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package org.egothor.stemmer;

import static org.junit.jupiter.api.Assertions.assertAll;
import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

@Tag("unit")
@Tag("core")
@Tag("stemmer")
@Tag("validation")
@DisplayName("WordTraversalDirection")
class WordTraversalDirectionTest {

    @Test
    @DisplayName("startIndex follows direction and validates negatives")
    void startIndexFollowsDirectionAndValidatesNegatives() {
        assertAll(() -> assertEquals(0, WordTraversalDirection.FORWARD.startIndex(3)),
                () -> assertEquals(2, WordTraversalDirection.BACKWARD.startIndex(3)),
                () -> assertEquals(-1, WordTraversalDirection.FORWARD.startIndex(0)),
                () -> assertThrows(IllegalArgumentException.class,
                        () -> WordTraversalDirection.BACKWARD.startIndex(-1)));
    }

    @Test
    @DisplayName("logicalIndex maps offsets in both directions")
    void logicalIndexMapsOffsetsInBothDirections() {
        assertAll(() -> assertEquals(0, WordTraversalDirection.FORWARD.logicalIndex(4, 0)),
                () -> assertEquals(3, WordTraversalDirection.BACKWARD.logicalIndex(4, 0)),
                () -> assertEquals(1, WordTraversalDirection.FORWARD.logicalIndex(4, 1)),
                () -> assertEquals(2, WordTraversalDirection.BACKWARD.logicalIndex(4, 1)),
                () -> assertThrows(IllegalArgumentException.class,
                        () -> WordTraversalDirection.FORWARD.logicalIndex(-1, 0)),
                () -> assertThrows(IllegalArgumentException.class,
                        () -> WordTraversalDirection.BACKWARD.logicalIndex(3, 3)));
    }

    @Test
    @DisplayName("traversal character conversion preserves and reverses as expected")
    void traversalCharacterConversionPreservesAndReversesAsExpected() {
        assertAll(() -> assertArrayEquals(new char[] { 'a', 'b', 'c' },
                WordTraversalDirection.FORWARD.toTraversalCharacters("abc")),
                () -> assertArrayEquals(new char[] { 'c', 'b', 'a' },
                        WordTraversalDirection.BACKWARD.toTraversalCharacters("abc")),
                () -> assertEquals("abc", WordTraversalDirection.FORWARD.traversalPathToLogicalKey("abc")),
                () -> assertEquals("cba", WordTraversalDirection.BACKWARD.traversalPathToLogicalKey("abc")),
                () -> assertThrows(NullPointerException.class,
                        () -> WordTraversalDirection.FORWARD.toTraversalCharacters(null)),
                () -> assertThrows(NullPointerException.class,
                        () -> WordTraversalDirection.BACKWARD.traversalPathToLogicalKey(null)));
    }
}
