Show ages on the AS and prefix pages in words (closes #163)

The Age column printed Go's duration format for every plural age, such
as "5m0s ago" or "360h0m0s ago".

The templates now register humanize.Time from go-humanize, which the
server already uses, as the timeSince function, and the hand-written
function is gone. Ages read "5 minutes ago", "3 hours ago" or "2 weeks
ago". An age under a minute reads "now" or in seconds instead of "just
now". An age over a month reads in months or years instead of a date.

Model: opus-5-5

internal/server/handlers_internal_test.go

@@ -512,6 +512,71 @@ func TestPagesSayOriginZeroIsNoKnownOrigin(t *testing.T) {
 	}
 }
 
+// TestPagesShowAgesInWords stores routes last updated about 5 minutes, 3 hours
+// and 15 days ago, and checks that the AS page and the prefix pages show each
+// age in words. Before the fix the ages read "5m0s ago", "3h0m0s ago" and
+// "360h0m0s ago" (https://git.eeqj.de/sneak/routewatch/issues/163).
+func TestPagesShowAgesInWords(t *testing.T) {
+	t.Parallel()
+
+	db, err := database.New(&config.Config{StateDir: t.TempDir()}, logger.New())
+	if err != nil {
+		t.Fatalf("database.New: %v", err)
+	}
+
+	t.Cleanup(func() { _ = db.Close() })
+
+	// Each age is well past a whole number of its unit, so the time the test
+	// takes to run does not change the words.
+	ages := []struct {
+		prefix string
+		age    time.Duration
+		want   string
+	}{
+		{testPrefixV4, 5*time.Minute + 30*time.Second, "5 minutes ago"},
+		{"198.51.100.0/24", 3*time.Hour + 30*time.Minute, "3 hours ago"},
+		{"203.0.113.0/24", 15 * 24 * time.Hour, "2 weeks ago"},
+	}
+
+	now := time.Now().UTC()
+	routes := make([]*database.LiveRoute, 0, len(ages))
+
+	for _, a := range ages {
+		routes = append(routes, &database.LiveRoute{
+			Prefix: a.prefix, MaskLength: 24, IPVersion: 4,
+			OriginASN: 64500, PeerIP: testPeerV4, ASPath: []int{64500},
+			NextHop: testPeerV4, LastUpdated: now.Add(-a.age),
+		})
+	}
+
+	err = db.UpsertLiveRouteBatch(routes)
+	if err != nil {
+		t.Fatalf("UpsertLiveRouteBatch: %v", err)
+	}
+
+	s := New(db, streamer.New(logger.New(), metrics.New()), logger.New(), &config.Config{})
+
+	for _, a := range ages {
+		cell := `<td class="age">` + a.want + `</td>`
+
+		for _, path := range []string{asPagePath, "/prefix/" + a.prefix} {
+			rec := httptest.NewRecorder()
+			s.router.ServeHTTP(rec, httptest.NewRequestWithContext(
+				t.Context(), http.MethodGet, path, nil))
+
+			if rec.Code != http.StatusOK {
+				t.Fatalf("%s: status %d, want %d; body %s",
+					path, rec.Code, http.StatusOK, rec.Body)
+			}
+
+			if !strings.Contains(rec.Body.String(), cell) {
+				t.Errorf("%s does not show the age of the route for %s as %q",
+					path, a.prefix, a.want)
+			}
+		}
+	}
+}
+
 // shortRequestDeadline is the deadline the tests below give a request. The
 // server's 30-second limit and the stats handlers' 4-second limit inherit it,
 // so the tests do not wait for either.