meshcore-analyzer/cmd/server/neighbor_api_test.go

package main

import (
	"database/sql"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/gorilla/mux"
	_ "github.com/mattn/go-sqlite3"
)

// ─── Helpers ───────────────────────────────────────────────────────────────────

// makeTestServer creates a Server with a pre-built neighbor graph for testing.
func makeTestServer(graph *NeighborGraph) *Server {
	srv := &Server{
		perfStats: NewPerfStats(),
	}
	srv.neighborGraph = graph
	return srv
}

// makeTestGraph creates a graph with given edges for testing.
func makeTestGraph(edges ...*NeighborEdge) *NeighborGraph {
	g := NewNeighborGraph()
	g.mu.Lock()
	for _, e := range edges {
		key := makeEdgeKey(e.NodeA, e.NodeB)
		if e.NodeB == "" {
			key = makeEdgeKey(e.NodeA, "prefix:"+e.Prefix)
		}
		e.NodeA = key.A
		if e.NodeB != "" {
			e.NodeB = key.B
		}
		g.edges[key] = e
		g.byNode[key.A] = append(g.byNode[key.A], e)
		if key.B != "" && key.B != key.A {
			g.byNode[key.B] = append(g.byNode[key.B], e)
		}
	}
	g.builtAt = time.Now()
	g.mu.Unlock()
	return g
}

func newEdge(a, b, prefix string, count int, lastSeen time.Time) *NeighborEdge {
	return &NeighborEdge{
		NodeA:     a,
		NodeB:     b,
		Prefix:    prefix,
		Count:     count,
		FirstSeen: lastSeen.Add(-24 * time.Hour),
		LastSeen:  lastSeen,
		Observers: map[string]bool{"obs1": true},
		SNRSum:    -8.0,
		SNRCount:  1,
	}
}

func newAmbiguousEdge(knownPK, prefix string, candidates []string, count int, lastSeen time.Time) *NeighborEdge {
	return &NeighborEdge{
		NodeA:      knownPK,
		NodeB:      "",
		Prefix:     prefix,
		Count:      count,
		FirstSeen:  lastSeen.Add(-24 * time.Hour),
		LastSeen:   lastSeen,
		Observers:  map[string]bool{"obs1": true},
		Ambiguous:  true,
		Candidates: candidates,
	}
}

func serveRequest(srv *Server, method, path string) *httptest.ResponseRecorder {
	router := mux.NewRouter()
	router.HandleFunc("/api/nodes/{pubkey}/neighbors", srv.handleNodeNeighbors).Methods("GET")
	router.HandleFunc("/api/analytics/neighbor-graph", srv.handleNeighborGraph).Methods("GET")

	req := httptest.NewRequest(method, path, nil)
	rr := httptest.NewRecorder()
	router.ServeHTTP(rr, req)
	return rr
}

// ─── Tests: /api/nodes/{pubkey}/neighbors ──────────────────────────────────────

func TestNeighborAPI_EmptyGraph(t *testing.T) {
	srv := makeTestServer(makeTestGraph())
	rr := serveRequest(srv, "GET", "/api/nodes/deadbeef/neighbors")

	if rr.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", rr.Code)
	}

	var resp NeighborResponse
	if err := json.Unmarshal(rr.Body.Bytes(), &resp); err != nil {
		t.Fatalf("bad JSON: %v", err)
	}
	if resp.Node != "deadbeef" {
		t.Errorf("node = %q, want deadbeef", resp.Node)
	}
	if len(resp.Neighbors) != 0 {
		t.Errorf("expected 0 neighbors, got %d", len(resp.Neighbors))
	}
	if resp.TotalObservations != 0 {
		t.Errorf("expected 0 observations, got %d", resp.TotalObservations)
	}
}

func TestNeighborAPI_SingleNeighbor(t *testing.T) {
	now := time.Now()
	e := newEdge("aaaa", "bbbb", "bb", 50, now)
	srv := makeTestServer(makeTestGraph(e))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors")
	if rr.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", rr.Code)
	}

	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 1 {
		t.Fatalf("expected 1 neighbor, got %d", len(resp.Neighbors))
	}
	n := resp.Neighbors[0]
	if n.Pubkey == nil || *n.Pubkey != "bbbb" {
		t.Errorf("expected pubkey bbbb, got %v", n.Pubkey)
	}
	if n.Count != 50 {
		t.Errorf("expected count 50, got %d", n.Count)
	}
	if n.Score <= 0 {
		t.Errorf("expected positive score, got %f", n.Score)
	}
	if n.Ambiguous {
		t.Error("expected not ambiguous")
	}
}

func TestNeighborAPI_MultipleNeighbors(t *testing.T) {
	now := time.Now()
	e1 := newEdge("aaaa", "bbbb", "bb", 100, now)
	e2 := newEdge("aaaa", "cccc", "cc", 10, now)
	srv := makeTestServer(makeTestGraph(e1, e2))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors")
	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 2 {
		t.Fatalf("expected 2 neighbors, got %d", len(resp.Neighbors))
	}
	// Should be sorted by score descending.
	if resp.Neighbors[0].Score < resp.Neighbors[1].Score {
		t.Error("expected sorted by score descending")
	}
	if resp.TotalObservations != 110 {
		t.Errorf("expected 110 total observations, got %d", resp.TotalObservations)
	}
}

func TestNeighborAPI_AmbiguousCandidates(t *testing.T) {
	now := time.Now()
	e := newAmbiguousEdge("aaaa", "c0", []string{"c0de01", "c0de02"}, 12, now)
	srv := makeTestServer(makeTestGraph(e))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors")
	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 1 {
		t.Fatalf("expected 1 neighbor, got %d", len(resp.Neighbors))
	}
	n := resp.Neighbors[0]
	if !n.Ambiguous {
		t.Error("expected ambiguous")
	}
	if n.Pubkey != nil {
		t.Errorf("expected nil pubkey for ambiguous, got %v", n.Pubkey)
	}
	if len(n.Candidates) != 2 {
		t.Fatalf("expected 2 candidates, got %d", len(n.Candidates))
	}
}

func TestNeighborAPI_UnresolvedPrefix(t *testing.T) {
	now := time.Now()
	e := newAmbiguousEdge("aaaa", "ff", []string{}, 3, now)
	srv := makeTestServer(makeTestGraph(e))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors")
	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 1 {
		t.Fatalf("expected 1 neighbor, got %d", len(resp.Neighbors))
	}
	n := resp.Neighbors[0]
	if !n.Unresolved {
		t.Error("expected unresolved=true")
	}
	if len(n.Candidates) != 0 {
		t.Error("expected empty candidates for unresolved")
	}
}

func TestNeighborAPI_MinCountFilter(t *testing.T) {
	now := time.Now()
	e1 := newEdge("aaaa", "bbbb", "bb", 100, now)
	e2 := newEdge("aaaa", "cccc", "cc", 2, now)
	srv := makeTestServer(makeTestGraph(e1, e2))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors?min_count=10")
	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 1 {
		t.Fatalf("expected 1 neighbor after min_count filter, got %d", len(resp.Neighbors))
	}
	if *resp.Neighbors[0].Pubkey != "bbbb" {
		t.Error("expected bbbb to survive filter")
	}
}

func TestNeighborAPI_MinScoreFilter(t *testing.T) {
	now := time.Now()
	e1 := newEdge("aaaa", "bbbb", "bb", 100, now)                     // score ~1.0
	e2 := newEdge("aaaa", "cccc", "cc", 1, now.Add(-30*24*time.Hour)) // very low score
	srv := makeTestServer(makeTestGraph(e1, e2))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors?min_score=0.5")
	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 1 {
		t.Fatalf("expected 1 neighbor after min_score filter, got %d", len(resp.Neighbors))
	}
}

func TestNeighborAPI_ExcludeAmbiguous(t *testing.T) {
	now := time.Now()
	e1 := newEdge("aaaa", "bbbb", "bb", 50, now)
	e2 := newAmbiguousEdge("aaaa", "c0", []string{"c0de01"}, 10, now)
	srv := makeTestServer(makeTestGraph(e1, e2))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors?include_ambiguous=false")
	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 1 {
		t.Fatalf("expected 1 non-ambiguous neighbor, got %d", len(resp.Neighbors))
	}
}

func TestNeighborAPI_UnknownNode(t *testing.T) {
	now := time.Now()
	e := newEdge("aaaa", "bbbb", "bb", 50, now)
	srv := makeTestServer(makeTestGraph(e))

	rr := serveRequest(srv, "GET", "/api/nodes/unknown1234/neighbors")
	if rr.Code != http.StatusOK {
		t.Fatalf("expected 200 for unknown node, got %d", rr.Code)
	}

	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)
	if len(resp.Neighbors) != 0 {
		t.Errorf("expected 0 neighbors for unknown node, got %d", len(resp.Neighbors))
	}
}

// ─── Tests: /api/analytics/neighbor-graph ──────────────────────────────────────

func TestNeighborGraphAPI_EmptyGraph(t *testing.T) {
	srv := makeTestServer(makeTestGraph())
	rr := serveRequest(srv, "GET", "/api/analytics/neighbor-graph")

	if rr.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", rr.Code)
	}

	var resp NeighborGraphResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Edges) != 0 {
		t.Errorf("expected 0 edges, got %d", len(resp.Edges))
	}
	if resp.Stats.TotalEdges != 0 {
		t.Errorf("expected 0 total edges, got %d", resp.Stats.TotalEdges)
	}
	if resp.Stats.TotalNodes != 0 {
		t.Errorf("expected 0 total nodes, got %d", resp.Stats.TotalNodes)
	}
}

func TestNeighborGraphAPI_WithEdges(t *testing.T) {
	now := time.Now()
	e1 := newEdge("aaaa", "bbbb", "bb", 100, now)
	e2 := newEdge("bbbb", "cccc", "cc", 50, now)
	srv := makeTestServer(makeTestGraph(e1, e2))

	rr := serveRequest(srv, "GET", "/api/analytics/neighbor-graph?min_count=1&min_score=0")
	var resp NeighborGraphResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Edges) != 2 {
		t.Fatalf("expected 2 edges, got %d", len(resp.Edges))
	}
	if resp.Stats.TotalNodes != 3 {
		t.Errorf("expected 3 nodes, got %d", resp.Stats.TotalNodes)
	}
	if resp.Stats.TotalEdges != 2 {
		t.Errorf("expected 2 total edges, got %d", resp.Stats.TotalEdges)
	}
}

func TestNeighborGraphAPI_MinCountDefault(t *testing.T) {
	now := time.Now()
	e1 := newEdge("aaaa", "bbbb", "bb", 100, now) // passes default min_count=5
	e2 := newEdge("aaaa", "cccc", "cc", 2, now)   // fails default min_count=5
	srv := makeTestServer(makeTestGraph(e1, e2))

	rr := serveRequest(srv, "GET", "/api/analytics/neighbor-graph")
	var resp NeighborGraphResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Edges) != 1 {
		t.Fatalf("expected 1 edge with default min_count=5, got %d", len(resp.Edges))
	}
}

func TestNeighborGraphAPI_AmbiguousEdgesCount(t *testing.T) {
	now := time.Now()
	e1 := newEdge("aaaa", "bbbb", "bb", 100, now)
	e2 := newAmbiguousEdge("aaaa", "c0", []string{"c0de01", "c0de02"}, 50, now)
	srv := makeTestServer(makeTestGraph(e1, e2))

	rr := serveRequest(srv, "GET", "/api/analytics/neighbor-graph?min_count=1&min_score=0")
	var resp NeighborGraphResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if resp.Stats.AmbiguousEdges != 1 {
		t.Errorf("expected 1 ambiguous edge, got %d", resp.Stats.AmbiguousEdges)
	}
}

func TestNeighborAPI_DistanceKm_WithGPS(t *testing.T) {
	db := setupTestDB(t)
	defer db.Close()

	db.conn.Exec(`INSERT INTO nodes (public_key, name, role, lat, lon, last_seen, first_seen)
		VALUES ('aaaa', 'NodeA', 'repeater', 51.5074, -0.1278, '2026-01-01T00:00:00Z', '2025-01-01T00:00:00Z')`)
	db.conn.Exec(`INSERT INTO nodes (public_key, name, role, lat, lon, last_seen, first_seen)
		VALUES ('bbbb', 'NodeB', 'repeater', 51.5200, -0.1200, '2026-01-01T00:00:00Z', '2025-01-01T00:00:00Z')`)

	cfg := &Config{Port: 3000}
	hub := NewHub()
	srv := NewServer(db, cfg, hub)
	srv.store = NewPacketStore(db, nil)

	now := time.Now()
	srv.neighborGraph = makeTestGraph(newEdge("aaaa", "bbbb", "bb", 50, now))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors")
	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 1 {
		t.Fatalf("expected 1 neighbor, got %d", len(resp.Neighbors))
	}
	n := resp.Neighbors[0]
	if n.DistanceKm == nil {
		t.Fatal("expected distance_km to be set for GPS-enabled nodes")
	}
	if *n.DistanceKm <= 0 {
		t.Errorf("expected positive distance, got %f", *n.DistanceKm)
	}
}

func TestNeighborAPI_DistanceKm_NoGPS(t *testing.T) {
	db := setupTestDB(t)
	defer db.Close()

	// Nodes with 0,0 coords → HasGPS=false
	db.conn.Exec(`INSERT INTO nodes (public_key, name, role, lat, lon, last_seen, first_seen)
		VALUES ('aaaa', 'NodeA', 'repeater', 0, 0, '2026-01-01T00:00:00Z', '2025-01-01T00:00:00Z')`)
	db.conn.Exec(`INSERT INTO nodes (public_key, name, role, lat, lon, last_seen, first_seen)
		VALUES ('bbbb', 'NodeB', 'repeater', 0, 0, '2026-01-01T00:00:00Z', '2025-01-01T00:00:00Z')`)

	cfg := &Config{Port: 3000}
	hub := NewHub()
	srv := NewServer(db, cfg, hub)
	srv.store = NewPacketStore(db, nil)

	now := time.Now()
	srv.neighborGraph = makeTestGraph(newEdge("aaaa", "bbbb", "bb", 50, now))

	rr := serveRequest(srv, "GET", "/api/nodes/aaaa/neighbors")
	var resp NeighborResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	if len(resp.Neighbors) != 1 {
		t.Fatalf("expected 1 neighbor, got %d", len(resp.Neighbors))
	}
	if resp.Neighbors[0].DistanceKm != nil {
		t.Errorf("expected nil distance_km for nodes without GPS, got %f", *resp.Neighbors[0].DistanceKm)
	}
}

func TestNeighborGraphAPI_RegionFilter(t *testing.T) {
	now := time.Now()
	// Edge with observer "obs-sjc" — would match region SJC if we had region resolution.
	// Without a store, region filtering returns nothing (no observers match).
	e1 := newEdge("aaaa", "bbbb", "bb", 100, now)
	srv := makeTestServer(makeTestGraph(e1))
	// No store → region filter has no observers → filters everything out.
	rr := serveRequest(srv, "GET", "/api/analytics/neighbor-graph?region=SJC&min_count=1&min_score=0")
	var resp NeighborGraphResponse
	json.Unmarshal(rr.Body.Bytes(), &resp)

	// With no store, regionObs is nil so filter is skipped → all edges returned.
	// Actually: region="" when store is nil → regionObs stays nil → no filtering.
	// Wait, we set region=SJC and store is nil → resolveRegionObservers won't be called
	// because s.store is nil. So regionObs is nil → filter not applied.
	// Let's just check it doesn't crash.
	if rr.Code != http.StatusOK {
		t.Fatalf("expected 200, got %d", rr.Code)
	}
}

func TestNeighborGraphAPI_ResponseShape(t *testing.T) {
	now := time.Now()
	e := newEdge("aaaa", "bbbb", "bb", 100, now)
	srv := makeTestServer(makeTestGraph(e))

	rr := serveRequest(srv, "GET", "/api/analytics/neighbor-graph?min_count=1&min_score=0")
	var raw map[string]interface{}
	if err := json.Unmarshal(rr.Body.Bytes(), &raw); err != nil {
		t.Fatalf("bad JSON: %v", err)
	}

	// Verify top-level keys.
	for _, key := range []string{"nodes", "edges", "stats"} {
		if _, ok := raw[key]; !ok {
			t.Errorf("missing key %q in response", key)
		}
	}

	// Verify stats keys.
	stats := raw["stats"].(map[string]interface{})
	for _, key := range []string{"total_nodes", "total_edges", "ambiguous_edges", "avg_cluster_size"} {
		if _, ok := stats[key]; !ok {
			t.Errorf("missing stats key %q", key)
		}
	}
}

// ─── Tests: buildNodeInfoMap observer enrichment (#753) ────────────────────────

func TestBuildNodeInfoMap_ObserverEnrichment(t *testing.T) {
	// Create a temp SQLite DB with nodes and observers tables.
	tmpDir := t.TempDir()
	dbPath := tmpDir + "/test.db"

	conn, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer conn.Close()

	// Create tables
	for _, stmt := range []string{
		"CREATE TABLE nodes (public_key TEXT, name TEXT, role TEXT, lat REAL, lon REAL)",
		"CREATE TABLE observers (id TEXT, name TEXT, iata TEXT, inactive INTEGER)",
		"INSERT INTO nodes VALUES ('AAAA1111', 'Repeater-1', 'repeater', 0, 0)",
		"INSERT INTO observers (id, name, iata) VALUES ('BBBB2222', 'Observer-Alpha', '')",
		"INSERT INTO observers (id, name, iata) VALUES ('AAAA1111', 'Obs-also-repeater', '')",
	} {
		if _, err := conn.Exec(stmt); err != nil {
			t.Fatalf("exec %q: %v", stmt, err)
		}
	}
	ensurePreparable(t, conn)
	conn.Close()

	// Open via our DB wrapper
	db, err := OpenDB(dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer db.conn.Close()

	// Build a PacketStore with this DB (minimal — just need getCachedNodesAndPM)
	store := NewPacketStore(db, nil)
	store.Load()

	srv := &Server{
		db:        db,
		store:     store,
		perfStats: NewPerfStats(),
	}

	m := srv.buildNodeInfoMap()

	// AAAA1111 should be from nodes table (repeater), NOT overwritten by observer
	if info, ok := m["aaaa1111"]; !ok {
		t.Error("expected aaaa1111 in map")
	} else if info.Role != "repeater" {
		t.Errorf("expected role=repeater for aaaa1111, got %q", info.Role)
	}

	// BBBB2222 should be enriched from observers table
	if info, ok := m["bbbb2222"]; !ok {
		t.Error("expected bbbb2222 in map (observer-only node)")
	} else {
		if info.Role != "observer" {
			t.Errorf("expected role=observer for bbbb2222, got %q", info.Role)
		}
		if info.Name != "Observer-Alpha" {
			t.Errorf("expected name=Observer-Alpha for bbbb2222, got %q", info.Name)
		}
	}
}

// TestBuildNodeInfoMap_FirstSeenIsCached asserts the regression introduced by
// #1627 r3 stays fixed: the per-pubkey first_seen field MUST come from the
// already-30s-cached getCachedNodesAndPM path, not from a fresh uncached
// `SELECT … FROM nodes` scan on every call.
//
// Method (no DB-driver wrapper needed): mutate the underlying SQLite file's
// first_seen via a separate rw connection between two consecutive calls to
// buildNodeInfoMap(). If first_seen is read fresh on every call (the
// regression), the second call sees the new value. If folded into the
// existing 30s node cache, both calls return the original value — same as
// every other nodeInfo field that comes from getAllNodes().
func TestBuildNodeInfoMap_FirstSeenIsCached(t *testing.T) {
	tmpDir := t.TempDir()
	dbPath := tmpDir + "/test.db"

	// Seed via rw connection.
	rw, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer rw.Close()
	for _, stmt := range []string{
		"CREATE TABLE nodes (public_key TEXT PRIMARY KEY, name TEXT, role TEXT, lat REAL, lon REAL, last_seen TEXT, first_seen TEXT, advert_count INTEGER)",
		"CREATE TABLE observers (id TEXT, name TEXT, iata TEXT, inactive INTEGER)",
		"INSERT INTO nodes VALUES ('AAAA1111', 'Repeater-1', 'repeater', 0, 0, '', '2024-01-01T00:00:00Z', 0)",
	} {
		if _, err := rw.Exec(stmt); err != nil {
			t.Fatalf("seed exec %q: %v", stmt, err)
		}
	}
	ensurePreparable(t, rw)

	db, err := OpenDB(dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer db.conn.Close()

	store := NewPacketStore(db, nil)
	store.Load()

	srv := &Server{
		db:        db,
		store:     store,
		perfStats: NewPerfStats(),
	}

	// Call 1: warm cache and record observed first_seen.
	m1 := srv.buildNodeInfoMap()
	first1 := m1["aaaa1111"].FirstSeen
	if first1 != "2024-01-01T00:00:00Z" {
		t.Fatalf("setup: expected first_seen=2024-01-01T00:00:00Z, got %q", first1)
	}

	// Mutate first_seen out-of-band via the rw connection. Any code path
	// that re-reads first_seen from disk (uncached) will see this new
	// value; a path that folds first_seen into the 30s node cache will
	// not, because the cache is well under 30s old.
	if _, err := rw.Exec("UPDATE nodes SET first_seen='2099-12-31T23:59:59Z' WHERE public_key='AAAA1111'"); err != nil {
		t.Fatalf("mutate: %v", err)
	}

	// Call 2: should match call 1 if first_seen is cached.
	m2 := srv.buildNodeInfoMap()
	first2 := m2["aaaa1111"].FirstSeen
	if first2 != first1 {
		t.Errorf("buildNodeInfoMap re-scanned nodes.first_seen uncached (#1627 r3 regression): "+
			"call 1 saw %q, call 2 saw %q after out-of-band UPDATE; expected both calls to return "+
			"the cached value because getCachedNodesAndPM has a 30s TTL",
			first1, first2)
	}
}

// TestGetAllNodes_FirstSeenSchemaFallback exercises the schema-probe rung that
// fires when nodes.first_seen is missing. The richest SELECT errors out, the
// loop falls through to the next-richest query, and the resulting nodeInfo
// values must have empty FirstSeen with no panic. Regression coverage for the
// existing fallback branch (#1632 review loop 1).
func TestGetAllNodes_FirstSeenSchemaFallback(t *testing.T) {
	tmpDir := t.TempDir()
	dbPath := tmpDir + "/test.db"

	// Seed a nodes table WITHOUT first_seen (advert_count + last_seen present).
	rw, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer rw.Close()
	for _, stmt := range []string{
		"CREATE TABLE nodes (public_key TEXT PRIMARY KEY, name TEXT, role TEXT, lat REAL, lon REAL, last_seen TEXT, advert_count INTEGER)",
		"CREATE TABLE observers (id TEXT, name TEXT, iata TEXT, inactive INTEGER)",
		"INSERT INTO nodes VALUES ('BBBB2222', 'Repeater-2', 'repeater', 0, 0, '2024-02-02T00:00:00Z', 3)",
	} {
		if _, err := rw.Exec(stmt); err != nil {
			t.Fatalf("seed exec %q: %v", stmt, err)
		}
	}
	ensurePreparable(t, rw)

	db, err := OpenDB(dbPath)
	if err != nil {
		t.Fatal(err)
	}
	defer db.conn.Close()

	store := NewPacketStore(db, nil)
	nodes := store.getAllNodes()
	if len(nodes) != 1 {
		t.Fatalf("expected 1 row from fallback rung, got %d", len(nodes))
	}
	n := nodes[0]
	if n.PublicKey != "BBBB2222" {
		t.Errorf("PublicKey mismatch: got %q", n.PublicKey)
	}
	if n.FirstSeen != "" {
		t.Errorf("FirstSeen should be empty when nodes.first_seen column is missing, got %q", n.FirstSeen)
	}
	if n.ObservationCount != 3 {
		t.Errorf("ObservationCount should still populate from advert_count fallback, got %d", n.ObservationCount)
	}
}