if changed := hp.apply(stateWith(key, 2, 2)); !changed {
		t.Fatal("expected changed=true on version bump")
	}
	if len(addCh) != 1 {
		t.Fatalf("expected 1 re-emit, got %d", len(addCh))
	}
}

func TestApply_RemovesVanishedPeer(t *testing.T) {
	hp, addCh, removeCh := testPoller(t)
	key := mustKey(t)

	hp.apply(stateWith(key, 2, 1))
	<-addCh

	// Empty state: the peer is gone.
	if changed := hp.apply(m.NetworkState{}); !changed {
		t.Fatal("expected changed=true when peer vanishes")
	}
	if len(removeCh) != 1 {
		t.Fatalf("expected 1 remove, got %d", len(removeCh))
	}
	if got := <-removeCh; got != key {
		t.Errorf("remove key mismatch")
	}
}