Refactor: Move wallpaper settings to new module

- Args parsing
- Config loading
- Improve readability of `main()`

src/main.rs

@@ -12,6 +12,7 @@ use x11rb::{
 };
 mod args;
 mod config;
+mod settings;
 mod wallpaper;
 
 fn main() -> Result<()> {
@@ -21,43 +22,8 @@ fn main() -> Result<()> {
     // Load config file if it exists. Can be missing.
     let config = config::Config::load().ok();
 
-    // Resolve wallpaper image path by precedence:
-    // 1. args (`--set`, `--update`): Use path from args.
-    // 2. config: Use path from config.
-    let image_path = match (&args.set, &args.update) {
-        // Case: arg `--set`: One-shot wallpaper change. Not persistent.
-        (Some(path), None) => path.clone(),
-
-        // Case: arg `--update`. Persist wallpaper path to config (create if missing), then apply it.
-        (None, Some(path)) => {
-            let cfg = config.unwrap_or_else(|| config::Config {
-                background_image: String::new(),
-                mode: None,
-            });
-
-            // Write to config.
-            cfg.update_background_image(
-                path.to_str()
-                    // Unsupported path format.
-                    .ok_or_else(|| anyhow::anyhow!("Non-UTF8 path"))?,
-            )?;
-            path.clone()
-        }
-
-        // Case: No args. Fallback to config file.
-        (None, None) => {
-            let cfg = config.ok_or_else(|| {
-                // No CLI args and no valid config.
-                anyhow::anyhow!("No or invalid image path specified in config or args.")
-            })?;
-
-            // Successfully loaded.
-            cfg.background_image.into()
-        }
-
-        // Case: Both args `--set` & `--update`. This case is already rejected during argument parsing.
-        _ => unreachable!(),
-    };
+    // Resolve wallpaper settings
+    let wallpaper_settings = settings::resolve_wallpaper(&args, config)?;
 
     // Connect to the running graphical session, the X11 server.
     let (conn, screen_num) = RustConnection::connect(None)?;
@@ -103,8 +69,8 @@ fn main() -> Result<()> {
 
     // Prepare wallpaper image (scaling + pixel format conversion)
     let prepared = wallpaper::prepare_wallpaper(
-        &image_path,
-        wallpaper::ScalingMode::Stretch, // default for now
+        &wallpaper_settings.path,
+        wallpaper_settings.mode,
         width.into(),
         height.into(),
     )?;

src/settings.rs

@@ -0,0 +1,56 @@
+use anyhow::Result;
+use std::path::PathBuf;
+
+use crate::{args, config};
+
+pub struct WallpaperSettings {
+    pub path: PathBuf,
+    pub mode: crate::wallpaper::ScalingMode,
+}
+
+pub fn resolve_wallpaper(
+    args: &args::Args,
+    config: Option<config::Config>,
+) -> Result<WallpaperSettings> {
+    // Resolve wallpaper image path by precedence:
+    // 1. args (`--set`, `--update`): Use path from args.
+    // 2. config: Use path from config.
+    let path = match (&args.set, &args.update) {
+        // Case: arg `--set`: One-shot wallpaper change. Not persistent.
+        (Some(path), None) => path.clone(),
+
+        // Case: arg `--update`. Persist wallpaper path to config (create if missing), then apply it.
+        (None, Some(path)) => {
+            let cfg = config.unwrap_or_else(|| config::Config {
+                background_image: String::new(),
+                mode: None,
+            });
+
+            // Write to config.
+            cfg.update_background_image(
+                path.to_str()
+                    // Unsupported path format.
+                    .ok_or_else(|| anyhow::anyhow!("Non-UTF8 path"))?,
+            )?;
+            path.clone()
+        }
+
+        // Case: No args. Fallback to config file.
+        (None, None) => {
+            let cfg = config.ok_or_else(|| {
+                // No CLI args and no valid config.
+                anyhow::anyhow!("No or invalid image path specified in config or args.")
+            })?;
+
+            // Successfully loaded.
+            cfg.background_image.into()
+        }
+
+        // Case: Both args `--set` & `--update`. This case is already rejected during argument parsing.
+        _ => unreachable!(),
+    };
+
+    let mode = crate::wallpaper::ScalingMode::Stretch; // Default for now. Fix later
+
+    Ok(WallpaperSettings { path, mode })
+}