feat(tui): support scrolling the kernel documentation

systeroid-tui/src/app.rs

@@ -1,7 +1,6 @@
 use crate::command::Command;
 use crate::error::Result;
-use crate::options::CopyOption;
-use crate::options::Direction;
+use crate::options::{CopyOption, Direction, ScrollArea};
 use crate::widgets::StatefulTable;
 #[cfg(feature = "clipboard")]
 use copypasta_ext::{display::DisplayServer, prelude::ClipboardProvider};
@@ -26,6 +25,8 @@ pub struct App<'a> {
     pub input_cursor: u16,
     /// Whether if the search mode is enabled.
     pub search_mode: bool,
+    /// Y-scroll offset for the documentation.
+    pub docs_scroll_amount: u16,
     /// Entries of the options menu.
     pub options: Option<StatefulTable<&'a str>>,
     /// List of sysctl parameters.
@@ -46,6 +47,7 @@ impl<'a> App<'a> {
             input_time: None,
             input_cursor: 0,
             search_mode: false,
+            docs_scroll_amount: 0,
             options: None,
             parameter_list: StatefulTable::default(),
             #[cfg(feature = "clipboard")]
@@ -92,6 +94,7 @@ impl<'a> App<'a> {
         } else {
             self.parameter_list = StatefulTable::with_items(self.sysctl.parameters.clone());
         }
+        self.docs_scroll_amount = 0;
     }
 
     /// Copies the selected entry to the clipboard.
@@ -165,10 +168,11 @@ impl<'a> App<'a> {
                     self.input_time = Some(Instant::now());
                 }
             }
-            Command::Scroll(Direction::Up, amount) => {
+            Command::Scroll(ScrollArea::List, Direction::Up, amount) => {
                 if let Some(options) = self.options.as_mut() {
                     options.previous();
                 } else if !self.parameter_list.items.is_empty() {
+                    self.docs_scroll_amount = 0;
                     if amount == 1 {
                         self.parameter_list.previous();
                     } else {
@@ -182,10 +186,11 @@ impl<'a> App<'a> {
                     }
                 }
             }
-            Command::Scroll(Direction::Down, amount) => {
+            Command::Scroll(ScrollArea::List, Direction::Down, amount) => {
                 if let Some(options) = self.options.as_mut() {
                     options.next();
                 } else if !self.parameter_list.items.is_empty() {
+                    self.docs_scroll_amount = 0;
                     if amount == 1 {
                         self.parameter_list.next();
                     } else {
@@ -204,16 +209,31 @@ impl<'a> App<'a> {
                     }
                 }
             }
-            Command::Scroll(Direction::Top, _) => {
+            Command::Scroll(ScrollArea::List, Direction::Top, _) => {
                 if !self.parameter_list.items.is_empty() {
+                    self.docs_scroll_amount = 0;
                     self.parameter_list.state.select(Some(0));
                 }
             }
-            Command::Scroll(Direction::Bottom, _) => {
+            Command::Scroll(ScrollArea::List, Direction::Bottom, _) => {
                 if let Some(last_index) = self.parameter_list.items.len().checked_sub(1) {
+                    self.docs_scroll_amount = 0;
                     self.parameter_list.state.select(Some(last_index))
                 }
             }
+            Command::Scroll(ScrollArea::Documentation, Direction::Up, amount) => {
+                self.docs_scroll_amount = self
+                    .docs_scroll_amount
+                    .checked_sub(amount.into())
+                    .unwrap_or_default();
+            }
+            Command::Scroll(ScrollArea::Documentation, Direction::Down, amount) => {
+                self.docs_scroll_amount = self
+                    .docs_scroll_amount
+                    .checked_add(amount.into())
+                    .unwrap_or(self.docs_scroll_amount);
+            }
+            Command::Scroll(_, _, _) => {}
             Command::EnableSearch => {
                 if self.input_time.is_some() {
                     self.input_time = None;
@@ -312,6 +332,7 @@ impl<'a> App<'a> {
             Command::Refresh => {
                 self.input = None;
                 self.sysctl.parameters = Sysctl::init(self.sysctl.config.clone())?.parameters;
+                self.docs_scroll_amount = 0;
                 self.parameter_list.items.iter_mut().for_each(|parameter| {
                     if let Some(param) = self
                         .sysctl

systeroid-tui/src/command.rs

@@ -1,4 +1,4 @@
-use crate::options::Direction;
+use crate::options::{Direction, ScrollArea};
 use std::str::FromStr;
 use termion::event::Key;
 
@@ -10,7 +10,7 @@ pub enum Command {
     /// Set the value of a parameter.
     Set(String, String),
     /// Scroll the widget.
-    Scroll(Direction, u8),
+    Scroll(ScrollArea, Direction, u8),
     /// Move cursor to right/left.
     MoveCursor(u8),
     /// Enable the search mode.
@@ -48,13 +48,10 @@ impl FromStr for Command {
                         values.next().ok_or(())?.to_string(),
                     ))
                 } else if s.starts_with("scroll") {
+                    let mut values = s.trim_start_matches("scroll").trim().split_whitespace();
                     Ok(Command::Scroll(
-                        Direction::try_from(
-                            *(s.split_whitespace()
-                                .collect::<Vec<&str>>()
-                                .get(1)
-                                .ok_or(())?),
-                        )?,
+                        ScrollArea::try_from(values.next().ok_or(())?)?,
+                        Direction::try_from(values.next().ok_or(())?)?,
                         1,
                     ))
                 } else {
@@ -81,12 +78,14 @@ impl Command {
             }
         } else {
             match key {
-                Key::Up => Command::Scroll(Direction::Up, 1),
-                Key::Down => Command::Scroll(Direction::Down, 1),
-                Key::PageUp => Command::Scroll(Direction::Up, 4),
-                Key::PageDown => Command::Scroll(Direction::Down, 4),
-                Key::Char('t') => Command::Scroll(Direction::Top, 0),
-                Key::Char('b') => Command::Scroll(Direction::Bottom, 0),
+                Key::Up => Command::Scroll(ScrollArea::List, Direction::Up, 1),
+                Key::Down => Command::Scroll(ScrollArea::List, Direction::Down, 1),
+                Key::PageUp => Command::Scroll(ScrollArea::List, Direction::Up, 4),
+                Key::PageDown => Command::Scroll(ScrollArea::List, Direction::Down, 4),
+                Key::Char('t') => Command::Scroll(ScrollArea::List, Direction::Top, 0),
+                Key::Char('b') => Command::Scroll(ScrollArea::List, Direction::Bottom, 0),
+                Key::Left => Command::Scroll(ScrollArea::Documentation, Direction::Up, 1),
+                Key::Right => Command::Scroll(ScrollArea::Documentation, Direction::Down, 1),
                 Key::Char(':') => Command::UpdateInput(' '),
                 Key::Char('/') => Command::EnableSearch,
                 Key::Char('\n') => Command::Select,

systeroid-tui/src/options.rs

@@ -54,3 +54,9 @@ generate_option!(
     Top => "top",
     Bottom => "bottom",
 );
+
+generate_option!(
+    ScrollArea,
+    List => "list",
+    Documentation => "documentation",
+);

systeroid-tui/src/ui.rs

@@ -38,7 +38,12 @@ pub fn render<B: Backend>(frame: &mut Frame<'_, B>, app: &mut App) {
         }
     }
     if let Some(documentation) = documentation {
-        render_parameter_documentation(frame, chunks[1], documentation);
+        render_parameter_documentation(
+            frame,
+            chunks[1],
+            documentation,
+            &mut app.docs_scroll_amount,
+        );
     }
 }
 
@@ -221,7 +226,18 @@ fn render_parameter_documentation<B: Backend>(
     frame: &mut Frame<'_, B>,
     rect: Rect,
     documentation: String,
+    scroll_amount: &mut u16,
 ) {
+    match (documentation.lines().count() * 2).checked_sub(rect.height.into()) {
+        Some(scroll_overflow) => {
+            if scroll_overflow < (*scroll_amount).into() {
+                *scroll_amount = scroll_overflow as u16;
+            }
+        }
+        None => {
+            *scroll_amount = scroll_amount.checked_sub(1).unwrap_or_default();
+        }
+    }
     frame.render_widget(
         Paragraph::new(documentation)
             .block(
@@ -236,6 +252,7 @@ fn render_parameter_documentation<B: Backend>(
                     .border_type(BorderType::Rounded)
                     .style(Style::default().bg(Color::Black)),
             )
+            .scroll((*scroll_amount, 0))
             .wrap(Wrap { trim: false }),
         rect,
     );