WIP

Author: Noam Lewis

src/main.rs

@@ -1,12 +1,17 @@
 extern crate crossterm;
 extern crate ratatui;
-use std::io;
+use std::{io, iter::FromIterator};
 
 use crossterm::event::{self, Event, KeyCode, KeyEvent, KeyModifiers};
-use ratatui::{DefaultTerminal, Frame};
+use ratatui::{
+    layout::Position,
+    text::{Line, Span, Text},
+    DefaultTerminal, Frame,
+};
 
 struct State {
-    text: Vec<char>,
+    lines: Vec<Vec<char>>,
+    cursor: Position,
 }
 
 impl State {
@@ -26,29 +31,104 @@ impl State {
                     modifiers: KeyModifiers::NONE,
                     ..
                 }) => self.insert_char(c),
+                Event::Key(KeyEvent {
+                    code: KeyCode::Backspace,
+                    modifiers: KeyModifiers::NONE,
+                    ..
+                }) => self.delete_prev_char(),
                 Event::Key(KeyEvent {
                     code: KeyCode::Enter,
                     modifiers: KeyModifiers::NONE,
                     ..
-                }) => self.insert_char('\n'),
+                }) => self.insert_line(),
+                Event::Key(KeyEvent {
+                    code: KeyCode::Left,
+                    modifiers: KeyModifiers::NONE,
+                    ..
+                }) => self.move_left(),
+                Event::Key(KeyEvent {
+                    code: KeyCode::Right,
+                    modifiers: KeyModifiers::NONE,
+                    ..
+                }) => self.move_right(),
+
                 _ => {}
             }
         }
     }
 
     fn insert_char(&mut self, c: char) {
-        self.text.push(c);
+        let line = self.lines.get_mut(self.cursor.y as usize);
+        match line {
+            None => {}
+            Some(v) => {
+                v.insert(self.cursor.x as usize, c);
+                self.cursor.x += 1;
+            }
+        }
+    }
+
+    fn delete_prev_char(&mut self) {
+        if self.cursor.x > 0 {
+            self.cursor.x -= 1;
+            let line = self.lines.get_mut(self.cursor.y as usize).unwrap();
+            line.remove(self.cursor.x as usize);
+        } else if self.cursor.y > 0 {
+            self.cursor.y -= 1;
+            let line = self.lines.remove((self.cursor.y + 1) as usize);
+            let prev_line = self.lines.get_mut(self.cursor.y as usize).unwrap();
+            self.cursor.x = prev_line.len() as u16;
+            prev_line.extend(line);
+        } else {
+            return;
+        }
+    }
+
+    fn insert_line(&mut self) {
+        self.cursor.y += 1;
+        self.cursor.x = 0;
+        self.lines.insert(self.cursor.y as usize, vec![]);
     }
 
     fn render(&self, frame: &mut Frame) {
-        let s: String = self.text.iter().collect();
-        frame.render_widget(s, frame.area());
+        fn to_line(l: &Vec<char>) -> Line<'_> {
+            let content = l.iter().collect::<String>();
+            Line::from(Span::raw(content))
+        }
+        frame.render_widget(
+            Text::from_iter(self.lines.iter().map(to_line)),
+            frame.area(),
+        );
+        frame.set_cursor_position(self.cursor);
+    }
+
+    fn move_left(&mut self) {
+        if self.cursor.x > 0 {
+            self.cursor.x -= 1;
+        } else if self.cursor.y > 0 {
+            self.cursor.y -= 1;
+            let prev_line = self.lines.get(self.cursor.y as usize).unwrap();
+            self.cursor.x = prev_line.len() as u16;
+        }
+    }
+
+    fn move_right(&mut self) {
+        let line = self.lines.get(self.cursor.y as usize).unwrap();
+        if self.cursor.x < line.len() as u16 {
+            self.cursor.x += 1;
+        } else if self.cursor.y + 1 < self.lines.len() as u16 {
+            self.cursor.y += 1;
+            self.cursor.x = 0;
+        }
     }
 }
 
 fn main() -> io::Result<()> {
     let terminal = ratatui::init();
-    let mut state: State = State { text: Vec::new() };
+    let mut state: State = State {
+        lines: vec![vec![]],
+        cursor: Position::new(0, 0),
+    };
     let result = state.run(terminal);
     ratatui::restore();
     result