[tui] Add EditorTab widget.

+ This adds support for tabbed editors wrapped by EditorTab widgets.
+ The Explorer widget now opens new EditorTabs when a file is selected
  with Enter.
+ The same file may not be opened multiple times.
+ Tabs can be switched with ALT+h or ALT+l (or ALT+ arrow keys)
+ Tabs cannot yet be closed :)

Fixes #9

src/tui.rs

@@ -1,6 +1,7 @@
 mod app;
 mod component;
 mod editor;
+mod editor_tab;
 mod explorer;
 mod logger;
 mod menu_bar;

src/tui/app.rs

@@ -1,21 +1,21 @@
 use crate::tui::app::AppComponent::{AppEditor, AppExplorer, AppLogger};
 use crate::tui::component::{Action, Component, Focus, FocusState};
-use crate::tui::editor::Editor;
+use crate::tui::editor_tab::EditorTab;
 use crate::tui::explorer::Explorer;
 use crate::tui::logger::Logger;
 use crate::tui::menu_bar::MenuBar;
 use AppComponent::AppMenuBar;
 use anyhow::{Context, Result};
-use log::{debug, error, info, trace, warn};
+use log::error;
+use ratatui::DefaultTerminal;
 use ratatui::buffer::Buffer;
 use ratatui::crossterm::event;
 use ratatui::crossterm::event::{
     Event, KeyCode, KeyEvent, KeyEventKind, KeyModifiers, MouseButton, MouseEventKind,
 };
 use ratatui::layout::{Constraint, Direction, Layout, Rect};
-use ratatui::prelude::{Color, Style, Widget};
-use ratatui::widgets::{Block, Borders, Padding, Paragraph, Tabs, Wrap};
-use ratatui::{DefaultTerminal, symbols};
+use ratatui::prelude::{Color, Widget};
+use ratatui::widgets::{Paragraph, Wrap};
 use std::path::PathBuf;
 use std::time::Duration;
 
@@ -31,7 +31,7 @@ pub enum AppComponent {
 }
 
 pub struct App<'a> {
-    editor: Editor,
+    editor_tabs: EditorTab,
     explorer: Explorer<'a>,
     logger: Logger,
     menu_bar: MenuBar,
@@ -45,7 +45,7 @@ impl<'a> App<'a> {
 
     pub fn new(root_path: PathBuf) -> Result<Self> {
         let app = Self {
-            editor: Editor::new(),
+            editor_tabs: EditorTab::new(&root_path),
             explorer: Explorer::new(&root_path)?,
             logger: Logger::new(),
             menu_bar: MenuBar::new(),
@@ -57,12 +57,16 @@ impl<'a> App<'a> {
     /// Logic that should be executed once on application startup.
     pub fn start(&mut self) -> Result<()> {
         let root_path = self.explorer.root_path.clone();
-        self.editor
+        let editor = self
+            .editor_tabs
+            .current_editor_mut()
+            .context("Failed to get current editor in App::start")?;
+        editor
             .set_contents(&root_path.join("src/tui/app.rs"))
             .context(format!(
                 "Failed to initialize editor contents to path: {root_path:?}"
             ))?;
-        self.editor.component_state.set_focus(Focus::Active);
+        editor.component_state.set_focus(Focus::Active);
         Ok(())
     }
 
@@ -92,7 +96,13 @@ impl<'a> App<'a> {
     fn draw_bottom_status(&self, area: Rect, buf: &mut Buffer) {
         // Determine help text from the most recently focused component.
         let help = match self.last_active {
-            AppEditor => self.editor.component_state.help_text.clone(),
+            AppEditor => match self.editor_tabs.current_editor() {
+                Some(editor) => editor.component_state.help_text.clone(),
+                None => {
+                    error!(target:Self::id(), "Failed to get Editor while drawing bottom status bar");
+                    "Failed to get current Editor while getting widget help text".to_string()
+                }
+            },
             AppExplorer => self.explorer.component_state.help_text.clone(),
             AppLogger => self.logger.component_state.help_text.clone(),
             AppMenuBar => self.menu_bar.component_state.help_text.clone(),
@@ -111,32 +121,14 @@ impl<'a> App<'a> {
         .render(area, buf);
     }
 
-    fn draw_tabs(&self, area: Rect, buf: &mut Buffer) {
-        // Determine the tab title from the current file (or use a fallback).
-        if let Some(title) = self.editor.file_path.clone() {
-            Tabs::new(vec![
-                title
-                    .file_name()
-                    .map(|f| f.to_str())
-                    .unwrap_or(Some("Unknown"))
-                    .unwrap(),
-            ])
-            .divider(symbols::DOT)
-            .block(
-                Block::default()
-                    .borders(Borders::NONE)
-                    .padding(Padding::new(0, 0, 0, 0)),
-            )
-            .highlight_style(Style::default().fg(Color::LightRed))
-            .render(area, buf);
-        } else {
-            error!(target:Self::id(), "Failed to get Editor file_path while drawing Tabs widget.");
-        }
-    }
-
     fn change_focus(&mut self, focus: AppComponent) {
         match focus {
-            AppEditor => self.editor.component_state.set_focus(Focus::Active),
+            AppEditor => match self.editor_tabs.current_editor_mut() {
+                None => {
+                    error!(target:Self::id(), "Failed to get current Editor while changing focus")
+                }
+                Some(editor) => editor.component_state.set_focus(Focus::Active),
+            },
             AppExplorer => self.explorer.component_state.set_focus(Focus::Active),
             AppLogger => self.logger.component_state.set_focus(Focus::Active),
             AppMenuBar => self.menu_bar.component_state.set_focus(Focus::Active),
@@ -147,20 +139,26 @@ impl<'a> App<'a> {
     /// Refresh the contents of the editor to match the selected TreeItem in the file Explorer.
     /// If the selected item is not a file, this does nothing.
     fn refresh_editor_contents(&mut self) -> Result<()> {
+        // TODO: This may be useful for a preview mode of the selected file prior to opening a tab.
         // Use the currently selected TreeItem or get an absolute path to this source file.
-        let selected_pathbuf = match self.explorer.selected() {
-            Ok(path) => PathBuf::from(path),
-            Err(_) => PathBuf::from(std::path::absolute(file!())?.to_string_lossy().to_string()),
-        };
-        let current_file_path = self
-            .editor
-            .file_path
-            .clone()
-            .context("Failed to get Editor current file_path")?;
-        if selected_pathbuf == current_file_path || !selected_pathbuf.is_file() {
-            return Ok(());
-        }
-        self.editor.set_contents(&selected_pathbuf)
+        // let selected_pathbuf = match self.explorer.selected() {
+        //     Ok(path) => PathBuf::from(path),
+        //     Err(_) => PathBuf::from(std::path::absolute(file!())?.to_string_lossy().to_string()),
+        // };
+        // match self.editor_tabs.current_editor_mut() {
+        //     None => bail!("Failed to get current Editor while refreshing editor contents"),
+        //     Some(editor) => {
+        //         let current_file_path = editor
+        //             .file_path
+        //             .clone()
+        //             .context("Failed to get Editor current file_path")?;
+        //         if selected_pathbuf == current_file_path || !selected_pathbuf.is_file() {
+        //             return Ok(());
+        //         }
+        //         editor.set_contents(&selected_pathbuf)
+        //     }
+        // }
+        Ok(())
     }
 }
 
@@ -196,9 +194,8 @@ impl<'a> Widget for &mut App<'a> {
             .split(horizontal[1]);
 
         self.draw_bottom_status(vertical[3], buf);
-        self.draw_tabs(editor_layout[0], buf);
-        let id = App::id().to_string();
-        self.editor.render(editor_layout[1], buf);
+        self.editor_tabs
+            .render(editor_layout[0], editor_layout[1], buf);
         self.explorer.render(horizontal[0], buf);
         self.logger.render(vertical[2], buf);
 
@@ -220,28 +217,47 @@ impl<'a> Component for App<'a> {
                 _ => {}
             }
         }
+        // Handle events for all components.
+        let action = match self.last_active {
+            AppEditor => self.editor_tabs.handle_event(event.clone())?,
+            AppExplorer => self.explorer.handle_event(event.clone())?,
+            AppLogger => self.logger.handle_event(event.clone())?,
+            AppMenuBar => self.menu_bar.handle_event(event.clone())?,
+        };
+
+        let editor = self
+            .editor_tabs
+            .current_editor_mut()
+            .context("Failed to get current editor while handling App events")?;
         // Components should always handle mouse events for click interaction.
         if let Some(mouse) = event.as_mouse_event() {
             if mouse.kind == MouseEventKind::Down(MouseButton::Left) {
-                self.editor.handle_mouse_events(mouse)?;
+                editor.handle_mouse_events(mouse)?;
                 self.explorer.handle_mouse_events(mouse)?;
                 self.logger.handle_mouse_events(mouse)?;
             }
         }
 
-        // Handle events for all components.
-        let action = match self.last_active {
-            AppEditor => self.editor.handle_event(event)?,
-            AppExplorer => self.explorer.handle_event(event)?,
-            AppLogger => self.logger.handle_event(event)?,
-            AppMenuBar => self.menu_bar.handle_event(event)?,
-        };
         match action {
-            Action::Quit | Action::Handled => return Ok(action),
-            Action::Save => self.editor.save()?,
-            _ => {}
+            Action::Quit | Action::Handled => Ok(action),
+            Action::Save => match editor.save() {
+                Ok(_) => Ok(Action::Handled),
+                Err(_) => {
+                    error!(target:Self::id(), "Failed to save editor contents");
+                    Ok(Action::Noop)
+                }
+            },
+            Action::OpenTab => {
+                if let Ok(path) = self.explorer.selected() {
+                    let path_buf = PathBuf::from(path);
+                    self.editor_tabs.open_tab(&path_buf)?;
+                    Ok(Action::Handled)
+                } else {
+                    Ok(Action::Noop)
+                }
+            }
+            _ => Ok(Action::Noop),
         }
-        Ok(Action::Noop)
     }
 
     /// Handles key events for the App Component only.
@@ -283,19 +299,6 @@ impl<'a> Component for App<'a> {
                 self.change_focus(AppMenuBar);
                 Ok(Action::Handled)
             }
-            KeyEvent {
-                code: KeyCode::Char('l'),
-                modifiers: KeyModifiers::ALT,
-                kind: KeyEventKind::Press,
-                state: _state,
-            } => {
-                error!(target:App::id(), "an error");
-                warn!(target:App::id(), "a warning");
-                info!(target:App::id(), "a two line info\nsecond line");
-                debug!(target:App::id(), "a debug");
-                trace!(target:App::id(), "a trace");
-                Ok(Action::Handled)
-            }
             KeyEvent {
                 code: KeyCode::Char('c'),
                 modifiers: KeyModifiers::CONTROL,

src/tui/component.rs

@@ -19,6 +19,7 @@ pub enum Action {
 
     /// The input was handled by a Component and should not be passed to the next component.
     Handled,
+    OpenTab,
 }
 
 pub trait Component {

src/tui/editor.rs

@@ -23,14 +23,17 @@ impl Editor {
         "Editor"
     }
 
+    // TODO: You shouldnt be able to construct the editor without a path?
     pub fn new() -> Self {
         Editor {
             state: EditorState::default(),
             event_handler: EditorEventHandler::default(),
             file_path: None,
             syntax_set: SyntaxSet::load_defaults_nonewlines(),
-            component_state: ComponentState::default()
-                .with_help_text("CTRL+S: Save file | Any other input is handled by vim"),
+            component_state: ComponentState::default().with_help_text(concat!(
+                "CTRL+S: Save file | ALT+(←/h): Previous tab | ALT+(l/→): Next tab |",
+                " All other input is handled by vim"
+            )),
         }
     }
 

src/tui/editor_tab.rs

@@ -0,0 +1,151 @@
+use crate::tui::component::{Action, Component};
+use crate::tui::editor::Editor;
+use anyhow::{Context, Result};
+use log::trace;
+use ratatui::buffer::Buffer;
+use ratatui::crossterm::event::{Event, KeyCode, KeyEvent, KeyModifiers};
+use ratatui::layout::Rect;
+use ratatui::prelude::{Color, Style};
+use ratatui::widgets::{Block, Borders, Padding, Tabs, Widget};
+use std::collections::HashMap;
+
+// Render the tabs with keys as titles
+// Tab keys can be file names.
+// Render the editor using the key as a reference for lookup
+pub struct EditorTab {
+    pub(crate) editors: HashMap<String, Editor>,
+    tab_order: Vec<String>,
+    current_editor: usize,
+}
+
+impl EditorTab {
+    fn id() -> &'static str {
+        "EditorTab"
+    }
+
+    pub fn new(path: &std::path::PathBuf) -> Self {
+        trace!(target:Self::id(), "Building EditorTab with path '{path:?}'");
+        let tab_order = vec![path.to_string_lossy().to_string()];
+        Self {
+            editors: HashMap::from([(tab_order.first().unwrap().to_owned(), Editor::new())]),
+            tab_order,
+            current_editor: 0,
+        }
+    }
+
+    pub fn next_editor(&mut self) {
+        self.current_editor = (self.current_editor + 1) % self.tab_order.len();
+    }
+
+    pub fn prev_editor(&mut self) {
+        self.current_editor = self
+            .current_editor
+            .checked_sub(1)
+            .unwrap_or(self.tab_order.len() - 1);
+    }
+
+    pub fn current_editor(&self) -> Option<&Editor> {
+        self.editors.get(&self.tab_order[self.current_editor])
+    }
+
+    pub fn current_editor_mut(&mut self) -> Option<&mut Editor> {
+        self.editors.get_mut(&self.tab_order[self.current_editor])
+    }
+
+    pub fn open_tab(&mut self, path: &std::path::PathBuf) -> Result<()> {
+        if self
+            .editors
+            .contains_key(&path.to_string_lossy().to_string())
+        {
+            return Ok(());
+        }
+
+        let path_str = path.to_string_lossy().to_string();
+        self.tab_order.push(path_str.clone());
+        let mut editor = Editor::new();
+        editor.set_contents(path).context("Failed to open tab")?;
+        self.editors.insert(path_str, editor);
+        self.current_editor = self.tab_order.len() - 1;
+        Ok(())
+    }
+
+    pub fn render(&mut self, tabs_area: Rect, editor_area: Rect, buf: &mut Buffer) {
+        // TODO: Only file name is displayed in tab title, so files with the same name in different
+        //    directories will appear confusing.
+        let tab_titles = self.tab_order.iter().map(|t| {
+            std::path::PathBuf::from(t)
+                .file_name()
+                .map(|f| f.to_string_lossy().to_string())
+                .unwrap_or("Unknown".to_string())
+        });
+        Tabs::new(tab_titles)
+            .select(self.current_editor)
+            .divider("|")
+            .block(
+                Block::default()
+                    .borders(Borders::NONE)
+                    .padding(Padding::new(0, 0, 0, 0)),
+            )
+            .highlight_style(Style::default().fg(Color::LightRed))
+            .render(tabs_area, buf);
+        Widget::render(self, editor_area, buf);
+    }
+}
+
+impl Widget for &mut EditorTab {
+    fn render(self, area: Rect, buf: &mut Buffer)
+    where
+        Self: Sized,
+    {
+        if let Some(editor) = self.current_editor_mut() {
+            editor.render(area, buf);
+        }
+    }
+}
+
+impl Component for EditorTab {
+    fn handle_event(&mut self, event: Event) -> Result<Action> {
+        if let Some(key) = event.as_key_event() {
+            let action = self.handle_key_events(key)?;
+            match action {
+                Action::Quit | Action::Handled => return Ok(action),
+                _ => {}
+            }
+        }
+        self.current_editor_mut()
+            .context("Failed to get current editor")?
+            .handle_event(event)
+    }
+
+    fn handle_key_events(&mut self, key: KeyEvent) -> Result<Action> {
+        match key {
+            KeyEvent {
+                code: KeyCode::Char('h'),
+                modifiers: KeyModifiers::ALT,
+                ..
+            }
+            | KeyEvent {
+                code: KeyCode::Left,
+                modifiers: KeyModifiers::ALT,
+                ..
+            } => {
+                self.prev_editor();
+                Ok(Action::Handled)
+            }
+            KeyEvent {
+                code: KeyCode::Char('l'),
+                modifiers: KeyModifiers::ALT,
+                ..
+            }
+            | KeyEvent {
+                code: KeyCode::Right,
+                modifiers: KeyModifiers::ALT,
+                ..
+            } => {
+                self.next_editor();
+                Ok(Action::Handled)
+            }
+            _ => Ok(Action::Noop),
+        }
+    }
+}

src/tui/explorer.rs

@@ -23,19 +23,20 @@ impl<'a> Explorer<'a> {
         "Explorer"
     }
 
-    pub fn new(path: &std::path::PathBuf) -> Result<Self> {
+    pub fn new(path: &PathBuf) -> Result<Self> {
         let explorer = Explorer {
             root_path: path.to_owned(),
             tree_items: Self::build_tree_from_path(path.to_owned())?,
             tree_state: TreeState::default(),
-            component_state: ComponentState::default().with_help_text(
-                "(↑/k)/(↓/j): Select item | ←/h: Close folder | →/l/Enter: Open folder",
-            ),
+            component_state: ComponentState::default().with_help_text(concat!(
+                "(↑/k)/(↓/j): Select item | ←/h: Close folder | →/l: Open folder |",
+                " Enter: Open editor tab"
+            )),
         };
         Ok(explorer)
     }
 
-    fn build_tree_from_path(path: std::path::PathBuf) -> Result<TreeItem<'static, String>> {
+    fn build_tree_from_path(path: PathBuf) -> Result<TreeItem<'static, String>> {
         let mut children = vec![];
         if let Ok(entries) = fs::read_dir(&path) {
             let mut paths = entries
@@ -126,6 +127,7 @@ impl<'a> Component for Explorer<'a> {
             // Handle events here that should not be passed on to the vim emulation handler.
             match self.handle_key_events(key_event)? {
                 Action::Handled => return Ok(Action::Handled),
+                Action::OpenTab => return Ok(Action::OpenTab),
                 _ => {}
             }
         }
@@ -139,6 +141,15 @@ impl<'a> Component for Explorer<'a> {
     }
 
     fn handle_key_events(&mut self, key: KeyEvent) -> Result<Action> {
+        if key.code == KeyCode::Enter {
+            if let Ok(selected) = self.selected() {
+                if PathBuf::from(&selected).is_file() {
+                    return Ok(Action::OpenTab);
+                }
+            }
+            return Ok(Action::Noop);
+        }
+
         let changed = match key.code {
             KeyCode::Up | KeyCode::Char('k') => self.tree_state.key_up(),
             KeyCode::Down | KeyCode::Char('j') => self.tree_state.key_down(),
@@ -148,7 +159,6 @@ impl<'a> Component for Explorer<'a> {
                 self.tree_state.close(key.as_ref())
             }
             KeyCode::Right | KeyCode::Char('l') => self.tree_state.key_right(),
-            KeyCode::Enter => self.tree_state.toggle_selected(),
             _ => false,
         };
         if changed {

src/tui/menu_bar.rs

@@ -1,4 +1,3 @@
-use crate::tui::component::Action::Pass;
 use crate::tui::component::{Action, Component, ComponentState};
 use crate::tui::menu_bar::MenuBarItemOption::{
     About, Exit, Reload, Save, ShowHideExplorer, ShowHideLogger,
@@ -33,12 +32,12 @@ enum MenuBarItemOption {
 impl MenuBarItemOption {
     fn id(&self) -> &str {
         match self {
-            MenuBarItemOption::Save => "Save",
-            MenuBarItemOption::Reload => "Reload",
-            MenuBarItemOption::Exit => "Exit",
-            MenuBarItemOption::ShowHideExplorer => "Show / hide explorer",
-            MenuBarItemOption::ShowHideLogger => "Show / hide logger",
-            MenuBarItemOption::About => "About",
+            Save => "Save",
+            Reload => "Reload",
+            Exit => "Exit",
+            ShowHideExplorer => "Show / hide explorer",
+            ShowHideLogger => "Show / hide logger",
+            About => "About",
         }
     }
 }
@@ -116,7 +115,7 @@ impl MenuBar {
         buf: &mut Buffer,
         opened: MenuBarItem,
     ) {
-        let popup_area = Self::rect_under_option(title_bar_anchor, area, 40, 10);
+        let popup_area = Self::rect_under_option(title_bar_anchor, area, 27, 10);
         Clear::default().render(popup_area, buf);
         let options = opened.options().iter().map(|i| ListItem::new(i.id()));
         StatefulWidget::render(