/// <summary>
/// Remove an item from the <see cref="IPagedDataSet"/> with the specified position
/// </summary>
/// <param name="dataSet">The dataset to modify</param>
/// <param name="offset">The position to remove relative to the dataset's caret</param>
/// <returns></returns>
public static async Task RemoveAtOffset(this IRemovable removable, IPagedDataSet dataSet, int offset)
{
var pi = await dataSet.GetCurrentPageIndex();
var ps = await dataSet.GetPageSize();
var sel = await dataSet.GetSelector();
if (sel == null)
{
throw new InvalidOperationException("The paged data set does not support selecting items that is required for this method to work");
}
await removable.RemoveAt(dataSet, pi *ps + offset + await sel.GetCaretPosition());
}
/// <summary>
/// Add an item into the <see cref="IPagedDataSet"/> with the position relative to the <see cref="ISelectable"/>'s caret
/// </summary>
/// <param name="addable">The adder to perform</param>
/// <param name="item">The item to add</param>
/// <param name="dataSet">the dataset to modify</param>
/// <param name="offset">The position to add relative to the <see cref="IPagedDataSet{TItem, TResult}"/> caret</param>
/// <returns></returns>
public static async Task AddOffset(this IAddable addable, IPagedDataSet dataSet, object item, int offset)
{
var selector = await dataSet.GetSelector();
if (selector == null)
{
throw new InvalidOperationException("PagedDataSet must support selector to use this function!");
}
var pi = await dataSet.GetCurrentPageIndex();
var ps = await dataSet.GetPageSize();
var caret = await selector.GetCaretPosition();
await addable.Add(item, pi *ps + caret + offset);
}