Settings page for analytics ID

server/analytics/settings.go

Index: server/analytics/settings.go
diff --git a/server/analytics/settings.go b/server/analytics/settings.go
new file mode 100644
index 0000000000000000000000000000000000000000..198dba6980207bd43907f6223e58cd3e4f29b99f
--- /dev/null
+++ b/server/analytics/settings.go
@@ -0,0 +1,145 @@
+// Copyright 2016 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package analytics
+
+import (
+	"fmt"
+	"html/template"
+	"regexp"
+
+	"golang.org/x/net/context"
+
+	"github.com/luci/luci-go/common/logging"
+	"github.com/luci/luci-go/server/settings"
+)
+
+// settingsKey is key for global GAE settings (described by analyticsSettings struct)
+// in the settings store. See github.com/luci/luci-go/server/settings.
+const settingsKey = "analytics"
+
+// analyticsSettings contain settings to enable Google Analytics.
+type analyticsSettings struct {
+	// AnalyticsID is a Google Analytics ID an admin can set to enable Analytics.
+	// The app must support analytics for this to work.
+	AnalyticsID string `json:"analytics_id"`
+}
+
+// fetchCachedSettings fetches analyticsSettings from the settings store or panics.
+//
+// Uses in-process global cache to avoid hitting datastore often. The cache
+// expiration time is 1 min (see analyticsSettings.expirationTime), meaning
+// the instance will refetch settings once a minute (blocking only one unlucky
+// request to do so).
+//
+// Panics only if there's no cached value (i.e. it is the first call to this
+// function in this process ever) and datastore operation fails. It is a good
+// idea to implement /_ah/warmup to warm this up.
+func fetchCachedSettings(c context.Context) analyticsSettings {
+	s := analyticsSettings{}
+	switch err := settings.Get(c, settingsKey, &s); {
+	case err == nil:
+		return s
+	case err == settings.ErrNoSettings:
+		// Defaults.
+		return analyticsSettings{
+			AnalyticsID: "",
+		}
+	default:
+		panic(fmt.Errorf("could not fetch GAE settings - %s", err))
+	}
+}
+
+// ID returns the Google Analytics ID if it's set, and "" otherwise.

[Vadim Sh., 2016/08/29 19:26:32]

nit: move ID() and Snippet() into analytics/analytics.go, so that settings.go
implements settings only.

[Ryan Tseng, 2016/08/29 19:36:01]

Done.

+func ID(c context.Context) string {
+	return fetchCachedSettings(c).AnalyticsID
+}
+
+var rAllowed = regexp.MustCompile("UA-\\d+-\\d+")
+
+// Snippet returns the html snippet for Google Analytics, including the
+// <script> tag and ID, if ID is set.
+func Snippet(c context.Context) template.HTML {
+	id := ID(c)
+	if id == "" {
+		return ""
+	}
+	if !rAllowed.MatchString(id) {
+		logging.Errorf(c, "Analytics ID %s does not match UA-\\d+-\\d+", id)
+		return ""
+	}
+	return template.HTML(fmt.Sprintf(`
+<script>
+	(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
+	(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
+	m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
+	})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
+
+	ga('create', '%s', 'auto');
+	ga('send', 'pageview');
+</script>
+`, id))
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// UI for GAE settings.
+
+type settingsUIPage struct {
+	settings.BaseUIPage
+}
+
+func (settingsUIPage) Title(c context.Context) (string, error) {
+	return "Google Analytics Related Settings", nil
+}
+
+func (settingsUIPage) Overview(c context.Context) (template.HTML, error) {
+	return template.HTML(`<p>To generate a Google Analytics Tracking ID</p>
+<ul>
+<li> Sign in to <a href="https://www.google.com/analytics/web/#home/">your Analytics account.</a></li>
+<li>Select the Admin tab.</li>
+<li>Select an account from the drop-down menu in the <i>ACCOUNT</i> column.</li>
+<li>Select a property from the drop-down menu in the <i>PROPERTY</i> column.</li>
+<li>Under <i>PROPERTY</i>, click <b>Tracking Info > Tracking Code.</b></li>
+</ul>`), nil
+}
+
+func (settingsUIPage) Fields(c context.Context) ([]settings.UIField, error) {
+	return []settings.UIField{
+		{
+			ID:    "AnalyticsID",
+			Title: "Google Analytics Tracking ID",
+			Type:  settings.UIFieldText,
+			Help: `Tracking ID used for Google Analytics. Filling this in enables
+Google Analytics tracking across the app.`,
+		},
+	}, nil
+}
+
+func (settingsUIPage) ReadSettings(c context.Context) (map[string]string, error) {
+	s := analyticsSettings{}
+	err := settings.GetUncached(c, settingsKey, &s)
+	if err != nil && err != settings.ErrNoSettings {
+		return nil, err
+	}
+	return map[string]string{
+		"AnalyticsID": s.AnalyticsID,
+	}, nil
+}
+
+func (settingsUIPage) WriteSettings(c context.Context, values map[string]string, who, why string) error {
+	modified := analyticsSettings{}
+	id := values["AnalyticsID"]
+	if id != "" {
+		if !rAllowed.MatchString(id) {
+			return fmt.Errorf("Analytics ID %s does not match format UA-\\d+-\\d+", id)
+		}
+		modified.AnalyticsID = id
+	}
+
+	return settings.SetIfChanged(c, settingsKey, &modified, who, why)
+}
+
+func init() {
+	settings.RegisterUIPage(settingsKey, settingsUIPage{})
+}