Tab theme configurable (#317)

Text style for tabs can be configured within
`theme.toml` with the dotted keys `tab.active` and `tab.inactive`.

The default style is the same as the former hard-coded style.

`theme.toml` has been restructured and comments have been
added to give a short documentation on each style item.

The documentation (`theme.toml.md`) has been enhanced, and
the excerpt of `theme.toml` with additional comments has
been removed from there.

That way it should be easier for devs to keep docs and the default
`theme.toml` in sync, and easier for users when the detail comments
can be found in the configuration file itself.

The conversion from `AppStyle` to `tui::style::Style` is now provided as
a function of `AppStyle` and a `From`-implementation for `Style` to
avoid having the same factory code repeating all over.

3 files changed, 44 insertions, 6 deletions

diff --git a/src/config/theme/app_theme.rs b/src/config/theme/app_theme.rs
index cdf5eac..fdf3ca0 100644
--- a/src/config/theme/app_theme.rs
+++ b/src/config/theme/app_theme.rs
@@ -9,6 +9,8 @@ use crate::error::JoshutoResult;
 #[derive(Clone, Debug, Deserialize, Default)]
 pub struct AppThemeRaw {
     #[serde(default)]
+    pub tabs: TabThemeRaw,
+    #[serde(default)]
     pub regular: AppStyleRaw,
     #[serde(default)]
     pub selection: AppStyleRaw,
@@ -28,8 +30,25 @@ pub struct AppThemeRaw {
     pub ext: HashMap<String, AppStyleRaw>,
 }
 
+#[derive(Clone, Debug, Deserialize, Default)]
+pub struct TabThemeRaw {
+    #[serde(default)]
+    pub inactive: AppStyleRaw,
+    #[serde(default)]
+    pub active: AppStyleRaw,
+}
+
+impl From<TabThemeRaw> for TabTheme {
+    fn from(crude: TabThemeRaw) -> Self {
+        let inactive = crude.inactive.to_style_theme();
+        let active = crude.active.to_style_theme();
+        Self { inactive, active }
+    }
+}
+
 impl From<AppThemeRaw> for AppTheme {
     fn from(crude: AppThemeRaw) -> Self {
+        let tabs = crude.tabs;
         let selection = crude.selection.to_style_theme();
         let visual_mode_selection = crude.visual_mode_selection.to_style_theme();
         let executable = crude.executable.to_style_theme();
@@ -57,12 +76,14 @@ impl From<AppThemeRaw> for AppTheme {
             link_invalid,
             socket,
             ext,
+            tabs: TabTheme::from(tabs),
         }
     }
 }
 
 #[derive(Clone, Debug)]
 pub struct AppTheme {
+    pub tabs: TabTheme,
     pub regular: AppStyle,
     pub selection: AppStyle,
     pub visual_mode_selection: AppStyle,
@@ -94,3 +115,9 @@ impl std::default::Default for AppTheme {
         Self::default_res().unwrap()
     }
 }
+
+#[derive(Clone, Debug)]
+pub struct TabTheme {
+    pub inactive: AppStyle,
+    pub active: AppStyle,
+}
diff --git a/src/config/theme/style.rs b/src/config/theme/style.rs
index 5fecdf8..e4ee599 100644
--- a/src/config/theme/style.rs
+++ b/src/config/theme/style.rs
@@ -2,7 +2,7 @@ use colors_transform::{Color, Rgb};
 
 use serde_derive::Deserialize;
 
-use tui::style;
+use tui::style::{self, Style};
 
 const fn default_color() -> style::Color {
     style::Color::Reset
@@ -117,6 +117,10 @@ impl AppStyle {
         self.modifier.insert(modifier);
         self
     }
+
+    pub fn as_style(&self) -> Style {
+        Style::from(self)
+    }
 }
 
 impl std::default::Default for AppStyle {
@@ -128,3 +132,12 @@ impl std::default::Default for AppStyle {
         }
     }
 }
+
+impl From<&AppStyle> for Style {
+    fn from(style: &AppStyle) -> Self {
+        Self::default()
+            .fg(style.fg)
+            .bg(style.bg)
+            .add_modifier(style.modifier)
+    }
+}
diff --git a/src/ui/widgets/tui_tab.rs b/src/ui/widgets/tui_tab.rs
index 76bfca5..35f6630 100644
--- a/src/ui/widgets/tui_tab.rs
+++ b/src/ui/widgets/tui_tab.rs
@@ -2,11 +2,11 @@ use std::ffi::OsStr;
 
 use tui::buffer::Buffer;
 use tui::layout::Rect;
-use tui::style::{Color, Modifier, Style};
 use tui::text::{Line, Span};
 use tui::widgets::{Paragraph, Widget, Wrap};
 
 use crate::context::TabContext;
+use crate::THEME_T;
 
 pub struct TuiTabBar<'a> {
     context: &'a TabContext,
@@ -20,10 +20,8 @@ impl<'a> TuiTabBar<'a> {
 
 impl<'a> Widget for TuiTabBar<'a> {
     fn render(self, area: Rect, buf: &mut Buffer) {
-        let regular_style = Style::default().fg(Color::White);
-        let selected_style = Style::default()
-            .fg(Color::White)
-            .add_modifier(Modifier::REVERSED);
+        let regular_style = THEME_T.tabs.inactive.as_style();
+        let selected_style = THEME_T.tabs.active.as_style();
 
         let index = self.context.index;
         let tab_order = self.context.tab_order.as_slice();