Use clap for command parsing

.gitignore

@@ -1,2 +1,3 @@
 /target
 disk-report.iml
+.idea

Cargo.toml

@@ -6,4 +6,5 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-itertools = "0.10.3"
+itertools = "0.10.3"
+clap = { version = "3.1.1", features = ["derive"] }

README.md

@@ -1,10 +1,20 @@
 # disk-report-rust
 
-A simple utility for displaying the relative size of the contents of a directory tree
-
 ## Usage
 
-`disk-report <directory>`
+```
+An application for displaying the relative size of the file contents of a directory tree
+
+USAGE:
+    disk-report [DIRECTORY]
+
+ARGS:
+    <DIRECTORY>    Directory to scan [default: .]
+
+OPTIONS:
+    -h, --help       Print help information
+    -V, --version    Print version information
+```
 
 ## Example
 
@@ -46,3 +56,4 @@ aoc-2021 - 100%, 773MB total / 0MB own
       build - 2%, 14MB total / 0MB own
   js - 3%, 27MB total / 0MB own```
     node_modules - 3%, 27MB total / 0MB own
+```

src/main.rs

@@ -73,17 +73,22 @@ fn format_tree(t: &Tree, depth: i32, total_size: u64) -> String {
     )
 }
 
+use clap::Parser;
+
+/// An application for displaying the relative size of the file contents of a directory tree
+#[derive(Parser, Debug)]
+#[clap(author, version, about, long_about = None)]
+struct Args {
+    /// Directory to scan
+    #[clap(default_value = ".")]
+    directory: String,
+}
+
 fn main() -> Result<(), Error> {
-    let mut args: Vec<String> = std::env::args().collect();
-    if args.is_empty() {
-        let program = args.pop().unwrap();
-        eprintln!("Usage: {} <path>", program);
-        std::process::exit(1);
-    }
-    let path = args.pop().unwrap();
+    let args = Args::parse();
 
     let mut file_count = 0;
-    let path = fs::canonicalize(&path).map_err(Error::IO)?;
+    let path = fs::canonicalize(&args.directory).map_err(Error::IO)?;
 
     println!("Disk report for {}\n", path.to_str().unwrap_or("??"));
     let tree = read_tree(path, &mut file_count)?;