1 files changed, 578 insertions, 0 deletions
diff --git a/core/src/test/java/coffee/liz/abstractionengine/app/ui/editor/vim/VimEngineTest.java b/core/src/test/java/coffee/liz/abstractionengine/app/ui/editor/vim/VimEngineTest.java
new file mode 100644
index 0000000..31d823a
--- /dev/null
+++ b/core/src/test/java/coffee/liz/abstractionengine/app/ui/editor/vim/VimEngineTest.java
@@ -0,0 +1,578 @@
+package coffee.liz.abstractionengine.app.ui.editor.vim;
+
+import coffee.liz.abstractionengine.app.ui.editor.CursorStyle;
+import coffee.liz.abstractionengine.app.ui.editor.KeyEvent;
+import coffee.liz.abstractionengine.app.ui.editor.LineNumberMode;
+import coffee.liz.abstractionengine.app.ui.editor.EditorModifier;
+import com.badlogic.gdx.Input;
+import java.util.Set;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class VimEngineTest {
+	private static class FakeBuffer implements EditorBuffer {
+		private String text;
+		private int cursor;
+		private int selectionStart;
+		private int selectionEnd;
+		private boolean hasSelection;
+
+		private FakeBuffer(final String text, final int cursor) {
+			this.text = text;
+			this.cursor = Math.max(0, Math.min(cursor, text.length()));
+			this.selectionStart = 0;
+			this.selectionEnd = 0;
+			this.hasSelection = false;
+		}
+
+		@Override
+		public String getText() {
+			return text;
+		}
+
+		@Override
+		public void setText(final String text) {
+			this.text = text;
+			this.cursor = Math.max(0, Math.min(cursor, text.length()));
+			if (hasSelection) {
+				this.selectionStart = Math.max(0, Math.min(selectionStart, text.length()));
+				this.selectionEnd = Math.max(0, Math.min(selectionEnd, text.length()));
+				this.hasSelection = selectionStart != selectionEnd;
+			}
+		}
+
+		@Override
+		public int getCursorPosition() {
+			return cursor;
+		}
+
+		@Override
+		public void setCursorPosition(final int cursorPosition) {
+			this.cursor = Math.max(0, Math.min(cursorPosition, text.length()));
+		}
+
+		@Override
+		public int getCursorLine() {
+			int line = 0;
+			for (int i = 0; i < Math.min(cursor, text.length()); i++) {
+				if (text.charAt(i) == '\n') {
+					line++;
+				}
+			}
+			return line;
+		}
+
+		@Override
+		public int getLines() {
+			if (text.isEmpty()) {
+				return 1;
+			}
+			int lines = 1;
+			for (int i = 0; i < text.length(); i++) {
+				if (text.charAt(i) == '\n') {
+					lines++;
+				}
+			}
+			return lines;
+		}
+
+		@Override
+		public void moveCursorLine(final int line) {
+			final int targetLine = Math.max(0, Math.min(line, getLines() - 1));
+			final int currentLineStart = findLineStartByNumber(getCursorLine());
+			final int currentColumn = cursor - currentLineStart;
+			final int targetStart = findLineStartByNumber(targetLine);
+			final int targetEndExclusive = findLineEndExclusive(targetStart);
+			this.cursor = Math.min(targetStart + currentColumn, targetEndExclusive);
+		}
+
+		@Override
+		public void setSelectionEndpoints(final int selectionStart, final int cursorPosition) {
+			final int clampedSelectionStart = Math.max(0, Math.min(selectionStart, text.length()));
+			this.cursor = Math.max(0, Math.min(cursorPosition, text.length()));
+			this.selectionStart = Math.min(clampedSelectionStart, this.cursor);
+			this.selectionEnd = Math.max(clampedSelectionStart, this.cursor);
+			this.hasSelection = this.selectionStart != this.selectionEnd;
+		}
+
+		@Override
+		public void clearSelection() {
+			this.hasSelection = false;
+			this.selectionStart = 0;
+			this.selectionEnd = 0;
+		}
+
+		private int findLineStartByNumber(final int targetLine) {
+			int line = 0;
+			int index = 0;
+			while (line < targetLine && index < text.length()) {
+				if (text.charAt(index) == '\n') {
+					line++;
+				}
+				index++;
+			}
+			return index;
+		}
+
+		private int findLineEndExclusive(final int lineStart) {
+			int index = lineStart;
+			while (index < text.length() && text.charAt(index) != '\n') {
+				index++;
+			}
+			return index;
+		}
+	}
+
+	@Test
+	public void visualSelectionAndEscapeRestoresCursorToSelectionStart() {
+		final FakeBuffer buffer = new FakeBuffer("abcdef\n", 1);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'v', 'l', 'l');
+
+		assertEquals(1, buffer.selectionStart);
+		assertEquals(3, buffer.selectionEnd);
+		assertEquals(3, buffer.getCursorPosition());
+
+		controller.handleKeyDown(Input.Keys.ESCAPE);
+
+		assertFalse(buffer.hasSelection);
+		assertEquals(1, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void normalModeUsesBlockCursorAndRelativeLines() {
+		final FakeBuffer buffer = new FakeBuffer("abc", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		assertEquals(CursorStyle.BLOCK, controller.getRenderState().cursorStyle());
+		assertEquals(LineNumberMode.RELATIVE, controller.getRenderState().lineNumberMode());
+	}
+
+	@Test
+	public void insertModeUsesCaretAndAbsoluteLines() {
+		final FakeBuffer buffer = new FakeBuffer("abc", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'i');
+
+		assertEquals(CursorStyle.CARET, controller.getRenderState().cursorStyle());
+		assertEquals(LineNumberMode.ABSOLUTE, controller.getRenderState().lineNumberMode());
+	}
+
+	@Test
+	public void enteringVisualModeDoesNotMoveCursor() {
+		final FakeBuffer buffer = new FakeBuffer("abcdef", 2);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('v');
+
+		assertEquals(2, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void visualModeCanMoveLeftToShrinkSelection() {
+		final FakeBuffer buffer = new FakeBuffer("abcdef", 1);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'v', 'l', 'l');
+		assertEquals(1, buffer.selectionStart);
+		assertEquals(3, buffer.selectionEnd);
+
+		type(controller, 'h');
+		assertEquals(1, buffer.selectionStart);
+		assertEquals(2, buffer.selectionEnd);
+		assertEquals(2, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void visualBackwardSelectionIncludesAnchorCharacter() {
+		final FakeBuffer buffer = new FakeBuffer("abcdef", 3);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'v', 'h');
+
+		assertTrue(buffer.hasSelection);
+		assertEquals("cd", buffer.getText().substring(buffer.selectionStart, buffer.selectionEnd));
+	}
+
+	@Test
+	public void visualZeroMotionBackwardIncludesAnchorCharacter() {
+		final FakeBuffer buffer = new FakeBuffer("abcdef", 3);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'v', '0');
+
+		assertTrue(buffer.hasSelection);
+		assertEquals("abcd", buffer.getText().substring(buffer.selectionStart, buffer.selectionEnd));
+	}
+
+	@Test
+	public void visualModeGgMovesToStartAndKeepsSelection() {
+		final FakeBuffer buffer = new FakeBuffer("one\ntwo\nthree", 7);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'v', 'g', 'g');
+
+		assertEquals(0, buffer.getCursorPosition());
+		assertTrue(buffer.hasSelection);
+		assertEquals("one\ntwo\n", buffer.getText().substring(buffer.selectionStart, buffer.selectionEnd));
+	}
+
+	@Test
+	public void visualLineSelectionWorksWithShiftV() {
+		final FakeBuffer buffer = new FakeBuffer("one\ntwo\nthree\n", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'V', 'j');
+
+		assertTrue(buffer.hasSelection);
+		assertEquals(0, buffer.selectionStart);
+		assertEquals(8, buffer.selectionEnd);
+	}
+
+	@Test
+	public void visualLineJThenKUpdatesSelectionAndCursorLine() {
+		final FakeBuffer buffer = new FakeBuffer("one\ntwo\nthree\n", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'V', 'j');
+		assertEquals(0, buffer.selectionStart);
+		assertEquals(8, buffer.selectionEnd);
+
+		type(controller, 'k');
+		assertEquals(0, buffer.selectionStart);
+		assertEquals(4, buffer.selectionEnd);
+		assertEquals(0, buffer.getCursorLine());
+	}
+
+	@Test
+	public void visualLineModeDoesNotMoveCursorPastLastRealTrailingEmptyLine() {
+		final FakeBuffer buffer = new FakeBuffer("a\n\n\n", 2);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'V', 'j');
+
+		assertEquals(3, buffer.getCursorPosition());
+		assertEquals(2, buffer.getCursorLine());
+	}
+
+	@Test
+	public void openLineBelowPlacesCursorOnNewLine() {
+		final FakeBuffer buffer = new FakeBuffer("abc\ndef", 1);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('o');
+
+		assertEquals("abc\n\ndef", buffer.getText());
+		assertEquals(4, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void moveDownCanReachTrailingEmptyLines() {
+		final FakeBuffer buffer = new FakeBuffer("a\n\n\n", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'j', 'j', 'j');
+
+		assertEquals(3, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void openLineBelowOnTrailingEmptyLineMovesOneLineDown() {
+		final FakeBuffer buffer = new FakeBuffer("a\n\n\n", 2);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('o');
+
+		assertEquals("a\n\n\n\n", buffer.getText());
+		assertEquals(3, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void gMovesToLastNavigableCharacter() {
+		final FakeBuffer buffer = new FakeBuffer("alpha\nbeta\n", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('G');
+
+		assertEquals(9, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void ggMovesToTopOfFile() {
+		final FakeBuffer buffer = new FakeBuffer("alpha\nbeta\n", 9);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'g', 'g');
+
+		assertEquals(0, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void ddThenPastePlacesLineBelow() {
+		final FakeBuffer buffer = new FakeBuffer("a\nb", 2);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'd', 'd', 'p');
+
+		assertEquals("a\nb\n", buffer.getText());
+	}
+
+	@Test
+	public void yyThenPastePlacesLineBelow() {
+		final FakeBuffer buffer = new FakeBuffer("one\ntwo\n", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'y', 'y', 'p');
+
+		assertEquals("one\none\ntwo\n", buffer.getText());
+	}
+
+	@Test
+	public void dwDeletesWord() {
+		final FakeBuffer buffer = new FakeBuffer("one two", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'd', 'w');
+
+		assertEquals("two", buffer.getText());
+	}
+
+	@Test
+	public void dlDeletesExactlyOneCharacter() {
+		final FakeBuffer buffer = new FakeBuffer("abcd", 1);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'd', 'l');
+
+		assertEquals("acd", buffer.getText());
+	}
+
+	@Test
+	public void dlOnLastCharacterDeletesLastCharacter() {
+		final FakeBuffer buffer = new FakeBuffer("abcd", 3);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'd', 'l');
+
+		assertEquals("abc", buffer.getText());
+		assertEquals(2, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void undoRevertsLatestEdit() {
+		final FakeBuffer buffer = new FakeBuffer("abc", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('x');
+		assertEquals("bc", buffer.getText());
+
+		controller.handleKeyTyped('u');
+		assertEquals("abc", buffer.getText());
+		assertEquals(0, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void ctrlRRedoesAfterUndo() {
+		final FakeBuffer buffer = new FakeBuffer("abc", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('x');
+		controller.handleKeyTyped('u');
+		controller.handleKeyDown(Input.Keys.R, true);
+
+		assertEquals("bc", buffer.getText());
+	}
+
+	@Test
+	public void keyDownMotionReturnsSuppressTypedAndMovesCursor() {
+		final FakeBuffer buffer = new FakeBuffer("abc\ndef", 1);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		final boolean handled = controller.onKeyDown(new KeyEvent(Input.Keys.J, Set.of()));
+
+		assertTrue(handled);
+		assertEquals(5, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void keyDownShiftVStartsVisualLineMode() {
+		final FakeBuffer buffer = new FakeBuffer("one\ntwo\nthree\n", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		final boolean handled = controller.onKeyDown(new KeyEvent(Input.Keys.V, Set.of(EditorModifier.SHIFT)));
+
+		assertTrue(handled);
+		assertEquals("-- VISUAL LINE --", controller.getStatusText());
+	}
+
+	@Test
+	public void controlCharacterRRedoesAfterUndo() {
+		final FakeBuffer buffer = new FakeBuffer("abc", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('x');
+		controller.handleKeyTyped('u');
+		controller.handleKeyTyped((char) 18);
+
+		assertEquals("bc", buffer.getText());
+	}
+
+	@Test
+	public void searchAndNextFindMatches() {
+		final FakeBuffer buffer = new FakeBuffer("cat dog cat", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('/');
+		controller.handleKeyTyped('c');
+		controller.handleKeyTyped('a');
+		controller.handleKeyTyped('t');
+		controller.handleKeyTyped('\n');
+
+		assertEquals(8, buffer.getCursorPosition());
+
+		controller.handleKeyTyped('n');
+		assertEquals(0, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void countMotionAdvancesMultipleCharacters() {
+		final FakeBuffer buffer = new FakeBuffer("abcdef", 0);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, '3', 'l');
+
+		assertEquals(3, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void bStopsAtPunctuationWordBeforeSymbols() {
+		final FakeBuffer buffer = new FakeBuffer("let lambda = ", 12);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'b');
+
+		assertEquals(11, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void wStopsAtPunctuationWordBeforeSymbols() {
+		final FakeBuffer buffer = new FakeBuffer("let lambda = ", 4);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'w');
+
+		assertEquals(11, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void secondWFromPunctuationMovesToNextIdentifier() {
+		final FakeBuffer buffer = new FakeBuffer("let lambda = x", 4);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'w', 'w');
+
+		assertEquals(13, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void secondBFromPunctuationMovesToPreviousIdentifier() {
+		final FakeBuffer buffer = new FakeBuffer("let lambda = ", 12);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'b', 'b');
+
+		assertEquals(4, buffer.getCursorPosition());
+	}
+
+	@Test
+	public void appendMovesPastCurrentCharacter() {
+		final FakeBuffer buffer = new FakeBuffer("abc", 1);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('a');
+		insertCharacter(buffer, 'X');
+		controller.handleKeyDown(Input.Keys.ESCAPE);
+
+		assertEquals("abXc", buffer.getText());
+	}
+
+	@Test
+	public void appendAtEndOfLineInsertsAfterLastCharacter() {
+		final FakeBuffer buffer = new FakeBuffer("abc", 2);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		controller.handleKeyTyped('a');
+		insertCharacter(buffer, 'X');
+		controller.handleKeyDown(Input.Keys.ESCAPE);
+
+		assertEquals("abcX", buffer.getText());
+	}
+
+	@Test
+	public void verticalMoveUsesCurrentColumnNotStaleColumn() {
+		final FakeBuffer buffer = new FakeBuffer("12345678\n12\n12345678\n", 6);
+		final VimEngine controller = new VimEngine(buffer, status -> {
+		});
+
+		type(controller, 'j');
+		assertEquals(10, buffer.getCursorPosition());
+
+		type(controller, 'h');
+		assertEquals(9, buffer.getCursorPosition());
+
+		type(controller, 'k');
+		assertEquals(0, buffer.getCursorPosition());
+	}
+
+	private static void type(final VimEngine controller, final char... chars) {
+		for (final char character : chars) {
+			controller.handleKeyTyped(character);
+		}
+	}
+
+	private static void insertCharacter(final FakeBuffer buffer, final char character) {
+		final int cursor = buffer.getCursorPosition();
+		final String text = buffer.getText();
+		buffer.setText(text.substring(0, cursor) + character + text.substring(cursor));
+		buffer.setCursorPosition(cursor + 1);
+	}
+}