Add config file support

src/main.rs

@@ -1,25 +1,22 @@
+mod config;
+mod error;
+
 use std::env::args;
 use std::net::UdpSocket;
 
-fn get_magic_pkt(mac: &str, magic_bytes: &mut [u8; 102]) {
-    let mut mac_bytes = [0u8; 6];
-    for (i, part) in mac.split(':').enumerate() {
-        mac_bytes[i] = u8::from_str_radix(part, 16)
-            .expect(&format!("'{}' is not a valid hex between 00-ff", part));
-    }
+use crate::config::{Config, Mac};
+use crate::error::EResult;
 
-    magic_bytes[..6].fill(0xFF);
-    for i in 0..16 {
-        let start = 6 + i * 6;
-        magic_bytes[start..start + 6].copy_from_slice(&mac_bytes);
-    }
-}
+fn main() -> EResult<()> {
+    let config = Config::create()?;
 
-fn main() {
-    let mac = args()
-        .nth(1)
-        .expect("no mac given; Usage woly aa:bb:cc:dd:ee:ff");
+    let arg_1 = args().nth(1);
+    let Some(arg_1) = arg_1 else {
+        print_usage();
+        return Ok(());
+    };
 
+    let mac = config.get_mac(&arg_1)?;
     let mut magic_bytes = [0u8; 102];
     get_magic_pkt(&mac, &mut magic_bytes);
 
@@ -28,17 +25,54 @@ fn main() {
     socket
         .send_to(&magic_bytes, "255.255.255.255:9")
         .expect("couldn't send data");
-    println!("Magic packet sent to 255.255.255.255:9 for Mac {:?}", mac);
+    println!("Magic packet sent to 255.255.255.255:9 for Mac {:}", mac);
+    Ok(())
+}
+
+fn get_magic_pkt(mac: &Mac, magic_bytes: &mut [u8; 102]) {
+    magic_bytes[..6].fill(0xFF);
+    for i in 0..16 {
+        let start = 6 + i * 6;
+        magic_bytes[start..start + 6].copy_from_slice(&mac.mac_bytes);
+    }
+}
+
+fn print_usage() {
+    println!(
+        "{}",
+        r#"usage: woly ARG
+
+Options:
+    ARG     Either the mac address of the device to send the wol magic
+            packet to, or a nickname specified in woly.conf to lookup
+            the mac.
+            Eg: woly aa:bb:cc:dd:ee:ff
+            Eg: woly potato
+                where potato is configured in the woly.conf file as
+                potato=aa:bb:cc:dd:ee:ff
+
+Config file:
+    Filename   woly.conf
+    Location   $WOLY_CONFIG_DIR/woly.conf, then $XDG_CONFIG_DIR/woly.conf,
+               then $HOME/woly.conf
+    Format     one KEY=VALUE per line without spaces
+    Example    potato=aa:bb:cc:dd:ee:ff
+               idly=12:34:23:e2:3d:ff
+"#
+    );
 }
 
 #[cfg(test)]
 mod tests {
-    use crate::get_magic_pkt;
+    use crate::{config::Mac, get_magic_pkt};
 
     #[test]
     fn test_magic_bytes_for_mac() {
         let mut magic_bytes = [0u8; 102];
-        get_magic_pkt("32:1a:ff:3e:10:ef", &mut magic_bytes);
+        let mac = Mac::create("32:1a:ff:3e:10:ef").expect("Test data is curated to be valid");
+        get_magic_pkt(&mac, &mut magic_bytes);
+
+        #[rustfmt::skip]
         let expected = [
             255, 255, 255, 255, 255, 255,
              50,  26, 255,  62,  16, 239,
@@ -59,6 +93,9 @@ mod tests {
              50,  26, 255,  62,  16, 239,
         ];
 
-        assert_eq!(magic_bytes, expected, "Magic bytes are not created correctly");
+        assert_eq!(
+            magic_bytes, expected,
+            "Magic bytes are not created correctly"
+        );
     }
 }