Cargo.lock

@@ -161,6 +161,7 @@ dependencies = [
  "camino",
  "clap",
  "m3u",
+ "once_cell",
 ]
 
 [[package]]

Cargo.toml

@@ -10,3 +10,4 @@ anyhow = "1.0.75"
 camino = "1.1.6"
 clap = { version = "4.4.0", features = ["derive"] }
 m3u = "1.0.0"
+once_cell = "1.18.0"

src/main.rs

@@ -2,6 +2,7 @@ use anyhow::Result;
 use camino::{Utf8Path, Utf8PathBuf};
 use clap::{Parser, Subcommand};
 use m3u::Entry;
+use once_cell::sync::Lazy;
 use std::collections::HashSet;
 
 /// Check if files in a playlist actually exist.
@@ -28,17 +29,57 @@ enum Mode {
     },
 }
 
-fn get_directories(base_directory: &str, is_relative: bool) -> Result<HashSet<String>> {
+static AUDIO_EXTENSIONS: Lazy<HashSet<&str>> =
+    Lazy::new(|| HashSet::from(["m4a", "mp3", "ogg", "flac", "opus"]));
+
+fn has_audio_files(path: &Utf8Path) -> Result<bool> {
+    let any_audio_file = path
+        .read_dir_utf8()?
+        .map(|entry| {
+            let entry = entry?;
+            if entry.metadata()?.is_file() {
+                if let Some(extension) = entry.path().extension() {
+                    Ok(AUDIO_EXTENSIONS.contains(extension))
+                } else {
+                    Ok(false)
+                }
+            } else {
+                Ok(false)
+            }
+        })
+        .any(|res: Result<bool>| res.unwrap_or(false));
+    Ok(any_audio_file)
+}
+
+fn get_directories(
+    base_directory: &Utf8Path,
+    relative_to: Option<String>,
+) -> Result<HashSet<String>> {
     let mut result = HashSet::<String>::new();
-    for entry in Utf8Path::new(base_directory).read_dir_utf8()? {
+    for entry in base_directory.read_dir_utf8()? {
         let entry = entry?;
         if entry.metadata()?.is_dir() {
-            let p = if is_relative {
-                entry.file_name().to_string()
+            // Skip dot directories
+            if entry.file_name().starts_with('.') {
+                continue;
+            }
+            let p = match &relative_to {
+                Some(base) => {
+                    if base.is_empty() {
+                        entry.file_name().to_owned()
                     } else {
-                entry.path().to_string()
+                        format!("{base}/{dir}", dir = entry.file_name())
+                    }
+                }
+                None => entry.path().to_string(),
             };
-            result.insert(p);
+            // The directory must have audio files to count
+            if has_audio_files(entry.path()).unwrap_or(false) {
+                result.insert(p.clone());
+            }
+            // Recursively check
+            let relative_to = relative_to.as_ref().map(|_| p);
+            result.extend(get_directories(entry.path(), relative_to).unwrap_or_default());
         }
     }
     Ok(result)
@@ -71,7 +112,8 @@ fn main() -> Result<()> {
                     }
                 }
             }
-            let actual_directories = get_directories(&base_directory, relative)?;
+            let relative_to = if relative { Some(String::new()) } else { None };
+            let actual_directories = get_directories(Utf8Path::new(&base_directory), relative_to)?;
             let mut missing_directories = actual_directories
                 .difference(&playlist_directories)
                 .collect::<Vec<_>>();