feat: e-mail templates (#1158)

* View definition added

* Get templates and texts from the database.

* Fill in texts in templates

* Fill in texts in templates

* Client API added

* Weekly backup

* Weekly backup

* Daily backup

* Weekly backup

* Tests added

* Corrections from merge branch

* Fixes from pull request review

internal/admin/repository/eventsourcing/handler/mail_text.go

@@ -0,0 +1,109 @@
+package handler
+
+import (
+	"github.com/caos/logging"
+
+	"github.com/caos/zitadel/internal/eventstore"
+	"github.com/caos/zitadel/internal/eventstore/models"
+	es_models "github.com/caos/zitadel/internal/eventstore/models"
+	"github.com/caos/zitadel/internal/eventstore/query"
+	"github.com/caos/zitadel/internal/eventstore/spooler"
+	"github.com/caos/zitadel/internal/iam/repository/eventsourcing/model"
+	iam_es_model "github.com/caos/zitadel/internal/iam/repository/eventsourcing/model"
+	iam_model "github.com/caos/zitadel/internal/iam/repository/view/model"
+)
+
+type MailText struct {
+	handler
+	subscription *eventstore.Subscription
+}
+
+func newMailText(handler handler) *MailText {
+	h := &MailText{
+		handler: handler,
+	}
+
+	h.subscribe()
+
+	return h
+}
+
+func (m *MailText) subscribe() {
+	m.subscription = m.es.Subscribe(m.AggregateTypes()...)
+	go func() {
+		for event := range m.subscription.Events {
+			query.ReduceEvent(m, event)
+		}
+	}()
+}
+
+const (
+	mailTextTable = "adminapi.mail_texts"
+)
+
+func (m *MailText) ViewModel() string {
+	return mailTextTable
+}
+
+func (_ *MailText) AggregateTypes() []es_models.AggregateType {
+	return []es_models.AggregateType{iam_es_model.IAMAggregate}
+}
+
+func (p *MailText) CurrentSequence(event *models.Event) (uint64, error) {
+	sequence, err := p.view.GetLatestMailTextSequence(string(event.AggregateType))
+	if err != nil {
+		return 0, err
+	}
+	return sequence.CurrentSequence, nil
+}
+
+func (m *MailText) EventQuery() (*models.SearchQuery, error) {
+	sequence, err := m.view.GetLatestMailTextSequence("")
+	if err != nil {
+		return nil, err
+	}
+	return es_models.NewSearchQuery().
+		AggregateTypeFilter(m.AggregateTypes()...).
+		LatestSequenceFilter(sequence.CurrentSequence), nil
+}
+
+func (m *MailText) Reduce(event *models.Event) (err error) {
+	switch event.AggregateType {
+	case model.IAMAggregate:
+		err = m.processMailText(event)
+	}
+	return err
+}
+
+func (m *MailText) processMailText(event *models.Event) (err error) {
+	mailText := new(iam_model.MailTextView)
+	switch event.Type {
+	case model.MailTextAdded:
+		err = mailText.AppendEvent(event)
+	case model.MailTextChanged:
+		err = mailText.SetData(event)
+		if err != nil {
+			return err
+		}
+		mailText, err = m.view.MailTextByIDs(event.AggregateID, mailText.MailTextType, mailText.Language)
+		if err != nil {
+			return err
+		}
+		err = mailText.AppendEvent(event)
+	default:
+		return m.view.ProcessedMailTextSequence(event)
+	}
+	if err != nil {
+		return err
+	}
+	return m.view.PutMailText(mailText, event)
+}
+
+func (m *MailText) OnError(event *models.Event, err error) error {
+	logging.LogWithFields("HANDL-5jk84", "id", event.AggregateID).WithError(err).Warn("something went wrong in label mailText handler")
+	return spooler.HandleError(event, err, m.view.GetLatestMailTextFailedEvent, m.view.ProcessedMailTextFailedEvent, m.view.ProcessedMailTextSequence, m.errorCountUntilSkip)
+}
+
+func (o *MailText) OnSuccess() error {
+	return spooler.HandleSuccess(o.view.UpdateMailTextSpoolerRunTimestamp)
+}