1 files changed, 48 insertions, 11 deletions

diff --git a/src/main.rs b/src/main.rs
index f393f9d..e07c972 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,10 +1,14 @@
 
 #[macro_use]
 extern crate glium; 
+
 extern crate image;
+extern crate getopts;
 
 use std::env;
 use std::u64;
+use std::process::exit;
+use getopts::Options;
 use glium::glutin::os::unix::WindowBuilderExt;
     
 mod util;
@@ -182,21 +186,54 @@ fn run(window_id: Option<u64>) {
 
 }
 
+fn print_usage(program: &str, opts: Options) {
+    let brief = format!("Usage: {} [options]", program);
+    print!("{}", opts.usage(&brief));
+}
+
 fn main() {
     let args: Vec<String> = env::args().collect();
-
-    let window_id: Option<u64> = {
-        if args.len() >= 2 {
-            let parsed = if (&args[1]).starts_with("0x") {
-                u64::from_str_radix(args[1].trim_left_matches('0').trim_left_matches('x'), 16)
-            } else {
-                args[1].parse::<u64>()
-            };
-            Some(parsed.expect("Failed to parse numerical arg"))
-        } else {
-            None
+    let program = args[0].clone();
+
+    // Turn, eg, "-root" into "--root"
+    let args = util::convert_xscreensaver_args(args);
+
+    let mut opts = Options::new();
+    opts.optflag("h", "help", "print this help menu");
+    opts.optflag("", "window", "run in a window (IGNORED)");
+    opts.optflag("", "root", "run in root window (IGNORED)");
+    opts.optopt("", "window-id", "X window id number", "NUM");
+
+    let matches = match opts.parse(&args[1..]) {
+        Ok(m) => { m }
+        Err(f) => {
+            print_usage(&program, opts);
+            println!("");
+            println!("{}", f.to_string());
+            exit(-1);
         }
     };
 
+    if matches.opt_present("help") {
+        print_usage(&program, opts);
+        exit(0);
+    }
+
+    // if no "--window-id", try environment variable (arg has priority though)
+    let window_id_string: Option<String> =
+        matches.opt_str("window-id")
+               .or(env::var("XSCREENSAVER_WINDOW").ok());
+
+    let window_id = window_id_string.map(|id| match util::dechex2u64(&id) {
+        Ok(y) => y,
+        Err(e) => {
+            println!("Couldn't parse numerical argument: {}", e);
+            exit(-1); },
+    });
+
+    if window_id.is_some() {
+        println!("Drawing on existing X window: 0x{:07X}", window_id.unwrap());
+    }
+
     run(window_id);
 }