updated logging to be configurable from the CLI.

src/main.rs

@@ -1,5 +1,6 @@
 //! This file contains all driver code for the program.
 use core::time;
+use std::ffi::OsString;
 use std::sync::Arc;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::thread;
@@ -54,15 +55,17 @@ fn default_loop(pf: &PlayerFinder, cfg: &Config, data: &mut Data, r: &Vec<String
 
 /// Main function. Mostly concerned with initialisation.
 fn main() {
+    // Parse cli flags
+    let cli = Cli::parse();
+
     // logging initialisation
-    std::env::set_var("RUST_LOG", "error");
+    std::env::set_var::<&str, OsString>("RUST_LOG", cli.log_level.into());
     if let Err(e) = env_logger::init() {
       error!("{e}");
       return
     }
 
-    // Cli flags, Config, Data, and PlayerFinder initialisation
-    let cli = Cli::parse();
+    // Config, Data, and PlayerFinder initialisation
     match confy::load::<Config>("polybar-now-playing", cli.config_file.as_str()) {
       Ok(cfg) => {
         let mut data: Data = Data::default();

src/structs/cli.rs

@@ -1,6 +1,31 @@
 //! This file contains structs and functionality that are relevant to the Command Line Interface part of the program.
+use std::ffi::OsString;
+
 use clap::Parser;
 
+/// Custom enum to define the desired loglevel during run-time.
+#[derive(clap::ValueEnum, Clone)]
+pub enum LogLevel {
+  TRACE,
+  DEBUG,
+  INFO,
+  WARN,
+  ERROR,
+}
+
+/// Implement Into<OsString> for LogLevel, so it can actually be used by env_logger.
+impl Into<OsString> for LogLevel {
+  fn into(self) -> OsString {
+    match self {
+      LogLevel::TRACE => "trace".into(),
+      LogLevel::DEBUG => "debug".into(),
+      LogLevel::INFO => "info".into(),
+      LogLevel::WARN => "warn".into(),
+      LogLevel::ERROR => "error".into(),
+    }
+  }
+}
+
 /// Program which finds the active mpris player and displays metadata about the playing piece of media.
 /// 
 /// This program is intended to be used with polybar.
@@ -15,4 +40,9 @@ pub struct Cli {
   /// This mode prints all active players to stdout, to allow one to find the appropriate player names to use in the config files.
   #[arg(short = 'l', long = "list")]
   pub list: bool,
+  /// Set log level.
+  /// 
+  /// Sets the log level to print to stdout.
+  #[arg(long = "log", value_enum, default_value = "error")]
+  pub log_level: LogLevel
 }