class ViewTemplate

final class ViewTemplate {
    private ?string $name = null;
    private ?string $description = null;
    
    /** @var list<string> */
    private ?array $attributeKeys = null;
    private ?AggregationInterface $aggregation = null;
    private function __construct() {
    }
    public static function create() : self {
        static $instance;
        return $instance ??= new self();
    }
    public function withName(string $name) : self {
        $self = clone $this;
        $self->name = $name;
        return $self;
    }
    public function withDescription(string $description) : self {
        $self = clone $this;
        $self->description = $description;
        return $self;
    }
    
    /**
     * @param list<string> $attributeKeys
     */
    public function withAttributeKeys(array $attributeKeys) : self {
        $self = clone $this;
        $self->attributeKeys = $attributeKeys;
        return $self;
    }
    public function withAggregation(?AggregationInterface $aggregation) : self {
        $self = clone $this;
        $self->aggregation = $aggregation;
        return $self;
    }
    public function project(Instrument $instrument) : ViewProjection {
        return new ViewProjection($this->name ?? $instrument->name, $instrument->unit, $this->description ?? $instrument->description, $this->attributeKeys, $this->aggregation);
    }

}