feat(assets): implement AssetDir directory iterator with rewind support

crates/molotov-core/src/assets/dir.rs

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+use std::ffi::CString;
+
+pub struct AssetDir {
+    entries: Vec<CString>,
+    cursor: usize,
+}
+
+impl AssetDir {
+    pub fn new(filenames: Vec<String>) -> Self {
+        let entries = filenames
+            .into_iter()
+            .filter_map(|s| CString::new(s).ok())
+            .collect();
+        Self { entries, cursor: 0 }
+    }
+
+    pub fn get_next_filename(&mut self) -> *const libc::c_char {
+        if self.cursor < self.entries.len() {
+            let ptr = self.entries[self.cursor].as_ptr();
+            self.cursor += 1;
+            ptr
+        } else {
+            std::ptr::null()
+        }
+    }
+
+    pub fn rewind(&mut self) {
+        self.cursor = 0;
+    }
+}

crates/molotov-core/src/assets/mod.rs

@@ -1,3 +1,4 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 pub mod asset;
+pub mod dir;
 pub mod types;

crates/molotov-core/tests/asset_dir_test.rs

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+use molotov_core::assets::dir::AssetDir;
+use std::ffi::CStr;
+
+#[test]
+fn test_asset_dir_iteration_and_rewind() {
+    let files = vec!["font.ttf".to_string(), "cursor.png".to_string(), "sound.ogg".to_string()];
+    let mut dir = AssetDir::new(files);
+
+    unsafe {
+        let f1 = dir.get_next_filename();
+        assert!(!f1.is_null());
+        assert_eq!(CStr::from_ptr(f1).to_str().unwrap(), "font.ttf");
+
+        let f2 = dir.get_next_filename();
+        assert_eq!(CStr::from_ptr(f2).to_str().unwrap(), "cursor.png");
+
+        dir.rewind();
+        let f1_again = dir.get_next_filename();
+        assert_eq!(CStr::from_ptr(f1_again).to_str().unwrap(), "font.ttf");
+    }
+}