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/iam/repository/eventsourcing/model/mail_template.go

@@ -0,0 +1,64 @@
+package model
+
+import (
+	b64 "encoding/base64"
+	"encoding/json"
+
+	"github.com/caos/zitadel/internal/errors"
+	"github.com/caos/zitadel/internal/eventstore/models"
+	es_models "github.com/caos/zitadel/internal/eventstore/models"
+	iam_model "github.com/caos/zitadel/internal/iam/model"
+)
+
+type MailTemplate struct {
+	models.ObjectRoot
+	State    int32 `json:"-"`
+	Template []byte
+}
+
+func MailTemplateToModel(template *MailTemplate) *iam_model.MailTemplate {
+	return &iam_model.MailTemplate{
+		ObjectRoot: template.ObjectRoot,
+		State:      iam_model.PolicyState(template.State),
+		Template:   template.Template,
+	}
+}
+
+func MailTemplateFromModel(template *iam_model.MailTemplate) *MailTemplate {
+	return &MailTemplate{
+		ObjectRoot: template.ObjectRoot,
+		State:      int32(template.State),
+		Template:   template.Template,
+	}
+}
+
+func (p *MailTemplate) Changes(changed *MailTemplate) map[string]interface{} {
+	changes := make(map[string]interface{}, 1)
+	if b64.StdEncoding.EncodeToString(changed.Template) != b64.StdEncoding.EncodeToString(p.Template) {
+		changes["template"] = b64.StdEncoding.EncodeToString(changed.Template)
+	}
+
+	return changes
+}
+
+func (i *IAM) appendAddMailTemplateEvent(event *es_models.Event) error {
+	i.DefaultMailTemplate = new(MailTemplate)
+	err := i.DefaultMailTemplate.SetDataLabel(event)
+	if err != nil {
+		return err
+	}
+	i.DefaultMailTemplate.ObjectRoot.CreationDate = event.CreationDate
+	return nil
+}
+
+func (i *IAM) appendChangeMailTemplateEvent(event *es_models.Event) error {
+	return i.DefaultMailTemplate.SetDataLabel(event)
+}
+
+func (p *MailTemplate) SetDataLabel(event *es_models.Event) error {
+	err := json.Unmarshal(event.Data, p)
+	if err != nil {
+		return errors.ThrowInternal(err, "MODEL-ikjhf", "unable to unmarshal data")
+	}
+	return nil
+}