basic flags

src/main.rs

@@ -1,8 +1,50 @@
 use phd;
+use std::process;
 
 fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    if args.len() < 2 {
+        print_usage();
+        return;
+    }
+
+    let dir = args.get(1).unwrap();
+    if dir == "--version" || dir == "-v" || dir == "-version" {
+        print_version();
+        return;
+    }
+
+    if dir == "--help" || dir == "-h" || dir == "-help" {
+        print_usage();
+        return;
+    }
+
+    if !dir.is_empty() && dir.starts_with('-') {
+        eprintln!("unknown flag: {}", dir);
+        process::exit(1);
+    }
+
     println!("-> Listening on localhost:7070");
     if let Err(e) = phd::start_server("localhost:7070") {
         eprintln!("{}", e);
     }
 }
+
+fn print_usage() {
+    println!(
+        "Usage:
+
+    phd [options] <root>
+
+Options:
+
+    -p, --port      Port to bind to.
+    -H, --host      Hostname to use when generating links.
+    -h, --help      Print this screen.
+    -v, --version   Print phd version."
+    );
+}
+
+fn print_version() {
+    println!("phd v{}", env!("CARGO_PKG_VERSION"));
+}