add shell typography and wallpaper support

shell/ferese-shell/src/config.rs

@@ -0,0 +1,124 @@
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+
+use serde::Deserialize;
+
+const DEFAULT_BACKGROUND: [u8; 3] = [11, 15, 20];
+
+#[derive(Clone, Debug, Default)]
+pub(crate) struct ShellConfig {
+    pub(crate) font_family: Option<String>,
+    pub(crate) wallpaper: WallpaperConfig,
+}
+
+#[derive(Clone, Debug, Default, Deserialize)]
+pub(crate) struct WallpaperConfig {
+    pub(crate) path: Option<PathBuf>,
+    #[serde(default)]
+    pub(crate) mode: WallpaperMode,
+}
+
+#[derive(Clone, Copy, Debug, Default, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub(crate) enum WallpaperMode {
+    #[default]
+    Fill,
+    Fit,
+}
+
+#[derive(Debug, Default, Deserialize)]
+struct FereseConfig {
+    #[serde(default)]
+    theme: ThemeConfig,
+}
+
+#[derive(Debug, Default, Deserialize)]
+struct ThemeConfig {
+    #[serde(default)]
+    typography: TypographyConfig,
+    #[serde(default)]
+    background: WallpaperConfig,
+}
+
+#[derive(Debug, Default, Deserialize)]
+struct TypographyConfig {
+    font_family: Option<String>,
+}
+
+pub(crate) fn load() -> ShellConfig {
+    let Some(path) = config_path() else {
+        return ShellConfig::default();
+    };
+    let Ok(source) = fs::read_to_string(&path) else {
+        return ShellConfig::default();
+    };
+
+    match toml::from_str::<FereseConfig>(&source) {
+        Ok(config) => ShellConfig {
+            font_family: config.theme.typography.font_family,
+            wallpaper: config.theme.background,
+        },
+        Err(error) => {
+            eprintln!("ferese-shell: failed to read {}: {error}", path.display());
+            ShellConfig::default()
+        }
+    }
+}
+
+pub(crate) const fn default_background() -> [u8; 3] {
+    DEFAULT_BACKGROUND
+}
+
+fn config_path() -> Option<PathBuf> {
+    if let Some(directory) = env::var_os("XDG_CONFIG_HOME").filter(|value| !value.is_empty()) {
+        return Some(PathBuf::from(directory).join("ferese/config.toml"));
+    }
+
+    env::var_os("HOME")
+        .filter(|value| !value.is_empty())
+        .map(PathBuf::from)
+        .map(|home| home.join(".config/ferese/config.toml"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_theme_without_rejecting_compositor_sections() {
+        let config: FereseConfig = toml::from_str(
+            r#"
+                [layout]
+                mode = "scrolling"
+
+                [theme.typography]
+                font_family = "JetBrainsMono Nerd Font"
+
+                [theme.background]
+                path = "/tmp/wallpaper.png"
+                mode = "fit"
+            "#,
+        )
+        .unwrap();
+
+        assert_eq!(
+            config.theme.typography.font_family.as_deref(),
+            Some("JetBrainsMono Nerd Font")
+        );
+        assert_eq!(
+            config.theme.background.path,
+            Some(PathBuf::from("/tmp/wallpaper.png"))
+        );
+        assert_eq!(config.theme.background.mode, WallpaperMode::Fit);
+    }
+
+    #[test]
+    fn defaults_to_the_ferese_visual_profile() {
+        let config: FereseConfig = toml::from_str("").unwrap();
+
+        assert_eq!(config.theme.typography.font_family, None);
+        assert_eq!(config.theme.background.path, None);
+        assert_eq!(config.theme.background.mode, WallpaperMode::Fill);
+    }
+}