Mavs reportedly had trade in place with the Thunder at trade deadline for Danilo Gallinari

The Dallas Mavericks and the Oklahoma City Thunder had an agreement in place for Danilo Gallinari at last NBA trade deadline.

Per RealGM, the deal fell through when he signaled he would test free agency and not agree to an extension.
The Miami Heat were also interested in trading for Gallinari at the deadline.
Gallinari is unlikely to re-sign with the Thunder and they could agree to a sign-and-trade with Dallas. Sign-and-trade agreements must be for a minimum of three seasons.