//! AES file container operations
//!
//! Should operate on streams to produce/consume instances of `format::key::aes::AesBody`.
use super::*;
use std::{
    path::Path,
};
use tokio::{
    io::BufReader,
    fs::OpenOptions,
};

/// Read an `AesBody` from a file.
///
/// Detect the container type if possible and then decode the AES key. Returning it as `format::key::aes::AesBody`.
#[instrument(skip(path), err, fields(path = ?path.as_ref()))]
pub async fn read_aes_container(path: impl AsRef<Path>, passwd: (config::op::Password, Option<&str>)) -> eyre::Result<format::key::aes::AesBody>
{
    // password function
    let passwd = passwd.0.into_password(passwd.1.unwrap_or("Enter password for input key: "))?;
    macro_rules! passwdfn {
	() => (|salt| passwd.as_ref().map(|string| crypto::password::Password::derive(string, salt)))
    }
    // read from `path`
    use config::op::KeyFormat;
    let aesbody = match resolve::find_key_format(&path, false).await
	.wrap_err(eyre!("Failed to detect file format for key"))
	.with_section(|| format!("{:?}", path.as_ref()).header("Path was"))
	.with_suggestion(|| "Are you sure this file is valid?")? {
	    #[cold] KeyFormat::PEM => unreachable!(),
	    other => {
		let mut file = OpenOptions::new()
		    .read(true)
		    .open(path).await
		    .wrap_err(eyre!("Failed to open file for reading a second time."))
		    .with_suggestion(|| "Has the file just been/is being modified as we are reading it?")
		    .with_section(|| format!("{:?}", other).header("File format was successfully detected as"))?;
		match other {
		    KeyFormat::Bin => {
			let sh = format::SuperHeader::<format::key::KeyHeader>::read_bytes(&mut file, passwdfn!()).await
			    .wrap_err(eyre!("Failed to read key super-header"))?;
			trace!("Read super {:?}", sh);
			let h = format::key::KeyHeader::read_bytes(&mut file, passwdfn!()).await
			    .wrap_err(eyre!("Failed to read key header"))?;
			trace!("Read header {:?}", h);
			format::key::aes::AesBody::read_bytes(&mut file, h.body_key()).await
			    .wrap_err(eyre!("Failed to read key body"))?
		    },
		    KeyFormat::Text => {
			let mut file = BufReader::new(file);
			let sh = format::SuperHeader::<format::key::KeyHeader>::read_text(&mut file, passwdfn!()).await
			    .wrap_err(eyre!("Failed to read key super-header"))?;
			trace!("Read super {:?}", sh);
			let h = format::key::KeyHeader::read_text(&mut file, passwdfn!()).await
			    .wrap_err(eyre!("Failed to read key header"))?;
			trace!("Read header {:?}", h);
			format::key::aes::AesBody::read_text(&mut file, h.body_key()).await
			    .wrap_err(eyre!("Failed to read key body"))?
		    },
		    #[cold] _ => unreachable!(),
		}
	    },
	};
    debug!("Read body {:?}", aesbody);

    Ok(aesbody)
}