Add website analytics

A Tianji-style Websites section: a small tracking script, a public collection endpoint, and a
page per website with visitors, page views, visits, bounce rate, a chart and top lists for pages,
referrers, browsers, systems, devices, countries, languages and events. No cookies and no stored
IP address or user agent. SANDBAR_TRUST_PROXY makes the client address come from the proxy.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/sandbar/analytics.go

@@ -0,0 +1,431 @@
+package sandbar
+
+import (
+	"crypto/sha256"
+	_ "embed"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"regexp"
+	"sort"
+	"strings"
+	"time"
+)
+
+// Website analytics, in the manner of Tianji, Plausible and Umami: a small script on a site sends
+// page views and custom events here, and the Websites page shows visitors, pages, referrers,
+// browsers, systems, devices, countries and events.
+//
+// Privacy by construction: no cookies, no stored IP address or user agent. A visitor is a hash of the
+// IP address, the user agent and the website, salted with a secret and the UTC date, so the same
+// person is the same visitor within a day and cannot be followed beyond it.
+
+//go:embed web/script.js
+var trackerJS []byte
+
+// Website is a site whose visits are counted.
+type Website struct {
+	ID     string `json:"id"`
+	Name   string `json:"name"`
+	Domain string `json:"domain"` // optional: when set, only hits from this host and its subdomains count
+}
+
+func prepareWebsite(v any, id string) error {
+	w := v.(*Website)
+	w.ID = id
+	w.Name = strings.TrimSpace(w.Name)
+	if w.Name == "" {
+		return errors.New("give the website a name")
+	}
+	d := strings.ToLower(strings.TrimSpace(w.Domain))
+	if d != "" {
+		if !strings.Contains(d, "//") {
+			d = "//" + d
+		}
+		u, err := url.Parse(d)
+		if err != nil || u.Hostname() == "" {
+			return errors.New("the domain should look like example.com")
+		}
+		d = u.Hostname()
+	}
+	w.Domain = d
+	return nil
+}
+
+func (s *Server) deleteWebsiteData(id string) {
+	s.st.db.Exec(`DELETE FROM hits WHERE website=?`, id)
+}
+
+// realIP is the address of the client. Behind a reverse proxy, set TrustProxy so the address the
+// proxy added (the last entry of X-Forwarded-For) is used; otherwise every visitor looks like the proxy.
+func (s *Server) realIP(r *http.Request) string {
+	if s.opts.TrustProxy {
+		if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
+			parts := strings.Split(xff, ",")
+			if ip := strings.TrimSpace(parts[len(parts)-1]); net.ParseIP(ip) != nil {
+				return ip
+			}
+		}
+		if ip := strings.TrimSpace(r.Header.Get("X-Real-IP")); net.ParseIP(ip) != nil {
+			return ip
+		}
+	}
+	h, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err != nil {
+		return r.RemoteAddr
+	}
+	return h
+}
+
+func (s *Server) serveTracker(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/javascript; charset=utf-8")
+	w.Header().Set("Cache-Control", "public, max-age=3600")
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Write(trackerJS)
+}
+
+var botRe = regexp.MustCompile(`(?i)bot|crawl|spider|slurp|headless|lighthouse|preview|monitor|curl/|wget|python-requests|go-http-client|okhttp`)
+
+// parseUA reduces a user agent to a browser, a system and a kind of device. Only these labels are stored.
+func parseUA(ua string) (browser, os, device string) {
+	switch {
+	case strings.Contains(ua, "Edg/") || strings.Contains(ua, "EdgA/") || strings.Contains(ua, "EdgiOS/"):
+		browser = "Edge"
+	case strings.Contains(ua, "OPR/") || strings.Contains(ua, "Opera"):
+		browser = "Opera"
+	case strings.Contains(ua, "SamsungBrowser"):
+		browser = "Samsung Internet"
+	case strings.Contains(ua, "Firefox/") || strings.Contains(ua, "FxiOS/"):
+		browser = "Firefox"
+	case strings.Contains(ua, "Chrome/") || strings.Contains(ua, "CriOS/"):
+		browser = "Chrome"
+	case strings.Contains(ua, "Safari/"):
+		browser = "Safari"
+	default:
+		browser = "Other"
+	}
+	switch {
+	case strings.Contains(ua, "Windows"):
+		os = "Windows"
+	case strings.Contains(ua, "Android"):
+		os = "Android"
+	case strings.Contains(ua, "iPhone") || strings.Contains(ua, "iPad") || strings.Contains(ua, "iPod"):
+		os = "iOS"
+	case strings.Contains(ua, "Mac OS X") || strings.Contains(ua, "Macintosh"):
+		os = "macOS"
+	case strings.Contains(ua, "CrOS"):
+		os = "ChromeOS"
+	case strings.Contains(ua, "Linux") || strings.Contains(ua, "X11"):
+		os = "Linux"
+	default:
+		os = "Other"
+	}
+	switch {
+	case strings.Contains(ua, "iPad") || strings.Contains(ua, "Tablet") || (strings.Contains(ua, "Android") && !strings.Contains(ua, "Mobile")):
+		device = "Tablet"
+	case strings.Contains(ua, "Mobi") || strings.Contains(ua, "iPhone"):
+		device = "Mobile"
+	default:
+		device = "Desktop"
+	}
+	return
+}
+
+// secret is the random value that salts visitor hashes. It is made once and kept with the other settings.
+func (s *Server) analyticsSecret() string {
+	s.anaMu.Lock()
+	defer s.anaMu.Unlock()
+	if s.anaSecret != "" {
+		return s.anaSecret
+	}
+	var v struct{ Secret string }
+	if s.st.get("setting", "analytics", &v) != nil || v.Secret == "" {
+		v.Secret = newToken()
+		s.st.put("setting", "analytics", &v)
+	}
+	s.anaSecret = v.Secret
+	return v.Secret
+}
+
+func (s *Server) visitorID(website, ip, ua string, now time.Time) string {
+	h := sha256.Sum256([]byte(s.analyticsSecret() + "|" + now.UTC().Format("2006-01-02") + "|" + website + "|" + ip + "|" + ua))
+	return hex.EncodeToString(h[:8])
+}
+
+// hitAllowed limits how fast one address can send hits: a script that loops must not fill the database.
+func (s *Server) hitAllowed(ip string) bool {
+	now := s.now()
+	s.anaMu.Lock()
+	defer s.anaMu.Unlock()
+	if len(s.anaTry) > 20000 {
+		s.anaTry = map[string][]time.Time{}
+	}
+	recent := s.anaTry[ip][:0]
+	for _, t := range s.anaTry[ip] {
+		if now.Sub(t) < time.Minute {
+			recent = append(recent, t)
+		}
+	}
+	if len(recent) >= 120 {
+		s.anaTry[ip] = recent
+		return false
+	}
+	s.anaTry[ip] = append(recent, now)
+	return true
+}
+
+func clip(s string, n int) string {
+	s = strings.TrimSpace(s)
+	if len(s) > n {
+		s = strings.ToValidUTF8(s[:n], "")
+	}
+	return s
+}
+
+// collect receives a page view or event from the tracker script. It is public by design, so it
+// answers 204 to everything it ignores and gives nothing away.
+func (s *Server) collect(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Access-Control-Allow-Methods", "POST, OPTIONS")
+	w.Header().Set("Access-Control-Allow-Headers", "Content-Type")
+	if r.Method == http.MethodOptions {
+		w.WriteHeader(204)
+		return
+	}
+	defer w.WriteHeader(204)
+	body, err := io.ReadAll(http.MaxBytesReader(w, r.Body, 4<<10))
+	if err != nil {
+		return
+	}
+	var in struct {
+		Website, Path, Referrer, Hostname, Language, Event string
+		Data                                               map[string]any
+	}
+	if json.Unmarshal(body, &in) != nil {
+		return
+	}
+	var site Website
+	if s.st.get("website", in.Website, &site) != nil {
+		return
+	}
+	host := strings.ToLower(in.Hostname)
+	if site.Domain != "" && host != site.Domain && !strings.HasSuffix(host, "."+site.Domain) {
+		return
+	}
+	ua := r.UserAgent()
+	if ua == "" || botRe.MatchString(ua) {
+		return
+	}
+	ip := s.realIP(r)
+	if !s.hitAllowed(ip) {
+		return
+	}
+	path := in.Path
+	if i := strings.IndexAny(path, "?"); i >= 0 {
+		path = path[:i]
+	}
+	if !strings.HasPrefix(path, "/") {
+		path = "/" + path
+	}
+	ref := ""
+	if u, err := url.Parse(in.Referrer); err == nil && u.Host != "" {
+		if rh := strings.TrimPrefix(strings.ToLower(u.Hostname()), "www."); rh != strings.TrimPrefix(host, "www.") {
+			ref = rh
+		}
+	}
+	country := strings.ToUpper(clip(r.Header.Get("CF-IPCountry"), 2))
+	if country == "" {
+		country = strings.ToUpper(clip(r.Header.Get("CloudFront-Viewer-Country"), 2))
+	}
+	if country == "XX" || country == "T1" {
+		country = ""
+	}
+	lang := strings.ToLower(clip(in.Language, 12))
+	if i := strings.IndexAny(lang, "-_"); i > 0 {
+		lang = lang[:i]
+	}
+	data := ""
+	if in.Event != "" && len(in.Data) > 0 {
+		if b, err := json.Marshal(in.Data); err == nil && len(b) <= 1024 {
+			data = string(b)
+		}
+	}
+	browser, osName, device := parseUA(ua)
+	now := s.now()
+	s.st.db.Exec(`INSERT INTO hits(website,time,visitor,event,path,referrer,browser,os,device,country,lang,data) VALUES(?,?,?,?,?,?,?,?,?,?,?,?)`,
+		site.ID, now.Unix(), s.visitorID(site.ID, ip, ua, now), clip(in.Event, 80), clip(path, 200), ref, browser, osName, device, country, lang, data)
+}
+
+// ---------- reading ----------
+
+type topRow struct {
+	Name     string `json:"name"`
+	Visitors int    `json:"visitors"`
+	Views    int    `json:"views"` // page views, or the number of times for an event
+}
+
+type seriesPoint struct {
+	Time     int64 `json:"t"`
+	Views    int   `json:"views"`
+	Visitors int   `json:"visitors"`
+}
+
+type siteStats struct {
+	Range      string        `json:"range"`
+	Bucket     string        `json:"bucket"` // "hour" or "day"
+	Visitors   int           `json:"visitors"`
+	Views      int           `json:"views"`
+	Visits     int           `json:"visits"`
+	BounceRate float64       `json:"bounceRate"` // percent of visits with one page view; -1 if no visits
+	Online     int           `json:"online"`     // distinct visitors in the last 5 minutes
+	Series     []seriesPoint `json:"series"`
+	Pages      []topRow      `json:"pages"`
+	Referrers  []topRow      `json:"referrers"`
+	Browsers   []topRow      `json:"browsers"`
+	Systems    []topRow      `json:"systems"`
+	Devices    []topRow      `json:"devices"`
+	Countries  []topRow      `json:"countries"`
+	Languages  []topRow      `json:"languages"`
+	Events     []topRow      `json:"events"`
+}
+
+var ranges = map[string]time.Duration{"24h": 24 * time.Hour, "7d": 7 * 24 * time.Hour, "30d": 30 * 24 * time.Hour, "90d": 90 * 24 * time.Hour}
+
+// visitGap is how long a visitor can be quiet before their next page view starts a new visit.
+const visitGap = 30 * 60
+
+func (s *Server) websiteStats(id, rng string) (*siteStats, error) {
+	span, ok := ranges[rng]
+	if !ok {
+		rng, span = "7d", ranges["7d"]
+	}
+	now := s.now()
+	from := now.Add(-span).Unix()
+	out := &siteStats{Range: rng, Bucket: "day", BounceRate: -1, Series: []seriesPoint{}}
+	step := int64(86400)
+	if rng == "24h" {
+		out.Bucket, step = "hour", 3600
+	}
+	db := s.st.db
+
+	db.QueryRow(`SELECT count(DISTINCT visitor), count(*) FROM hits WHERE website=? AND time>=? AND event=''`, id, from).Scan(&out.Visitors, &out.Views)
+	db.QueryRow(`SELECT count(DISTINCT visitor) FROM hits WHERE website=? AND time>=?`, id, now.Add(-5*time.Minute).Unix()).Scan(&out.Online)
+
+	// Visits and bounces: a visitor's page views, split wherever they were quiet for half an hour.
+	if rows, err := db.Query(`SELECT visitor,time FROM hits WHERE website=? AND time>=? AND event='' ORDER BY visitor,time`, id, from); err == nil {
+		var prev string
+		var prevT int64
+		views, bounces := 0, 0
+		closeVisit := func() {
+			if views > 0 {
+				out.Visits++
+			}
+			if views == 1 {
+				bounces++
+			}
+		}
+		for rows.Next() {
+			var v string
+			var t int64
+			if rows.Scan(&v, &t) != nil {
+				continue
+			}
+			if v != prev || t-prevT > visitGap {
+				closeVisit()
+				views = 0
+			}
+			views++
+			prev, prevT = v, t
+		}
+		closeVisit()
+		rows.Close()
+		if out.Visits > 0 {
+			out.BounceRate = float64(bounces) * 100 / float64(out.Visits)
+		}
+	}
+
+	// The chart: one point per hour or UTC day, empty ones included so the line has no gaps.
+	buckets := map[int64]seriesPoint{}
+	if rows, err := db.Query(`SELECT (time/?)*?, count(*), count(DISTINCT visitor) FROM hits WHERE website=? AND time>=? AND event='' GROUP BY 1`, step, step, id, from); err == nil {
+		for rows.Next() {
+			var p seriesPoint
+			if rows.Scan(&p.Time, &p.Views, &p.Visitors) == nil {
+				buckets[p.Time] = p
+			}
+		}
+		rows.Close()
+	}
+	for t := (from / step) * step; t <= now.Unix(); t += step {
+		p := buckets[t]
+		p.Time = t
+		out.Series = append(out.Series, p)
+	}
+
+	top := func(col string, events bool, empty string) []topRow {
+		cond := "event=''"
+		sel := col
+		if events {
+			cond, sel = "event!=''", "event"
+		}
+		rows, err := db.Query(`SELECT `+sel+`, count(DISTINCT visitor), count(*) FROM hits WHERE website=? AND time>=? AND `+cond+
+			` GROUP BY 1 ORDER BY 3 DESC, 1 LIMIT 10`, id, from)
+		list := []topRow{}
+		if err != nil {
+			return list
+		}
+		defer rows.Close()
+		for rows.Next() {
+			var r topRow
+			if rows.Scan(&r.Name, &r.Visitors, &r.Views) == nil {
+				if r.Name == "" {
+					r.Name = empty
+				}
+				list = append(list, r)
+			}
+		}
+		return list
+	}
+	out.Pages = top("path", false, "/")
+	out.Referrers = top("referrer", false, "Direct")
+	out.Browsers = top("browser", false, "Other")
+	out.Systems = top("os", false, "Other")
+	out.Devices = top("device", false, "Other")
+	out.Countries = top("country", false, "Unknown")
+	out.Languages = top("lang", false, "Unknown")
+	out.Events = top("", true, "")
+	sort.SliceStable(out.Series, func(i, j int) bool { return out.Series[i].Time < out.Series[j].Time })
+	return out, nil
+}
+
+func (s *Server) websiteStatsHandler(w http.ResponseWriter, r *http.Request) {
+	id := r.PathValue("id")
+	var site Website
+	if s.st.get("website", id, &site) != nil {
+		writeJSON(w, 404, map[string]string{"error": "No such website."})
+		return
+	}
+	st, _ := s.websiteStats(id, r.URL.Query().Get("range"))
+	writeJSON(w, 200, st)
+}
+
+// websiteSummary gives the list page a number for each site: visitors and page views in the last day.
+func (s *Server) websiteSummary(w http.ResponseWriter, r *http.Request) {
+	out := map[string]map[string]int{}
+	since := s.now().Add(-24 * time.Hour).Unix()
+	rows, err := s.st.db.Query(`SELECT website, count(DISTINCT visitor), count(*) FROM hits WHERE time>=? AND event='' GROUP BY website`, since)
+	if err == nil {
+		defer rows.Close()
+		for rows.Next() {
+			var id string
+			var v, p int
+			if rows.Scan(&id, &v, &p) == nil {
+				out[id] = map[string]int{"visitors": v, "views": p}
+			}
+		}
+	}
+	writeJSON(w, 200, out)
+}

internal/sandbar/analytics_test.go

@@ -0,0 +1,175 @@
+package sandbar
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+const (
+	uaChrome = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36"
+	uaPhone  = "Mozilla/5.0 (iPhone; CPU iPhone OS 17_5 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.5 Mobile/15E148 Safari/604.1"
+)
+
+func TestParseUA(t *testing.T) {
+	for _, c := range []struct{ ua, browser, os, device string }{
+		{uaChrome, "Chrome", "Windows", "Desktop"},
+		{uaPhone, "Safari", "iOS", "Mobile"},
+		{"Mozilla/5.0 (X11; Linux x86_64; rv:127.0) Gecko/20100101 Firefox/127.0", "Firefox", "Linux", "Desktop"},
+		{"Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 Chrome/126.0 Safari/537.36 Edg/126.0", "Edge", "Windows", "Desktop"},
+		{"Mozilla/5.0 (Linux; Android 14; Pixel 8) AppleWebKit/537.36 Chrome/126.0 Mobile Safari/537.36", "Chrome", "Android", "Mobile"},
+		{"Mozilla/5.0 (Linux; Android 13; SM-X700) AppleWebKit/537.36 Chrome/126.0 Safari/537.36", "Chrome", "Android", "Tablet"},
+	} {
+		b, o, d := parseUA(c.ua)
+		if b != c.browser || o != c.os || d != c.device {
+			t.Errorf("%q: got %s/%s/%s, want %s/%s/%s", c.ua, b, o, d, c.browser, c.os, c.device)
+		}
+	}
+}
+
+func TestWebsiteAnalytics(t *testing.T) {
+	s, _, _ := newTestServer(t)
+	s.st.put("website", "w1", &Website{ID: "w1", Name: "Blog", Domain: "example.com"})
+	ts := httptest.NewServer(s.Handler())
+	defer ts.Close()
+
+	send := func(ua string, body string) int {
+		req, _ := http.NewRequest("POST", ts.URL+"/api/send", strings.NewReader(body))
+		req.Header.Set("Content-Type", "text/plain")
+		req.Header.Set("User-Agent", ua)
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatal(err)
+		}
+		resp.Body.Close()
+		return resp.StatusCode
+	}
+	view := func(ua, path, ref string) {
+		b, _ := json.Marshal(map[string]string{"website": "w1", "hostname": "www.example.com", "path": path, "referrer": ref, "language": "en-GB"})
+		if code := send(ua, string(b)); code != 204 {
+			t.Fatalf("send: %d", code)
+		}
+	}
+	view(uaChrome, "/", "https://news.example.org/story?id=1")
+	view(uaChrome, "/about?utm=x", "")
+	view(uaPhone, "/", "")
+	send(uaChrome, `{"website":"w1","hostname":"example.com","path":"/pricing","event":"signup","data":{"plan":"pro"}}`)
+
+	// Things that must not be counted.
+	send("Googlebot/2.1", `{"website":"w1","hostname":"example.com","path":"/bot"}`)
+	send(uaChrome, `{"website":"w1","hostname":"evil.test","path":"/wrong-host"}`)
+	send(uaChrome, `{"website":"nope","hostname":"example.com","path":"/unknown-site"}`)
+	send(uaChrome, `not json`)
+
+	c := newAPIClient(t, ts)
+	if code := c.do("GET", "/api/v1/websites/w1/stats", nil, nil); code != 401 {
+		t.Fatalf("stats without sign-in: %d", code)
+	}
+	c.setup()
+	var st siteStats
+	if code := c.do("GET", "/api/v1/websites/w1/stats?range=7d", nil, &st); code != 200 {
+		t.Fatalf("stats: %d", code)
+	}
+	if st.Views != 3 || st.Visitors != 2 || st.Visits != 2 || st.BounceRate != 50 {
+		t.Fatalf("totals: views %d visitors %d visits %d bounce %.0f", st.Views, st.Visitors, st.Visits, st.BounceRate)
+	}
+	has := func(rows []topRow, name string, views int) bool {
+		for _, r := range rows {
+			if r.Name == name && r.Views == views {
+				return true
+			}
+		}
+		return false
+	}
+	for _, c := range []struct {
+		what string
+		rows []topRow
+		name string
+		n    int
+	}{
+		{"page /", st.Pages, "/", 2}, {"page /about without the query", st.Pages, "/about", 1},
+		{"referrer host only", st.Referrers, "news.example.org", 1}, {"direct", st.Referrers, "Direct", 2},
+		{"browser", st.Browsers, "Chrome", 2}, {"os", st.Systems, "iOS", 1},
+		{"device", st.Devices, "Mobile", 1}, {"language", st.Languages, "en", 3}, {"event", st.Events, "signup", 1},
+	} {
+		if !has(c.rows, c.name, c.n) {
+			t.Errorf("%s: %q x%d not in %+v", c.what, c.name, c.n, c.rows)
+		}
+	}
+	for _, p := range st.Pages {
+		if p.Name == "/bot" || p.Name == "/wrong-host" || p.Name == "/unknown-site" || p.Name == "/pricing" {
+			t.Errorf("counted something it should not: %+v", p)
+		}
+	}
+	if st.Online != 2 {
+		t.Fatalf("online %d", st.Online)
+	}
+	nonEmpty := 0
+	for _, p := range st.Series {
+		if p.Views > 0 {
+			nonEmpty++
+		}
+	}
+	if nonEmpty != 1 || len(st.Series) < 7 {
+		t.Fatalf("series: %d points, %d with views", len(st.Series), nonEmpty)
+	}
+
+	// No IP address or user agent is stored.
+	var n int
+	s.st.db.QueryRow(`SELECT count(*) FROM hits WHERE visitor LIKE '%127.0.0.1%' OR browser LIKE '%Mozilla%'`).Scan(&n)
+	if n != 0 {
+		t.Fatal("raw identifiers stored")
+	}
+
+	// The script and the browser preflight.
+	resp, _ := http.Get(ts.URL + "/script.js")
+	body := make([]byte, 64)
+	resp.Body.Read(body)
+	resp.Body.Close()
+	if resp.StatusCode != 200 || !strings.Contains(resp.Header.Get("Content-Type"), "javascript") {
+		t.Fatalf("script.js: %d %s", resp.StatusCode, resp.Header.Get("Content-Type"))
+	}
+	req, _ := http.NewRequest("OPTIONS", ts.URL+"/api/send", nil)
+	resp, _ = http.DefaultClient.Do(req)
+	resp.Body.Close()
+	if resp.StatusCode != 204 || resp.Header.Get("Access-Control-Allow-Origin") != "*" {
+		t.Fatalf("preflight: %d", resp.StatusCode)
+	}
+
+	// Deleting the website deletes its hits.
+	if code := c.do("DELETE", "/api/v1/websites/w1", nil, nil); code != 200 {
+		t.Fatalf("delete: %d", code)
+	}
+	s.st.db.QueryRow(`SELECT count(*) FROM hits`).Scan(&n)
+	if n != 0 {
+		t.Fatalf("%d hits left after deleting the website", n)
+	}
+}
+
+func TestHitRateLimitAndProxy(t *testing.T) {
+	s, _, _ := newTestServer(t)
+	for i := 0; i < 120; i++ {
+		if !s.hitAllowed("1.2.3.4") {
+			t.Fatalf("hit %d refused too early", i)
+		}
+	}
+	if s.hitAllowed("1.2.3.4") {
+		t.Fatal("the 121st hit in a minute should be refused")
+	}
+	if !s.hitAllowed("5.6.7.8") {
+		t.Fatal("another address has its own allowance")
+	}
+
+	r := httptest.NewRequest("GET", "/", nil)
+	r.RemoteAddr = "10.0.0.1:5555"
+	r.Header.Set("X-Forwarded-For", "6.6.6.6, 9.9.9.9")
+	if ip := s.realIP(r); ip != "10.0.0.1" {
+		t.Fatalf("without TrustProxy the connection address is used, got %s", ip)
+	}
+	s.opts.TrustProxy = true
+	if ip := s.realIP(r); ip != "9.9.9.9" {
+		t.Fatalf("the proxy's entry is the last one, got %s", ip)
+	}
+}

internal/sandbar/api.go

@@ -25,6 +25,9 @@ func (s *Server) Handler() http.Handler {
 	mux.HandleFunc("GET /status.json", s.statusJSON)
 	mux.HandleFunc("GET /healthz", func(w http.ResponseWriter, r *http.Request) { io.WriteString(w, "ok") })
 	mux.HandleFunc("GET /metrics", s.metrics)
+	mux.HandleFunc("GET /script.js", s.serveTracker)
+	mux.HandleFunc("POST /api/send", s.collect)
+	mux.HandleFunc("OPTIONS /api/send", s.collect)
 	mux.HandleFunc("GET /api/v1/hb/{token}", s.heartbeat)
 	mux.HandleFunc("POST /api/v1/hb/{token}", s.heartbeat)
 
@@ -105,6 +108,9 @@ func (s *Server) Handler() http.Handler {
 		}
 		return nil
 	}, nil)
+	s.crud(mux, "websites", "website", true, func() any { return &Website{} }, prepareWebsite, nil)
+	mux.HandleFunc("GET /api/v1/websites/{id}/stats", s.auth(false, s.websiteStatsHandler))
+	mux.HandleFunc("GET /api/v1/website-summary", s.auth(false, s.websiteSummary))
 	mux.HandleFunc("GET /api/v1/system/update", s.auth(true, s.updateStatus))
 	mux.HandleFunc("POST /api/v1/system/update", s.auth(true, s.updateApply))
 	mux.HandleFunc("POST /api/v1/channels/{id}/test", s.auth(true, s.testChannel))
@@ -349,6 +355,9 @@ func (s *Server) crud(mux *http.ServeMux, path, kind string, adminWrite bool, ne
 		if kind == "monitor" {
 			s.deleteMonitorData(id)
 		}
+		if kind == "website" {
+			s.deleteWebsiteData(id)
+		}
 		fail2(w, s.st.del(kind, id))
 	}))
 }

internal/sandbar/auth.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"database/sql"
 	"errors"
-	"net"
 	"net/http"
 	"strings"
 	"time"
@@ -144,19 +143,11 @@ func (s *Server) noteFailure(ip string) {
 	s.loginMu.Unlock()
 }
 
-func clientIP(r *http.Request) string {
-	h, _, err := net.SplitHostPort(r.RemoteAddr)
-	if err != nil {
-		return r.RemoteAddr
-	}
-	return h
-}
-
 var errThrottled = errors.New("too many attempts, try again in a few minutes")
 
 // login checks credentials and starts a session.
 func (s *Server) login(w http.ResponseWriter, r *http.Request, email, password string) (*User, error) {
-	ip := clientIP(r)
+	ip := s.realIP(r)
 	if s.throttled(ip) {
 		return nil, errThrottled
 	}

internal/sandbar/bars_test.go

@@ -38,7 +38,7 @@ func TestUptimeBars(t *testing.T) {
 	}
 
 	// The rollup survives pruning the raw checks.
-	s.st.prune(clk.Now().AddDate(0, 0, 60), 30, 1)
+	s.st.prune(clk.Now().AddDate(0, 0, 60), 30, 1, 365)
 	if got := s.dailyUptime(m.ID, 5, clk.Now()); got[2] != [2]int{4, 1} {
 		t.Fatalf("rollup lost after pruning: %v", got)
 	}

internal/sandbar/server.go

@@ -23,8 +23,10 @@ type Options struct {
 	MasterKey    string
 	MetricsToken string
 	SMTP         SMTPConfig
-	MessageDays  int // how long topic messages are kept (default 30)
-	CheckDays    int // how long monitor results are kept (default 30)
+	MessageDays  int  // how long topic messages are kept (default 30)
+	CheckDays    int  // how long monitor results are kept (default 30)
+	HitDays      int  // how long website analytics are kept (default 365)
+	TrustProxy   bool // take the client address from X-Forwarded-For, for use behind a reverse proxy
 
 	// Self-update (see update.go). Version is the running release, such as v0.2.0; anything else
 	// ("dev") never updates. Restart is called after a new binary is installed and should close
@@ -55,6 +57,10 @@ type Server struct {
 
 	upd updateState
 
+	anaMu     sync.Mutex // website analytics: the visitor salt and a per-address rate limit
+	anaSecret string
+	anaTry    map[string][]time.Time
+
 	stop chan struct{}
 	wg   sync.WaitGroup
 }
@@ -66,7 +72,10 @@ func New(opts Options, st *Store) *Server {
 	if opts.CheckDays <= 0 {
 		opts.CheckDays = 30
 	}
-	return &Server{opts: opts, st: st, hub: newHub(), running: map[string]bool{}, loginTry: map[string][]time.Time{}, stop: make(chan struct{})}
+	if opts.HitDays <= 0 {
+		opts.HitDays = 365
+	}
+	return &Server{opts: opts, st: st, hub: newHub(), running: map[string]bool{}, loginTry: map[string][]time.Time{}, anaTry: map[string][]time.Time{}, stop: make(chan struct{})}
 }
 
 func (s *Server) now() time.Time {
@@ -80,7 +89,7 @@ func (s *Server) now() time.Time {
 func (s *Server) Start() {
 	s.every(time.Second, func() { s.runDueMonitors(s.now()) })
 	s.every(5*time.Second, func() { s.escalate(s.now()) })
-	s.every(time.Hour, func() { s.st.prune(s.now(), s.opts.MessageDays, s.opts.CheckDays) })
+	s.every(time.Hour, func() { s.st.prune(s.now(), s.opts.MessageDays, s.opts.CheckDays, s.opts.HitDays) })
 }
 
 func (s *Server) Close() {

internal/sandbar/store.go

@@ -48,6 +48,12 @@ CREATE INDEX IF NOT EXISTS checks_monitor ON checks(monitor_id, time);
 -- One row per monitor per UTC day, kept far longer than raw checks: it feeds the status page's uptime bars.
 CREATE TABLE IF NOT EXISTS daily (
 	monitor_id TEXT NOT NULL, day TEXT NOT NULL, checks INTEGER NOT NULL, fails INTEGER NOT NULL, PRIMARY KEY (monitor_id, day));
+-- Website analytics: one row per page view or event. No IP address or user agent is kept, only labels.
+CREATE TABLE IF NOT EXISTS hits (
+	website TEXT NOT NULL, time INTEGER NOT NULL, visitor TEXT NOT NULL, event TEXT NOT NULL, path TEXT NOT NULL,
+	referrer TEXT NOT NULL, browser TEXT NOT NULL, os TEXT NOT NULL, device TEXT NOT NULL, country TEXT NOT NULL,
+	lang TEXT NOT NULL, data TEXT NOT NULL);
+CREATE INDEX IF NOT EXISTS hits_site ON hits(website, time);
 CREATE TABLE IF NOT EXISTS mstate (
 	monitor_id TEXT PRIMARY KEY, status TEXT NOT NULL, since INTEGER NOT NULL, last_check INTEGER NOT NULL,
 	last_ms INTEGER NOT NULL, fails INTEGER NOT NULL, last_ping INTEGER NOT NULL, detail TEXT NOT NULL);
@@ -246,7 +252,8 @@ func (s *Store) events(scope, ref string) []Event {
 }
 
 // prune deletes data past its retention.
-func (s *Store) prune(now time.Time, messageDays, checkDays int) {
+func (s *Store) prune(now time.Time, messageDays, checkDays, hitDays int) {
+	s.db.Exec(`DELETE FROM hits WHERE time < ?`, now.AddDate(0, 0, -hitDays).Unix())
 	s.db.Exec(`DELETE FROM messages WHERE time < ?`, now.AddDate(0, 0, -messageDays).Unix())
 	s.db.Exec(`DELETE FROM checks WHERE time < ?`, now.AddDate(0, 0, -checkDays).Unix())
 	s.db.Exec(`DELETE FROM daily WHERE day < ?`, now.UTC().AddDate(0, 0, -400).Format("2006-01-02"))

internal/sandbar/web/index.html

@@ -227,6 +227,28 @@
   .feed .empty { margin:0; }
   .msg { border:var(--border-w) solid var(--border); border-radius:var(--radius); padding:var(--s2) var(--s3); display:flex; flex-direction:column; gap:var(--s1); }
   .msg .tag { margin-right:var(--s1); }
+  /* website analytics */
+  .stats { display:grid; grid-template-columns:repeat(auto-fit,minmax(104px,1fr)); gap:var(--s3); margin-bottom:var(--s4); }
+  .stat { background:var(--surface); border:var(--border-w) solid var(--border); border-radius:var(--radius-lg); padding:var(--s3) var(--s4); }
+  .stat .n { font-size:var(--text-xl); font-weight:600; font-variant-numeric:tabular-nums; }
+  .stat .l { font-size:var(--text-sm); color:var(--text-muted); }
+  .chart { display:flex; align-items:flex-end; gap:2px; height:180px; margin-top:var(--s3); }
+  .chart .col { position:relative; flex:1; min-width:0; height:100%; display:flex; align-items:flex-end; }
+  .chart .col:hover { background:var(--surface-2); }
+  .chart .v, .chart .u { position:absolute; left:0; right:0; bottom:0; border-radius:2px 2px 0 0; }
+  .chart .v { background:color-mix(in srgb, var(--accent) 35%, var(--surface)); }
+  .chart .u { background:var(--accent); }
+  .axis2 { display:flex; justify-content:space-between; margin-top:var(--s1); font-size:var(--text-xs); color:var(--text-faint); }
+  .legend { display:flex; gap:var(--s4); font-size:var(--text-sm); color:var(--text-muted); flex-wrap:wrap; }
+  .legend i { display:inline-block; width:10px; height:10px; border-radius:2px; margin-right:var(--s1); vertical-align:baseline; }
+  .cols { display:grid; grid-template-columns:repeat(auto-fit,minmax(300px,1fr)); gap:var(--s4); margin-top:var(--s4); }
+  .cols .card { margin:0; }
+  .top { width:100%; border-collapse:collapse; font-size:var(--text-sm); }
+  .top td { padding:var(--s1) var(--s2); }
+  .top td:first-child { background:linear-gradient(to right, var(--accent-soft) var(--w), transparent var(--w)); overflow-wrap:anywhere; }
+  .top td.num { text-align:right; white-space:nowrap; width:1%; }
+  .top th { text-align:right; font-weight:500; color:var(--text-muted); padding:var(--s1) var(--s2); }
+  .top th:first-child { text-align:left; }
 </style>
 </head>
 <body>
@@ -360,6 +382,7 @@ const ICONS = {
   incidents:'<path d="m21.73 18-8-14a2 2 0 0 0-3.48 0l-8 14A2 2 0 0 0 4 21h16a2 2 0 0 0 1.73-3"/><path d="M12 9v4M12 17h.01"/>',
   oncall:'<rect x="3" y="4" width="18" height="18" rx="2"/><path d="M16 2v4M8 2v4M3 10h18"/>',
   monitors:'<path d="M22 12h-4l-3 9L9 3l-3 9H2"/>',
+  websites:'<path d="M3 3v18h18"/><path d="M18 17V9"/><path d="M13 17V5"/><path d="M8 17v-3"/>',
   topics:'<path d="M21 15a2 2 0 0 1-2 2H7l-4 4V5a2 2 0 0 1 2-2h14a2 2 0 0 1 2 2z"/>',
   channels:'<path d="m22 2-7 20-4-9-9-4z"/><path d="M22 2 11 13"/>',
   status:'<circle cx="12" cy="12" r="10"/><path d="M2 12h20"/><path d="M12 2a15.3 15.3 0 0 1 4 10 15.3 15.3 0 0 1-4 10 15.3 15.3 0 0 1-4-10 15.3 15.3 0 0 1 4-10z"/>',
@@ -420,6 +443,7 @@ const PAGES = {
   incidents: ['Incidents', 'Coordinate the response when something is wrong, and keep a record of what happened.'],
   oncall:    ['On-call', 'Who is responsible right now, and who is told next when nobody answers.'],
   monitors:  ['Monitors', 'Checks that tell you when a website, port, certificate or scheduled job stops working.'],
+  websites:  ['Websites', 'Count visitors and page views on your sites, without cookies or personal data.'],
   topics:    ['Topics', 'Publish and subscribe to messages with plain HTTP requests. Phones can use the ntfy app.'],
   channels:  ['Channels', 'Email addresses and webhooks that receive every alert and incident update.'],
   users:     ['People', 'Everyone who can sign in, and how to reach them.'],
@@ -427,7 +451,7 @@ const PAGES = {
 };
 const NAV = [
   ['Respond', [['alerts', 'Alerts', 'alerts'], ['incidents', 'Incidents', 'incidents'], ['oncall', 'On-call', 'oncall']]],
-  ['Observe', [['monitors', 'Monitors', 'monitors'], ['topics', 'Topics', 'topics']]],
+  ['Observe', [['monitors', 'Monitors', 'monitors'], ['websites', 'Websites', 'websites'], ['topics', 'Topics', 'topics']]],
   ['Set up', [['channels', 'Channels', 'channels'], ['users', 'People', 'users']]],
 ];
 function route() {
@@ -754,6 +778,75 @@ function passwordDialog(u) {
   dialogForm('Set a password for ' + u.name, 'They are signed out everywhere.', [field('New password', pw, 'At least 10 characters')], 'Set password', async () => { await api('POST', `${V1}/users/${u.id}/password`, {password:pw.value}); toast('Password changed.'); });
 }
 
+// ---------- websites (analytics) ----------
+const RANGES = [['24h', 'Last 24 hours'], ['7d', 'Last 7 days'], ['30d', 'Last 30 days'], ['90d', 'Last 90 days']];
+const num = n => Number(n || 0).toLocaleString();
+function regionName(code) { try { return new Intl.DisplayNames(undefined, {type:'region'}).of(code) || code; } catch (e) { return code; } }
+function languageName(code) { try { return new Intl.DisplayNames(undefined, {type:'language'}).of(code) || code; } catch (e) { return code; } }
+
+views.websites = async () => {
+  if (S.arg) return websiteDetail(S.arg);
+  const admin = S.me.role === 'admin';
+  S.headerAction = admin ? ['Add website', () => websiteDialog()] : null;
+  const [sites, sum] = await Promise.all([api('GET', V1 + '/websites'), api('GET', V1 + '/website-summary')]);
+  if (!sites.length) return emptyState('websites', 'No websites yet', 'Add a website, then paste one line of code into its pages. Visitors and page views show up here. No cookies are set and no personal data is kept.',
+    admin ? h('button', {class:'btn', onclick:() => websiteDialog()}, 'Add website') : null);
+  return table(['Website', 'Visitors, last 24 hours', 'Page views, last 24 hours', ''], sites.map(w => { const s = sum[w.id] || {};
+    return h('tr', {}, h('td', {}, h('a', {href:'#websites/' + w.id}, w.name), w.domain ? h('div', {class:'small dim'}, w.domain) : null),
+      h('td', {class:'num'}, num(s.visitors)), h('td', {class:'num'}, num(s.views)),
+      h('td', {}, h('div', {class:'actions'}, h('button', {class:'ghost', onclick:() => trackingDialog(w)}, 'Tracking code'),
+        admin ? h('button', {class:'ghost', onclick:() => websiteDialog(w)}, 'Edit') : null,
+        admin ? h('button', {class:'ghost danger', onclick:ask({title:`Delete ${w.name}?`, body:'The website and all of its visits and events are removed. This cannot be undone.', confirm:'Delete website'}, async () => { await api('DELETE', `${V1}/websites/${w.id}`); toast('Website deleted.'); refresh(); })}, 'Delete') : null)));
+  }));
+};
+function websiteDialog(w) {
+  const e = !!w, f = { name: h('input', {value:w ? w.name : ''}), domain: h('input', {value:w ? w.domain : '', placeholder:'example.com'}) };
+  dialogForm(e ? 'Edit ' + w.name : 'Add a website', null, [field('Name', f.name), field('Domain', f.domain, 'Optional. When set, visits from other domains are ignored, which stops others counting against your site.')], e ? 'Save changes' : 'Add website',
+    async () => { const saved = await api(e ? 'PUT' : 'POST', e ? `${V1}/websites/${w.id}` : V1 + '/websites', {...(w || {}), name:f.name.value, domain:f.domain.value}); toast(e ? 'Website saved.' : 'Website added.'); await refresh(); if (!e) trackingDialog(saved); });
+}
+function trackingDialog(w) {
+  const tag = `<script defer src="${origin()}/script.js" data-website="${w.id}"><\/script>`;
+  const done = modal('Tracking code for ' + w.name, h('div', {class:'stack'},
+    h('p', {class:'dim', style:'margin:0'}, 'Paste this inside the head of every page you want to count.'), cmdBox(tag),
+    h('p', {class:'dim', style:'margin:0'}, 'Single-page sites are counted as people move between pages. To count something else, such as a sign-up, call this from your code:'),
+    cmdBox('sandbar.track("signup", { plan: "pro" })'),
+    h('p', {class:'small dim', style:'margin:0'}, 'The script sets no cookies, keeps no IP address, and does nothing when the visitor has Do Not Track on. Behind a reverse proxy, set SANDBAR_TRUST_PROXY=1 so visitors are told apart.'),
+    h('div', {class:'actions form-actions'}, h('button', {class:'btn', onclick:() => done()}, 'Done'))));
+}
+async function websiteDetail(id) {
+  S.noHeader = true;
+  const range = S.siteRange || '7d';
+  const [sites, st] = await Promise.all([api('GET', V1 + '/websites'), api('GET', `${V1}/websites/${id}/stats?range=${range}`)]);
+  setTimeout(() => { S.noHeader = false; });
+  const w = sites.find(x => x.id === id);
+  if (!w) return emptyState('websites', 'That website no longer exists', 'It may have been deleted.', h('a', {class:'btn', href:'#websites'}, 'Back to websites'));
+  const tabs = h('div', {class:'tabs2', role:'group', 'aria-label':'Time range'}, RANGES.map(([k, l]) => h('button', {class:range === k ? 'on' : '', 'aria-pressed':range === k, onclick:() => { S.siteRange = k; refresh(); }}, l)));
+  const tile = (n, l) => h('div', {class:'stat'}, h('div', {class:'n'}, n), h('div', {class:'l'}, l));
+  const stats = h('div', {class:'stats'}, tile(num(st.visitors), 'Visitors'), tile(num(st.views), 'Page views'), tile(num(st.visits), 'Visits'),
+    tile(st.bounceRate >= 0 ? Math.round(st.bounceRate) + '%' : 'No data', 'Bounce rate'), tile(num(st.online), 'Online now'));
+  const max = Math.max(1, ...st.series.map(p => p.views));
+  const fmt = p => new Date(p.t * 1000).toLocaleString(undefined, st.bucket === 'hour' ? {month:'short', day:'numeric', hour:'numeric'} : {month:'short', day:'numeric', year:'numeric'});
+  const chart = h('div', {class:'chart', role:'img', 'aria-label':`${num(st.views)} page views from ${num(st.visitors)} visitors in the ${RANGES.find(r => r[0] === range)[1].toLowerCase()}`},
+    st.series.map(p => h('div', {class:'col', title:`${fmt(p)}: ${num(p.visitors)} visitors, ${num(p.views)} page views`},
+      h('div', {class:'v', style:`height:${p.views ? Math.max(2, p.views * 100 / max) : 0}%`}), h('div', {class:'u', style:`height:${p.visitors ? Math.max(2, p.visitors * 100 / max) : 0}%`}))));
+  const list = (title, rows, label, nameOf) => {
+    const top = Math.max(1, ...rows.map(r => r.views));
+    return h('div', {class:'card'}, h('h2', {}, title), rows.length ? h('table', {class:'top'}, h('thead', {}, h('tr', {}, h('th', {scope:'col'}, label), h('th', {scope:'col'}, 'Visitors'), h('th', {scope:'col'}, 'Views'))),
+      h('tbody', {}, rows.map(r => h('tr', {}, h('td', {style:`--w:${Math.round(r.views * 100 / top)}%`}, nameOf ? nameOf(r.name) : r.name), h('td', {class:'num'}, num(r.visitors)), h('td', {class:'num'}, num(r.views))))))
+      : h('p', {class:'dim', style:'margin:0'}, 'Nothing yet.'));
+  };
+  const nothing = !st.views && !st.events.length;
+  return h('div', {}, h('div', {class:'page-h'}, h('div', {}, h('a', {href:'#websites', class:'small'}, 'Back to websites'), h('h1', {}, w.name), h('p', {}, w.domain || 'Any domain')),
+      h('button', {class:'ghost', onclick:() => trackingDialog(w)}, 'Tracking code')),
+    tabs, h('div', {style:'height:16px'}), stats,
+    nothing ? emptyState('websites', 'No visits in this period', 'Paste the tracking code into your pages, then open one. The first visit appears within a few seconds.', h('button', {class:'btn', onclick:() => trackingDialog(w)}, 'Show tracking code')) : h('div', {},
+      card('Visitors and page views', h('div', {class:'legend'}, h('span', {}, h('i', {style:'background:var(--accent)'}), 'Visitors'), h('span', {}, h('i', {style:'background:color-mix(in srgb, var(--accent) 35%, var(--surface))'}), 'Page views')), chart,
+        h('div', {class:'axis2', 'aria-hidden':'true'}, h('span', {}, fmt(st.series[0])), h('span', {}, 'Now'))),
+      h('div', {class:'cols'}, list('Pages', st.pages, 'Path'), list('Referrers', st.referrers, 'Source'), list('Browsers', st.browsers, 'Browser'), list('Operating systems', st.systems, 'System'),
+        list('Devices', st.devices, 'Device'), list('Countries', st.countries, 'Country', n => n.length === 2 ? regionName(n) : n), list('Languages', st.languages, 'Language', n => n.length <= 3 ? languageName(n) : n),
+        list('Events', st.events, 'Event'))));
+}
+
 // ---------- account ----------
 // Administrators see which release is running and can install a newer one. The server restarts
 // into the new binary, so the page waits for it to come back.

internal/sandbar/web/script.js

@@ -0,0 +1,66 @@
+/* Sandbar website analytics. Add to a page:
+   <script defer src="https://sandbar.example.com/script.js" data-website="WEBSITE_ID"></script>
+   It sets no cookies and stores nothing in the browser. It sends the page path, the referrer, the
+   language and the browser's own user agent, and it honors Do Not Track.
+   Options on the tag: data-hash (count #hash changes as pages), data-auto="false" (send nothing
+   until you call sandbar.view() yourself). Custom events: sandbar.track("signup", {plan: "pro"}). */
+(function () {
+  var tag = document.currentScript;
+  if (!tag) return;
+  var site = tag.getAttribute('data-website');
+  if (!site) return;
+  var base = tag.src.replace(/\/script\.js(\?.*)?$/, '');
+  var dnt = navigator.doNotTrack === '1' || window.doNotTrack === '1' || navigator.msDoNotTrack === '1';
+  var withHash = tag.hasAttribute('data-hash');
+  var last = '';
+  var first = true;
+
+  function send(body) {
+    if (dnt) return;
+    body.website = site;
+    body.hostname = location.hostname;
+    body.language = navigator.language || '';
+    var json = JSON.stringify(body);
+    // text/plain keeps this a "simple" cross-origin request, so no preflight is needed
+    try {
+      if (navigator.sendBeacon && navigator.sendBeacon(base + '/api/send', new Blob([json], { type: 'text/plain' }))) return;
+    } catch (e) { /* fall through to fetch */ }
+    try {
+      fetch(base + '/api/send', { method: 'POST', body: json, headers: { 'Content-Type': 'text/plain' }, keepalive: true, mode: 'cors', credentials: 'omit' });
+    } catch (e) { /* analytics must never break the page */ }
+  }
+
+  function view() {
+    var path = location.pathname + (withHash ? location.hash : '');
+    if (path === last) return;
+    last = path;
+    send({ path: path, referrer: first ? document.referrer : '' });
+    first = false;
+  }
+
+  function hook(name) {
+    var orig = history[name];
+    if (!orig) return;
+    history[name] = function () {
+      var r = orig.apply(this, arguments);
+      setTimeout(view, 0);
+      return r;
+    };
+  }
+  hook('pushState');
+  hook('replaceState');
+  window.addEventListener('popstate', function () { setTimeout(view, 0); });
+  if (withHash) window.addEventListener('hashchange', function () { setTimeout(view, 0); });
+
+  window.sandbar = {
+    view: view,
+    track: function (name, data) {
+      if (!name) return;
+      send({ path: location.pathname, event: String(name).slice(0, 80), data: data });
+    }
+  };
+
+  if (tag.getAttribute('data-auto') === 'false') return;
+  if (document.readyState === 'complete') view();
+  else window.addEventListener('load', view);
+})();