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use crate::result::aws::AWSError::UnrecognizedChunkFormat;
use crate::result::Error::AWS;
use crate::volume;
/// A chunk of real-time data within a volume. Chunks are ordered and when concatenated together
/// form a complete volume of radar data. All chunks contain an LDM record with radar data messages.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum Chunk<'a> {
/// The start of a new volume. This chunk will begin with an Archive II volume header followed
/// by a compressed LDM record.
Start(volume::File),
/// An intermediate or end chunk. This chunk will contain a compressed LDM record with radar
/// data messages.
IntermediateOrEnd(volume::Record<'a>),
}
impl Chunk<'_> {
/// Creates a new chunk from the provided data. The data is expected to be in one of two formats:
///
/// 1. An Archive II volume header followed by a compressed LDM record, or a "start" chunk.
/// 2. A compressed LDM record, or an "intermediate" or "end" chunk.
///
/// The chunk type is determined by the data's format.
pub fn new(data: Vec<u8>) -> crate::result::Result<Self> {
// Check if the data begins with an Archive II volume header, indicating a "start" chunk
if data.len() >= 3 && data.get(0..3) == Some(b"AR2".as_slice()) {
let file = volume::File::new(data);
return Ok(Self::Start(file));
}
// Check if the data begins with a BZ compressed record, indicating an "intermediate" or "end" chunk
if data.len() >= 6 && data.get(4..6) == Some(b"BZ".as_slice()) {
let record = volume::Record::new(data);
return Ok(Self::IntermediateOrEnd(record));
}
Err(AWS(UnrecognizedChunkFormat))
}
/// The data contained within this chunk.
pub fn data(&self) -> &[u8] {
match self {
Self::Start(file) => file.data(),
Self::IntermediateOrEnd(record) => record.data(),
}
}
}