1 files changed, 154 insertions, 0 deletions
diff --git a/libs/bsa_ffi/src/archive/reader.rs b/libs/bsa_ffi/src/archive/reader.rs
new file mode 100644
index 0000000..21b291c
--- /dev/null
+++ b/libs/bsa_ffi/src/archive/reader.rs
@@ -0,0 +1,154 @@
+//! BSA reading with parallel extraction
+
+use anyhow::{bail, Context, Result};
+use ba2::tes4::{Archive, File as BsaFile, FileCompressionOptions};
+use ba2::{ByteSlice, Reader};
+use rayon::prelude::*;
+use std::collections::HashSet;
+use std::path::Path;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use tracing::debug;
+
+/// Entry for a file in a BSA archive
+#[derive(Debug, Clone)]
+pub struct BsaFileEntry {
+    pub path: String,
+}
+
+/// List all files in a BSA archive
+pub fn list_files(bsa_path: &Path) -> Result<Vec<BsaFileEntry>> {
+    let (archive, _): (Archive, _) = Archive::read(bsa_path)
+        .with_context(|| format!("Failed to open BSA: {}", bsa_path.display()))?;
+
+    let mut files = Vec::new();
+
+    for (dir_key, folder) in archive.iter() {
+        let dir_name = String::from_utf8_lossy(dir_key.name().as_bytes());
+
+        for (file_key, _file) in folder.iter() {
+            let file_name = String::from_utf8_lossy(file_key.name().as_bytes());
+
+            // Build full path with backslash (BSA convention)
+            let full_path = if dir_name.is_empty() || dir_name == "." {
+                file_name.to_string()
+            } else {
+                format!("{}\\{}", dir_name, file_name)
+            };
+
+            files.push(BsaFileEntry { path: full_path });
+        }
+    }
+
+    debug!("Listed {} files in BSA {}", files.len(), bsa_path.display());
+    Ok(files)
+}
+
+/// Extract a single file from a BSA archive
+#[allow(dead_code)]
+pub fn extract_file(bsa_path: &Path, file_path: &str) -> Result<Vec<u8>> {
+    let (archive, options): (Archive, _) = Archive::read(bsa_path)
+        .with_context(|| format!("Failed to open BSA: {}", bsa_path.display()))?;
+
+    // Convert archive options to compression options (includes version info)
+    let compression_options: FileCompressionOptions = (&options).into();
+
+    // Normalize to backslashes and split
+    let normalized = file_path.replace('/', "\\");
+    let (dir_name, file_name) = if let Some(idx) = normalized.rfind('\\') {
+        (&normalized[..idx], &normalized[idx + 1..])
+    } else {
+        ("", normalized.as_str())
+    };
+
+    // Search case-insensitively
+    for (dir_key, folder) in archive.iter() {
+        let current_dir = String::from_utf8_lossy(dir_key.name().as_bytes());
+
+        if current_dir.eq_ignore_ascii_case(dir_name) {
+            for (file_key, file) in folder.iter() {
+                let current_file = String::from_utf8_lossy(file_key.name().as_bytes());
+
+                if current_file.eq_ignore_ascii_case(file_name) {
+                    // Extract with decompression if needed (uses version from archive options)
+                    let data = if file.is_decompressed() {
+                        file.as_bytes().to_vec()
+                    } else {
+                        file.decompress(&compression_options)?.as_bytes().to_vec()
+                    };
+                    return Ok(data);
+                }
+            }
+        }
+    }
+
+    bail!(
+        "File not found in BSA: {} (dir='{}', file='{}')",
+        file_path,
+        dir_name,
+        file_name
+    )
+}
+
+/// Extract multiple files from a BSA archive in a single parallel pass.
+/// Opens the archive once, collects matching entries, then decompresses
+/// and writes them in parallel using rayon.
+/// `wanted` should contain lowercase backslash-separated paths.
+pub fn extract_files_batch<F>(
+    bsa_path: &Path,
+    wanted: &HashSet<String>,
+    callback: F,
+) -> Result<usize>
+where
+    F: Fn(&str, Vec<u8>) -> Result<()> + Send + Sync,
+{
+    let (archive, options): (Archive, _) = Archive::read(bsa_path)
+        .with_context(|| format!("Failed to open BSA: {}", bsa_path.display()))?;
+
+    let compression_options: FileCompressionOptions = (&options).into();
+
+    // Collect matching entries with references to file data
+    let mut entries: Vec<(String, &BsaFile)> = Vec::new();
+    for (dir_key, folder) in archive.iter() {
+        let dir_name = String::from_utf8_lossy(dir_key.name().as_bytes());
+
+        for (file_key, file) in folder.iter() {
+            let file_name = String::from_utf8_lossy(file_key.name().as_bytes());
+
+            let full_path = if dir_name.is_empty() || dir_name == "." {
+                file_name.to_string()
+            } else {
+                format!("{}\\{}", dir_name, file_name)
+            };
+
+            let lookup = full_path.to_lowercase();
+            if wanted.contains(&lookup) {
+                entries.push((full_path, file));
+            }
+        }
+    }
+
+    // Decompress + write in parallel
+    let extracted = AtomicUsize::new(0);
+    entries
+        .par_iter()
+        .try_for_each(|(path, file)| -> Result<()> {
+            let data = if file.is_decompressed() {
+                file.as_bytes().to_vec()
+            } else {
+                file.decompress(&compression_options)?.as_bytes().to_vec()
+            };
+
+            callback(path, data)?;
+            extracted.fetch_add(1, Ordering::Relaxed);
+            Ok(())
+        })?;
+
+    let count = extracted.load(Ordering::Relaxed);
+    debug!(
+        "Batch extracted {} of {} wanted files from BSA {}",
+        count,
+        wanted.len(),
+        bsa_path.display()
+    );
+    Ok(count)
+}