refactor: pass globally mutable config reference

Before, copies of the configuration were passed over. This change also
causes configuration reloads to affect the entire application and is
easier to maintain but introduces some RwLock overhead.

src/config.rs

@@ -1,14 +1,15 @@
 use std::collections::HashMap;
-use std::fs;
 use std::path::{Path, PathBuf};
-use std::sync::RwLock;
+use std::sync::{RwLock, RwLockReadGuard};
+use std::{fs, process};
 
+use cursive::theme::Theme;
 use platform_dirs::AppDirs;
 
 pub const CLIENT_ID: &str = "d420a117a32841c2b3474932e49fb54b";
 
 #[derive(Clone, Serialize, Deserialize, Debug, Default)]
-pub struct Config {
+pub struct ConfigValues {
     pub default_keybindings: Option<bool>,
     pub keybindings: Option<HashMap<String, String>>,
     pub theme: Option<ConfigTheme>,
@@ -57,9 +58,40 @@ lazy_static! {
     pub static ref BASE_PATH: RwLock<Option<PathBuf>> = RwLock::new(None);
 }
 
-pub fn load() -> Result<Config, String> {
+pub struct Config {
+    values: RwLock<ConfigValues>,
+}
+
+impl Config {
+    pub fn new() -> Self {
+        let values = load().unwrap_or_else(|e| {
+            eprintln!("could not load config: {}", e);
+            process::exit(1);
+        });
+
+        Self {
+            values: RwLock::new(values),
+        }
+    }
+
+    pub fn values(&self) -> RwLockReadGuard<ConfigValues> {
+        self.values.read().expect("can't readlock config values")
+    }
+
+    pub fn build_theme(&self) -> Theme {
+        let theme = &self.values().theme;
+        crate::theme::load(theme)
+    }
+
+    pub fn reload(&self) {
+        let cfg = load().expect("could not reload config");
+        *self.values.write().expect("can't writelock config values") = cfg
+    }
+}
+
+fn load() -> Result<ConfigValues, String> {
     let path = config_path("config.toml");
-    load_or_generate_default(path, |_| Ok(Config::default()), false)
+    load_or_generate_default(path, |_| Ok(ConfigValues::default()), false)
 }
 
 fn proj_dirs() -> AppDirs {