Make the default macOS theme depend on Dark Mode

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Features
 
+- Make the default macOS theme depend on Dark Mode. See #2197, #1746 (@Enselic)
+
 ## Bugfixes
 
 ## Other

src/assets.rs

@@ -69,10 +69,57 @@ impl HighlightingAssets {
         }
     }
 
+    /// The default theme.
+    ///
+    /// ### Windows and Linux
+    ///
+    /// Windows and most Linux distributions has a dark terminal theme by
+    /// default. On these platforms, this function always returns a theme that
+    /// looks good on a dark background.
+    ///
+    /// ### macOS
+    ///
+    /// On macOS the default terminal background is light, but it is common that
+    /// Dark Mode is active, which makes the terminal background dark. On this
+    /// platform, the default theme depends on
+    /// ```bash
+    /// defaults read -globalDomain AppleInterfaceStyle
+    /// ````
+    /// To avoid the overhead of the check on macOS, simply specify a theme
+    /// explicitly via `--theme`, `BAT_THEME`, or `~/.config/bat`.
+    ///
+    /// See <https://github.com/sharkdp/bat/issues/1746> and
+    /// <https://github.com/sharkdp/bat/issues/1928> for more context.
     pub fn default_theme() -> &'static str {
+        #[cfg(not(target_os = "macos"))]
+        {
+            Self::default_dark_theme()
+        }
+        #[cfg(target_os = "macos")]
+        {
+            if macos_dark_mode_active() {
+                Self::default_dark_theme()
+            } else {
+                Self::default_light_theme()
+            }
+        }
+    }
+
+    /**
+     * The default theme that looks good on a dark background.
+     */
+    fn default_dark_theme() -> &'static str {
         "Monokai Extended"
     }
 
+    /**
+     * The default theme that looks good on a light background.
+     */
+    #[cfg(target_os = "macos")]
+    fn default_light_theme() -> &'static str {
+        "Monokai Extended Light"
+    }
+
     pub fn from_cache(cache_path: &Path) -> Result<Self> {
         Ok(HighlightingAssets::new(
             SerializedSyntaxSet::FromFile(cache_path.join("syntaxes.bin")),
@@ -352,6 +399,16 @@ fn asset_from_cache<T: serde::de::DeserializeOwned>(
         .map_err(|_| format!("Could not parse cached {}", description).into())
 }
 
+#[cfg(target_os = "macos")]
+fn macos_dark_mode_active() -> bool {
+    let mut defaults_cmd = std::process::Command::new("defaults");
+    defaults_cmd.args(&["read", "-globalDomain", "AppleInterfaceStyle"]);
+    match defaults_cmd.output() {
+        Ok(output) => output.stdout == b"Dark\n",
+        Err(_) => true,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

tests/integration_tests.rs

@@ -1427,6 +1427,8 @@ fn ansi_passthrough_emit() {
 fn ignored_suffix_arg() {
     bat()
         .arg("-f")
+        .arg("--theme")
+        .arg("Monokai Extended")
         .arg("-p")
         .arg("test.json~")
         .assert()
@@ -1436,6 +1438,8 @@ fn ignored_suffix_arg() {
 
     bat()
         .arg("-f")
+        .arg("--theme")
+        .arg("Monokai Extended")
         .arg("-p")
         .arg("--ignored-suffix=.suffix")
         .arg("test.json.suffix")
@@ -1446,6 +1450,8 @@ fn ignored_suffix_arg() {
 
     bat()
         .arg("-f")
+        .arg("--theme")
+        .arg("Monokai Extended")
         .arg("-p")
         .arg("test.json.suffix")
         .assert()
@@ -1463,6 +1469,8 @@ fn highlighting_is_skipped_on_long_lines() {
 
     bat()
         .arg("-f")
+        .arg("--theme")
+        .arg("Monokai Extended")
         .arg("-p")
         .arg("longline.json")
         .assert()
@@ -1482,6 +1490,8 @@ fn all_global_git_config_locations_syntax_mapping_work() {
     bat()
         .env("XDG_CONFIG_HOME", fake_home.join(".config").as_os_str())
         .arg("-f")
+        .arg("--theme")
+        .arg("Monokai Extended")
         .arg("-p")
         .arg("git/.config/git/config")
         .assert()
@@ -1492,6 +1502,8 @@ fn all_global_git_config_locations_syntax_mapping_work() {
     bat()
         .env("HOME", fake_home.as_os_str())
         .arg("-f")
+        .arg("--theme")
+        .arg("Monokai Extended")
         .arg("-p")
         .arg("git/.config/git/config")
         .assert()
@@ -1502,6 +1514,8 @@ fn all_global_git_config_locations_syntax_mapping_work() {
     bat()
         .env("HOME", fake_home.as_os_str())
         .arg("-f")
+        .arg("--theme")
+        .arg("Monokai Extended")
         .arg("-p")
         .arg("git/.gitconfig")
         .assert()