2 files changed, 91 insertions, 37 deletions

diff --git a/src/main.rs b/src/main.rs
index 4c93cb7..3745553 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -114,6 +114,64 @@ impl State {
         write!(stdout(), "\x1b[{}G", self.cursor_col+1)?;
         return Ok(());
     }
+
+    fn up(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.cursor_row == 0 && self.row_start == 0 {
+            return Ok(());
+        }
+        if self.cursor_row == 0 {
+            self.row_start -= 1;
+            self.repaint_all()?;
+        } else {
+            self.cursor_row -= 1;
+        }
+        return Ok(());
+    }
+
+    fn down(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.row_start+self.cursor_row == self.buf.lines() {
+            return Ok(());
+        }
+        let size = term::size()?;
+        if self.cursor_row == usize::from(size.ws_row - 1) {
+            self.row_start += 1;
+            self.repaint_all()?;
+        } else {
+            self.cursor_row += 1;
+        }
+        return Ok(());
+    }
+
+    fn left(&mut self) -> Result<(), Box<dyn Error>> {
+        if self.cursor_col > self.line_cols {
+            self.cursor_col = self.line_cols;
+        }
+        if self.cursor_col == 0 && self.cursor_row == 0 {
+            return Ok(());
+        }
+        if self.cursor_col == 0 {
+            self.up()?;
+            self.repaint_line_full()?;
+            self.cursor_col = self.line_cols;
+        } else {
+            self.cursor_col -= 1;
+        }
+        return Ok(());
+    }
+
+    fn right(&mut self) -> Result<(), Box<dyn Error>> {
+        let size = term::size()?;
+        if self.cursor_col >= self.line_cols && self.cursor_row == usize::from(size.ws_row-1) {
+            return Ok(());
+        }
+        if self.cursor_col >= self.line_cols {
+            self.down()?;
+            self.cursor_col = 0;
+        } else {
+            self.cursor_col += 1;
+        }
+        return Ok(());
+    }
 }
 
 fn edit(file: &OsStr) -> Result<(), Box<dyn Error>> {
@@ -143,51 +201,34 @@ fn edit(file: &OsStr) -> Result<(), Box<dyn Error>> {
                 let _ = state.buf.save(Path::new(file));
             }
             Key::Up => {
-                if state.cursor_row == 0 && state.row_start == 0 {
-                    continue;
-                }
-                if state.cursor_row == 0 {
-                    state.row_start -= 1;
-                    let _ = state.repaint_all();
-                } else {
-                    state.cursor_row -= 1;
-                }
+                let _ = state.up();
                 let _ = state.repaint_line_full();
                 let _ = stdout().flush();
             }
             Key::Down => {
-                if state.row_start+state.cursor_row == state.buf.lines() {
-                    continue;
-                }
-                if state.cursor_row == usize::from(size.ws_row - 1) {
-                    state.row_start += 1;
-                    let _ = state.repaint_all();
-                } else {
-                    state.cursor_row += 1;
-                }
+                let _ = state.down();
                 let _ = state.repaint_line_full();
                 let _ = stdout().flush();
             }
             Key::Left => {
-                state.cursor_col = std::cmp::min(state.cursor_col, state.line_cols);
-                if state.cursor_col == 0 {
-                    state.cursor_row -= 1;
-                    let _ = state.repaint_line_full();
-                    state.cursor_col = state.line_cols;
-                    let _ = state.repaint_line_full();
-                } else {
-                    state.cursor_col -= 1;
-                    let _ = state.repaint_line_full();
-                }
+                let _ = state.left();
+                let _ = state.repaint_line_full();
                 let _ = stdout().flush();
             }
             Key::Right => {
-                if state.cursor_col >= state.line_cols {
-                    state.cursor_row += 1;
-                    state.cursor_col = 0;
+                let _ = state.right();
+                let _ = state.repaint_line_full();
+                let _ = stdout().flush();
+            }
+            Key::Char(b'\r') => {
+                state.buf = state.buf.insert(state.buf.line_idx(state.row_start+state.cursor_row)+state.line_offset, b'\n');
+                if state.cursor_row == usize::from(size.ws_row - 1) {
+                    state.row_start += 1;
                 } else {
-                    state.cursor_col += 1;
+                    state.cursor_row += 1;
                 }
+                state.cursor_col = 0;
+                let _ = state.repaint_all();
                 let _ = state.repaint_line_full();
                 let _ = stdout().flush();
             }
diff --git a/src/rope.rs b/src/rope.rs
index 11a030b..5454557 100644
--- a/src/rope.rs
+++ b/src/rope.rs
@@ -152,11 +152,24 @@ impl Rope {
                     new_buf[pos + 1..].copy_from_slice(&l.bytes()[pos..]);
                     return Rope::leaf(new_buf);
                 }
-                let mut buf_left = vec![0; pos + 1];
-                buf_left[..pos].copy_from_slice(&l.bytes()[..pos]);
-                buf_left[pos] = c;
-                let mut buf_right = Vec::new();
-                buf_right.extend_from_slice(&l.bytes()[pos..]);
+                let half = MAX_NODE_SIZE / 2;
+                let mut buf_left;
+                let mut buf_right;
+                if pos <= half {
+                    buf_left = vec![0; half+1];
+                    buf_right = vec![0; half];
+                    buf_left[..pos].copy_from_slice(&l.bytes()[..pos]);
+                    buf_left[pos] = c;
+                    buf_left[pos+1..].copy_from_slice(&l.bytes()[pos..half]);
+                    buf_right.copy_from_slice(&l.bytes()[half..]);
+                } else {
+                    buf_left = vec![0; half];
+                    buf_right = vec![0; half+1];
+                    buf_left.copy_from_slice(&l.bytes()[..half]);
+                    buf_right[..pos-half].copy_from_slice(&l.bytes()[half..pos]);
+                    buf_right[pos-half] = c;
+                    buf_right[pos-half+1..].copy_from_slice(&l.bytes()[pos..]);
+                }
                 return Rope::leaf(buf_left).concat(&Rope::leaf(buf_right));
             }
             Rope(Node::Branch(b)) => {