libdeflate_ex

use libdeflater::{CompressionLvl, Compressor, Decompressor};
use rustler::{Binary, Env, NewBinary};

// ── Compression ──────────────────────────────────────────────────────────────

/// Compress data using raw deflate (no header).
/// `level` must be 1..=12 (libdeflate supports levels 1-12).
#[rustler::nif]
fn deflate_compress<'a>(env: Env<'a>, data: Binary, level: i32) -> Result<Binary<'a>, String> {
    let lvl = CompressionLvl::new(level).map_err(|_| format!("invalid compression level: {level}"))?;
    let mut compressor = Compressor::new(lvl);
    let max_sz = compressor.deflate_compress_bound(data.len());
    let mut buf = vec![0u8; max_sz];
    let actual = compressor
        .deflate_compress(data.as_slice(), &mut buf)
        .map_err(|e| format!("deflate compress failed: {e:?}"))?;
    let mut out = NewBinary::new(env, actual);
    out.as_mut_slice().copy_from_slice(&buf[..actual]);
    Ok(out.into())
}

/// Compress data using zlib format (deflate with zlib header).
/// `level` must be 1..=12.
#[rustler::nif]
fn zlib_compress<'a>(env: Env<'a>, data: Binary, level: i32) -> Result<Binary<'a>, String> {
    let lvl = CompressionLvl::new(level).map_err(|_| format!("invalid compression level: {level}"))?;
    let mut compressor = Compressor::new(lvl);
    let max_sz = compressor.zlib_compress_bound(data.len());
    let mut buf = vec![0u8; max_sz];
    let actual = compressor
        .zlib_compress(data.as_slice(), &mut buf)
        .map_err(|e| format!("zlib compress failed: {e:?}"))?;
    let mut out = NewBinary::new(env, actual);
    out.as_mut_slice().copy_from_slice(&buf[..actual]);
    Ok(out.into())
}

/// Compress data using gzip format.
/// `level` must be 1..=12.
#[rustler::nif]
fn gzip_compress<'a>(env: Env<'a>, data: Binary, level: i32) -> Result<Binary<'a>, String> {
    let lvl = CompressionLvl::new(level).map_err(|_| format!("invalid compression level: {level}"))?;
    let mut compressor = Compressor::new(lvl);
    let max_sz = compressor.gzip_compress_bound(data.len());
    let mut buf = vec![0u8; max_sz];
    let actual = compressor
        .gzip_compress(data.as_slice(), &mut buf)
        .map_err(|e| format!("gzip compress failed: {e:?}"))?;
    let mut out = NewBinary::new(env, actual);
    out.as_mut_slice().copy_from_slice(&buf[..actual]);
    Ok(out.into())
}

// ── Decompression ────────────────────────────────────────────────────────────

/// Decompress raw deflate data (no zlib/gzip header).
/// Requires the exact uncompressed size to be known.
#[rustler::nif]
fn deflate_decompress<'a>(env: Env<'a>, data: Binary, uncompressed_size: usize) -> Result<Binary<'a>, String> {
    let mut decompressor = Decompressor::new();
    let mut out = NewBinary::new(env, uncompressed_size);
    decompressor
        .deflate_decompress(data.as_slice(), out.as_mut_slice())
        .map_err(|e| format!("deflate decompress failed: {e:?}"))?;
    Ok(out.into())
}

/// Decompress zlib-wrapped data (deflate with zlib header).
/// Requires the exact uncompressed size to be known.
#[rustler::nif]
fn zlib_decompress<'a>(env: Env<'a>, data: Binary, uncompressed_size: usize) -> Result<Binary<'a>, String> {
    let mut decompressor = Decompressor::new();
    let mut out = NewBinary::new(env, uncompressed_size);
    decompressor
        .zlib_decompress(data.as_slice(), out.as_mut_slice())
        .map_err(|e| format!("zlib decompress failed: {e:?}"))?;
    Ok(out.into())
}

/// Decompress gzip data.
/// Requires the exact uncompressed size to be known.
#[rustler::nif]
fn gzip_decompress<'a>(env: Env<'a>, data: Binary, uncompressed_size: usize) -> Result<Binary<'a>, String> {
    let mut decompressor = Decompressor::new();
    let mut out = NewBinary::new(env, uncompressed_size);
    decompressor
        .gzip_decompress(data.as_slice(), out.as_mut_slice())
        .map_err(|e| format!("gzip decompress failed: {e:?}"))?;
    Ok(out.into())
}

rustler::init!("Elixir.LibdeflateEx.Native");