fix(event handling): use internal pubsub for view update (#1118)

* start sub

* start implement subsciptions

* start subscription

* implementation for member done

* admin done

* fix: tests

* extend handlers

* prepary notification

* no errors in adminapi

* changed current sequence in all packages

* ignore mocks

* works

* subscriptions as singleton

* tests

* refactor: rename function scope var

internal/eventstore/query/handler.go

@@ -1,8 +1,11 @@
 package query
 
 import (
+	"context"
 	"time"
 
+	"github.com/caos/logging"
+	"github.com/caos/zitadel/internal/eventstore"
 	"github.com/caos/zitadel/internal/eventstore/models"
 )
 
@@ -14,4 +17,42 @@ type Handler interface {
 	OnSuccess() error
 	MinimumCycleDuration() time.Duration
 	QueryLimit() uint64
+
+	AggregateTypes() []models.AggregateType
+	CurrentSequence(*models.Event) (uint64, error)
+	Eventstore() eventstore.Eventstore
+}
+
+func ReduceEvent(handler Handler, event *models.Event) {
+	currentSequence, err := handler.CurrentSequence(event)
+	if err != nil {
+		logging.Log("HANDL-BmpkC").WithError(err).Warn("unable to get current sequence")
+		return
+	}
+	if event.PreviousSequence > currentSequence {
+		searchQuery := models.NewSearchQuery().
+			AggregateTypeFilter(handler.AggregateTypes()...).
+			SequenceBetween(currentSequence, event.PreviousSequence)
+
+		events, err := handler.Eventstore().FilterEvents(context.Background(), searchQuery)
+		if err != nil {
+			logging.LogWithFields("HANDL-L6YH1", "seq", event.Sequence).Warn("filter failed")
+			return
+		}
+		for _, previousEvent := range events {
+			//if other process already updated view
+			//TODO: correct?
+			if event.PreviousSequence > previousEvent.Sequence {
+				continue
+			}
+			err = handler.Reduce(previousEvent)
+			logging.LogWithFields("HANDL-V42TI", "seq", previousEvent.Sequence).OnError(err).Warn("reduce failed")
+			return
+		}
+	} else if event.PreviousSequence > 0 && event.PreviousSequence < currentSequence {
+		logging.LogWithFields("HANDL-w9Bdy", "previousSeq", event.PreviousSequence, "currentSeq", currentSequence).Debug("already processed")
+		return
+	}
+	err = handler.Reduce(event)
+	logging.LogWithFields("HANDL-wQDL2", "seq", event.Sequence).OnError(err).Warn("reduce failed")
 }