@angelineuniverse/design/src/component/Pagination/controller.ts

Angeline Design UI Library

function range(start: number, end: number) {
    let length = end - start + 1;
    return Array.from({ length }, (_, idx) => idx + start);
}
export const dots = "......";
export function paginateController(totalPage: number,currentPage:number,siblingCount = 1) {
    // Pages count is determined as siblingCount + firstPage + lastPage + currentPage + 2*DOTS
    const totalPageNumbers = siblingCount + 5;

    /*
        If the number of pages is less than the page numbers we want to show in our
        paginationComponent, we return the range [1..totalPage]
    */
    if (totalPageNumbers >= totalPage) {
        return range(1, totalPage);
    }

    const leftSiblingIndex = Math.max(currentPage - siblingCount, 1);
    const rightSiblingIndex = Math.min(
        currentPage + siblingCount,
        totalPage
    );

    /*
        We do not want to show dots if there is only one position left 
        after/before the left/right page count as that would lead to a change if our Pagination
        component size which we do not want
    */
    const shouldShowLeftDots = leftSiblingIndex > 2;
    const shouldShowRightDots = rightSiblingIndex < totalPage - 2;

    const firstPageIndex = 1;
    const lastPageIndex = totalPage;

    if (!shouldShowLeftDots && shouldShowRightDots) {
        let leftItemCount = 3 + 2 * siblingCount;
        let leftRange = range(1, leftItemCount);

        return [...leftRange, dots, totalPage];
    }

    if (shouldShowLeftDots && !shouldShowRightDots) {
        let rightItemCount = 3 + 2 * siblingCount;
        let rightRange = range(
        totalPage - rightItemCount + 1,
        totalPage
        );
        return [firstPageIndex, dots, ...rightRange];
    }

    if (shouldShowLeftDots && shouldShowRightDots) {
        let middleRange = range(leftSiblingIndex, rightSiblingIndex);
        return [firstPageIndex, dots, ...middleRange, dots, lastPageIndex];
    }
    return true;
}