/// <summary>
/// Finds the contiguous time series entry that is the most close to the lower interval boundary.
/// </summary>
/// <param name="interval">The interface to the lower interval boundary to find the lower entry.</param>
/// <param name="origin">The origin lower entry position to start the search from.</param>
/// <returns>The contiguous time series entry if found; otherwise, null.</returns>
public T FindLower(IInterval <DateTime> interval, T origin)
{
if (interval != null)
{
var entry = origin = origin ?? Head;
if (entry != null)
{
if (origin.Parent == this)
{
var reference = interval.IsLowerLimit(entry.Sample);
while (entry != null)
{
switch (reference)
{
case bool last when last:
entry = origin.Prev;
if (entry != null)
{
switch (interval.IsLowerLimit(entry.Sample))
{
case bool next when next: origin = entry; reference = next; break;
default: entry = null; break;
}
}
break;
case bool last when !last:
entry = origin = origin.Next;
if (entry != null)
{
switch (interval.IsLowerLimit(entry.Sample))
{
case bool next when !next: reference = next; break;
default: entry = null; break;
}
}
break;
}
}
if (origin != null && !interval.IsUpperLimit(origin.Sample))
{
origin = null;
}
}
else
{
throw new ArgumentException($"The origin time series entry is bound to other container: {origin}", nameof(origin));
}
}
return(origin);
}
else
{
throw new ArgumentNullException(nameof(interval));
}
}