//! List a remote HDF5 file and read one dataset, then print what it cost.
//!
//! ```text
//! cargo run -p clawhdf5-remote --example read_url -- URL [DATASET]
//! ```

use clawhdf5::File;
use clawhdf5_remote::{Options, storage_for_url};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut args = std::env::args().skip(1);
    let url = args.next().ok_or("usage: read_url URL [DATASET]")?;
    let dataset = args.next();

    let storage = storage_for_url(&url, &Options::default())?;
    let file = File::open_storage(storage.clone())?;

    // Walk the tree.
    let mut stack = vec![("/".to_string(), file.root())];
    while let Some((path, group)) = stack.pop() {
        for (name, addr) in group.entries()? {
            let child = format!("{}/{name}", path.trim_end_matches('/'));
            match file.dataset_at(addr) {
                Ok(ds) => println!("{child}  dataset {:?} {:?}", ds.shape()?, ds.dtype()?),
                Err(_) => {
                    println!("{child}  group");
                    stack.push((child, file.group_at(addr)));
                }
            }
        }
    }

    if let Some(name) = dataset {
        let values = file.dataset(&name)?.read_f64()?;
        let shown: Vec<_> = values.iter().take(8).collect();
        println!("{name}: {} values, first {shown:?}", values.len());
    }

    let s = storage.stats();
    println!(
        "{} range requests (the one at open included), {} bytes fetched, {} bytes cached",
        s.requests, s.bytes_fetched, s.cached_bytes
    );
    Ok(())
}