3 files changed, 23 insertions, 5 deletions

diff --git a/src/main.rs b/src/main.rs
index 54b644d..139b4c3 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -140,6 +140,7 @@ impl State {
         } else {
             self.cursor_row -= 1;
         }
+        self.repaint_line_full()?;
         return Ok(());
     }
 
@@ -154,6 +155,7 @@ impl State {
         } else {
             self.cursor_row += 1;
         }
+        self.repaint_line_full()?;
         return Ok(());
     }
 
@@ -166,11 +168,11 @@ impl State {
         }
         if self.cursor_col == 0 {
             self.up()?;
-            self.repaint_line_full()?;
             self.cursor_col = self.line_cols;
         } else {
             self.cursor_col -= 1;
         }
+        self.repaint_line_full()?;
         return Ok(());
     }
 
@@ -185,6 +187,7 @@ impl State {
         } else {
             self.cursor_col += 1;
         }
+        self.repaint_line_full()?;
         return Ok(());
     }
 }
@@ -217,21 +220,31 @@ fn edit(file: &OsStr) -> Result<(), Box<dyn Error>> {
             }
             Key::Up => {
                 let _ = state.up();
-                let _ = state.repaint_line_full();
                 let _ = stdout().flush();
             }
             Key::Down => {
                 let _ = state.down();
-                let _ = state.repaint_line_full();
                 let _ = stdout().flush();
             }
             Key::Left => {
                 let _ = state.left();
-                let _ = state.repaint_line_full();
                 let _ = stdout().flush();
             }
             Key::Right => {
                 let _ = state.right();
+                let _ = stdout().flush();
+            }
+            Key::Backspace => {
+                if state.row_start == 0 && state.cursor_row == 0 && state.cursor_col == 0 {
+                    continue;
+                }
+                let offset = state.buf.line_idx(state.row_start+state.cursor_row)+state.line_offset;
+                let need_refresh_all = state.cursor_col == 0;
+                let _ = state.left();
+                state.buf = state.buf.slice(0, state.buf.floor_char_boundary(offset-1)).concat(&state.buf.slice(offset, state.buf.len()));
+                if need_refresh_all {
+                    let _ = state.repaint_all();
+                }
                 let _ = state.repaint_line_full();
                 let _ = stdout().flush();
             }
diff --git a/src/rope.rs b/src/rope.rs
index 7d00dcd..25da1fc 100644
--- a/src/rope.rs
+++ b/src/rope.rs
@@ -124,7 +124,7 @@ impl Rope {
         }
     }
 
-    fn concat(&self, other: &Rope) -> Rope {
+    pub fn concat(&self, other: &Rope) -> Rope {
         if self.len() == 0 {
             return other.clone();
         }
diff --git a/src/term.rs b/src/term.rs
index c23dc4e..8f44b23 100644
--- a/src/term.rs
+++ b/src/term.rs
@@ -65,12 +65,14 @@ pub enum Key {
     Down,
     Left,
     Right,
+    Backspace,
     Char(u8),
 }
 
 pub fn read_key(stdin: &mut Stdin) -> Result<Key, Box<dyn Error>> {
     const CTRL_Q: u8 = 17;
     const CTRL_S: u8 = 19;
+    const BACKSPACE: u8 = 127;
     const ESC: u8 = 27;
 
     loop {
@@ -82,6 +84,9 @@ pub fn read_key(stdin: &mut Stdin) -> Result<Key, Box<dyn Error>> {
         if buf[0] == CTRL_S {
             return Ok(Key::CtrlS);
         }
+        if buf[0] == BACKSPACE {
+            return Ok(Key::Backspace);
+        }
         if buf[0] != ESC {
             return Ok(Key::Char(buf[0]));
         }