Merge pull request #31 from foomo/sesamy-go-0.4.2

feat: collect

integration/loki/loki.go

@@ -151,9 +151,16 @@ func (l *Loki) Write(payload mpv2.Payload[any]) {
 			l.l.Warn("buffer size reached", zap.Int("size", l.bufferSize))
 		}
 
+		var timestamp time.Time
+		if payload.TimestampMicros > 0 {
+			timestamp = time.UnixMicro(payload.TimestampMicros)
+		} else {
+			timestamp = time.Now()
+		}
+
 		l.entries <- logproto.Entry{
 			Line:      string(lineBytes),
-			Timestamp: time.UnixMicro(payload.TimestampMicros),
+			Timestamp: timestamp,
 			StructuredMetadata: push.LabelsAdapter{
 				{
 					Name:  "event_name",

integration/loki/middleware.go

@@ -0,0 +1,42 @@
+package loki
+
+import (
+	"net/http"
+
+	"github.com/foomo/sesamy-go/pkg/encoding/gtag"
+	"github.com/foomo/sesamy-go/pkg/encoding/gtagencode"
+	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
+	gtaghttp "github.com/foomo/sesamy-go/pkg/http/gtag"
+	mpv2http "github.com/foomo/sesamy-go/pkg/http/mpv2"
+	"github.com/pkg/errors"
+	"go.uber.org/zap"
+)
+
+func GTagMiddleware(loki *Loki) gtaghttp.Middleware {
+	return func(next gtaghttp.MiddlewareHandler) gtaghttp.MiddlewareHandler {
+		return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *gtag.Payload) error {
+			err := next(l, w, r, payload)
+			if err != nil {
+				// encode to mpv2
+				var mpv2Payload mpv2.Payload[any]
+				if err := gtagencode.MPv2(*payload, &mpv2Payload); err != nil {
+					return errors.Wrap(err, "failed to encode gtag to mpv2")
+				}
+				loki.Write(mpv2Payload)
+			}
+			return err
+		}
+	}
+}
+
+func MPv2Middleware(loki *Loki) mpv2http.Middleware {
+	return func(next mpv2http.MiddlewareHandler) mpv2http.MiddlewareHandler {
+		return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+			err := next(l, w, r, payload)
+			if err != nil {
+				loki.Write(*payload)
+			}
+			return err
+		}
+	}
+}

integration/watermill/gtag/messagehandler_test.go

@@ -99,7 +99,7 @@ func TestMPv2MessageHandler(t *testing.T) {
 	var done atomic.Bool
 	router.AddHandler("gtag", "in", pubSub, "out", pubSub, gtag.MPv2MessageHandler)
 	router.AddNoPublisherHandler("mpv2", "out", pubSub, func(msg *message.Message) error {
-		expected := `{"client_id":"C123456","events":[{"name":"add_to_cart","params":{}}],"debug_mode":true}`
+		expected := `{"client_id":"C123456","consent":{"ad_user_data":"GRANTED","ad_personalization":"GRANTED","analytics_storage":"GRANTED"},"events":[{"name":"add_to_cart","params":{"page_location":"https://foomo.org","page_title":"Home"}}],"debug_mode":true}`
 		if !assert.JSONEq(t, expected, string(msg.Payload)) {
 			fmt.Println(string(msg.Payload))
 		}

integration/watermill/gtag/subscriber.go

@@ -3,15 +3,13 @@ package gtag
 import (
 	"context"
 	"encoding/json"
-	"fmt"
-	"io"
 	"net/http"
-	"net/url"
 	"strings"
 
 	"github.com/ThreeDotsLabs/watermill"
 	"github.com/ThreeDotsLabs/watermill/message"
 	"github.com/foomo/sesamy-go/pkg/encoding/gtag"
+	gtaghttp "github.com/foomo/sesamy-go/pkg/http/gtag"
 	"github.com/pkg/errors"
 	"go.uber.org/zap"
 )
@@ -22,12 +20,10 @@ type (
 		uuidFunc    func() string
 		messages    chan *message.Message
 		messageFunc func(l *zap.Logger, r *http.Request, msg *message.Message) error
-		middlewares []SubscriberMiddleware
+		middlewares []gtaghttp.Middleware
 		closed      bool
 	}
-	SubscriberOption     func(*Subscriber)
+	SubscriberOption func(*Subscriber)
-	SubscriberHandler    func(l *zap.Logger, r *http.Request, payload *gtag.Payload) error
-	SubscriberMiddleware func(next SubscriberHandler) SubscriberHandler
 )
 
 // ------------------------------------------------------------------------------------------------
@@ -46,7 +42,7 @@ func SubscriberWithMessageFunc(v func(l *zap.Logger, r *http.Request, msg *messa
 	}
 }
 
-func SubscriberWithMiddlewares(v ...SubscriberMiddleware) SubscriberOption {
+func SubscriberWithMiddlewares(v ...gtaghttp.Middleware) SubscriberOption {
 	return func(o *Subscriber) {
 		o.middlewares = append(o.middlewares, v...)
 	}
@@ -69,52 +65,8 @@ func NewSubscriber(l *zap.Logger, opts ...SubscriberOption) *Subscriber {
 }
 
 func (s *Subscriber) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	var values url.Values
+	// retrieve payload
-
+	payload := gtaghttp.Handler(w, r)
-	switch r.Method {
-	case http.MethodGet:
-		values = r.URL.Query()
-	case http.MethodPost:
-		values = r.URL.Query()
-
-		// read request body
-		out, err := io.ReadAll(r.Body)
-		if err != nil {
-			http.Error(w, fmt.Sprintf("failed to read body: %s", err.Error()), http.StatusInternalServerError)
-			return
-		}
-		defer r.Body.Close()
-
-		// append request body to query
-		if len(out) > 0 {
-			v, err := url.ParseQuery(string(out))
-			if err != nil {
-				http.Error(w, fmt.Sprintf("failed to parse extended url: %s", err.Error()), http.StatusInternalServerError)
-				return
-			}
-			for s2, i := range v {
-				values.Set(s2, i[0])
-			}
-		} else {
-			values = r.URL.Query()
-		}
-	default:
-		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
-		return
-	}
-
-	// unmarshal event
-	var payload *gtag.Payload
-	if err := gtag.Decode(values, &payload); err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	// validate
-	if payload.EventName == nil || payload.EventName.String() == "" {
-		http.Error(w, "missing event name", http.StatusBadRequest)
-		return
-	}
 
 	// compose middlewares
 	next := s.handle
@@ -123,13 +75,13 @@ func (s *Subscriber) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// run handler
-	if err := next(s.l, r, payload); err != nil {
+	if err := next(s.l, w, r, payload); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 }
 
-func (s *Subscriber) handle(l *zap.Logger, r *http.Request, payload *gtag.Payload) error {
+func (s *Subscriber) handle(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *gtag.Payload) error {
 	// marshal message payload
 	data, err := json.Marshal(payload)
 	if err != nil {

integration/watermill/gtag/subscribermiddleware.go

@@ -1,40 +0,0 @@
-package gtag
-
-import (
-	"net/http"
-
-	"github.com/foomo/sesamy-go/pkg/encoding/gtag"
-	"go.opentelemetry.io/otel/trace"
-	"go.uber.org/zap"
-)
-
-func SubscriberMiddlewareUserID(cookieName string) SubscriberMiddleware {
-	return func(next SubscriberHandler) SubscriberHandler {
-		return func(l *zap.Logger, r *http.Request, payload *gtag.Payload) error {
-			if cookie, err := r.Cookie(cookieName); err == nil {
-				payload.UserID = gtag.Set(cookie.Value)
-			}
-			return next(l, r, payload)
-		}
-	}
-}
-
-func SubscriberMiddlewareLogger(next SubscriberHandler) SubscriberHandler {
-	return func(l *zap.Logger, r *http.Request, payload *gtag.Payload) error {
-		if spanCtx := trace.SpanContextFromContext(r.Context()); spanCtx.IsValid() && spanCtx.IsSampled() {
-			l = l.With(zap.String("trace_id", spanCtx.TraceID().String()), zap.String("span_id", spanCtx.SpanID().String()))
-		}
-		l = l.With(
-			zap.String("event_name", gtag.GetDefault(payload.EventName, "-").String()),
-			zap.String("event_user_id", gtag.GetDefault(payload.UserID, "-")),
-			zap.String("event_session_id", gtag.GetDefault(payload.SessionID, "-")),
-		)
-		err := next(l, r, payload)
-		if err != nil {
-			l.Error("handled event", zap.Error(err))
-		} else {
-			l.Info("handled event")
-		}
-		return err
-	}
-}

integration/watermill/mpv2/subscriber.go

@@ -9,6 +9,7 @@ import (
 	"github.com/ThreeDotsLabs/watermill"
 	"github.com/ThreeDotsLabs/watermill/message"
 	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
+	mpv2http "github.com/foomo/sesamy-go/pkg/http/mpv2"
 	"github.com/pkg/errors"
 	"go.uber.org/zap"
 )
@@ -19,12 +20,10 @@ type (
 		uuidFunc    func() string
 		messages    chan *message.Message
 		messageFunc func(l *zap.Logger, r *http.Request, msg *message.Message) error
-		middlewares []SubscriberMiddleware
+		middlewares []mpv2http.Middleware
 		closed      bool
 	}
-	SubscriberOption     func(*Subscriber)
+	SubscriberOption func(*Subscriber)
-	SubscriberHandler    func(l *zap.Logger, r *http.Request, payload *mpv2.Payload[any]) error
-	SubscriberMiddleware func(next SubscriberHandler) SubscriberHandler
 )
 
 // ------------------------------------------------------------------------------------------------
@@ -43,7 +42,7 @@ func SubscriberWithMessageFunc(v func(l *zap.Logger, r *http.Request, msg *messa
 	}
 }
 
-func SubscriberWithMiddlewares(v ...SubscriberMiddleware) SubscriberOption {
+func SubscriberWithMiddlewares(v ...mpv2http.Middleware) SubscriberOption {
 	return func(o *Subscriber) {
 		o.middlewares = append(o.middlewares, v...)
 	}
@@ -70,30 +69,8 @@ func NewSubscriber(l *zap.Logger, opts ...SubscriberOption) *Subscriber {
 // ------------------------------------------------------------------------------------------------
 
 func (s *Subscriber) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	if r.Method != http.MethodPost {
+	// retrieve payload
-		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
+	payload := mpv2http.Handler(w, r)
-		return
-	}
-
-	// read request body
-	var payload *mpv2.Payload[any]
-	err := json.NewDecoder(r.Body).Decode(&payload)
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	// validate required fields
-	if len(payload.Events) == 0 {
-		http.Error(w, "missing events", http.StatusBadRequest)
-		return
-	}
-	for _, event := range payload.Events {
-		if event.Name == "" {
-			http.Error(w, "missing event name", http.StatusBadRequest)
-			return
-		}
-	}
 
 	// compose middlewares
 	next := s.handle
@@ -102,13 +79,13 @@ func (s *Subscriber) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// run handler
-	if err := next(s.l, r, payload); err != nil {
+	if err := next(s.l, w, r, payload); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 }
 
-func (s *Subscriber) handle(l *zap.Logger, r *http.Request, payload *mpv2.Payload[any]) error {
+func (s *Subscriber) handle(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
 	// marshal message payload
 	jsonPayload, err := json.Marshal(payload)
 	if err != nil {

integration/watermill/mpv2/subscribermiddleware.go

@@ -1,101 +0,0 @@
-package mpv2
-
-import (
-	"net/http"
-	"strings"
-	"time"
-
-	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
-	"github.com/foomo/sesamy-go/pkg/session"
-	"github.com/pkg/errors"
-	"go.opentelemetry.io/otel/trace"
-	"go.uber.org/zap"
-)
-
-func SubscriberMiddlewareSessionID(measurementID string) SubscriberMiddleware {
-	measurementID = strings.Split(measurementID, "-")[1]
-	return func(next SubscriberHandler) SubscriberHandler {
-		return func(l *zap.Logger, r *http.Request, payload *mpv2.Payload[any]) error {
-			if payload.SessionID == "" {
-				value, err := session.ParseGASessionID(r, measurementID)
-				if err != nil && !errors.Is(err, http.ErrNoCookie) {
-					return err
-				}
-				payload.SessionID = value
-			}
-			return next(l, r, payload)
-		}
-	}
-}
-
-func SubscriberMiddlewareClientID(next SubscriberHandler) SubscriberHandler {
-	return func(l *zap.Logger, r *http.Request, payload *mpv2.Payload[any]) error {
-		if payload.ClientID == "" {
-			value, err := session.ParseGAClientID(r)
-			if err != nil && !errors.Is(err, http.ErrNoCookie) {
-				return err
-			}
-			payload.ClientID = value
-		}
-		return next(l, r, payload)
-	}
-}
-
-func SubscriberMiddlewareDebugMode(next SubscriberHandler) SubscriberHandler {
-	return func(l *zap.Logger, r *http.Request, payload *mpv2.Payload[any]) error {
-		if !payload.DebugMode && session.IsGTMDebug(r) {
-			payload.DebugMode = true
-		}
-		return next(l, r, payload)
-	}
-}
-
-func SubscriberMiddlewareUserID(cookieName string) SubscriberMiddleware {
-	return func(next SubscriberHandler) SubscriberHandler {
-		return func(l *zap.Logger, r *http.Request, payload *mpv2.Payload[any]) error {
-			if payload.UserID == "" {
-				value, err := r.Cookie(cookieName)
-				if err != nil && !errors.Is(err, http.ErrNoCookie) {
-					return err
-				}
-				payload.UserID = value.Value
-			}
-			return next(l, r, payload)
-		}
-	}
-}
-
-func SubscriberMiddlewareTimestamp(next SubscriberHandler) SubscriberHandler {
-	return func(l *zap.Logger, r *http.Request, payload *mpv2.Payload[any]) error {
-		if payload.TimestampMicros == 0 {
-			payload.TimestampMicros = time.Now().UnixMicro()
-		}
-		return next(l, r, payload)
-	}
-}
-
-func SubscriberMiddlewareLogger(next SubscriberHandler) SubscriberHandler {
-	return func(l *zap.Logger, r *http.Request, payload *mpv2.Payload[any]) error {
-		eventNames := make([]string, len(payload.Events))
-		for i, event := range payload.Events {
-			eventNames[i] = event.Name.String()
-		}
-
-		if spanCtx := trace.SpanContextFromContext(r.Context()); spanCtx.IsValid() && spanCtx.IsSampled() {
-			l = l.With(zap.String("trace_id", spanCtx.TraceID().String()), zap.String("span_id", spanCtx.SpanID().String()))
-		}
-
-		l = l.With(
-			zap.String("event_names", strings.Join(eventNames, ",")),
-			zap.String("event_user_id", payload.UserID),
-		)
-
-		err := next(l, r, payload)
-		if err != nil {
-			l.Error("handled event", zap.Error(err))
-		} else {
-			l.Info("handled event")
-		}
-		return err
-	}
-}

pkg/client/mpv2.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"time"
 
 	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
 	"github.com/foomo/sesamy-go/pkg/sesamy"
@@ -110,16 +109,14 @@ func (c *MPv2) HTTPClient() *http.Client {
 // ------------------------------------------------------------------------------------------------
 
 func (c *MPv2) Collect(r *http.Request, events ...sesamy.AnyEvent) error {
-	anyEvents := make([]sesamy.Event[any], len(events))
+	payload := mpv2.NewPayload[any]()
-	for i, event := range events {
+	for _, event := range events {
-		anyEvents[i] = event.AnyEvent()
+		payload.Events = append(payload.Events, event.AnyEvent())
-	}
-
-	payload := &mpv2.Payload[any]{
-		Events:          anyEvents,
-		TimestampMicros: time.Now().UnixMicro(),
 	}
+	return c.SendPayload(r, payload)
+}
 
+func (c *MPv2) SendPayload(r *http.Request, payload *mpv2.Payload[any]) error {
 	next := c.SendRaw
 	for _, middleware := range c.middlewares {
 		next = middleware(next)

pkg/client/mpv2middleware.go

@@ -3,7 +3,6 @@ package client
 import (
 	"net/http"
 	"strings"
-	"time"
 
 	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
 	"github.com/foomo/sesamy-go/pkg/session"
@@ -62,12 +61,3 @@ func MPv2MiddlewareUserID(cookieName string) MPv2Middleware {
 		}
 	}
 }
-
-func MPv2MiddlewareTimestamp(next MPv2Handler) MPv2Handler {
-	return func(r *http.Request, payload *mpv2.Payload[any]) error {
-		if payload.TimestampMicros == 0 {
-			payload.TimestampMicros = time.Now().UnixMicro()
-		}
-		return next(r, payload)
-	}
-}

pkg/collect/collect.go

@@ -0,0 +1,184 @@
+package collect
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/foomo/sesamy-go/pkg/encoding/gtag"
+	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
+	gtaghttp "github.com/foomo/sesamy-go/pkg/http/gtag"
+	mpv2http "github.com/foomo/sesamy-go/pkg/http/mpv2"
+	"github.com/pkg/errors"
+	"go.uber.org/zap"
+)
+
+type (
+	Collect struct {
+		l                   *zap.Logger
+		taggingURL          string
+		taggingClient       *http.Client
+		gtagHTTPMiddlewares []gtaghttp.Middleware
+		mpv2HTTPMiddlewares []mpv2http.Middleware
+	}
+	Option func(*Collect) error
+)
+
+// ------------------------------------------------------------------------------------------------
+// ~ Options
+// ------------------------------------------------------------------------------------------------
+
+func WithTagging(v string) Option {
+	return func(c *Collect) error {
+		c.taggingURL = v
+		return nil
+	}
+}
+
+func WithTaggingClient(v *http.Client) Option {
+	return func(c *Collect) error {
+		c.taggingClient = v
+		return nil
+	}
+}
+
+func WithGTagHTTPMiddlewares(v ...gtaghttp.Middleware) Option {
+	return func(c *Collect) error {
+		c.gtagHTTPMiddlewares = append(c.gtagHTTPMiddlewares, v...)
+		return nil
+	}
+}
+
+func WithMPv2HTTPMiddlewares(v ...mpv2http.Middleware) Option {
+	return func(c *Collect) error {
+		c.mpv2HTTPMiddlewares = append(c.mpv2HTTPMiddlewares, v...)
+		return nil
+	}
+}
+
+// ------------------------------------------------------------------------------------------------
+// ~ Constructor
+// ------------------------------------------------------------------------------------------------
+
+func New(l *zap.Logger, opts ...Option) (*Collect, error) {
+	inst := &Collect{
+		l:             l,
+		taggingClient: http.DefaultClient,
+	}
+
+	for _, opt := range opts {
+		if opt != nil {
+			if err := opt(inst); err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	return inst, nil
+}
+
+// ------------------------------------------------------------------------------------------------
+// ~ Public methods
+// ------------------------------------------------------------------------------------------------
+
+func (c *Collect) GTagHTTPHandler(w http.ResponseWriter, r *http.Request) {
+	// retrieve payload
+	payload := gtaghttp.Handler(w, r)
+
+	// compose middlewares
+	next := c.gtagHandler
+	for _, middleware := range c.gtagHTTPMiddlewares {
+		next = middleware(next)
+	}
+
+	// run handler
+	if err := next(c.l, w, r, payload); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+}
+
+func (c *Collect) MPv2HTTPHandler(w http.ResponseWriter, r *http.Request) {
+	// retrieve payload
+	payload := mpv2http.Handler(w, r)
+
+	// compose middlewares
+	next := c.mpv2Handler
+	for _, middleware := range c.mpv2HTTPMiddlewares {
+		next = middleware(next)
+	}
+
+	// run handler
+	if err := next(c.l, w, r, payload); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+}
+
+// ------------------------------------------------------------------------------------------------
+// ~ Private methods
+// ------------------------------------------------------------------------------------------------
+
+func (c *Collect) gtagHandler(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *gtag.Payload) error {
+	values, body, err := gtag.Encode(payload)
+	if err != nil {
+		return err
+	}
+
+	req, err := http.NewRequestWithContext(r.Context(), http.MethodPost, fmt.Sprintf("%s%s?%s", c.taggingURL, "/g/collect", gtag.EncodeValues(values)), body)
+	if err != nil {
+		return errors.Wrap(err, "failed to create request")
+	}
+
+	// copy headers
+	req.Header = r.Header.Clone()
+
+	resp, err := c.taggingClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	// copy headers
+	r.Header = resp.Header.Clone()
+
+	if _, err := io.Copy(w, resp.Body); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *Collect) mpv2Handler(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+
+	req, err := http.NewRequestWithContext(r.Context(), http.MethodPost, fmt.Sprintf("%s%s", c.taggingURL, "/mp/collect"), bytes.NewReader(body))
+	if err != nil {
+		return errors.Wrap(err, "failed to create request")
+	}
+
+	// copy headers
+	req.Header = r.Header.Clone()
+	// copy raw query
+	req.URL.RawQuery = r.URL.RawQuery
+
+	resp, err := c.taggingClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	// copy headers
+	r.Header = resp.Header.Clone()
+
+	if _, err := io.Copy(w, resp.Body); err != nil {
+		return err
+	}
+
+	return nil
+}

pkg/encoding/gtag/consent.go

@@ -1,9 +1,11 @@
 package gtag
 
 import (
+	"slices"
 	"strings"
 )
 
+// See https://developers.google.com/tag-platform/security/concepts/consent-mode
 type Consent struct {
 	// Current Google Consent Status. Format 'G1'+'AdsStorageBoolStatus'`+'AnalyticsStorageBoolStatus'
 	// Example:  G101
@@ -17,6 +19,11 @@ type Consent struct {
 	// Will be added with the value "1" if the Google Consent had a default value before getting an update
 	// Example: G111
 	GoogleConsentDefault *string `json:"google_consent_default,omitempty" gtag:"gcd,omitempty"`
+	// Example: 1
+	// DigitalMarketAct *string `json:"digital_market_act,omitempty" gtag:"dma,omitempty"`
+	// Example: sypham
+	// DigitalMarketActParameters *string `json:"digital_market_act_parameters,omitempty" gtag:"dma_cps,omitempty"`
+	// Example: noapi | denied
 }
 
 // ------------------------------------------------------------------------------------------------
@@ -24,6 +31,12 @@ type Consent struct {
 // ------------------------------------------------------------------------------------------------
 
 func (c Consent) AdStorage() bool {
+	if c.GoogleConsentDefault != nil {
+		gcd := strings.Split(*c.GoogleConsentDefault, "")
+		if len(gcd) > 3 {
+			return slices.Contains([]string{"l", "t", "r", "n", "u", "v"}, gcd[2])
+		}
+	}
 	if c.GoogleConsentUpdate != nil {
 		gcs := *c.GoogleConsentUpdate
 		if strings.HasPrefix(gcs, "G1") && len(gcs) == 4 {
@@ -35,6 +48,12 @@ func (c Consent) AdStorage() bool {
 }
 
 func (c Consent) AnalyticsStorage() bool {
+	if c.GoogleConsentDefault != nil {
+		gcd := strings.Split(*c.GoogleConsentDefault, "")
+		if len(gcd) > 5 {
+			return slices.Contains([]string{"l", "t", "r", "n", "u", "v"}, gcd[4])
+		}
+	}
 	if c.GoogleConsentUpdate != nil {
 		gcs := *c.GoogleConsentUpdate
 		if strings.HasPrefix(gcs, "G1") && len(gcs) == 4 {
@@ -44,3 +63,23 @@ func (c Consent) AnalyticsStorage() bool {
 	}
 	return true
 }
+
+func (c Consent) AdUserData() bool {
+	if c.GoogleConsentDefault != nil {
+		gcd := strings.Split(*c.GoogleConsentDefault, "")
+		if len(gcd) > 7 {
+			return slices.Contains([]string{"l", "t", "r", "n", "u", "v"}, gcd[6])
+		}
+	}
+	return c.AdStorage()
+}
+
+func (c Consent) AdPersonalization() bool {
+	if c.GoogleConsentDefault != nil {
+		gcd := strings.Split(*c.GoogleConsentDefault, "")
+		if len(gcd) > 9 {
+			return slices.Contains([]string{"l", "t", "r", "n", "u", "v"}, gcd[8])
+		}
+	}
+	return c.AdStorage()
+}

pkg/encoding/gtag/decode_test.go

@@ -40,7 +40,7 @@ func TestDecode(t *testing.T) {
 		},
 		{
 			name: "add_to_cart",
-			args: GTagAddToCart,
+			args: "v=2&tid=G-F9XM71K45T&gtm=45he45m0v9184715813z89184708445za200zb9184708445&_p=1716795486104&_dbg=1&gcd=13l3l3l2l1&npa=1&dma_cps=sypham&dma=1&cid=179294588.1715353601&ecid=788548699&ul=en-us&sr=2056x1329&_fplc=0&ur=&uaa=arm&uab=64&uafvl=Chromium%3B124.0.6367.201%7CGoogle%2520Chrome%3B124.0.6367.201%7CNot-A.Brand%3B99.0.0.0&uamb=0&uam=&uap=macOS&uapv=14.4.1&uaw=0&are=1&frm=0&pscdl=noapi&sst.gcd=13l3l3l2l1&sst.tft=1716795486104&sst.ude=0&_s=4&cu=USD&sid=1716793773&sct=14&seg=1&dl=https%3A%2F%2Fsesamy.local.bestbytes.net%2F%3Fgtm_debug%3D1716795486020&dr=https%3A%2F%2Ftagassistant.google.com%2F&dt=Home&en=add_to_cart&pr1=idSKU_12345~nmStan%20and%20Friends%20Tee~afGoogle%20Merchandise%20Store~cpSUMMER_FUN~ds2.22~lp0~brGoogle~caApparel~c2Adult~c3Shirts~c4Crew~c5Short%20sleeve~lirelated_products~lnRelated%20Products~vagreen~loChIJIQBpAG2ahYAR_6128GcTUEo~pr10.01~qt3&ep.enable_page_views=false&epn.value=30.03&_et=1255&tfd=145479&richsstsse",
 			want: `{"consent":{"google_consent_default":"13l3l3l2l1"},"campaign":{},"ecommerce":{"currency":"USD","items":[{"affiliation":"Google Merchandise Store","coupon":"SUMMER_FUN","discount":"2.22","item_brand":"Google","item_category":"Apparel","item_category2":"Adult","item_category3":"Shirts","item_category4":"Crew","item_category5":"Short sleeve","item_id":"SKU_12345","item_list_id":"related_products","item_list_name":"Related Products","item_name":"Stan and Friends Tee","item_variant":"green","item_list_position":"0","location_id":"ChIJIQBpAG2ahYAR_6128GcTUEo","price":"10.01","quantity":"3"}]},"client_hints":{"screen_resolution":"2056x1329","user_language":"en-us","user_agent_architecture":"arm","user_agent_bitness":"64","user_agent_full_version_list":"Chromium;124.0.6367.201|Google%20Chrome;124.0.6367.201|Not-A.Brand;99.0.0.0","user_agent_mobile":"0","user_agent_model":"","user_agent_platform":"macOS","user_agent_platform_version":"14.4.1","user_agent_wow_64":"0","user_region":""},"protocol_version":"2","tracking_id":"G-F9XM71K45T","gtmhash_info":"45he45m0v9184715813z89184708445za200zb9184708445","client_id":"179294588.1715353601","richsstsse":"","document_location":"https://sesamy.local.bestbytes.net/?gtm_debug=1716795486020","document_title":"Home","document_referrer":"https://tagassistant.google.com/","is_debug":"1","event_name":"add_to_cart","event_parameter":{"enable_page_views":"false"},"event_parameter_number":{"value":"30.03"},"session_id":"1716793773","non_personalized_ads":"1","sst":{"tft":"1716795486104","gcd":"13l3l3l2l1","ude":"0"}}`,
 		},
 		{

pkg/encoding/gtag/payload.go

@@ -151,11 +151,6 @@ type Payload struct {
 	NonPersonalizedAds *string `json:"non_personalized_ads,omitempty" gtag:"npa,omitempty"`
 	// Example: 1
 	// ARE *string `json:"are,omitempty" gtag:"are,omitempty"`
-	// Example: 1
-	// DigitalMarketAct *string `json:"digital_market_act,omitempty" gtag:"dma,omitempty"`
-	// Example: sypham
-	// DigitalMarketActParameters *string `json:"digital_market_act_parameters,omitempty" gtag:"dma_cps,omitempty"`
-	// Example: noapi | denied
 	// PrivacySandboxCookieDeprecationLabel *string `json:"privacy_sandbox_cookie_deprecation_label,omitempty" gtag:"pscdl,omitempty"`
 	// A timestamp measuring the difference between the moment this parameter gets populated and the moment the navigation started on that particular page.
 	// TFD *string `json:"tfd,omitempty" gtag:"tfd,omitempty"`

pkg/encoding/gtag/sst.go

@@ -13,7 +13,7 @@ type SST struct {
 	GCSub *string `json:"gcsub,omitempty" gtag:"gcsub,omitempty"`
 	// Example: DE
 	UC *string `json:"uc,omitempty" gtag:"uc,omitempty"`
-	// Example: 1708250245344
+	// Session start time, time first seen. Example: 1708250245344
 	TFT *string `json:"tft,omitempty" gtag:"tft,omitempty"`
 	// Example: 13l3l3l3l1
 	GCD *string `json:"gcd,omitempty" gtag:"gcd,omitempty"`

pkg/encoding/gtagencode/mpv2.go

@@ -7,6 +7,7 @@ import (
 	"strconv"
 
 	"github.com/foomo/sesamy-go/pkg/encoding/gtag"
+	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
 	"github.com/mitchellh/mapstructure"
 	"github.com/pkg/errors"
 )
@@ -26,12 +27,19 @@ func MPv2(source gtag.Payload, target any) error {
 	targetData := map[string]any{
 		"client_id":            source.ClientID,
 		"user_id":              source.UserID,
+		"session_id":           source.SessionID,
 		"non_personalized_ads": source.NonPersonalizedAds,
 		"debug_mode":           source.IsDebug,
 	}
-	if source.SST != nil && source.SST.TFT != nil {
+
-		targetData["timestamp_micros"] = gtag.Get(source.SST.TFT) + "000"
+	// consent
+	targetConsentData := map[string]any{
+		"add_storage":        mpv2.ConsentText(source.AdStorage()),
+		"ad_user_data":       mpv2.ConsentText(source.AdUserData()),
+		"ad_personalization": mpv2.ConsentText(source.AdPersonalization()),
+		"analytics_storage":  mpv2.ConsentText(source.AnalyticsStorage()),
 	}
+	targetData["consent"] = targetConsentData
 
 	// combine user properties
 	targetUserProperties := map[string]any{}
@@ -52,6 +60,15 @@ func MPv2(source gtag.Payload, target any) error {
 		"name": source.EventName,
 	}
 	targetEventDataParams := map[string]any{}
+	if value, ok := sourceData["document_title"]; ok {
+		targetEventDataParams["page_title"] = value
+	}
+	if value, ok := sourceData["document_referrer"]; ok {
+		targetEventDataParams["page_referrer"] = value
+	}
+	if value, ok := sourceData["document_location"]; ok {
+		targetEventDataParams["page_location"] = value
+	}
 	if node, ok := sourceData["ecommerce"].(map[string]any); ok {
 		maps.Copy(targetEventDataParams, node)
 	}

pkg/encoding/mpv2/consent.go

@@ -6,3 +6,10 @@ const (
 	ConsentDenied  Consent = "DENIED"
 	ConsentGranted Consent = "GRANTED"
 )
+
+func ConsentText(v bool) Consent {
+	if v {
+		return ConsentGranted
+	}
+	return ConsentDenied
+}

pkg/encoding/mpv2/payload.go

@@ -1,6 +1,8 @@
 package mpv2
 
 import (
+	"time"
+
 	"github.com/foomo/sesamy-go/pkg/sesamy"
 )
 
@@ -17,3 +19,9 @@ type Payload[P any] struct {
 	SessionID          string            `json:"session_id,omitempty"`
 	EngagementTimeMSec int64             `json:"engagement_time_msec,omitempty"`
 }
+
+func NewPayload[P any]() *Payload[P] {
+	return &Payload[P]{
+		TimestampMicros: time.Now().UnixMicro(),
+	}
+}

pkg/encoding/mpv2encode/gtag.go

@@ -48,17 +48,23 @@ func GTag[P any](source mpv2.Payload[P], target any) error {
 		targetData["event_name"] = sourceData["name"]
 
 		if params, ok := sourceData["params"].(map[string]any); ok {
+			targetData["document_title"] = params["page_title"]
+			delete(params, "page_title")
+			targetData["document_referrer"] = params["page_referrer"]
+			delete(params, "page_referrer")
+			targetData["document_location"] = params["page_location"]
+			delete(params, "page_location")
 			targetData["currency"] = params["currency"]
-			targetData["promotion_id"] = params["promotion_id"]
-			targetData["promotion_name"] = params["promotion_name"]
-			targetData["location_id"] = params["location_id"]
-			targetData["is_conversion"] = params["is_conversion"]
-			targetData["items"] = params["items"]
 			delete(params, "currency")
+			targetData["promotion_id"] = params["promotion_id"]
 			delete(params, "promotion_id")
+			targetData["promotion_name"] = params["promotion_name"]
 			delete(params, "promotion_name")
+			targetData["location_id"] = params["location_id"]
 			delete(params, "location_id")
+			targetData["is_conversion"] = params["is_conversion"]
 			delete(params, "is_conversion")
+			targetData["items"] = params["items"]
 			delete(params, "items")
 			{ // user_property
 				targetEventProperty := map[string]any{}

pkg/event/params/pageview.go

@@ -3,5 +3,6 @@ package params
 // PageView https://developers.google.com/analytics/devguides/collection/ga4/views?client_type=gtag#manually_send_page_view_events
 type PageView struct {
 	PageTitle    string `json:"page_title,omitempty"`
+	PageReferrer string `json:"page_referrer,omitempty"`
 	PageLocation string `json:"page_location,omitempty"`
 }

pkg/http/eventhandler.go

@@ -0,0 +1,10 @@
+package http
+
+import (
+	"net/http"
+
+	"github.com/foomo/sesamy-go/pkg/sesamy"
+	"go.uber.org/zap"
+)
+
+type EventHandler func(l *zap.Logger, r *http.Request, event *sesamy.Event[any]) error

pkg/http/gtag/handler.go

@@ -0,0 +1,61 @@
+package gtag
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+
+	"github.com/foomo/sesamy-go/pkg/encoding/gtag"
+)
+
+func Handler(w http.ResponseWriter, r *http.Request) *gtag.Payload {
+	var values url.Values
+
+	switch r.Method {
+	case http.MethodGet:
+		values = r.URL.Query()
+	case http.MethodPost:
+		values = r.URL.Query()
+
+		// read request body
+		out, err := io.ReadAll(r.Body)
+		if err != nil {
+			http.Error(w, fmt.Sprintf("failed to read body: %s", err.Error()), http.StatusInternalServerError)
+			return nil
+		}
+		defer r.Body.Close()
+
+		// append request body to query
+		if len(out) > 0 {
+			v, err := url.ParseQuery(string(out))
+			if err != nil {
+				http.Error(w, fmt.Sprintf("failed to parse extended url: %s", err.Error()), http.StatusInternalServerError)
+				return nil
+			}
+			for s2, i := range v {
+				values.Set(s2, i[0])
+			}
+		} else {
+			values = r.URL.Query()
+		}
+	default:
+		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
+		return nil
+	}
+
+	// unmarshal event
+	var payload *gtag.Payload
+	if err := gtag.Decode(values, &payload); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return nil
+	}
+
+	// validate
+	if payload.EventName == nil || payload.EventName.String() == "" {
+		http.Error(w, "missing event name", http.StatusBadRequest)
+		return nil
+	}
+
+	return payload
+}

pkg/http/gtag/middleware.go

@@ -0,0 +1,73 @@
+package gtag
+
+import (
+	"net/http"
+
+	"github.com/foomo/sesamy-go/pkg/encoding/gtag"
+	"github.com/foomo/sesamy-go/pkg/encoding/gtagencode"
+	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
+	"github.com/foomo/sesamy-go/pkg/encoding/mpv2encode"
+	sesamyhttp "github.com/foomo/sesamy-go/pkg/http"
+	"github.com/pkg/errors"
+	"go.opentelemetry.io/otel/trace"
+	"go.uber.org/zap"
+)
+
+type (
+	Middleware        func(next MiddlewareHandler) MiddlewareHandler
+	MiddlewareHandler func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *gtag.Payload) error
+)
+
+func MiddlewareEventHandler(h sesamyhttp.EventHandler) Middleware {
+	return func(next MiddlewareHandler) MiddlewareHandler {
+		return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *gtag.Payload) error {
+			var mpv2Payload *mpv2.Payload[any]
+			if err := gtagencode.MPv2(*payload, &mpv2Payload); err != nil {
+				return errors.Wrap(err, "failed to encode gtag to mpv2")
+			}
+
+			for i, event := range mpv2Payload.Events {
+				if err := h(l, r, &event); err != nil {
+					return err
+				}
+				mpv2Payload.Events[i] = event
+			}
+
+			if err := mpv2encode.GTag[any](*mpv2Payload, &payload); err != nil {
+				return errors.Wrap(err, "failed to encode mpv2 to gtag")
+			}
+			return next(l, w, r, payload)
+		}
+	}
+}
+
+func MiddlewareUserID(cookieName string) Middleware {
+	return func(next MiddlewareHandler) MiddlewareHandler {
+		return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *gtag.Payload) error {
+			if cookie, err := r.Cookie(cookieName); err == nil {
+				payload.UserID = gtag.Set(cookie.Value)
+			}
+			return next(l, w, r, payload)
+		}
+	}
+}
+
+func MiddlewareLogger(next MiddlewareHandler) MiddlewareHandler {
+	return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *gtag.Payload) error {
+		if spanCtx := trace.SpanContextFromContext(r.Context()); spanCtx.IsValid() && spanCtx.IsSampled() {
+			l = l.With(zap.String("trace_id", spanCtx.TraceID().String()), zap.String("span_id", spanCtx.SpanID().String()))
+		}
+		l = l.With(
+			zap.String("event_name", gtag.GetDefault(payload.EventName, "-").String()),
+			zap.String("event_user_id", gtag.GetDefault(payload.UserID, "-")),
+			zap.String("event_session_id", gtag.GetDefault(payload.SessionID, "-")),
+		)
+		err := next(l, w, r, payload)
+		if err != nil {
+			l.Error("handled event", zap.Error(err))
+		} else {
+			l.Info("handled event")
+		}
+		return err
+	}
+}

pkg/http/mpv2/handler.go

@@ -0,0 +1,37 @@
+package mpv2
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
+)
+
+func Handler(w http.ResponseWriter, r *http.Request) *mpv2.Payload[any] {
+	if r.Method != http.MethodPost {
+		http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
+		return nil
+	}
+
+	// read request body
+	var payload *mpv2.Payload[any]
+	err := json.NewDecoder(r.Body).Decode(&payload)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return nil
+	}
+
+	// validate required fields
+	if len(payload.Events) == 0 {
+		http.Error(w, "missing events", http.StatusBadRequest)
+		return nil
+	}
+	for _, event := range payload.Events {
+		if event.Name == "" {
+			http.Error(w, "missing event name", http.StatusBadRequest)
+			return nil
+		}
+	}
+
+	return payload
+}

pkg/http/mpv2/middleware.go

@@ -0,0 +1,170 @@
+package mpv2
+
+import (
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/foomo/sesamy-go/pkg/encoding/mpv2"
+	sesamyhttp "github.com/foomo/sesamy-go/pkg/http"
+	"github.com/foomo/sesamy-go/pkg/session"
+	"github.com/pkg/errors"
+	"go.opentelemetry.io/otel/trace"
+	"go.uber.org/zap"
+)
+
+type (
+	MiddlewareHandler func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error
+	Middleware        func(next MiddlewareHandler) MiddlewareHandler
+)
+
+func MiddlewareEventHandler(h sesamyhttp.EventHandler) Middleware {
+	return func(next MiddlewareHandler) MiddlewareHandler {
+		return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+			for i, event := range payload.Events {
+				if err := h(l, r, &event); err != nil {
+					return err
+				}
+				payload.Events[i] = event
+			}
+			return next(l, w, r, payload)
+		}
+	}
+}
+
+func MiddlewareSessionID(measurementID string) Middleware {
+	measurementID = strings.Split(measurementID, "-")[1]
+	return func(next MiddlewareHandler) MiddlewareHandler {
+		return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+			if payload.SessionID == "" {
+				value, err := session.ParseGASessionID(r, measurementID)
+				if err != nil && !errors.Is(err, http.ErrNoCookie) {
+					return err
+				}
+				payload.SessionID = value
+			}
+			return next(l, w, r, payload)
+		}
+	}
+}
+
+func MiddlewareClientID(next MiddlewareHandler) MiddlewareHandler {
+	return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+		if payload.ClientID == "" {
+			value, err := session.ParseGAClientID(r)
+			if err != nil && !errors.Is(err, http.ErrNoCookie) {
+				return err
+			}
+			payload.ClientID = value
+		}
+		return next(l, w, r, payload)
+	}
+}
+
+func MiddlewareDebugMode(next MiddlewareHandler) MiddlewareHandler {
+	return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+		if !payload.DebugMode && session.IsGTMDebug(r) {
+			payload.DebugMode = true
+		}
+		return next(l, w, r, payload)
+	}
+}
+
+func MiddlewareUserID(cookieName string) Middleware {
+	return func(next MiddlewareHandler) MiddlewareHandler {
+		return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+			if payload.UserID == "" {
+				value, err := r.Cookie(cookieName)
+				if err != nil && !errors.Is(err, http.ErrNoCookie) {
+					return err
+				}
+				payload.UserID = value.Value
+			}
+			return next(l, w, r, payload)
+		}
+	}
+}
+
+func MiddlewareTimestamp(next MiddlewareHandler) MiddlewareHandler {
+	return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+		if payload.TimestampMicros == 0 {
+			payload.TimestampMicros = time.Now().UnixMicro()
+		}
+		return next(l, w, r, payload)
+	}
+}
+
+func MiddlewareUserAgent(next MiddlewareHandler) MiddlewareHandler {
+	return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+		if userAgent := r.Header.Get("User-Agent"); userAgent != "" {
+			for i, event := range payload.Events {
+				if value, ok := event.Params.(map[string]any); ok {
+					value["user_agent"] = userAgent
+					payload.Events[i] = event
+				}
+			}
+		}
+		return next(l, w, r, payload)
+	}
+}
+
+func MiddlewareIPOverride(next MiddlewareHandler) MiddlewareHandler {
+	return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+		var ipOverride string
+		for _, key := range []string{"CF-Connecting-IP", "X-Original-Forwarded-For", "X-Forwarded-For", "X-Real-Ip"} {
+			if value := r.Header.Get(key); value != "" {
+				ipOverride = value
+				break
+			}
+		}
+		if ipOverride != "" {
+			for i, event := range payload.Events {
+				if value, ok := event.Params.(map[string]any); ok {
+					value["ip_override"] = ipOverride
+					payload.Events[i] = event
+				}
+			}
+		}
+		return next(l, w, r, payload)
+	}
+}
+
+func MiddlewarePageLocation(next MiddlewareHandler) MiddlewareHandler {
+	return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+		if referrer := r.Header.Get("Referer"); referrer != "" {
+			for i, event := range payload.Events {
+				if value, ok := event.Params.(map[string]any); ok {
+					value["page_location"] = referrer
+					payload.Events[i] = event
+				}
+			}
+		}
+		return next(l, w, r, payload)
+	}
+}
+
+func MiddlewareLogger(next MiddlewareHandler) MiddlewareHandler {
+	return func(l *zap.Logger, w http.ResponseWriter, r *http.Request, payload *mpv2.Payload[any]) error {
+		eventNames := make([]string, len(payload.Events))
+		for i, event := range payload.Events {
+			eventNames[i] = event.Name.String()
+		}
+
+		if spanCtx := trace.SpanContextFromContext(r.Context()); spanCtx.IsValid() && spanCtx.IsSampled() {
+			l = l.With(zap.String("trace_id", spanCtx.TraceID().String()), zap.String("span_id", spanCtx.SpanID().String()))
+		}
+
+		l = l.With(
+			zap.String("event_names", strings.Join(eventNames, ",")),
+			zap.String("event_user_id", payload.UserID),
+		)
+
+		err := next(l, w, r, payload)
+		if err != nil {
+			l.Error("handled event", zap.Error(err))
+		} else {
+			l.Info("handled event")
+		}
+		return err
+	}
+}

pkg/sesamy/event.go

@@ -36,3 +36,7 @@ func (e Event[P]) Decode(output any) error {
 func (e Event[P]) DecodeParams(output any) error {
 	return Decode(e.Params, output)
 }
+
+func (e Event[P]) EncodeParams(input any) error {
+	return Decode(input, &e.Params)
+}

pkg/sesamy/event_test.go

@@ -0,0 +1,35 @@
+package sesamy_test
+
+import (
+	"testing"
+
+	"github.com/foomo/sesamy-go/pkg/sesamy"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDecodeParams(t *testing.T) {
+	type params struct {
+		Title string `json:"title"`
+	}
+
+	event := sesamy.Event[any]{
+		Name: "test",
+		Params: map[string]any{
+			"title":       "foo",
+			"description": "foo",
+		},
+	}
+
+	var p params
+	require.NoError(t, event.DecodeParams(&p))
+	assert.Equal(t, "foo", p.Title)
+
+	p.Title = "bar"
+
+	require.NoError(t, event.EncodeParams(p))
+	assert.Equal(t, map[string]any{
+		"title":       "bar",
+		"description": "foo",
+	}, event.Params)
+}