Allow to specify spread, freq, and seed as arguments.

src/main.rs

@@ -1,20 +1,84 @@
+extern crate getopts;
 extern crate rand;
 extern crate ansi_term;
 
 use std::io;
 use std::io::prelude::*;
 use std::f32::consts::PI;
+use std::env;
 
+use getopts::Options;
 use rand::{thread_rng, Rng};
 use ansi_term::Colour::RGB;
 
+fn print_usage(program: &str, opts: Options) {
+    let brief = format!("Usage: {} [OPTION]... [FILE]...", program);
+
+    print!("{}", opts.usage(&brief));
+}
+
 fn main() {
-    let mut s = 1.0; // thread_rng().gen_range(0.0, 256.0);
+    let args: Vec<String> = env::args().collect();
+    let program = args[0].clone();
+
+    let mut opts = Options::new();
+
+    opts.optopt("p", "spread", "Rainbow spread", "<f>");
+    opts.optopt("F", "freq", "Rainbow frequency", "<f>");
+    opts.optopt("S", "seed", "Rainbow seed, 0 = random", "<i>");
+    opts.optflag("h", "help", "Show this message");
+
+    let matches = match opts.parse(&args[1..]) {
+        Ok(m) => { m }
+        Err(f) => { panic!(f.to_string()) }
+    };
+
+    if matches.opt_present("h") {
+        print_usage(&program, opts);
+
+        return;
+    }
+
+    // @todo this is nasty... fix this.
+    let spread : f32 = match matches.opt_default("spread", "3.0") {
+        Some(s) => {
+            match s.parse() {
+                Ok(0.0) => 3.0,
+                Ok(n) => n,
+                _ => 3.0
+            }
+        },
+        None => 3.0
+    };
+
+    // @todo this is nasty... fix this.
+    let freq : f32 = match matches.opt_default("freq", "0.1") {
+        Some(s) => {
+            match s.parse() {
+                Ok(0.0) => 0.1,
+                Ok(n) => n,
+                _ => 0.1
+            }
+        },
+        None => 0.1
+    };
+
+    // @todo this is nasty... fix this.
+    let mut seed : i32 = match matches.opt_default("seed", "0") {
+        Some(s) => {
+            match s.parse() {
+                Ok(0) => thread_rng().gen_range(0, 256),
+                Ok(n) => n,
+                _ => thread_rng().gen_range(0, 256)
+            }
+        },
+        None => thread_rng().gen_range(0, 256)
+    };
 
     let stdin = io::stdin();
 
     for line in stdin.lock().lines() {
-        s += 1.0;
+        seed += 1;
 
         let mut d = 0;
 
@@ -24,7 +88,7 @@ fn main() {
                 _ => 1
             };
 
-            let (red, green, blue) = rainbow(0.1, (s + d as f32) / 3.0);
+            let (red, green, blue) = rainbow(freq, (seed + d) as f32 / spread);
 
             print!("{}", RGB(red, green, blue).paint(c.to_string()));
         }