refactor(v2): init eventstore package (#7806)

* refactor(v2): init database package

* refactor(v2): init eventstore package

* add mock package

* test query constructors

* option based push analog to query

internal/v2/eventstore/unique_constraint.go

@@ -0,0 +1,80 @@
+package eventstore
+
+type UniqueConstraint struct {
+	// UniqueType is the table name for the unique constraint
+	UniqueType string
+	// UniqueField is the unique key
+	UniqueField string
+	// Action defines if unique constraint should be added or removed
+	Action UniqueConstraintAction
+	// ErrorMessage defines the translation file key for the error message
+	ErrorMessage string
+	// IsGlobal defines if the unique constraint is globally unique or just within a single instance
+	IsGlobal bool
+}
+
+type UniqueConstraintAction int8
+
+const (
+	UniqueConstraintAdd UniqueConstraintAction = iota
+	UniqueConstraintRemove
+	UniqueConstraintInstanceRemove
+
+	uniqueConstraintActionCount
+)
+
+func (f UniqueConstraintAction) Valid() bool {
+	return f >= 0 && f < uniqueConstraintActionCount
+}
+
+func NewAddEventUniqueConstraint(
+	uniqueType,
+	uniqueField,
+	errMessage string) *UniqueConstraint {
+	return &UniqueConstraint{
+		UniqueType:   uniqueType,
+		UniqueField:  uniqueField,
+		ErrorMessage: errMessage,
+		Action:       UniqueConstraintAdd,
+	}
+}
+
+func NewRemoveUniqueConstraint(
+	uniqueType,
+	uniqueField string) *UniqueConstraint {
+	return &UniqueConstraint{
+		UniqueType:  uniqueType,
+		UniqueField: uniqueField,
+		Action:      UniqueConstraintRemove,
+	}
+}
+
+func NewRemoveInstanceUniqueConstraints() *UniqueConstraint {
+	return &UniqueConstraint{
+		Action: UniqueConstraintInstanceRemove,
+	}
+}
+
+func NewAddGlobalUniqueConstraint(
+	uniqueType,
+	uniqueField,
+	errMessage string) *UniqueConstraint {
+	return &UniqueConstraint{
+		UniqueType:   uniqueType,
+		UniqueField:  uniqueField,
+		ErrorMessage: errMessage,
+		IsGlobal:     true,
+		Action:       UniqueConstraintAdd,
+	}
+}
+
+func NewRemoveGlobalUniqueConstraint(
+	uniqueType,
+	uniqueField string) *UniqueConstraint {
+	return &UniqueConstraint{
+		UniqueType:  uniqueType,
+		UniqueField: uniqueField,
+		IsGlobal:    true,
+		Action:      UniqueConstraintRemove,
+	}
+}