feat: add experience improvement module and system config storage (#1248)

- Add experience module for product telemetry
- Add system_config table for persistent settings
- Update privacy policy documentation

experience/experience.go

@@ -0,0 +1,188 @@
+// Package experience handles product telemetry
+package experience
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"sync"
+	"time"
+)
+
+const (
+	telemetryEndpoint = "https://www.google-analytics.com/mp/collect"
+	tid               = "G-14J8SY6F0J"
+	tk                = "sgPLmshGTPiF-X57rzEIKA"
+)
+
+var (
+	client     *Client
+	clientOnce sync.Once
+	httpClient = &http.Client{Timeout: 5 * time.Second}
+)
+
+type Client struct {
+	enabled        bool
+	installationID string
+	mu             sync.RWMutex
+}
+
+type TradeEvent struct {
+	Exchange   string
+	TradeType  string
+	Symbol     string
+	AmountUSD  float64
+	Leverage   int
+	UserID     string
+	TraderID   string
+}
+
+type telemetryPayload struct {
+	ClientID string           `json:"client_id"`
+	Events   []telemetryEvent `json:"events"`
+}
+
+type telemetryEvent struct {
+	Name   string                 `json:"name"`
+	Params map[string]interface{} `json:"params"`
+}
+
+func Init(enabled bool, installationID string) {
+	clientOnce.Do(func() {
+		client = &Client{
+			enabled:        enabled,
+			installationID: installationID,
+		}
+	})
+}
+
+func SetInstallationID(id string) {
+	if client == nil {
+		return
+	}
+	client.mu.Lock()
+	defer client.mu.Unlock()
+	client.installationID = id
+}
+
+func GetInstallationID() string {
+	if client == nil {
+		return ""
+	}
+	client.mu.RLock()
+	defer client.mu.RUnlock()
+	return client.installationID
+}
+
+func SetEnabled(enabled bool) {
+	if client == nil {
+		return
+	}
+	client.mu.Lock()
+	defer client.mu.Unlock()
+	client.enabled = enabled
+}
+
+func IsEnabled() bool {
+	if client == nil {
+		return false
+	}
+	client.mu.RLock()
+	defer client.mu.RUnlock()
+	return client.enabled
+}
+
+func TrackTrade(event TradeEvent) {
+	if client == nil || !IsEnabled() {
+		return
+	}
+
+	// Send asynchronously to not block trading
+	go func() {
+		_ = sendTradeEvent(event)
+	}()
+}
+
+// sendTradeEvent sends the trade event to GA4
+func sendTradeEvent(event TradeEvent) error {
+	client.mu.RLock()
+	installationID := client.installationID
+	client.mu.RUnlock()
+
+	payload := telemetryPayload{
+		ClientID: installationID,
+		Events: []telemetryEvent{
+			{
+				Name: "trade",
+				Params: map[string]interface{}{
+					"exchange":             event.Exchange,
+					"trade_type":           event.TradeType,
+					"symbol":               event.Symbol,
+					"amount_usd":           event.AmountUSD,
+					"leverage":             event.Leverage,
+					"installation_id":      installationID,  // For counting active installations
+					"user_id":              event.UserID,    // For counting active users
+					"trader_id":            event.TraderID,  // For counting active traders
+					"engagement_time_msec": 1,               // Required by GA4
+				},
+			},
+		},
+	}
+
+	jsonData, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+
+	url := telemetryEndpoint + "?measurement_id=" + tid + "&api_secret=" + tk
+	req, err := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	return nil
+}
+
+func TrackStartup(version string) {
+	if client == nil || !IsEnabled() {
+		return
+	}
+
+	go func() {
+		client.mu.RLock()
+		installationID := client.installationID
+		client.mu.RUnlock()
+
+		payload := telemetryPayload{
+			ClientID: installationID,
+			Events: []telemetryEvent{
+				{
+					Name: "app_startup",
+					Params: map[string]interface{}{
+						"version":              version,
+						"installation_id":      installationID,
+						"engagement_time_msec": 1,
+					},
+				},
+			},
+		}
+
+		jsonData, _ := json.Marshal(payload)
+		url := telemetryEndpoint + "?measurement_id=" + tid + "&api_secret=" + tk
+		req, _ := http.NewRequest("POST", url, bytes.NewBuffer(jsonData))
+		if req != nil {
+			req.Header.Set("Content-Type", "application/json")
+			resp, err := httpClient.Do(req)
+			if err == nil {
+				resp.Body.Close()
+			}
+		}
+	}()
+}