Add ability to advance lines

src/app/lyrics.rs

@@ -22,6 +22,21 @@ impl Lyrics {
 		self.lines[line_no].set_content(new_content);
 	}
 
+	pub fn advance_line(&mut self, current_line: usize) {
+		let new_line = current_line + 1;
+
+		if new_line == self.lines.len() {
+			self.lines.push(Lyric::new())
+		}
+
+		self.lines.get_mut(new_line)
+			.expect("Unexpected .advance_line with index beyond # of lines")
+			.select();
+		self.lines.get_mut(current_line)
+			.unwrap()
+			.deselect();
+	}
+
 	pub fn view(&mut self) -> Element<Message> {
 		self.lines.iter_mut()
 			.enumerate()
@@ -52,10 +67,19 @@ impl Lyric {
 			&self.value,
 			move|new_value| Message::LyricChanged { line_no, new_value },
 		)
+			.on_submit(Message::LineAdvanced(line_no))
 			.into()
 	}
 
 	pub fn set_content(&mut self, content: String) {
 		self.value = content;
 	}
+
+	pub fn select(&mut self) {
+		self.state.focus();
+	}
+
+	pub fn deselect(&mut self) {
+		self.state.unfocus();
+	}
 }

src/app/mod.rs

@@ -21,6 +21,7 @@ pub enum Message {
 		line_no: usize,
 		new_value: String,
 	},
+	LineAdvanced(usize),
 }
 
 impl Sandbox for DelyriumApp {
@@ -42,6 +43,9 @@ impl Sandbox for DelyriumApp {
 			Message::LyricChanged { line_no, new_value } => {
 				self.lyrics_component.update_line(new_value, line_no);
 			},
+			Message::LineAdvanced(current_line) => {
+				self.lyrics_component.advance_line(current_line);
+			}
 		}
 	}