use flate2::Compression;
use flate2::read::{GzDecoder, GzEncoder};
use std::io::Read;
use crate::error::ArchiveError;

/// Gzip compress data.
pub fn compress(data: &[u8]) -> Result<Vec<u8>, ArchiveError> {
    let mut encoder = GzEncoder::new(data, Compression::default());
    let mut compressed = Vec::new();
    encoder.read_to_end(&mut compressed)
        .map_err(|e| ArchiveError::Io(e))?;
    Ok(compressed)
}

/// Gzip decompress data.
pub fn decompress(data: &[u8]) -> Result<Vec<u8>, ArchiveError> {
    let mut decoder = GzDecoder::new(data);
    let mut decompressed = Vec::new();
    decoder.read_to_end(&mut decompressed)
        .map_err(|e| ArchiveError::Io(e))?;
    Ok(decompressed)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_roundtrip() {
        let data = b"Hello, this is test data for compression!";
        let compressed = compress(data).unwrap();
        let decompressed = decompress(&compressed).unwrap();
        assert_eq!(data.as_slice(), decompressed.as_slice());
    }

    #[test]
    fn test_compression_reduces_size() {
        // Highly compressible data
        let data = vec![b'A'; 10000];
        let compressed = compress(&data).unwrap();
        assert!(compressed.len() < data.len());
    }
}