Stirling-PDF/src/test/java/stirling/software/SPDF/controller/api/RearrangePagesPDFControllerTest.java

package stirling.software.SPDF.controller.api;

import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.CsvSource;

import java.util.Arrays;
import java.util.List;

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

class RearrangePagesPDFControllerTest {

    /**
     * Tests the behavior of the oddEvenMerge method when there are no pages in the document.
     */
    @Test
    void oddEvenMerge_noPages() {
        RearrangePagesPDFController sut = new RearrangePagesPDFController();
        int totalNumberOfPages = 0;

        List<Integer> newPageOrder = sut.oddEvenMerge(totalNumberOfPages);

        assertNotNull(newPageOrder, "Returning null instead of page order list");
        assertEquals(List.of(), newPageOrder, "Page order doesn't match");
    }

    /**
     * Tests the behavior of the oddEvenMerge method when there are odd total pages in the document.
     */
    @Test
    void oddEvenMerge_oddTotalPageNumber() {
        RearrangePagesPDFController sut = new RearrangePagesPDFController();
        int totalNumberOfPages = 5;

        List<Integer> newPageOrder = sut.oddEvenMerge(totalNumberOfPages);

        assertNotNull(newPageOrder, "Returning null instead of page order list");
        assertEquals(Arrays.asList(0,3,1,4,2), newPageOrder, "Page order doesn't match");
    }

    /**
     * Tests the behavior of the oddEvenMerge method when there are even total pages in the document.
     */
    @Test
    void oddEvenMerge_evenTotalPageNumber() {
        RearrangePagesPDFController sut = new RearrangePagesPDFController();
        int totalNumberOfPages = 6;

        List<Integer> newPageOrder = sut.oddEvenMerge(totalNumberOfPages);

        assertNotNull(newPageOrder, "Returning null instead of page order list");
        assertEquals(Arrays.asList(0,3,1,4,2,5), newPageOrder, "Page order doesn't match");
    }

    /**
     * Tests the behavior of the oddEvenMerge method with multiple test cases of multiple pages.
     * @param totalNumberOfPages The total number of pages in the document.
     * @param expectedPageOrder The expected order of the pages after rearranging.
     */
    @ParameterizedTest
    @CsvSource({
            "1, '0'",
            "2, '0,1'",
            "3, '0,2,1'",
            "4, '0,2,1,3'",
            "5, '0,3,1,4,2'",
            "6, '0,3,1,4,2,5'",
            "10, '0,5,1,6,2,7,3,8,4,9'",
            "50, '0,25,1,26,2,27,3,28,4,29,5,30,6,31,7,32,8,33,9,34,10,35," +
                    "11,36,12,37,13,38,14,39,15,40,16,41,17,42,18,43,19,44,20,45,21,46," +
                    "22,47,23,48,24,49'"
    })
    void oddEvenMerge_multi_test(int totalNumberOfPages, String expectedPageOrder) {
        RearrangePagesPDFController sut = new RearrangePagesPDFController();

        List<Integer> newPageOrder = sut.oddEvenMerge(totalNumberOfPages);

        assertNotNull(newPageOrder, "Returning null instead of page order list");
        assertEquals(Arrays.stream(expectedPageOrder.split(",")).map(Integer::parseInt).toList(), newPageOrder, "Page order doesn't match");
    }
}