package appeng.util;

import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.jupiter.api.Assertions.assertThrows;

import java.util.EnumSet;

import org.junit.jupiter.api.Test;

class EnumCyclerTest {

    @Test
    void testRotateEnumForwardWithOnlySomeValidOptions() {
        EnumSet<RotateTestEnum> validOptions = EnumSet.of(RotateTestEnum.A, RotateTestEnum.C, RotateTestEnum.E);
        assertThat(EnumCycler.rotateEnum(RotateTestEnum.A, false, validOptions)).isEqualTo(RotateTestEnum.C);
        assertThat(EnumCycler.rotateEnum(RotateTestEnum.C, false, validOptions)).isEqualTo(RotateTestEnum.E);
        assertThat(EnumCycler.rotateEnum(RotateTestEnum.E, false, validOptions)).isEqualTo(RotateTestEnum.A);
    }

    @Test
    void testRotateEnumBackwardsWithOnlySomeValidOptions() {
        EnumSet<RotateTestEnum> validOptions = EnumSet.of(RotateTestEnum.A, RotateTestEnum.C, RotateTestEnum.E);
        assertThat(EnumCycler.rotateEnum(RotateTestEnum.A, true, validOptions)).isEqualTo(RotateTestEnum.E);
        assertThat(EnumCycler.rotateEnum(RotateTestEnum.C, true, validOptions)).isEqualTo(RotateTestEnum.A);
        assertThat(EnumCycler.rotateEnum(RotateTestEnum.E, true, validOptions)).isEqualTo(RotateTestEnum.C);
    }

    /**
     * When there are no valid options, the function should reject the arguments.
     */
    @Test
    void testRotateEnumNoValidOptions() {
        assertThrows(IllegalArgumentException.class, () -> {
            EnumCycler.rotateEnum(TestEnum.A, false, EnumSet.noneOf(TestEnum.class));
        });
    }

    /**
     * When the current enum literal is not part of the valid options, it should just skip to the next valid option
     * instead.
     */
    @Test
    void testRotateEnumCurrentIsNotAValidOption() {
        assertThat(EnumCycler.rotateEnum(TestEnum.B, false, EnumSet.of(TestEnum.A))).isEqualTo(TestEnum.A);
        assertThat(EnumCycler.rotateEnum(TestEnum.B, true, EnumSet.of(TestEnum.A))).isEqualTo(TestEnum.A);
    }

    /**
     * When there's only one valid option, it should just rotate back to it.
     */
    @Test
    void testRotateEnumOnlyOneValidOption() {
        assertThat(EnumCycler.rotateEnum(TestEnum.A, false, EnumSet.of(TestEnum.A))).isEqualTo(TestEnum.A);
        assertThat(EnumCycler.rotateEnum(TestEnum.A, true, EnumSet.of(TestEnum.A))).isEqualTo(TestEnum.A);
    }

    @Test
    void testNext() {
        assertThat(EnumCycler.next(TestEnum.A)).isEqualTo(TestEnum.B);
        assertThat(EnumCycler.next(TestEnum.B)).isEqualTo(TestEnum.C);
        assertThat(EnumCycler.next(TestEnum.C)).isEqualTo(TestEnum.A);
        assertThat(EnumCycler.next(SingleLiteralEnum.A)).isEqualTo(SingleLiteralEnum.A);
    }

    @Test
    void testPrev() {
        assertThat(EnumCycler.prev(TestEnum.A)).isEqualTo(TestEnum.C);
        assertThat(EnumCycler.prev(TestEnum.B)).isEqualTo(TestEnum.A);
        assertThat(EnumCycler.prev(TestEnum.C)).isEqualTo(TestEnum.B);
        assertThat(EnumCycler.prev(SingleLiteralEnum.A)).isEqualTo(SingleLiteralEnum.A);
    }

    enum TestEnum {
        A,
        B,
        C
    }

    enum RotateTestEnum {
        A,
        B,
        C,
        D,
        E
    }

    enum SingleLiteralEnum {
        A
    }

}