Set scaling mode from args and configs

src/config.rs

@@ -7,7 +7,7 @@ use std::path::PathBuf;
 #[derive(Debug, Deserialize, Serialize)]
 pub struct Config {
     pub background_image: String,
-    pub mode: Option<String>, // Unused now, deal with it later
+    pub mode: Option<String>,
 }
 
 impl Config {

src/settings.rs

@@ -1,4 +1,4 @@
-use anyhow::Result;
+use anyhow::{Context, Result};
 use std::path::PathBuf;
 
 use crate::{args, config, wallpaper};
@@ -12,6 +12,13 @@ pub fn resolve_wallpaper(
     args: &args::Args,
     config: Option<config::Config>,
 ) -> Result<WallpaperSettings> {
+    // Borrow the config once as `Option<&Config>`.
+    //
+    // Avoids moving `config`, allows to:
+    // - read values multiple times
+    // - decide later whether we need to write a new config
+    let cfg_ref = config.as_ref();
+
     // Resolve wallpaper image path by precedence:
     // 1. args (`--set`, `--update`): Use path from args.
     // 2. config: Use path from config.
@@ -21,10 +28,16 @@ pub fn resolve_wallpaper(
 
         // 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,
-            });
+            // Use existing config if present.
+            // Otherwise, create a minimal temporary config only for writing.
+            // Avoids moving or cloning the original config, keeps ownership simple.
+            let cfg = match cfg_ref {
+                Some(cfg) => cfg,
+                None => &config::Config {
+                    background_image: String::new(),
+                    mode: None,
+                },
+            };
 
             // Write to config.
             cfg.update_background_image(
@@ -37,21 +50,42 @@ pub fn resolve_wallpaper(
 
         // Case: No args. Fallback to config file.
         (None, None) => {
-            let cfg = config.ok_or_else(|| {
+            let cfg = cfg_ref.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()
+            cfg.background_image.clone().into()
         }
 
         // Case: Both args `--set` & `--update`. This case is already rejected during argument parsing.
         _ => unreachable!(),
     };
 
-    //let mode = wallpaper::ScalingMode::Stretch; // 
-    let mode = wallpaper::ScalingMode::Fill; // Default
+    // Resolve scaling mode by precedence:
+    // 1. CLI argument (`--mode`) if provided
+    // 2. Config file value if present
+    // 3. Default to Fill
+    let mode = if let Some(mode_arg) = &args.mode {
+        // CLI has highest priority
+        mode_arg
+            .parse::<wallpaper::ScalingMode>()
+            .with_context(|| "Invalid wallpaper mode in CLI")?
+    } else if let Some(cfg) = cfg_ref {
+        if let Some(mode_str) = &cfg.mode {
+            // Config-specified mode
+            mode_str
+                .parse::<wallpaper::ScalingMode>()
+                .with_context(|| "Invalid wallpaper mode in config")?
+        } else {
+            // Config exists, but mode not specified
+            wallpaper::ScalingMode::Fill
+        }
+    } else {
+        // No CLI and no config → default
+        wallpaper::ScalingMode::Fill
+    };
 
     Ok(WallpaperSettings { path, mode })
 }

src/wallpaper.rs

@@ -1,15 +1,26 @@
 use anyhow::{Context, Result};
 use image::{RgbaImage, imageops};
-use std::path::Path;
+use std::{path::Path, str::FromStr};
 
 /// Supported wallpaper scaling modes.
-///
-/// Others are defined so the public API does not need to change later.
 #[derive(Debug, Clone, Copy)]
 pub enum ScalingMode {
     Stretch,
     Fill,
-    // Fit,
+}
+
+impl FromStr for ScalingMode {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        // Accept human-friendly strings from CLI / config.
+        // Case-insensitive to reduce user friction.
+        match s.to_lowercase().as_str() {
+            "fill" => Ok(ScalingMode::Fill),
+            "stretch" => Ok(ScalingMode::Stretch),
+            _ => Err(anyhow::anyhow!("Invalid wallpaper mode: {s}")),
+        }
+    }
 }
 
 /// Result of preparing a wallpaper image for the screen.
@@ -116,9 +127,10 @@ pub fn prepare_wallpaper(
         .with_context(|| format!("Failed to open image: {}", image_path.display()))?
         .to_rgba8();
 
+        // Scaling mode
     let prepared = match mode {
+        ScalingMode::Fill => prepare_fill(&img, screen_width, screen_height),   // Default  
         ScalingMode::Stretch => prepare_stretch(&img, screen_width, screen_height),
-        ScalingMode::Fill => prepare_fill(&img, screen_width, screen_height),
     };
 
     Ok(prepared)