Add CLI functionality to list files in a directory

Cargo.toml

@@ -4,3 +4,4 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+clap = { version = "4.5.29", features = ["derive"] }

src/main.rs

@@ -1,3 +1,57 @@
-fn main() {
+use clap::Parser;
-    println!("Hello, world!");
+use std::fs;
+use std::path::{Path, PathBuf};
+
+#[derive(Parser)]
+struct Cli {
+    input: String,
+}
+
+#[derive(Debug)]
+enum Error {
+    Io(std::io::Error),
+    StripPrefix(std::path::StripPrefixError),
+}
+
+impl From<std::io::Error> for Error {
+    fn from(e: std::io::Error) -> Self {
+        Error::Io(e)
+    }
+}
+
+impl From<std::path::StripPrefixError> for Error {
+    fn from(e: std::path::StripPrefixError) -> Self {
+        Error::StripPrefix(e)
+    }
+}
+
+fn get_list<T>(path: T) -> Result<Vec<PathBuf>, Error>
+where
+    T: AsRef<Path> + Copy,
+{
+    match fs::metadata(&path) {
+        Ok(md) => {
+            if md.is_dir() {
+                let entries = fs::read_dir(path)?;
+                let mut list = Vec::new();
+                for entry in entries {
+                    let entry_path = entry?.path();
+                    let relative = entry_path.strip_prefix(&path)?;
+                    list.push(relative.to_owned());
+                }
+                Ok(list)
+            } else {
+                Ok(vec![path.as_ref().to_owned()])
+            }
+        }
+        Err(e) => Err(Error::Io(e)),
+    }
+}
+
+fn main() {
+    let cli = Cli::parse();
+    let list = get_list(&cli.input).unwrap();
+    for path in list {
+        println!("{}", path.display());
+    }
 }