NEAR Spinner

lib.rs

use near_sdk::{
    borsh::{self, BorshDeserialize, BorshSerialize},
    env,
    json_types::U64,
    log, near_bindgen, Promise,
};

#[derive(BorshSerialize, BorshDeserialize, Default, Debug)]
#[near_bindgen]
struct Contract {}

#[near_bindgen]
impl Contract {
    pub fn with_transfers(&mut self, count: u32) -> Promise {
        let mut p = Promise::new(env::current_account_id()).transfer(1);

        for _ in 0..count {
            p = p.then(Promise::new(env::current_account_id()).transfer(1));
        }

        p.then(Self::ext(env::current_account_id()).end(env::block_height().into()))
    }

    pub fn with_callbacks(&mut self, count: u32, start_block_height: Option<U64>) -> Promise {
        let start_block_height = start_block_height.unwrap_or_else(|| env::block_height().into());

        if count == 0 {
            Self::ext(env::current_account_id()).end(start_block_height)
        } else {
            Self::ext(env::current_account_id()).with_callbacks(count - 1, Some(start_block_height))
        }
    }

    pub fn end(&mut self, start_block_height: U64) -> U64 {
        let block_height = env::block_height();
        let delta = block_height - start_block_height.0;
        log!("Block height delta: {}", delta);
        log!("Used gas: {}", env::used_gas().0);
        log!("Prepaid gas: {}", env::prepaid_gas().0);

        delta.into()
    }
}