cat.rs

use crate::util;
use tame_gcs::{http, objects::Object};

#[derive(clap::Parser, Debug)]
pub struct Args {
    #[clap(
        short,
        allow_hyphen_values = true,
        long_help = "Causes gsutil to output just the specified byte range of the object.

Ranges are can be of these forms:
* start-end (e.g., -r 256-5939)
* start-    (e.g., -r 256-)
* -numbytes (e.g., -r -5)

where offsets start at 0, start-end means to return bytes start
through end (inclusive), start- means to return bytes start
through the end of the object, and -numbytes means to return the
last numbytes of the object."
    )]
    range: Option<String>,
    /// The gs:// url to the object
    url: url::Url,
}

pub async fn cmd(ctx: &util::RequestContext, args: Args) -> Result<(), anyhow::Error> {
    let oid = util::gs_url_to_object_id(&args.url)?;

    let mut download_req = Object::download(
        &(
            oid.bucket(),
            oid.object()
                .ok_or_else(|| anyhow::anyhow!("invalid object name specified"))?,
        ),
        None,
    )?;

    if let Some(range) = args.range {
        // The format specified in the arguments exactly matches those HTTP range
        // value, so we just pass it along (almost) verbatim and let GCS actually
        // handle nefarious users for us
        download_req.headers_mut().insert(
            http::header::RANGE,
            http::header::HeaderValue::from_str(&format!("bytes={}", range))?,
        );
    }

    let mut response: tame_gcs::objects::DownloadObjectResponse =
        util::execute(ctx, download_req).await?;

    std::io::copy(&mut response, &mut std::io::stdout())?;

    Ok(())
}