Pagination for graph data

[Sciederrick]

• Use the graph midpoint to calculate the current xLabel (represents the day(date) as a two digit string - dd)
• Find the corresponding id
• Use the id to calculate the index for the extreme left(prevKey) and extreme right (nextKey)
• If either of this values is closer to the beginning or end of the cachedGraphValues based on some threshold, then
• fetch more values to the left or to the right and shift a similar length of values from the cachedGraphValues such that cachedGraphValues always has a constant size.
• Use prevKey or nextKey to fetch the subsequent batch of data of a specified size (pageSize).