[tui] Add function for refreshing editor contents.

It's still temporary, but at least it isn't done ad-hoc.

src/tui/app.rs

@@ -8,6 +8,7 @@ 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 std::path::PathBuf;
 use std::time::Duration;
 
 pub struct App<'a> {
@@ -16,7 +17,7 @@ pub struct App<'a> {
 }
 
 impl<'a> App<'a> {
-    pub(crate) fn new(root_path: std::path::PathBuf) -> Self {
+    pub(crate) fn new(root_path: PathBuf) -> Self {
         let mut app = Self {
             explorer: Explorer::new(&root_path),
             editor: Editor::new(),
@@ -90,6 +91,21 @@ impl<'a> App<'a> {
             .wrap(Wrap { trim: false })
             .render(area, buf);
     }
+
+    /// 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) {
+        if let Some(current_file_path) = self.editor.file_path.clone() {
+            if let Some(selected_path_string) = self.explorer.selected() {
+                let selected_pathbuf = PathBuf::from(selected_path_string);
+                if std::path::absolute(&selected_pathbuf).unwrap().is_file()
+                    && selected_pathbuf != current_file_path
+                {
+                    self.editor.set_contents(&selected_pathbuf.into()).ok();
+                }
+            }
+        }
+    }
 }
 
 // TODO: Separate complex components into their own widgets.
@@ -129,16 +145,7 @@ impl<'a> Widget for &mut App<'a> {
         self.explorer.render(horizontal[0], buf);
 
         self.draw_tabs(editor_layout[0], buf);
-
+        self.refresh_editor_contents();
-        if let Some(editor) = self.editor.file_path.clone() {
-            let editor_abs = std::path::absolute(editor).unwrap();
-            if let Some(selected) = self.explorer.selected() {
-                let selected_abs = std::path::absolute(selected).unwrap();
-                if selected_abs.is_file() && selected_abs != editor_abs {
-                    self.editor.set_contents(&selected_abs).ok();
-                }
-            }
-        }
         self.editor.render(editor_layout[1], buf);
     }
 }

src/tui/editor.rs

@@ -9,6 +9,7 @@ use ratatui::crossterm::event::{Event, KeyCode, KeyEvent, KeyModifiers};
 use ratatui::layout::{Alignment, Rect};
 use ratatui::prelude::{Color, Style};
 use ratatui::widgets::{Block, Borders, Padding, Widget};
+use syntect::parsing::SyntaxSet;
 
 // TODO: Consider using editor-command https://docs.rs/editor-command/latest/editor_command/
 // TODO: Title should be detected programming language name
@@ -52,20 +53,30 @@ impl Editor {
 
 impl Widget for &mut Editor {
     fn render(self, area: Rect, buf: &mut Buffer) {
-        // TODO: Use current file extension for syntax highlighting here.
+        let lang = self
+            .file_path
+            .as_ref()
+            .and_then(|p| p.extension())
+            .map(|e| e.to_str().unwrap_or("md"))
+            .unwrap_or("md");
+        let lang_name = SyntaxSet::load_defaults_nonewlines()
+            .find_syntax_by_extension(lang)
+            .map(|s| s.name.to_string())
+            .unwrap_or_else(|| "Unknown".to_string());
+
         EditorView::new(&mut self.state)
             .wrap(true)
             .theme(
                 EditorTheme::default().block(
                     Block::default()
-                        .title("Rust")
+                        .title(lang_name.to_owned())
                         .title_style(Style::default().fg(Color::Yellow))
                         .title_alignment(Alignment::Right)
                         .borders(Borders::ALL)
                         .padding(Padding::new(0, 0, 0, 1)),
                 ),
             )
-            .syntax_highlighter(SyntaxHighlighter::new("dracula", "rs").ok())
+            .syntax_highlighter(SyntaxHighlighter::new("dracula", lang).ok())
             .tab_width(2)
             .line_numbers(LineNumbers::Absolute)
             .render(area, buf);