Auth

#[contracttype]
pub enum DataKey {
    Counter(Address),
}

#[contract]
pub struct IncrementContract;

#[contractimpl]
impl IncrementContract {
    /// Increment increments a counter for the user, and returns the value.
    pub fn increment(env: Env, user: Address, value: u32) -> u32 {
        // Requires `user` to have authorized call of the `increment` of this
        // contract with all the arguments passed to `increment`, i.e. `user`
        // and `value`. This will panic if auth fails for any reason.
        // When this is called, Soroban host performs the necessary
        // authentication, manages replay prevention and enforces the user's
        // authorization policies.
        // The contracts normally shouldn't worry about these details and just
        // write code in generic fashion using `Address` and `require_auth` (or
        // `require_auth_for_args`).
        user.require_auth();

        // This call is equilvalent to the above:
        // user.require_auth_for_args((&user, value).into_val(&env));

        // The following has less arguments but is equivalent in authorization
        // scope to the above calls (the user address doesn't have to be
        // included in args as it's guaranteed to be authenticated).
        // user.require_auth_for_args((value,).into_val(&env));

        // Construct a key for the data being stored. Use an enum to set the
        // contract up well for adding other types of data to be stored.
        let key = DataKey::Counter(user.clone());

        // Get the current count for the invoker.
        let mut count: u32 = env.storage().persistent().get(&key).unwrap_or_default();

        // Increment the count.
        count += value;

        // Save the count.
        env.storage().persistent().set(&key, &count);

        // Return the count to the caller.
        count
    }
}

#![cfg(test)]
extern crate std;

#[test]
fn test() {
    let env = Env::default();
    env.mock_all_auths();

    let contract_id = env.register(IncrementContract, {});
    let client = IncrementContractClient::new(&env, &contract_id);

    let user_1 = Address::generate(&env);
    let user_2 = Address::generate(&env);

    assert_eq!(client.increment(&user_1, &5), 5);
    // Verify that the user indeed had to authorize a call of `increment` with
    // the expected arguments:
    assert_eq!(
        env.auths(),
        std::vec![(
            // Address for which authorization check is performed
            user_1.clone(),
            // Invocation tree that needs to be authorized
            AuthorizedInvocation {
                // Function that is authorized. Can be a contract function or
                // a host function that requires authorization.
                function: AuthorizedFunction::Contract((
                    // Address of the called contract
                    contract_id.clone(),
                    // Name of the called function
                    symbol_short!("increment"),
                    // Arguments used to call `increment` (converted to the env-managed vector via `into_val`)
                    (user_1.clone(), 5_u32).into_val(&env),
                )),
                // The contract doesn't call any other contracts that require
                // authorization,
                sub_invocations: std::vec![]
            }
        )]
    );

    // Do more `increment` calls. It's not necessary to verify authorizations
    // for every one of them as we don't expect the auth logic to change from
    // call to call.
    assert_eq!(client.increment(&user_1, &2), 7);
    assert_eq!(client.increment(&user_2, &1), 1);
    assert_eq!(client.increment(&user_1, &3), 10);
    assert_eq!(client.increment(&user_2, &4), 5);
}