generate function

Cargo.toml

@@ -11,3 +11,4 @@ docopt = "1.1.0"
 serde = "1.0.91"
 log = "0.4.6"
 pretty_env_logger = "0.3.0"
+rand = "0.6.5"

src/main.rs

@@ -1,6 +1,10 @@
 use docopt::Docopt;
+use log::debug;
+use rand::rngs::OsRng;
+use rand::seq::IteratorRandom;
+use rand::seq::SliceRandom;
 use serde::Deserialize;
-use log::{debug};
+use std::iter::FromIterator;
 
 static USAGE: &'static str = "
 foil
@@ -28,6 +32,45 @@ struct Args {
     arg_spec: Option<String>,
 }
 
+fn generate(spec: &str) {
+    let (len, rest) = {
+        let mut separated = spec.splitn(2, ",");
+        let len = separated.next().unwrap();
+        let rest = separated.next().unwrap();
+        (len, rest)
+    };
+    let mut rnd = OsRng::new().unwrap();
+
+    let mut password_vec: Vec<char> = rest
+        .chars()
+        .cycle()
+        .map(|c| match c {
+            'a' => "abcdefghijklmnopqrstuvwxyz"
+                .chars()
+                .choose(&mut rnd)
+                .expect("Could not get random element"),
+            'A' => "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                .chars()
+                .choose(&mut rnd)
+                .expect("Could not get random element"),
+            '1' => "1234567890"
+                .chars()
+                .choose(&mut rnd)
+                .expect("Could not get random element"),
+            '.' => ".,/?-=#%^"
+                .chars()
+                .choose(&mut rnd)
+                .expect("Could not get random element"),
+            _ => panic!("Unknown character spec: {}", c),
+        })
+        .take(len.parse().unwrap())
+        .collect();
+
+    password_vec.shuffle(&mut rnd);
+    let shuffled: String = String::from_iter(password_vec.into_iter());
+    println!("{}", shuffled);
+}
+
 fn main() {
     pretty_env_logger::init();
     let args: Args = Docopt::new(USAGE)
@@ -35,4 +78,8 @@ fn main() {
         .unwrap_or_else(|e| e.exit());
     debug!("{:?}", args);
 
+    if args.cmd_generate {
+        generate(&args.arg_spec.unwrap());
+        return;
+    }
 }