/**
     * @return bool
     * @throws \yii\db\Exception
     */
    public function save()
    {
        $this->beforeSave();
        $transaction = Yii::$app->db->beginTransaction();
        try {
            $modelRevision = new EstimateRevision();
            $modelRevision->discount = empty($this->discount) ? 0 : $this->discount;
            $modelRevision->discountInPercent = $this->discountInPercent;
            $modelRevision->edited_by = $this->username;

            $modelRevision->nds = empty($this->nds) ? 0 : $this->nds;
            $modelRevision->has_nds = $this->hasNds;

            if (!$this->estimate->isNewRecord) {
                $version = $this->revision->version + 1;
            } else {
                $version = 1;
            }
            if (!$this->estimate->save()) {
                $transaction->rollBack();
                Yii::error('unable to save estimate');
                return false;
            }

            $modelRevision->attributes = [
                'estimate_id' => $this->estimate->id,
                'version' => $version,
            ];
            if (!$modelRevision->save()) {
                $transaction->rollBack();
                Yii::error('unable to save estimate revision');
                return false;
            }

            $this->revision = $modelRevision;
            $this->estimate->current_revision_id = $modelRevision->id;
            if (!$this->estimate->save()) {
                $transaction->rollBack();
                Yii::error('unable to save estimate with revision');
                return false;
            }

            foreach ($this->groups as $keyGroup => $group) {
                $group->estimate_id = $modelRevision->id;
                if (!$group->save()) {
                    $transaction->rollBack();
                    Yii::error('unable to save estimate group');
                    return false;
                }
                foreach ($this->resources[$keyGroup] as $res) {
                    $res->group_id = $group->id;
                    if (!$res->save()) {
                        $transaction->rollBack();
                        Yii::error('unable to save estimate group resources');
                        return false;
                    }
                }
            }

            foreach ($this->attrValues as $key => $value) {
                $this->oldEAVAttributes[$key]->save();
                $value->estimate_id = $this->estimate->id;
                $value->attribute_id = $this->oldEAVAttributes[$key]->id;
                if (!$value->save()) {
                    $transaction->rollBack();
                    Yii::error('unable to save estimate attribute values');
                    return false;
                }
            }

            $transaction->commit();
            return true;
        } catch (Exception $ex) {
            $transaction->rollBack();
            Yii::error($ex->getMessage() . "\n" . $ex->getTraceAsString());
            return false;
        }
    }