chore: document items in the config module

Sometimes the use of an item wasn't clear without reading the code. This
should help with that.

src/command.rs

@@ -43,6 +43,7 @@ impl Default for MoveAmount {
     }
 }
 
+/// Keys that can be used to sort songs on.
 #[derive(Display, Clone, Serialize, Deserialize, Debug)]
 #[strum(serialize_all = "lowercase")]
 pub enum SortKey {

src/config.rs

@@ -15,6 +15,7 @@ use crate::serialization::{Serializer, CBOR, TOML};
 pub const CLIENT_ID: &str = "d420a117a32841c2b3474932e49fb54b";
 pub const CACHE_VERSION: u16 = 1;
 
+/// The playback state when ncspot is started.
 #[derive(Clone, Serialize, Deserialize, Debug, PartialEq, Eq)]
 pub enum PlaybackState {
     Playing,
@@ -23,6 +24,7 @@ pub enum PlaybackState {
     Default,
 }
 
+/// The focussed library tab when ncspot is started.
 #[derive(Clone, Serialize, Deserialize, Debug, Hash, strum::EnumIter)]
 #[serde(rename_all = "lowercase")]
 pub enum LibraryTab {
@@ -34,6 +36,7 @@ pub enum LibraryTab {
     Browse,
 }
 
+/// The format used to represent tracks in a list.
 #[derive(Serialize, Deserialize, Debug, Default, Clone)]
 pub struct TrackFormat {
     pub left: Option<String>,
@@ -51,6 +54,7 @@ impl TrackFormat {
     }
 }
 
+/// The format used when sending desktop notifications about playback status.
 #[derive(Serialize, Deserialize, Debug, Default, Clone)]
 pub struct NotificationFormat {
     pub title: Option<String>,
@@ -66,6 +70,7 @@ impl NotificationFormat {
     }
 }
 
+/// The configuration of ncspot.
 #[derive(Clone, Serialize, Deserialize, Debug, Default)]
 pub struct ConfigValues {
     pub command_key: Option<char>,
@@ -96,12 +101,14 @@ pub struct ConfigValues {
     pub credentials: Option<Credentials>,
 }
 
+/// Commands used to obtain user credentials automatically.
 #[derive(Serialize, Deserialize, Debug, Default, Clone)]
 pub struct Credentials {
     pub username_cmd: Option<String>,
     pub password_cmd: Option<String>,
 }
 
+/// The ncspot theme.
 #[derive(Serialize, Deserialize, Debug, Default, Clone)]
 pub struct ConfigTheme {
     pub background: Option<String>,
@@ -125,12 +132,14 @@ pub struct ConfigTheme {
     pub search_match: Option<String>,
 }
 
+/// The ordering that is used when representing a playlist.
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct SortingOrder {
     pub key: SortKey,
     pub direction: SortDirection,
 }
 
+/// The runtime state of the music queue.
 #[derive(Serialize, Default, Deserialize, Debug, Clone)]
 pub struct QueueState {
     pub current_track: Option<usize>,
@@ -139,6 +148,7 @@ pub struct QueueState {
     pub queue: Vec<Playable>,
 }
 
+/// Runtime state that should be persisted accross sessions.
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct UserState {
     pub volume: u16,
@@ -165,16 +175,22 @@ impl Default for UserState {
 }
 
 lazy_static! {
+    /// Configuration files are read/written relative to this directory.
     pub static ref BASE_PATH: RwLock<Option<PathBuf>> = RwLock::new(None);
 }
 
+/// The complete configuration (state + user configuration) of ncspot.
 pub struct Config {
+    /// The configuration file path.
     filename: PathBuf,
+    /// Configuration set by the user, read only.
     values: RwLock<ConfigValues>,
+    /// Runtime state which can't be edited by the user, read/write.
     state: RwLock<UserState>,
 }
 
 impl Config {
+    /// Generate the configuration from the user configuration file and the runtime state file.
     pub fn new(filename: PathBuf) -> Self {
         let values = load(&filename.to_string_lossy()).unwrap_or_else(|e| {
             eprintln!("could not load config: {e}");
@@ -244,11 +260,18 @@ impl Config {
     }
 }
 
+/// Parse the configuration file with name `filename` at the configuration base path.
 fn load(filename: &str) -> Result<ConfigValues, String> {
     let path = config_path(filename);
     TOML.load_or_generate_default(path, || Ok(ConfigValues::default()), false)
 }
 
+/// Returns the platform app directories for ncspot.
+///
+/// # Panics
+///
+/// This panics if the project directories could not be determined. Use `try_proj_dirs` for a
+/// non-panicking version.
 fn proj_dirs() -> AppDirs {
     try_proj_dirs().unwrap()
 }
@@ -271,6 +294,11 @@ pub fn try_proj_dirs() -> Result<AppDirs, String> {
     }
 }
 
+/// Force create the configuration directory at the default project location, removing anything that
+/// isn't a directory but has the same name. Return the path to the configuration file inside the
+/// directory.
+///
+/// This doesn't create the file, only the containing directory.
 pub fn config_path(file: &str) -> PathBuf {
     let proj_dirs = proj_dirs();
     let cfg_dir = &proj_dirs.config_dir;
@@ -285,6 +313,10 @@ pub fn config_path(file: &str) -> PathBuf {
     cfg
 }
 
+/// Create the cache directory at the default project location, preserving it if it already exists,
+/// and return the path to the cache file inside the directory.
+///
+/// This doesn't create the file, only the containing directory.
 pub fn cache_path(file: &str) -> PathBuf {
     let proj_dirs = proj_dirs();
     let cache_dir = &proj_dirs.cache_dir;