package dev.kske.undoredo.core;

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.*;

/**
 * @author Kai S. K. Engelbart
 * @since 0.0.1
 */
class ChangeManagerTest {

	ChangeManager<IntChange>	manager;
	IntWrapper					wrapper;
	IntChange					change;

	@BeforeEach
	void prepareChangeManager() {
		manager	= new UnlimitedChangeManager<>();
		wrapper	= new IntWrapper();
		change	= new IntChange(wrapper, 1);
	}

	/**
	 * Tests adding a change.
	 *
	 * @since 0.0.1
	 */
	@Test
	@Order(10)
	void testAddChange() {
		assertSame(0, wrapper.value);
		assertTrue(manager.addChange(change));
		assertSame(1, wrapper.value);
	}

	/**
	 * Tests whether identity changes are ignored when adding them to the change manager.
	 *
	 * @since 0.0.1
	 */
	@Test
	@Order(15)
	void testDiscardIdentity() {
		manager.addChange(change);
		assertFalse(manager.addChange(new IntChange(wrapper, 0)));
		assertSame(1, wrapper.value);
	}

	/**
	 * Tests retrieving the last change.
	 *
	 * @since 0.0.1
	 */
	@Test
	@Order(20)
	void testLastChange() {
		assertTrue(manager.getLastChange().isEmpty());
		manager.addChange(change);
		assertEquals(change, manager.getLastChange().get());
	}

	/**
	 * Tests the consistency of the change list.
	 *
	 * @since 0.0.1
	 */
	@Test
	@Order(30)
	void testGetChanges() {
		assertTrue(manager.getChanges().isEmpty());
		manager.addChange(change);
		assertSame(1, manager.getChanges().size());
		assertEquals(change, manager.getChanges().get(0));
	}

	/**
	 * Test undoing a change.
	 *
	 * @since 0.0.1
	 */
	@Test
	@Order(40)
	void testUndo() {
		assertFalse(manager.isUndoAvailable());
		assertFalse(manager.undo());
		manager.addChange(change);
		assertTrue(manager.isUndoAvailable());
		assertTrue(manager.undo());
		assertFalse(manager.isUndoAvailable());
		assertFalse(manager.undo());
		assertTrue(manager.getLastChange().isEmpty());
	}

	/**
	 * Tests redoing a change.
	 *
	 * @since 0.0.1
	 */
	@Test
	@Order(50)
	void testRedo() {
		assertFalse(manager.isRedoAvailable());
		assertFalse(manager.redo());
		manager.addChange(change);
		assertFalse(manager.isRedoAvailable());
		assertFalse(manager.redo());
		manager.undo();
		assertTrue(manager.isRedoAvailable());
		assertTrue(manager.redo());
		assertFalse(manager.isRedoAvailable());
		assertFalse(manager.redo());
		assertEquals(change, manager.getLastChange().get());
	}

	/**
	 * Tests whether the changes after the current index are discarded when adding a change.
	 *
	 * @since 0.0.1
	 */
	@Test
	@Order(55)
	void testDiscardDivergentHistory() {
		manager.addChange(change);
		manager.undo();
		assertTrue(manager.addChange(new IntChange(wrapper, 2)));
		assertFalse(manager.isRedoAvailable());
		assertSame(2, wrapper.value);
	}

	/**
	 * Tests marking a change.
	 *
	 * @since 0.0.1
	 */
	@Test
	@Order(60)
	void testMark() {
		assertTrue(manager.isAtMarkedIndex());
		manager.addChange(change);
		assertFalse(manager.isAtMarkedIndex());
		manager.mark();
		assertTrue(manager.isAtMarkedIndex());
		manager.undo();
		assertFalse(manager.isAtMarkedIndex());
	}
}