add command line option to specify configuration file

Cargo.toml

@@ -19,6 +19,7 @@ tokio = { version = "1.29.1", features = ["full"] }
 async-std = "1.7.0"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
+clap = { version = "4.0.0", features = ["derive"] }
 
 [target.'cfg(target_os = "linux")'.dependencies]
 pulsectl-rs = "0.3.2"

src/config.rs

@@ -1,3 +1,5 @@
+use std::path::PathBuf;
+
 #[derive(serde::Deserialize, serde::Serialize)]
 #[serde(rename_all = "camelCase")]
 pub struct Config {
@@ -15,7 +17,7 @@ pub struct Device {
     pub usage_page: u16,
 }
 
-pub fn get_config() -> Config {
+pub fn get_config(maybe_path: Option<PathBuf>) -> Config {
     let default_config = Config {
         device: Device {
             vendor_id: 0,
@@ -27,17 +29,21 @@ pub fn get_config() -> Config {
         reconnect_delay: 5000,
     };
 
-    if let Ok(file) = std::fs::read_to_string("./qmk-hid-host.json") {
+    let path = maybe_path.unwrap_or("./qmk-hid-host.json".into());
+
+    if let Ok(file) = std::fs::read_to_string(&path) {
         if let Ok(file_config) = serde_json::from_str::<Config>(&file) {
-            tracing::info!("Read config from file");
+            tracing::info!("Read config from file {}", path.to_string_lossy());
             return file_config;
+        } else {
+            tracing::error!("Error while parsing JSON from file config file");
         }
-
+    } else {
         tracing::error!("Error while reading config from file");
     }
 
     let file_content = serde_json::to_string_pretty(&default_config).unwrap();
-    std::fs::write("./qmk-hid-host.json", &file_content).unwrap();
+    std::fs::write(&path, &file_content).unwrap();
     tracing::info!("New config file created");
 
     return default_config;

src/main.rs

@@ -8,14 +8,24 @@ mod data_type;
 mod keyboard;
 mod providers;
 
+use std::path::PathBuf;
+
 use std::thread;
 use tokio::sync::{broadcast, mpsc};
 use config::get_config;
 use keyboard::Keyboard;
+use clap::Parser;
+
+#[derive(Parser, Debug)]
+struct Args {
+    /// Path to the configuration file
+    #[arg(short, long)]
+    config: Option<PathBuf>,
+}
+
 #[cfg(not(target_os = "macos"))]
 use providers::{_base::Provider, layout::LayoutProvider, time::TimeProvider, media::MediaProvider, volume::VolumeProvider};
 
-
 #[cfg(target_os = "macos")]
 use {
     providers::{_base::Provider, layout::LayoutProvider, time::TimeProvider, volume::VolumeProvider},
@@ -76,7 +86,8 @@ fn main() {
         .from_env_lossy();
     let tracing_subscriber = tracing_subscriber::fmt().with_env_filter(env_filter).finish();
     let _ = tracing::subscriber::set_global_default(tracing_subscriber);
-    let config = get_config();
+    let args = Args::parse();
+    let config = get_config(args.config);
 
     let keyboard = Keyboard::new(config.device, config.reconnect_delay);
     let (connected_sender, data_sender) = keyboard.connect();