Private/Test-DateDifference.ps1
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function Test-DateDifference([array]$date,[datetime]$compare) { # The Test-DateDifference function is used to compare a series of dates against a desired date to find the closest matching date/time in the past # Thus, a date/time that is one hour older than the request would be valid, but one hour in the future would not be valid # $date = An array of ISO 8601 style dates (e.g. YYYY-MM-DDTHH:MM:SSZ) # $compare = A single ISO 8601 style date to compare against the $date array # A simple hashtable is created to compare each date value against one another # The value that is closest to 0 (e.g. least distance away from the $compare date) is stored # A "placeholder" value of 999999999 is used to find the first value that is greater than 0 # Otherwise, the date of $null is returned meaning no match $datematrix = @{ date = $null value = 9999999999 } foreach ($_ in $date) { # The $c is just a check variable used to hold the total number of days between the current $date item and the $compare value $c = (New-TimeSpan -Start $_ -End $compare).TotalDays # Should we find a value that is less than the existing winning value, and it's 0 or greater, store it # Note: 0 would be a perfect match (e.g. 0 days different between what we found and what the user wants in $compare) # Note: Negative values indicate a future (e.g. supply yesterday for $compare but finding a $date from today) if ($c -lt $datematrix.value -and $c -ge 0) { $datematrix.date = $_ $datematrix.value = [int]$c } } return $datematrix.date } |