Automate VM shutdown/startup with timezone offset

Test.ps1

    $TimezoneOffset = -6

    $currentTime = (Get-Date).ToUniversalTime()
    Write-Output "Runbook started"
    Write-Output "Current UTC/GMT time [$($currentTime.ToString("dddd, yyyy MMM dd HH:mm:ss"))] will be checked against schedules"
	  Write-Output "A TimeZone offset of [$TimezoneOffset] will be used in comparisons"
	
    $TimeRange = "29 January"
    	
    # Initialize variables
    $rangeStart, $rangeEnd, $parsedDay = $null
    $currentTime = (Get-Date).ToUniversalTime()
    $midnight = $currentTime.AddDays(1).Date	        

    try
    {
        # Parse as range if contains '->'
        if($TimeRange -like "*->*")
        {
            $timeRangeComponents = $TimeRange -split "->" | foreach {$_.Trim()}
            if($timeRangeComponents.Count -eq 2)
            {
                $rangeStart = (Get-Date $timeRangeComponents[0]).AddHours(-1 * $TimezoneOffset)                
                $rangeEnd = (Get-Date $timeRangeComponents[1]).AddHours(-1 * $TimezoneOffset)

                # Check for crossing midnight
                if($rangeStart -gt $rangeEnd)
                {
                    # If current time is between the start of range and midnight tonight, interpret start time as earlier today and end time as tomorrow
                    if($currentTime -ge $rangeStart -and $currentTime -lt $midnight)
                    {
                        $rangeEnd = $rangeEnd.AddDays(1)
                    }
                    # Otherwise interpret start time as yesterday and end time as today   
                    else
                    {
                        $rangeStart = $rangeStart.AddDays(-1)
                    }
                }
            }
            else
            {
                Write-Error "`tWARNING: Invalid time range format. Expects valid .Net DateTime-formatted start time and end time separated by '->'" 
            }
        }
        # Otherwise attempt to parse as a full day entry, e.g. 'Monday' or 'December 25' 
        else
        {
            # If specified as day of week, check if today            
            if([System.DayOfWeek].GetEnumValues() -contains $TimeRange)
            {
                $todayOffset = (Get-Date).ToUniversalTime().AddHours($TimezoneOffset)
                Write-Output "Today offset: $todayOffset"
                
                if($TimeRange -eq $todayOffset.DayOfWeek)
                {
                    $rangeStart = $todayOffset.Date.AddHours(-1 * $TimezoneOffset)
                }
                else
                {
                    # Skip detected day of week that isn't today
                }
            }
            # Otherwise attempt to parse as a date, e.g. 'December 25'
            else
            {
                $rangeStart = (Get-Date $TimeRange).ToUniversalTime().AddHours(-1 * $TimezoneOffset)
            }

            if($rangeStart -ne $null)
            {
                $rangeEnd = $rangeStart.AddHours(23).AddMinutes(59).AddSeconds(59) # End of the same day
            }
            
            Write-Output $rangeStart
            Write-Output $rangeEnd
        }
    }
    catch
    {
        # Record any errors and return false by default
        Write-Error "`tWARNING: Exception encountered while parsing time range. Details: $($_.Exception.Message). Check the syntax of entry, e.g. '<StartTime> -> <EndTime>', or days/dates like 'Sunday' and 'December 25'"   
        return $false
    }

    # Check if current time falls within range			
    if($currentTime -ge $rangeStart -and $currentTime -le $rangeEnd)
    {
        return $true
    }
    else
    {
        return $false
    }
	  
    Write-Output "Runbook completed"