Created
August 19, 2016 23:37
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| <# | |
| Author: Joshua Barton | |
| Version: 1.0 | |
| Version History: | |
| Purpose: Get last expected reboot time for a server that reboots on Nth Xday of the Month | |
| #> | |
| function Get-MonthlyReboot () { | |
| param( | |
| [ValidateSet(1,2,3,4,'Last')] | |
| $Nth, | |
| [ValidateSet('Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday')] | |
| [string] | |
| $Day, | |
| [ValidatePattern('[0-9]:[0-9][0-9]$')] | |
| [string] | |
| $Time | |
| ) | |
| $CurrentDate = Get-Date | |
| # Check for last Xday of the month. Step backwards until found. | |
| if ($Nth -eq 'Last') { | |
| $DaysInMonth = [DateTime]::DaysInMonth($CurrentDate.Year, $CurrentDate.Month) | |
| $LastDayOfMonth = Get-Date -Day $DaysInMonth -Date $Time | |
| do { | |
| $DateFound = $LastDayOfMonth | |
| # Find First Iteration of Day | |
| while ($DateFound.DayOfWeek -ne $Day) { | |
| $DateFound = $DateFound.AddDays(-1) | |
| } | |
| # Set back a month in case $DateFound -gt $CurrentDate | |
| $LastDayOfMonth = $LastDayOfMonth.AddMonths(-1) | |
| } until ($DateFound -le $CurrentDate) | |
| # Check for Nth Xday of the month. Step forward until found. | |
| } else { | |
| $FirstDayOfMonth = Get-Date -Day 1 -Date $Time | |
| $WeekNum = 1 | |
| do { | |
| $DateFound = $FirstDayOfMonth | |
| # Find First Iteration of Day | |
| while ($DateFound.DayOfWeek -ne $Day) { | |
| $DateFound = $DateFound.AddDays(1) | |
| } | |
| # Find Expected Iteration of Day | |
| while ($WeekNum -ne $Nth) { | |
| $DateFound = $DateFound.AddDays(7) | |
| $WeekNum++ | |
| } | |
| # Set back a month in case $ExpectedDate -gt $CurrentDate | |
| $FirstDayOfMonth = $FirstDayOfMonth.AddMonths(-1) | |
| $WeekNum = 1 | |
| } until ($DateFound -le $CurrentDate) | |
| } | |
| $DateFound | |
| } |
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