1 files changed, 125 insertions, 0 deletions
diff --git a/libs/bsa_ffi/src/archive/ba2_reader.rs b/libs/bsa_ffi/src/archive/ba2_reader.rs
new file mode 100644
index 0000000..e6dd984
--- /dev/null
+++ b/libs/bsa_ffi/src/archive/ba2_reader.rs
@@ -0,0 +1,125 @@
+//! BA2 (Fallout 4/Starfield) archive reading
+//!
+//! Provides read support for FO4 format BA2 files (Fallout 4, Fallout 76, Starfield).
+
+use anyhow::{bail, Context, Result};
+use ba2::fo4::{Archive, File as Ba2File, FileWriteOptions};
+use ba2::prelude::*;
+use ba2::ByteSlice;
+use rayon::prelude::*;
+use std::collections::HashSet;
+use std::io::Cursor;
+use std::path::Path;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use tracing::debug;
+
+/// Entry for a file in a BA2 archive
+#[derive(Debug, Clone)]
+pub struct Ba2FileEntry {
+    pub path: String,
+}
+
+/// List all files in a BA2 archive
+pub fn list_files(ba2_path: &Path) -> Result<Vec<Ba2FileEntry>> {
+    let (archive, _options): (Archive, _) = Archive::read(ba2_path)
+        .with_context(|| format!("Failed to open BA2: {}", ba2_path.display()))?;
+
+    let mut files = Vec::new();
+
+    for (key, _file) in archive.iter() {
+        let path = String::from_utf8_lossy(key.name().as_bytes()).to_string();
+
+        files.push(Ba2FileEntry { path });
+    }
+
+    debug!("Listed {} files in BA2 {}", files.len(), ba2_path.display());
+    Ok(files)
+}
+
+/// Extract a single file from a BA2 archive
+#[allow(dead_code)]
+pub fn extract_file(ba2_path: &Path, file_path: &str) -> Result<Vec<u8>> {
+    let (archive, options): (Archive, _) = Archive::read(ba2_path)
+        .with_context(|| format!("Failed to open BA2: {}", ba2_path.display()))?;
+
+    let write_options: FileWriteOptions = options.into();
+
+    // Normalize path for comparison (BA2 uses forward slashes typically)
+    let normalized = file_path.replace('\\', "/").to_lowercase();
+    let normalized_backslash = file_path.replace('/', "\\").to_lowercase();
+
+    for (key, file) in archive.iter() {
+        let current_path = String::from_utf8_lossy(key.name().as_bytes()).to_lowercase();
+
+        // Try both slash conventions
+        if current_path == normalized
+            || current_path == normalized_backslash
+            || current_path.replace('\\', "/") == normalized
+            || current_path.replace('/', "\\") == normalized_backslash
+        {
+            // Write to memory buffer
+            let mut buffer = Cursor::new(Vec::new());
+            file.write(&mut buffer, &write_options)
+                .with_context(|| format!("Failed to extract file: {}", file_path))?;
+
+            return Ok(buffer.into_inner());
+        }
+    }
+
+    bail!(
+        "File not found in BA2: {} (searched for '{}')",
+        file_path,
+        normalized
+    )
+}
+
+/// Extract multiple files from a BA2 archive in parallel.
+/// Opens the archive once, collects matching entries, then decompresses
+/// and writes them in parallel using rayon.
+/// `wanted` should contain lowercase forward-slash-separated paths.
+pub fn extract_files_batch<F>(
+    ba2_path: &Path,
+    wanted: &HashSet<String>,
+    callback: F,
+) -> Result<usize>
+where
+    F: Fn(&str, Vec<u8>) -> Result<()> + Send + Sync,
+{
+    let (archive, options): (Archive, _) = Archive::read(ba2_path)
+        .with_context(|| format!("Failed to open BA2: {}", ba2_path.display()))?;
+
+    let write_options: FileWriteOptions = options.into();
+
+    // Collect matching entries with references
+    let mut entries: Vec<(String, &Ba2File)> = Vec::new();
+    for (key, file) in archive.iter() {
+        let path = String::from_utf8_lossy(key.name().as_bytes()).to_string();
+        let lookup = path.replace('\\', "/").to_lowercase();
+        if wanted.contains(&lookup) {
+            entries.push((path, file));
+        }
+    }
+
+    // Decompress + write in parallel
+    let extracted = AtomicUsize::new(0);
+    entries
+        .par_iter()
+        .try_for_each(|(path, file)| -> Result<()> {
+            let mut buffer = Cursor::new(Vec::new());
+            file.write(&mut buffer, &write_options)
+                .with_context(|| format!("Failed to extract file: {}", path))?;
+
+            callback(path, buffer.into_inner())?;
+            extracted.fetch_add(1, Ordering::Relaxed);
+            Ok(())
+        })?;
+
+    let count = extracted.load(Ordering::Relaxed);
+    debug!(
+        "Batch extracted {} of {} wanted files from BA2 {}",
+        count,
+        wanted.len(),
+        ba2_path.display()
+    );
+    Ok(count)
+}