Fetch the header for a specific block if available

CopyHTTP/1.1 200 OK
Content-Type: application/json
 
{
  "hash": "{hash}",
  "parent_hash": "{parent-hash}",
  "number": {number},
  "state_root": "{state-root}",
  "extrinsics_root": "{extrinsics-root}",
  "extension": {
    "rows": {rows},
    "cols": {cols},
    "data_root": "{data-root}", // Optional
    "commitments": [
      "{commitment}", ...
    ],
    "app_lookup": {
      "size": {size},
      "index": [
        {
          "app_id": {app-id},
          "start": {start}
        }
      ]
    }
  }
}

CopyHTTP/1.1 400 Bad Request

Copyuse reqwest::{StatusCode, Client};
use serde::{Deserialize, Serialize};
 
#[derive(Debug, Serialize, Deserialize)]
struct BlockHeaderResponse {
    hash: String,
    parent_hash: String,
    number: u32,
    state_root: String,
    extrinsics_root: String,
    extension: Extension,
}
 
#[derive(Debug, Serialize, Deserialize)]
struct Extension {
    rows: u32,
    cols: u32,
    data_root: Option<String>,
    commitments: Vec<String>,
    app_lookup: AppLookup,
}
 
#[derive(Debug, Serialize, Deserialize)]
struct AppLookup {
    size: u32,
    index: Vec<AppIndex>,
}
 
#[derive(Debug, Serialize, Deserialize)]
struct AppIndex {
    app_id: Option<u32>,
    start: u32,
}
 
const LIGHT_CLIENT_URL: &str = "https://api.lightclient.mainnet.avail.so";
 
#[tokio::main]
async fn main() {
    let block_number = 592445; // Example block number
    let client = Client::new();
    let header_url = format!("{LIGHT_CLIENT_URL}/v2/blocks/{block_number}/header");
    let response = client.get(header_url).send().await.unwrap();
 
    match response.status() {
        StatusCode::OK => {
            let block_header: BlockHeaderResponse = response.json().await.unwrap();
            println!("Block header: {:?}", block_header);
        }
        StatusCode::BAD_REQUEST => {
            println!("Header not available for block {}", block_number);
        }
        _ => {
            eprintln!("Failed to get block header: {}", response.status());
        }
    }
    // ...error handling...
}