function getPaginationPageItems(dataArray, itemsPerPage: number, pageNumber: number){

    let p = pageNumber - 1,
        offset = p * itemsPerPage,
        limit = itemsPerPage
    ;

    return dataArray.slice(offset, offset + limit);
}

function getPaginationPageNumber(itemsPerPage: number, totalPageCount: number, pageNumber: number, pageOperation?: string){

    let p = pageNumber;

    if(pageOperation){

        switch(pageOperation){
            case "first":
                p = 1;
                break;
            case "prev":
                if(pageNumber > 1){
                    p = pageNumber - 1;
                }
                break;
            case "next":
                if(pageNumber < totalPageCount){
                    p = pageNumber + 1;
                }
                break;
            case "last":
                p = totalPageCount;
                break;
            default:
                break;
        }
    }

    return p;
}

export function getPaginationPage(dataArray, itemsPerPage=100, pageNumber = 1, pageOperation?: string){

    let totalPageCount = Math.ceil(dataArray.length / itemsPerPage),
        p = getPaginationPageNumber(itemsPerPage, totalPageCount, pageNumber, pageOperation)
    ;

    return getPaginationPageItems(dataArray, itemsPerPage, p);
}

export function getPaginationRange(totalPages, rangeSize = 7, pageNumber = 1){

    let p = pageNumber,
        n = pageNumber,
        rangeArray = [pageNumber]
    ;

    if(totalPages < rangeSize)
        rangeSize = totalPages;

    while(rangeArray.length < rangeSize){

        if (p > 1){
            p = p - 1;
            rangeArray.unshift(p);
        }


        if(n < totalPages){
            n = n + 1;
            rangeArray.push(n);
        }
    }

    return rangeArray;
}

export function getPaginationRangeSize(totalPages: number) : number {

    let rangeSize = 7;
    if(rangeSize > totalPages){
        rangeSize = totalPages;
    }

    return rangeSize;
}

export function copyPaginatedPayload(payload, pagination){

    let rows,
        payloadCopy = {
            data: undefined,
            hasError: payload.hasError,
            isInvalidated: payload.isInvalidated,
            updatedAt: new Date()
        };

    if(payload.data){

        rows = getPaginationPage(payload.data.rows, pagination.itemsPerPage, pagination.pageNumber);
        payloadCopy.data = {
            columns: payload.data.columns,
            rows: rows,
            query: payload.data.query
        };
    }

    return payloadCopy
}