Sharepoint list item status depending on previous item

I am using ajax call to get list items:

var oDataUrl = _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('tasks')/items?$select=ID,start,end,finished,Title,status,Modified,objects/Title&$expand=objects";
        $.ajax({
                url: oDataUrl,
                type: "GET",
                dataType: "json",
                headers: {
                        "accept": "application/json;odata=verbose"
                },
                success: successFunction,
                error: errorFunction
        });

I have a function, which calculates statuses

function calculateStatus(rowData) {
    var obj = rowData.objects.Title;
    var ID = rowData.ID;
    
    var today = moment();
    var startDate = moment(rowData.start);
    var endDate = moment(rowData.end);
    var finishedDate = moment(rowData.finished);
    var daysUntilend = endDate.diff(today, 'days');

    if (startDate.isBefore(today) && endDate.isSameOrAfter(today) && daysUntilend <= 14 && !finishedDate.isValid()) {
        return 'Approaching';
    } else if (startDate.isAfter(today) && !finishedDate.isValid() ) {
        return 'Not_started';
    } else if (startDate.isSameOrBefore(today) && endDate.isAfter(today) && !finishedDate.isValid()) {
        return 'In_Progress';
    } else if (startDate.isSameOrBefore(today) && endDate.isBefore(today) && !finishedDate.isValid()) {
        return 'Late';
    } else if (finishedDate.isValid() && finishedDate.isSameOrBefore(endDate)) {
        return 'Finished_on_time';
    } else if (finishedDate.isValid() && finishedDate.isAfter(endDate)) {
        return 'Finished_with_delay';
    } else {
        return '';
    }
}  

And displays it in Datatable column

{"mData": "status",
"render": function (data, type, row) {
          var calculatedStatus = calculateStatus(row);
          if (calculatedStatus === null) return "";
          else
          return "<label class='badge1 badge-" + calculatedStatus + "'>" + calculatedStatus + "</label>"
}
},

It all works fine, but I need to modify status checking logic, that it would check if PREVIOUS ITEM WITH THE SAME OBJECT has the finished date entered. If the finished date is entered (finished value not empty) check all conditions, but if the finished date is empty, calculate status of that item and then all OTHER ITEMS WITH THE SAME OBJECT would have status Not_started.

Example of Datatable statuses which I want to achieve: