feat: support `themes` directory (#1577)

* feat: add serde struct for theme file

* feat: update client to load the theme palette

* feat: merge themes in the setup phase

* chore: delete debug message in test

* feat: add theme_dir options

* fix: boxing large enum variant

8 files changed, 148 insertions, 8 deletions

diff --git a/zellij-utils/src/cli.rs b/zellij-utils/src/cli.rs
index c8a3ba1d0..a947f9434 100644
--- a/zellij-utils/src/cli.rs
+++ b/zellij-utils/src/cli.rs
@@ -91,7 +91,7 @@ pub enum Sessions {
 
         /// Change the behaviour of zellij
         #[clap(subcommand, name = "options")]
-        options: Option<SessionCommand>,
+        options: Option<Box<SessionCommand>>,
     },
 
     /// Kill the specific session
diff --git a/zellij-utils/src/input/config.rs b/zellij-utils/src/input/config.rs
index 4b9f4100b..6d3946369 100644
--- a/zellij-utils/src/input/config.rs
+++ b/zellij-utils/src/input/config.rs
@@ -11,7 +11,7 @@ use std::convert::{TryFrom, TryInto};
 use super::keybinds::{Keybinds, KeybindsFromYaml};
 use super::options::Options;
 use super::plugins::{PluginsConfig, PluginsConfigError, PluginsConfigFromYaml};
-use super::theme::{ThemesFromYaml, UiConfigFromYaml};
+use super::theme::{ThemesFromYamlIntermediate, UiConfigFromYaml};
 use crate::cli::{CliArgs, Command};
 use crate::envs::EnvironmentVariablesFromYaml;
 use crate::setup;
@@ -26,7 +26,7 @@ pub struct ConfigFromYaml {
     #[serde(flatten)]
     pub options: Option<Options>,
     pub keybinds: Option<KeybindsFromYaml>,
-    pub themes: Option<ThemesFromYaml>,
+    pub themes: Option<ThemesFromYamlIntermediate>,
     #[serde(flatten)]
     pub env: Option<EnvironmentVariablesFromYaml>,
     #[serde(default)]
@@ -39,7 +39,7 @@ pub struct ConfigFromYaml {
 pub struct Config {
     pub keybinds: Keybinds,
     pub options: Options,
-    pub themes: Option<ThemesFromYaml>,
+    pub themes: Option<ThemesFromYamlIntermediate>,
     pub plugins: PluginsConfig,
     pub ui: Option<UiConfigFromYaml>,
     pub env: EnvironmentVariablesFromYaml,
diff --git a/zellij-utils/src/input/options.rs b/zellij-utils/src/input/options.rs
index 8af9c8a4d..460712efd 100644
--- a/zellij-utils/src/input/options.rs
+++ b/zellij-utils/src/input/options.rs
@@ -59,6 +59,10 @@ pub struct Options {
     /// subdirectory of config dir
     #[clap(long, value_parser)]
     pub layout_dir: Option<PathBuf>,
+    /// Set the theme_dir, defaults to
+    /// subdirectory of config dir
+    #[clap(long, value_parser)]
+    pub theme_dir: Option<PathBuf>,
     #[clap(long, value_parser)]
     #[serde(default)]
     /// Set the handling of mouse events (true or false)
@@ -139,6 +143,7 @@ impl Options {
         let default_shell = other.default_shell.or_else(|| self.default_shell.clone());
         let default_layout = other.default_layout.or_else(|| self.default_layout.clone());
         let layout_dir = other.layout_dir.or_else(|| self.layout_dir.clone());
+        let theme_dir = other.theme_dir.or_else(|| self.theme_dir.clone());
         let theme = other.theme.or_else(|| self.theme.clone());
         let on_force_close = other.on_force_close.or(self.on_force_close);
         let scroll_buffer_size = other.scroll_buffer_size.or(self.scroll_buffer_size);
@@ -156,6 +161,7 @@ impl Options {
             default_shell,
             default_layout,
             layout_dir,
+            theme_dir,
             mouse_mode,
             pane_frames,
             mirror_session,
@@ -192,6 +198,7 @@ impl Options {
         let default_shell = other.default_shell.or_else(|| self.default_shell.clone());
         let default_layout = other.default_layout.or_else(|| self.default_layout.clone());
         let layout_dir = other.layout_dir.or_else(|| self.layout_dir.clone());
+        let theme_dir = other.theme_dir.or_else(|| self.theme_dir.clone());
         let theme = other.theme.or_else(|| self.theme.clone());
         let on_force_close = other.on_force_close.or(self.on_force_close);
         let scroll_buffer_size = other.scroll_buffer_size.or(self.scroll_buffer_size);
@@ -209,6 +216,7 @@ impl Options {
             default_shell,
             default_layout,
             layout_dir,
+            theme_dir,
             mouse_mode,
             pane_frames,
             mirror_session,
@@ -262,6 +270,7 @@ impl From<CliOptions> for Options {
             default_shell: opts.default_shell,
             default_layout: opts.default_layout,
             layout_dir: opts.layout_dir,
+            theme_dir: opts.theme_dir,
             mouse_mode: opts.mouse_mode,
             pane_frames: opts.pane_frames,
             mirror_session: opts.mirror_session,
diff --git a/zellij-utils/src/input/theme.rs b/zellij-utils/src/input/theme.rs
index fc8329a7e..b148e0d43 100644
--- a/zellij-utils/src/input/theme.rs
+++ b/zellij-utils/src/input/theme.rs
@@ -2,15 +2,26 @@ use serde::{
     de::{Error, Visitor},
     Deserialize, Deserializer, Serialize, Serializer,
 };
+
+use std::fs::File;
+use std::io::Read;
+use std::path::Path;
 use std::{collections::HashMap, fmt};
 
-use super::options::Options;
+use super::{config::ConfigError, options::Options};
 use crate::data::{Palette, PaletteColor};
 use crate::shared::detect_theme_hue;
 
 /// Intermediate deserialization of themes
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
-pub struct ThemesFromYaml(HashMap<String, Theme>);
+pub struct ThemesFromYamlIntermediate(HashMap<String, Theme>);
+
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct ThemesFromYaml {
+    pub themes: ThemesFromYamlIntermediate,
+}
+
+type ThemesFromYamlResult = Result<ThemesFromYaml, ConfigError>;
 
 #[derive(Debug, Default, Clone, Copy, PartialEq, Deserialize, Serialize)]
 pub struct UiConfigFromYaml {
@@ -23,7 +34,12 @@ pub struct FrameConfigFromYaml {
 }
 
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
-struct Theme {
+struct ThemeFromYaml {
+    palette: PaletteFromYaml,
+}
+
+#[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
+pub struct Theme {
     #[serde(flatten)]
     palette: PaletteFromYaml,
 }
@@ -125,6 +141,30 @@ impl Default for PaletteColorFromYaml {
 }
 
 impl ThemesFromYaml {
+    pub fn from_path(theme_path: &Path) -> ThemesFromYamlResult {
+        let mut theme_file = File::open(&theme_path)
+            .or_else(|_| File::open(&theme_path.with_extension("yaml")))
+            .map_err(|e| ConfigError::IoPath(e, theme_path.into()))?;
+
+        let mut theme = String::new();
+        theme_file.read_to_string(&mut theme)?;
+
+        let theme: ThemesFromYaml = match serde_yaml::from_str(&theme) {
+            Err(e) => return Err(ConfigError::Serde(e)),
+            Ok(theme) => theme,
+        };
+
+        Ok(theme)
+    }
+}
+
+impl From<ThemesFromYaml> for ThemesFromYamlIntermediate {
+    fn from(yaml: ThemesFromYaml) -> Self {
+        yaml.themes
+    }
+}
+
+impl ThemesFromYamlIntermediate {
     pub fn theme_config(self, opts: &Options) -> Option<Palette> {
         let mut from_yaml = self;
         match &opts.theme {
@@ -182,3 +222,8 @@ impl From<PaletteColorFromYaml> for PaletteColor {
         }
     }
 }
+
+// The unit test location.
+#[cfg(test)]
+#[path = "./unit/theme_test.rs"]
+mod theme_test;
diff --git a/zellij-utils/src/input/unit/fixtures/themes/dracula.yaml b/zellij-utils/src/input/unit/fixtures/themes/dracula.yaml
new file mode 100644
index 000000000..b9c8a5afb
--- /dev/null
+++ b/zellij-utils/src/input/unit/fixtures/themes/dracula.yaml
@@ -0,0 +1,16 @@
+# Dracula Theme
+
+themes:
+  dracula:
+    # From https://github.com/dracula/zellij
+    bg: [40, 42, 54]
+    red: [255, 85, 85]
+    green: [80, 250, 123]
+    yellow: [241, 250, 140]
+    blue: [98, 114, 164]
+    magenta: [255, 121, 198]
+    orange: [255, 184, 108]
+    fg: [248, 248, 242]
+    cyan: [139, 233, 253]
+    black: [0, 0, 0]
+    white: [255, 255, 255]
diff --git a/zellij-utils/src/input/unit/fixtures/themes/nord.yaml b/zellij-utils/src/input/unit/fixtures/themes/nord.yaml
new file mode 100644
index 000000000..61851ad20
--- /dev/null
+++ b/zellij-utils/src/input/unit/fixtures/themes/nord.yaml
@@ -0,0 +1,16 @@
+# Nord theme
+
+themes:
+  nord:
+    fg: [216, 222, 233] #D8DEE9
+    bg: [46, 52, 64] #2E3440
+    black: [59, 66, 82] #3B4252
+    red: [191, 97, 106] #BF616A
+    green: [163, 190, 140] #A3BE8C
+    yellow: [235,203,139] #EBCB8B
+    blue: [129, 161, 193] #81A1C1
+    magenta: [180, 142, 173] #B48EAD
+    cyan: [136, 192, 208] #88C0D0
+    white: [229, 233, 240] #E5E9F0
+    orange: [208, 135, 112] #D08770
+
diff --git a/zellij-utils/src/input/unit/theme_test.rs b/zellij-utils/src/input/unit/theme_test.rs
new file mode 100644
index 000000000..ad5b480af
--- /dev/null
+++ b/zellij-utils/src/input/unit/theme_test.rs
@@ -0,0 +1,22 @@
+use super::super::theme::*;
+use std::path::PathBuf;
+
+fn theme_test_dir(theme: String) -> PathBuf {
+    let root = Path::new(env!("CARGO_MANIFEST_DIR"));
+    let theme_dir = root.join("src/input/unit/fixtures/themes");
+    theme_dir.join(theme)
+}
+
+#[test]
+fn dracula_theme_is_ok() {
+    let path = theme_test_dir("dracula.yaml".into());
+    let theme = ThemesFromYaml::from_path(&path);
+    assert!(theme.is_ok());
+}
+
+#[test]
+fn no_theme_is_err() {
+    let path = theme_test_dir("nonexistent.yaml".into());
+    let theme = ThemesFromYaml::from_path(&path);
+    assert!(theme.is_err());
+}
diff --git a/zellij-utils/src/setup.rs b/zellij-utils/src/setup.rs
index 9b2c36b23..209dc1897 100644
--- a/zellij-utils/src/setup.rs
+++ b/zellij-utils/src/setup.rs
@@ -8,6 +8,7 @@ use crate::{
         config::{Config, ConfigError},
         layout::{LayoutFromYaml, LayoutFromYamlIntermediate},
         options::Options,
+        theme::ThemesFromYaml,
     },
 };
 use clap::{Args, IntoApp};
@@ -80,6 +81,10 @@ pub fn get_layout_dir(config_dir: Option<PathBuf>) -> Option<PathBuf> {
     config_dir.map(|dir| dir.join("layouts"))
 }
 
+pub fn get_theme_dir(config_dir: Option<PathBuf>) -> Option<PathBuf> {
+    config_dir.map(|dir| dir.join("themes"))
+}
+
 pub fn dump_asset(asset: &[u8]) -> std::io::Result<()> {
     std::io::stdout().write_all(asset)?;
     Ok(())
@@ -213,7 +218,7 @@ impl Setup {
             );
         };
 
-        let config = if !clean {
+        let mut config = if !clean {
             match Config::try_from(opts) {
                 Ok(config) => config,
                 Err(e) => {
@@ -244,6 +249,24 @@ impl Setup {
             },
         };
 
+        if let Some(theme_dir) = config_options
+            .theme_dir
+            .clone()
+            .or_else(|| get_theme_dir(opts.config_dir.clone().or_else(find_default_config_dir)))
+        {
+            if theme_dir.is_dir() {
+                for entry in (theme_dir.read_dir()?).flatten() {
+                    if let Some(extension) = entry.path().extension() {
+                        if extension == "yaml" || extension == "yml" {
+                            if let Ok(themes) = ThemesFromYaml::from_path(&entry.path()) {
+                                config.themes = config.themes.map(|t| t.merge(themes.into()));
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
         if let Some(Command::Setup(ref setup)) = &opts.command {
             setup
                 .from_cli_with_options(opts, &config_options)
@@ -333,6 +356,10 @@ impl Setup {
             .layout_dir
             .clone()
             .or_else(|| get_layout_dir(config_dir.clone()));
+        let theme_dir = config_options
+            .theme_dir
+            .clone()
+            .or_else(|| get_theme_dir(config_dir.clone()));
         let system_data_dir = PathBuf::from(SYSTEM_DEFAULT_DATA_DIR_PREFIX).join("share/zellij");
         let config_file = opts
             .config
@@ -386,6 +413,11 @@ impl Setup {
         } else {
             message.push_str("[LAYOUT DIR]: Not Found\n");
         }
+        if let Some(theme_dir) = theme_dir {
+            writeln!(&mut message, "[THEME DIR]: {:?}", theme_dir).unwrap();
+        } else {
+            message.push_str("[THEME DIR]: Not Found\n");
+        }
         writeln!(&mut message, "[SYSTEM DATA DIR]: {:?}", system_data_dir).unwrap();
 
         writeln!(&mut message, "[ARROW SEPARATOR]: {}", ARROW_SEPARATOR).unwrap();