import org.junit.jupiter.api.Disabled;

import org.junit.jupiter.api.DisplayName;

import org.junit.jupiter.api.Test;

import java.util.List;

import static org.assertj.core.api.Assertions.assertThat;

import static org.assertj.core.api.Assertions.assertThatExceptionOfType;

public class PovTest {

@Test

@DisplayName("Results in the same tree if the input tree is a singleton")

public void testFromPovGivenSingletonTree() {

Tree tree = Tree.of("x");

Tree expected = Tree.of("x");

assertThat(tree.fromPov("x")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Can reroot a tree with a parent and one sibling")

public void testFromPovGivenTreeWithParentAndOneSibling() {

Tree tree = Tree.of("parent",

List.of(Tree.of("x"),

Tree.of("sibling")));

Tree expected = Tree.of("x",

List.of(Tree.of("parent",

List.of(Tree.of("sibling")))));

assertThat(tree.fromPov("x")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Can reroot a tree with a parent and many siblings")

public void testFromPovGivenTreeWithParentAndManySibling() {

Tree tree = Tree.of("parent",

List.of(Tree.of("x"),

Tree.of("a"),

Tree.of("b"),

Tree.of("c")));

Tree expected = Tree.of("x",

List.of(Tree.of("parent",

List.of(Tree.of("a"),

Tree.of("b"),

Tree.of("c")))));

assertThat(tree.fromPov("x")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("an reroot a tree with new root deeply nested in the tree")

public void testFromPovGivenTreeWithNewRootDeeplyNested() {

Tree tree = Tree.of("level-0",

List.of(Tree.of("level-1",

List.of(Tree.of("level-2",

List.of(Tree.of("level-3",

List.of(Tree.of("x")))))))));

Tree expected = Tree.of("x",

List.of(Tree.of("level-3",

List.of(Tree.of("level-2",

List.of(Tree.of("level-1",

List.of(Tree.of("level-0")))))))));

assertThat(tree.fromPov("x")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Moves children of the new root to same level as former parent")

public void testFromPovGivenMovesChildrenOfNewRootToSameLevelAsFormerParent() {

Tree tree = Tree.of("parent",

List.of(Tree.of("x",

List.of(Tree.of("kid-0"),

Tree.of("kid-1")))));

Tree expected = Tree.of("x",

List.of(Tree.of("kid-0"),

Tree.of("kid-1"),

Tree.of("parent")));

assertThat(tree.fromPov("x")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Can reroot a complex tree with cousins")

public void testFromPovGivenComplexTreeWithCousins() {

Tree tree = Tree.of("grandparent",

List.of(Tree.of("parent",

List.of(Tree.of("x",

List.of(Tree.of("kid-0"),

Tree.of("kid-1"))),

Tree.of("sibling-0"),

Tree.of("sibling-1"))),

Tree.of("uncle",

List.of(Tree.of("cousin-0"),

Tree.of("cousin-1")))));

Tree expected = Tree.of("x",

List.of(Tree.of("kid-1"),

Tree.of("kid-0"),

Tree.of("parent",

List.of(Tree.of("sibling-0"),

Tree.of("sibling-1"),

Tree.of("grandparent",

List.of(Tree.of("uncle",

List.of(Tree.of("cousin-0"),

Tree.of("cousin-1")))))))));

assertThat(tree.fromPov("x")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Errors if target does not exist in a singleton tree")

public void testFromPovGivenNonExistentTargetInSingletonTree() {

Tree tree = Tree.of("x");

assertThatExceptionOfType(UnsupportedOperationException.class)

.isThrownBy(() -> tree.fromPov("nonexistent"))

.withMessage("Tree could not be reoriented");

}

@Disabled("Remove to run test")

@Test

@DisplayName("Errors if target does not exist in a larger tree")

public void testFromPovGivenNonExistentTargetInLargeTree() {

Tree tree = Tree.of("parent",

List.of(Tree.of("x",

List.of(Tree.of("kid-0"),

Tree.of("kid-1"))),

Tree.of("sibling-0"),

Tree.of("sibling-1")));

assertThatExceptionOfType(UnsupportedOperationException.class)

.isThrownBy(() -> tree.fromPov("nonexistent"))

.withMessage("Tree could not be reoriented");

}

@Disabled("Remove to run test")

@Test

@DisplayName("Can find path to parent")

public void testPathToCanFindPathToParent() {

Tree tree = Tree.of("parent",

List.of(Tree.of("x"),

Tree.of("sibling")));

List<String> expected = List.of("x", "parent");

assertThat(tree.pathTo("x", "parent")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

public void testPathToCanFindPathToSibling() {

Tree tree = Tree.of("parent",

List.of(Tree.of("a"),

Tree.of("x"),

Tree.of("b"),

Tree.of("c")));

List<String> expected = List.of("x", "parent", "b");

assertThat(tree.pathTo("x", "b")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Can find path to cousin")

public void testPathToCanFindPathToCousin() {

Tree tree = Tree.of("grandparent",

List.of(Tree.of("parent",

List.of(Tree.of("x",

List.of(Tree.of("kid-0"),

Tree.of("kid-1"))),

Tree.of("sibling-0"),

Tree.of("sibling-1"))),

Tree.of("uncle",

List.of(Tree.of("cousin-0"),

Tree.of("cousin-1")))));

List<String> expected = List.of("x", "parent", "grandparent", "uncle", "cousin-1");

assertThat(tree.pathTo("x", "cousin-1")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Can find path not involving root")

public void testPathToCanFindPathNotEnvolvingRoot() {

Tree tree = Tree.of("grandparent",

List.of(Tree.of("parent",

List.of(Tree.of("x"),

Tree.of("sibling-0"),

Tree.of("sibling-1")))));

List<String> expected = List.of("x", "parent", "sibling-1");

assertThat(tree.pathTo("x", "sibling-1")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Can find path from nodes other than x")

public void testPathToCanFindPathFromNodesOtherThanX() {

Tree tree = Tree.of("parent",

List.of(Tree.of("a"),

Tree.of("x"),

Tree.of("b"),

Tree.of("c")));

List<String> expected = List.of("a", "parent", "c");

assertThat(tree.pathTo("a", "c")).isEqualTo(expected);

}

@Disabled("Remove to run test")

@Test

@DisplayName("Errors if destination does not exist")

public void testPathWhenDestinationDoesNotExist() {

Tree tree = Tree.of("parent",

List.of(Tree.of("x",

List.of(Tree.of("kid-0"),

Tree.of("kid-1"))),

Tree.of("sibling-0"),

Tree.of("sibling-1")));

assertThatExceptionOfType(UnsupportedOperationException.class)

.isThrownBy(() -> tree.pathTo("x", "nonexistent"))

.withMessage("No path found");

}

@Disabled("Remove to run test")

@Test

@DisplayName("Errors if source does not exist")

public void testPathWhenSourceDoesNotExist() {

Tree tree = Tree.of("parent",

List.of(Tree.of("x",

List.of(Tree.of("kid-0"),

Tree.of("kid-1"))),

Tree.of("sibling-0"),

Tree.of("sibling-1")));

assertThatExceptionOfType(UnsupportedOperationException.class)

.isThrownBy(() -> tree.pathTo("nonexistent", "x"))

.withMessage("No path found");

}

}