// Copyright 2019-2020 Parity Technologies (UK) Ltd.
// This file is part of substrate-subxt.
//
// subxt is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// subxt is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with substrate-subxt.  If not, see <http://www.gnu.org/licenses/>.

use substrate_subxt::{
    ClientBuilder,
    KusamaRuntime,
};

#[async_std::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    env_logger::init();

    let client = ClientBuilder::<KusamaRuntime>::new()
        .set_url("wss://kusama-rpc.polkadot.io")
        .build()
        .await?;

    let block_number = 1;

    let block_hash = client.block_hash(Some(block_number.into())).await?;

    if let Some(hash) = block_hash {
        println!("Block hash for block number {}: {}", block_number, hash);
    } else {
        println!("Block number {} not found.", block_number);
    }

    Ok(())
}