What is the best way to call a contract (based on the Substrate Blokchain) on the backend side from the code? I know there is Polkadot.js but it's rather a frontend focused tool, and there is also cargo-contract which enables us to call a contract from the command line.
In my case I am building a backend, where I will store account with private keys, loaded with the native tokens for gas fees, to call a given contract. Moreover, I am also looking for a way to sign a message with Polakdot wallet on the frontend, and send this message to backend, to verify the signer. Possibly, the solution should be written in Rust - therefore cargo-contract always comes to my mind, I am just not sure how could I execute the call function straight inside of the code, instead executing it in the command line.
Thanks in advance for any tip