wow-mpq 0.6.2

High-performance parser for World of Warcraft MPQ archives with parallel processing support
Documentation 
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//! PKWare compression implementation using implode crate for MPQ archives

use crate::Result;
use crate::compression::error_helpers::{compression_error, decompression_error};
use implode::exploder::Exploder;
use implode::symbol::DEFAULT_CODE_TABLE;
use pklib::{CompressionMode, DictionarySize, implode_bytes};

/// Compress data using PKWare DCL algorithm
pub(crate) fn compress(data: &[u8]) -> Result<Vec<u8>> {
    // Handle empty data
    if data.is_empty() {
        return Ok(Vec::new());
    }

    // Use ASCII mode with 2KB dictionary as default for MPQ archives
    // This provides good compression ratio for most data types
    implode_bytes(data, CompressionMode::ASCII, DictionarySize::Size2K)
        .map_err(|e| compression_error("PKWare", e))
}

/// Decompress PKWare compressed data using implode crate (for MPQ archives)
pub(crate) fn decompress(data: &[u8], expected_size: usize) -> Result<Vec<u8>> {
    // Handle empty data
    if data.is_empty() {
        return Ok(Vec::new());
    }

    log::debug!(
        "PKWare decompress input: {} bytes, expected output: {} bytes, first 16 bytes: {:02X?}",
        data.len(),
        expected_size,
        &data[..std::cmp::min(16, data.len())]
    );

    // Use the implode crate for PKWare decompression in MPQ archives
    // Based on the working implementation in msierks/mpq-rust
    let mut exploder = Exploder::new(&DEFAULT_CODE_TABLE);
    let mut output = Vec::with_capacity(expected_size);
    let mut input_pos = 0;
    let mut total_output = 0;

    while !exploder.ended && input_pos < data.len() && total_output < expected_size {
        let remaining_input = &data[input_pos..];

        match exploder.explode_block(remaining_input) {
            Ok((consumed, output_block)) => {
                input_pos += consumed;

                // Copy output block to our buffer
                let copy_len = std::cmp::min(output_block.len(), expected_size - total_output);
                output.extend_from_slice(&output_block[..copy_len]);
                total_output += copy_len;

                log::debug!(
                    "PKWare explode block: consumed {consumed} bytes, produced {copy_len} bytes, total output: {total_output}"
                );
            }
            Err(e) => {
                log::error!("PKWare decompression failed at input position {input_pos}: {e:?}");
                return Err(decompression_error("PKWare", format!("{e:?}")));
            }
        }
    }

    log::debug!(
        "PKWare decompress complete: input {} bytes -> output {} bytes (expected {})",
        data.len(),
        output.len(),
        expected_size
    );

    Ok(output)
}

/// Compress data using PKWare DCL algorithm with specific parameters
#[allow(dead_code)]
pub(crate) fn compress_with_options(
    data: &[u8],
    mode: CompressionMode,
    dict_size: DictionarySize,
) -> Result<Vec<u8>> {
    // Handle empty data
    if data.is_empty() {
        return Ok(Vec::new());
    }

    implode_bytes(data, mode, dict_size).map_err(|e| compression_error("PKWare", e))
}

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

    #[test]
    fn test_pkware_empty_data() {
        // Test decompression of empty data
        let empty_data = b"";
        let result = decompress(empty_data, 0);
        assert!(result.is_ok());
        assert_eq!(result.unwrap(), Vec::<u8>::new());
    }
}