Simplify theme overrides

Theme overrides are now loaded the same way key overrides are loaded.
The config file, `theme.ron`, does not have to contain a complete theme
anymore. Instead, it is possible to specify only the values that are
supposed to override their corresponding default values.

Author: cruessler

CHANGELOG.md

@@ -29,6 +29,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Breaking Change
 * `focus_XYZ` key bindings are merged into the `move_XYZ` set, so only one way to bind arrow-like keys from now on ([#1539](https://github.com/extrawurst/gitui/issues/1539))
+* The format of `theme.ron` has changed
 
 ### Added
 * allow reset (soft,mixed,hard) from commit log ([#1500](https://github.com/extrawurst/gitui/issues/1500))
@@ -41,6 +42,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * allow `copy` file path on revision files and status tree [[@yanganto]](https://github.com/yanganto)  ([#1516](https://github.com/extrawurst/gitui/pull/1516))
 * print message of where log will be written if `-l` is set ([#1472](https://github.com/extrawurst/gitui/pull/1472))
 * show remote branches in log [[@cruessler](https://github.com/cruessler)] ([#1501](https://github.com/extrawurst/gitui/issues/1501))
+* simplify theme overrides [[@cruessler](https://github.com/cruessler)] ([#1367](https://github.com/extrawurst/gitui/issues/1367))
 
 ### Fixes
 * fixed side effect of crossterm 0.26 on windows that caused double input of all keys [[@pm100]](https://github/pm100) ([#1686](https://github.com/extrawurst/gitui/pull/1686))

src/main.rs

@@ -138,9 +138,7 @@ fn main() -> Result<()> {
 	let key_config = KeyConfig::init()
 		.map_err(|e| eprintln!("KeyConfig loading error: {e}"))
 		.unwrap_or_default();
-	let theme = Theme::init(&cliargs.theme)
-		.map_err(|e| eprintln!("Theme loading error: {e}"))
-		.unwrap_or_default();
+	let theme = Theme::init(&cliargs.theme);
 
 	setup_terminal()?;
 	defer! {

src/ui/style.rs

@@ -1,21 +1,13 @@
-use anyhow::Result;
 use asyncgit::{DiffLineType, StatusItemType};
 use ratatui::style::{Color, Modifier, Style};
-use ron::{
-	de::from_bytes,
-	ser::{to_string_pretty, PrettyConfig},
-};
 use serde::{Deserialize, Serialize};
-use std::{
-	fs::{self, File},
-	io::{Read, Write},
-	path::PathBuf,
-	rc::Rc,
-};
+use std::{fs::File, path::PathBuf, rc::Rc};
+use struct_patch::Patch;
 
 pub type SharedTheme = Rc<Theme>;
 
-#[derive(Serialize, Deserialize, Debug, Copy, Clone)]
+#[derive(Serialize, Deserialize, Debug, Copy, Clone, Patch)]
+#[patch_derive(Deserialize)]
 pub struct Theme {
 	selected_tab: Color,
 	command_fg: Color,
@@ -261,44 +253,16 @@ impl Theme {
 			.bg(self.push_gauge_bg)
 	}
 
-	// This will only be called when theme.ron doesn't already exists
-	fn save(&self, theme_file: &PathBuf) -> Result<()> {
-		let mut file = File::create(theme_file)?;
-		let data = to_string_pretty(self, PrettyConfig::default())?;
-		file.write_all(data.as_bytes())?;
-		Ok(())
-	}
-
-	fn read_file(theme_file: PathBuf) -> Result<Self> {
-		let mut f = File::open(theme_file)?;
-		let mut buffer = Vec::new();
-		f.read_to_end(&mut buffer)?;
-		Ok(from_bytes(&buffer)?)
-	}
+	pub fn init(theme_path: &PathBuf) -> Self {
+		let mut theme = Self::default();
 
-	pub fn init(file: &PathBuf) -> Result<Self> {
-		if file.exists() {
-			match Self::read_file(file.clone()) {
-				Err(e) => {
-					let config_path = file.clone();
-					let config_path_old =
-						format!("{}.old", file.to_string_lossy());
-					fs::rename(
-						config_path.clone(),
-						config_path_old.clone(),
-					)?;
-
-					Self::default().save(file)?;
-
-					Err(anyhow::anyhow!("{}\n Old file was renamed to {:?}.\n Defaults loaded and saved as {:?}",
-                        e,config_path_old,config_path.to_string_lossy()))
-				}
-				Ok(res) => Ok(res),
+		if let Ok(file) = File::open(theme_path) {
+			if let Ok(patch) = ron::de::from_reader(file) {
+				theme.apply(patch);
 			}
-		} else {
-			Self::default().save(file)?;
-			Ok(Self::default())
 		}
+
+		theme
 	}
 }
 
@@ -329,3 +293,31 @@ impl Default for Theme {
 		}
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use pretty_assertions::assert_eq;
+	use std::io::Write;
+	use tempfile::NamedTempFile;
+
+	#[test]
+	fn test_smoke() {
+		let mut file = NamedTempFile::new().unwrap();
+
+		writeln!(
+			file,
+			r"
+(
+	selection_bg: Some(White),
+)
+"
+		)
+		.unwrap();
+
+		let theme = Theme::init(&file.path().to_path_buf());
+
+		assert_eq!(theme.selection_fg, Theme::default().selection_fg);
+		assert_eq!(theme.selection_bg, Color::White);
+	}
+}