Introduce some logging

Currently, only flag invalid config file and missing icon.

Remove the catch-all fallback for a missing icon in the default config.

This should make it easy for the user to troubleshoot missing icons.

Since the config is live-reloaded, it should all be a pretty smooth
experience.

Cargo.toml

@@ -11,3 +11,5 @@ i3ipc = "0.10.1"
 dirs = "2.0.2"
 serde_yaml = "0.8.9"
 structopt = "0.3.1"
+pretty_env_logger = "0.3.1"
+log = "0.4.8"

TODO.md

@@ -1,3 +1,4 @@
-Proper error handling
-  Also, log things properly with a logger.
+More logging
 Decide if I want to pursue something more robust than the app name using the app id
+README
+publish crate

src/config.rs

@@ -31,9 +31,13 @@ fn get_icon_mappings_from_config(config: &PathBuf) -> Result<Vec<(String, String
     let mut config_file = File::open(config)?;
     let mut content = String::new();
     config_file.read_to_string(&mut content)?;
-    // TODO: log that error
-    serde_yaml::from_str(&content)
-        .map_err(|_| Error::new(ErrorKind::Other, "Invalid configuration file"))
+    serde_yaml::from_str(&content).map_err(|_| {
+        log::error!(
+            "Error parsing configuration file.\nInvalid syntax in {:#?}.",
+            config
+        );
+        Error::new(ErrorKind::Other, "Invalid configuration file")
+    })
 }
 
 fn get_icon_mappings_from_default_config() -> Vec<(String, String)> {

src/main.rs

@@ -80,8 +80,9 @@ fn pretty_window(window: &String, icon_mappings: &[(String, String)]) -> String
             return icon.clone();
         }
     }
-    println!("Couldn't identify window: {}", window);
-    "".into()
+    log::error!("Couldn't identify window: {}", window);
+    log::info!("Make sure to add an icon for this file in your config file!");
+    " ".into()
 }
 
 fn pretty_windows(windows: &Vec<Option<String>>, icon_mappings: &[(String, String)]) -> String {
@@ -96,6 +97,7 @@ fn pretty_windows(windows: &Vec<Option<String>>, icon_mappings: &[(String, Strin
 }
 
 fn main() {
+    pretty_env_logger::init();
     let _ = Options::from_args();
     let mut wm = I3Connection::connect().unwrap();
     let mut listener = I3EventListener::connect().unwrap();