feat: add extra time in events (#1)

### Purpose of this PR
This PR introduces a new config field to add delay to the timestamp

README.md

@@ -46,6 +46,7 @@ There are some customization possibles, all of them are defined by using the sys
 * **MAIL_HISTORY_DURATION**: duration, using Golang pattern, which is used to delete messages older than that duration;
 * **STORAGE_FILE**: when defined, instead of creating a randomized temporary file, the given file name will be used;
 * **BLOCK_DELETE_ALL**: when value is `true`, deleting all messages will not be allowed;
+* **EVENT_TIMESTAMP_DELAY**_ duration, using Golang pattern, which is used to add extra time to the events;
 
 ## Container (Docker)
 

internal/config/config.go

@@ -1,10 +1,11 @@
 package config
 
 import (
-	"github.com/rapatao/go-injector"
-	"github.com/rs/zerolog/log"
 	"os"
 	"time"
+
+	"github.com/rapatao/go-injector"
+	"github.com/rs/zerolog/log"
 )
 
 const (
@@ -20,6 +21,7 @@ type Config struct {
 	WebStaticFiles string
 	StorageFile    string
 	BlockDeleteAll bool
+	MessageDelay   time.Duration
 }
 
 func (c *Config) Initialize(_ *injector.Container) error {
@@ -29,6 +31,7 @@ func (c *Config) Initialize(_ *injector.Container) error {
 	c.webStaticFiles()
 	c.storageDir()
 	c.blockDeleteAll()
+	c.messageDelay()
 
 	return nil
 }
@@ -105,6 +108,21 @@ func (c *Config) storageDir() {
 	c.StorageFile = storage
 }
 
+func (c *Config) messageDelay() {
+	duration, err := time.ParseDuration(os.Getenv("EVENT_TIMESTAMP_DELAY"))
+	if err != nil {
+		log.Error().Err(err).Msgf("failed to parse EVENT_TIMESTAMP_DELAY, using default 0")
+
+		c.MessageDelay = 0
+
+		return
+	}
+
+	c.MessageDelay = duration
+
+	return
+}
+
 func (c *Config) blockDeleteAll() {
 	env := os.Getenv("BLOCK_DELETE_ALL")
 	if env == "true" {

internal/eventsender/click.go

@@ -10,7 +10,7 @@ func (s *Service) TriggerClick(ctx context.Context, message *model.Message, user
 		return
 	}
 
-	event := baseEvent(message)
+	event := s.baseEvent(message)
 
 	event["event"] = "click"
 	event["useragent"] = userAgent

internal/eventsender/delivery.go

@@ -10,7 +10,7 @@ func (s *Service) TriggerDeliveryEvent(ctx context.Context, message *model.Messa
 		return
 	}
 
-	event := baseEvent(message)
+	event := s.baseEvent(message)
 
 	var (
 		eventName   string

internal/eventsender/helper.go

@@ -5,15 +5,15 @@ import (
 	"time"
 )
 
-func baseEvent(message *model.Message) map[string]any {
+func (s *Service) baseEvent(message *model.Message) map[string]any {
 	event := map[string]any{}
 
 	for key, value := range message.CustomArgs {
 		event[key] = value
 	}
 
 	event["email"] = message.To.Address
-	event["timestamp"] = time.Now().Unix()
+	event["timestamp"] = time.Now().Add(s.config.MessageDelay).Unix()
 	event["smtp-id"] = message.EventID + "." + message.MessageID + "@mock"
 	event["sg_event_id"] = message.EventID
 	event["sg_message_id"] = message.MessageID

internal/eventsender/open.go

@@ -10,7 +10,7 @@ func (s *Service) TriggerOpen(ctx context.Context, message *model.Message, userA
 		return
 	}
 
-	event := baseEvent(message)
+	event := s.baseEvent(message)
 
 	event["event"] = "open"
 	event["useragent"] = userAgent