Status line, commands, and normal mode errors

src/main.rs

@@ -20,10 +20,8 @@ use std::io::{stdout, Stdout, Write};
 
 use crossterm::{
     cursor,
-    event::{ Event, KeyCode, KeyEvent, read },
-    terminal,
-    ExecutableCommand,
-    Result
+    event::{read, Event, KeyCode, KeyEvent},
+    terminal, ExecutableCommand, Result,
 };
 use ropey::Rope;
 
@@ -38,8 +36,13 @@ impl Buffer {
         }
     }
 
-    pub fn draw(&self, scroll: Cursor, out: &mut (impl ExecutableCommand + Write)) -> Result<u32> {
-        let (cols, rows) = terminal::size()?;
+    pub fn draw(
+        &self,
+        cols: u16,
+        rows: u16,
+        scroll: Cursor,
+        out: &mut (impl ExecutableCommand + Write),
+    ) -> Result<u32> {
         let lr_width = self.text.len_lines().ilog10() + 1;
         let gutter_width = lr_width + 1;
         let text_width = cols as usize - gutter_width as usize;
@@ -126,28 +129,44 @@ struct Cursor {
     pub line: usize,
 }
 
+#[derive(Clone, Debug, Default)]
+struct NormalState {
+    pub error: Option<String>,
+}
+
+#[derive(Clone, Debug, Default)]
+struct CommandState {
+    pub buf: String,
+    pub cursor: usize,
+}
+
 #[derive(Copy, Clone, Debug)]
 struct InsertState {
     append: bool,
 }
 
-#[derive(Copy, Clone, Debug, Default)]
+#[derive(Clone, Debug)]
 enum Mode {
-    #[default]
-    Normal,
-    Command,
+    Normal(NormalState),
+    Command(CommandState),
     Visual,
     Insert(InsertState),
 }
 
+impl Default for Mode {
+    fn default() -> Self {
+        Mode::Normal(Default::default())
+    }
+}
+
 impl Mode {
     pub fn cursor_style(&self) -> cursor::SetCursorStyle {
         use cursor::SetCursorStyle as Style;
         match self {
-            Mode::Normal => Style::SteadyBlock,
+            Mode::Normal(_) => Style::SteadyBlock,
             Mode::Visual => Style::BlinkingBlock,
             Mode::Insert(_) => Style::BlinkingBar,
-            Mode::Command => Style::SteadyUnderScore,
+            Mode::Command(_) => Style::SteadyUnderScore,
         }
     }
 }
@@ -184,72 +203,137 @@ impl State {
     }
 
     pub fn draw(&self, out: &mut impl Write) -> Result<()> {
+        // begin update
+        let (cols, rows) = terminal::size()?;
         out.execute(terminal::BeginSynchronizedUpdate)?;
         out.execute(terminal::Clear(terminal::ClearType::All))?;
-        let lr_width = self.buffer.draw(self.scroll, out)?;
-        let cursor = self.buffer.clamped_cursor(self.cursor);
-        let col = cursor.column.saturating_sub(self.scroll.column) as u16;
-        let row = cursor.line.saturating_sub(self.scroll.line) as u16;
-        let col = col + lr_width as u16;
-        out.execute(cursor::MoveTo(col, row))?;
+
+        // draw status line
+        let mut set_cursor_pos = None;
+        let mut show_status_bar = false;
+
+        match &self.mode {
+            Mode::Command(CommandState { buf, cursor }) => {
+                let col = *cursor as u16 + 1;
+                let row = rows - 1;
+                out.execute(cursor::MoveTo(0, row))?;
+                write!(out, ":{}", buf)?;
+                set_cursor_pos = Some((col, row));
+                show_status_bar = true;
+            }
+            Mode::Normal(NormalState { error: Some(error) }) => {
+                out.execute(cursor::MoveTo(0, rows - 1))?;
+                write!(out, "{}", error)?;
+                show_status_bar = true;
+            }
+            _ => {}
+        }
+
+        // draw buffer
+        let buffer_rows = if show_status_bar { rows - 1 } else { rows };
+        let lr_width = self.buffer.draw(cols, buffer_rows, self.scroll, out)?;
+
+        // draw cursor
+        let cursor_pos = set_cursor_pos.unwrap_or_else(|| {
+            // calculate cursor position on buffer
+            let cursor = self.buffer.clamped_cursor(self.cursor);
+            let col = cursor.column.saturating_sub(self.scroll.column) as u16;
+            let row = cursor.line.saturating_sub(self.scroll.line) as u16;
+            let col = col + lr_width as u16;
+            (col, row)
+        });
+
+        out.execute(cursor::MoveTo(cursor_pos.0, cursor_pos.1))?;
         out.execute(self.mode.cursor_style())?;
+
+        // finish update
         out.execute(terminal::EndSynchronizedUpdate)?;
         Ok(())
     }
 
     pub fn on_event(&mut self, event: Event) {
-        match self.mode {
-            Mode::Normal => self.on_normal_event(event),
-            Mode::Command => self.on_command_event(event),
+        match &self.mode {
+            Mode::Normal(state) => self.on_normal_event(event, state.clone()),
+            Mode::Command(state) => self.on_command_event(event, state.clone()),
             Mode::Visual => self.on_visual_event(event),
-            Mode::Insert(state) => self.on_insert_event(event, state),
+            Mode::Insert(state) => self.on_insert_event(event, state.clone()),
         }
     }
 
-    fn on_normal_event(&mut self, event: Event) {
+    fn on_normal_event(&mut self, event: Event, mut state: NormalState) {
+        // reset the error from the last event
+        state.error = None;
+
         match event {
             Event::Key(KeyEvent { code, .. }) => match code {
                 KeyCode::Char('i') => {
-                    let state = InsertState { append: false }; 
+                    let state = InsertState { append: false };
                     self.mode = Mode::Insert(state);
                 }
                 KeyCode::Char('a') => {
-                    let state = InsertState { append: true, };
+                    let state = InsertState { append: true };
                     self.move_cursor(Direction::Right);
                     self.mode = Mode::Insert(state);
                 }
                 KeyCode::Char(':') => {
-                    self.mode = Mode::Command;
+                    self.mode = Mode::Command(Default::default());
                 }
                 KeyCode::Char('v') => {
                     self.mode = Mode::Visual;
                 }
-                KeyCode::Esc => {
-                    self.quit = true;
-                }
                 code => self.on_any_key(code),
             },
             event => self.on_any_event(event),
         }
+
+        match self.mode {
+            Mode::Normal(_) => self.mode = Mode::Normal(state),
+            _ => {}
+        }
     }
 
-    fn on_command_event(&mut self, event: Event) {
+    fn on_command_event(&mut self, event: Event, mut state: CommandState) {
         match event {
             Event::Key(KeyEvent { code, .. }) => match code {
-                KeyCode::Esc => {
-                    self.mode = Mode::Normal;
+                KeyCode::Char(c) => {
+                    state.buf.insert(state.cursor, c);
+                    state.cursor += 1;
                 }
-                code => self.on_any_key(code),
+                KeyCode::Backspace => {
+                    if state.cursor > 0 {
+                        state.cursor -= 1;
+                        state.buf.remove(state.cursor);
+                    }
+                }
+                KeyCode::Delete if state.cursor < state.buf.len() => {
+                    state.buf.remove(state.cursor);
+                }
+                KeyCode::Left if state.cursor > 0 => {
+                    state.cursor -= 1;
+                }
+                KeyCode::Right if state.cursor < state.buf.len() => {
+                    state.cursor += 1;
+                }
+                KeyCode::Enter => {
+                    // TODO add to command history
+                    let result = self.execute_command(&state.buf);
+                    let error = result.err();
+                    self.mode = Mode::Normal(NormalState { error });
+                    return;
+                }
+                code => return self.on_any_key(code),
             },
-            event => self.on_any_event(event),
+            event => return self.on_any_event(event),
         }
+
+        self.mode = Mode::Command(state);
     }
 
     fn on_visual_event(&mut self, event: Event) {
         match event {
             Event::Key(KeyEvent { code, .. }) => match code {
                 KeyCode::Esc => {
-                    self.mode = Mode::Normal;
+                    self.mode = Mode::default();
                 }
                 code => self.on_any_key(code),
             },
@@ -284,7 +368,8 @@ impl State {
                     if state.append {
                         self.move_cursor(Direction::Left);
                     }
-                    self.mode = Mode::Normal;
+
+                    self.mode = Mode::default();
                 }
                 code => self.on_any_key(code),
             },
@@ -304,7 +389,7 @@ impl State {
 
     fn on_any_key(&mut self, code: KeyCode) {
         match code {
-            KeyCode::Esc => self.mode = Mode::Normal,
+            KeyCode::Esc => self.mode = Mode::default(),
             KeyCode::Char('h') | KeyCode::Left => self.move_cursor(Direction::Left),
             KeyCode::Char('j') | KeyCode::Down => self.move_cursor(Direction::Down),
             KeyCode::Char('k') | KeyCode::Up => self.move_cursor(Direction::Up),
@@ -313,6 +398,15 @@ impl State {
         }
     }
 
+    fn execute_command(&mut self, command: &str) -> std::result::Result<(), String> {
+        match command {
+            "q" => self.quit = true,
+            command => return Err(format!("unrecognized command {:?}", command)),
+        }
+
+        Ok(())
+    }
+
     fn move_cursor(&mut self, direction: Direction) {
         self.buffer.move_cursor(&mut self.cursor, direction, true);