Walk through filesystem and print metadata

src/filesystem.rs

@@ -0,0 +1,22 @@
+use std::path::Path;
+
+use walkdir::WalkDir;
+
+const MUSIC_EXTENSIONS: &[&str] = &[
+    "mp3", "flac", "ogg", "opus", "m4a", "mp4", "wav", "aif", "aiff", "wv", "ape", "mpc",
+];
+
+fn is_music_file(path: &Path) -> bool {
+    path.extension()
+        .and_then(|ext| ext.to_str())
+        .is_some_and(|ext| MUSIC_EXTENSIONS.contains(&ext.to_ascii_lowercase().as_str()))
+}
+
+/// Returns an iterator over music file paths found recursively under `dir`.
+pub fn walk_music_files(dir: &Path) -> impl Iterator<Item = std::path::PathBuf> + '_ {
+    WalkDir::new(dir)
+        .into_iter()
+        .filter_map(|e| e.ok())
+        .filter(|e| is_music_file(e.path()))
+        .map(|e| e.into_path())
+}

src/main.rs

@@ -0,0 +1,30 @@
+mod filesystem;
+mod metadata;
+
+use std::env;
+use std::path::Path;
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    if args.len() != 2 {
+        eprintln!("Usage: {} <directory>", args[0]);
+        std::process::exit(1);
+    }
+
+    let dir = Path::new(&args[1]);
+
+    for path in filesystem::walk_music_files(dir) {
+        println!("{}", path.display());
+
+        match metadata::read_track_metadata(&path) {
+            Ok(Some(meta)) => {
+                let unknown = "(unknown)";
+                println!("  Title:  {}", meta.title.as_deref().unwrap_or(unknown));
+                println!("  Artist: {}", meta.artist.as_deref().unwrap_or(unknown));
+                println!("  Album:  {}", meta.album.as_deref().unwrap_or(unknown));
+            }
+            Ok(None) => println!("  (no metadata tags found)"),
+            Err(e) => eprintln!("  warning: could not read metadata: {e}"),
+        }
+    }
+}

src/metadata.rs

@@ -0,0 +1,25 @@
+use std::path::Path;
+
+use lofty::file::TaggedFileExt;
+use lofty::tag::Accessor;
+
+pub struct TrackMetadata {
+    pub title: Option<String>,
+    pub artist: Option<String>,
+    pub album: Option<String>,
+}
+
+/// Read metadata from a music file, returning `None` if no tags are present.
+pub fn read_track_metadata(path: &Path) -> Result<Option<TrackMetadata>, lofty::error::LoftyError> {
+    let tagged_file = lofty::read_from_path(path)?;
+
+    let Some(tag) = tagged_file.primary_tag().or_else(|| tagged_file.first_tag()) else {
+        return Ok(None);
+    };
+
+    Ok(Some(TrackMetadata {
+        title: tag.title().map(|s| s.into_owned()),
+        artist: tag.artist().map(|s| s.into_owned()),
+        album: tag.album().map(|s| s.into_owned()),
+    }))
+}