package mesh

import (
	"testing"
	"time"
)

func TestPeerCacheSelectsAdjacentWarmPeersWithinLimit(t *testing.T) {
	local := PeerIdentity{ClusterID: "cluster-1", NodeID: "node-b"}
	cache := NewPeerCache(PeerCacheConfig{
		Local: local,
		PeerEndpoints: map[string]string{
			"node-a": "http://node-a:19000",
			"node-r": "http://node-r:19000",
			"node-c": "http://node-c:19000",
		},
		Routes: []SyntheticRoute{
			peerCacheRoute("route-1", []string{"node-a", local.NodeID, "node-r", "node-c"}),
		},
		RecoverySeeds: []PeerRecoverySeed{
			{NodeID: "node-seed", Endpoint: "https://seed.example.test", Transport: "direct_tcp_tls", Priority: 10},
		},
		WarmPeerLimit: 2,
		Now:           time.Date(2026, 4, 28, 12, 0, 0, 0, time.UTC),
	})

	warm := cache.WarmPeerIDs()
	if len(warm) != 2 || warm[0] != "node-a" || warm[1] != "node-r" {
		t.Fatalf("warm peers = %+v, want adjacent node-a/node-r", warm)
	}
	snapshot := cache.Snapshot()
	if snapshot.PeerCount != 4 || snapshot.RecoverySeedCount != 1 {
		t.Fatalf("unexpected snapshot counts: %+v", snapshot)
	}
}

func TestPeerCachePromotesRecoverySeedAfterRoutePeers(t *testing.T) {
	local := PeerIdentity{ClusterID: "cluster-1", NodeID: "node-b"}
	cache := NewPeerCache(PeerCacheConfig{
		Local: local,
		Routes: []SyntheticRoute{
			peerCacheRoute("route-1", []string{"node-a", local.NodeID, "node-r"}),
		},
		RecoverySeeds: []PeerRecoverySeed{
			{NodeID: "node-seed", Endpoint: "wss://seed.example.test/mesh", Transport: "wss", ConnectivityMode: "direct", Priority: 1},
		},
		WarmPeerLimit: 3,
		Now:           time.Date(2026, 4, 28, 12, 0, 0, 0, time.UTC),
	})

	warm := cache.WarmPeerIDs()
	if len(warm) != 3 || warm[0] != "node-a" || warm[1] != "node-r" || warm[2] != "node-seed" {
		t.Fatalf("warm peers = %+v, want adjacent peers then seed", warm)
	}
	seed, ok := peerCacheEntryByID(cache.Snapshot(), "node-seed")
	if !ok || !seed.RecoverySeed || seed.WarmReason != "recovery_seed" {
		t.Fatalf("unexpected seed entry: %+v", seed)
	}
}

func TestPeerCacheUsesBestEndpointCandidate(t *testing.T) {
	local := PeerIdentity{ClusterID: "cluster-1", NodeID: "node-a"}
	now := time.Date(2026, 4, 28, 12, 0, 0, 0, time.UTC)
	cache := NewPeerCache(PeerCacheConfig{
		Local: local,
		PeerEndpointCandidates: map[string][]PeerEndpointCandidate{
			"node-b": {
				{
					EndpointID:       "node-b-relay",
					NodeID:           "node-b",
					Transport:        "relay",
					Address:          "relay.example.test",
					Reachability:     "relay",
					ConnectivityMode: "relay_required",
					Priority:         20,
				},
				{
					EndpointID:       "node-b-public",
					NodeID:           "node-b",
					Transport:        "direct_tcp_tls",
					Address:          "203.0.113.20:443",
					Reachability:     "public",
					NATType:          "none",
					ConnectivityMode: "direct",
					Priority:         1,
					LastVerifiedAt:   &now,
				},
			},
		},
		WarmPeerLimit: 1,
		Now:           now,
	})

	entry, ok := peerCacheEntryByID(cache.Snapshot(), "node-b")
	if !ok {
		t.Fatal("node-b missing from cache")
	}
	if entry.BestCandidateID != "node-b-public" || !entry.Warm {
		t.Fatalf("unexpected candidate selection: %+v", entry)
	}
}

func TestPeerCacheUsesPreferredCorporateEndpointAddress(t *testing.T) {
	local := PeerIdentity{ClusterID: "cluster-1", NodeID: "node-a"}
	cache := NewPeerCache(PeerCacheConfig{
		Local: local,
		PeerEndpoints: map[string]string{
			"node-b": "https://node-b.public.example.test:443",
		},
		PeerEndpointCandidates: map[string][]PeerEndpointCandidate{
			"node-b": {
				{
					EndpointID:       "node-b-public",
					NodeID:           "node-b",
					Transport:        "direct_tcp_tls",
					Address:          "https://node-b.public.example.test:443",
					Reachability:     "public",
					NATType:          "none",
					ConnectivityMode: "direct",
					Region:           "corp-eu",
					Priority:         10,
				},
				{
					EndpointID:       "node-b-corp-lan",
					NodeID:           "node-b",
					Transport:        "direct_tcp_tls",
					Address:          "http://10.24.10.20:19001",
					Reachability:     "private",
					NATType:          "none",
					ConnectivityMode: "direct",
					Region:           "corp-eu",
					Priority:         1,
					PolicyTags:       []string{"corp-lan"},
				},
			},
		},
		PreferredRegion: "corp-eu",
		WarmPeerLimit:   1,
		Now:             time.Date(2026, 4, 28, 12, 0, 0, 0, time.UTC),
	})

	entry, ok := peerCacheEntryByID(cache.Snapshot(), "node-b")
	if !ok {
		t.Fatal("node-b missing from peer cache")
	}
	if entry.BestCandidateID != "node-b-corp-lan" || entry.Endpoint != "http://10.24.10.20:19001" {
		t.Fatalf("peer cache did not choose corp LAN endpoint: %+v", entry)
	}
}

func peerCacheRoute(routeID string, hops []string) SyntheticRoute {
	return SyntheticRoute{
		RouteID:           routeID,
		ClusterID:         "cluster-1",
		SourceNodeID:      hops[0],
		DestinationNodeID: hops[len(hops)-1],
		Hops:              append([]string{}, hops...),
		AllowedChannels:   []string{SyntheticChannelFabricControl},
		ExpiresAt:         time.Now().UTC().Add(time.Hour),
	}
}

func peerCacheEntryByID(snapshot PeerCacheSnapshot, nodeID string) (PeerCacheEntry, bool) {
	for _, entry := range snapshot.Entries {
		if entry.NodeID == nodeID {
			return entry, true
		}
	}
	return PeerCacheEntry{}, false
}