Calculates the worktime since month beginning

getWorkTime.ps1

#*=============================================================================
#* Script Name: getWorkTime
#* Based on True Percent Uptime, https://gallery.technet.microsoft.com/scriptcenter/True-Uptime-Calculator-5903cf22
#* Created: 20/02/2018
#* Authors: James Keeler, Mist Poryvaev
#*
#* Params:    [int]$Holidays - number of holidays, default is 0.
#*
#*=============================================================================
#* Purpose: Calculates the worktime since month beginning.
#*
#*
#*=============================================================================
#*
#* Note: call "Set-ExecutionPolicy Unrestricted  -Scope CurrentUser" before first run
#*
#*=============================================================================

    Param(          
        [int] $Holidays = 0
    )
    Process {
        $ComputerName = $env:computername
        [timespan]$uptime = 0

        $startingDate = Get-Date ((("01/" + (Get-Date).Month).ToString() + "/" + ((Get-Date).Year).ToString() + " 00:00:00"))
                            
        Write-Host -NoNewline "Retrieving shutdown and startup events from "
        Write-Host "$ComputerName from the month beginning..."
                            
        $events = Invoke-Command -ScriptBlock {`
            param($date) 
            Get-EventLog `
                -After ($date) `
                -Log System `
            | Where-Object { 
# kernel start
                ($_.EventID -eq 12 -AND $_.Source -eq "Microsoft-Windows-Kernel-General")`
                -OR `
                ($_.EventID -eq 1 -AND $_.Source -eq "Microsoft-Windows-Power-Troubleshooter")`
                -OR `
# kernel finish
                ($_.EventID -eq 13 -AND $_.Source -eq "Microsoft-Windows-Kernel-General")`
                -OR `
                ($_.EventID -eq 42 -AND $_.Source -eq "Microsoft-Windows-Kernel-Power") `
                -OR `
                ($_.EventID -eq 41 -AND $_.Source -eq "Microsoft-Windows-Kernel-Power")
            }
        } -ArgumentList $startingDate -ErrorAction Stop
                
        $sortedList = New-object system.collections.sortedlist
                
        ForEach($event in $events)
        {
            $sortedList.Add( $event.TimeGenerated, $event.EventID )
        } 

        $sortedList.Add($(Get-Date((Get-Date).toString("dd/MM/yy HH:mm:ss"))), 0 )
                
        For($i = 1; $i -lt $sortedList.Count; $i = $i + 2 )
        { 
            $day = $sortedList.Keys[$i].Day
            $duration = ($sortedList.Keys[$i] - $sortedList.Keys[$i-1])
            $uptime += $duration
                    
            Write-Output "$day `t$duration"
        } #end for item
                
        $NumberOfDays = 0
        For($i = 0; $i -lt (Get-Date).Day; $i++ )
        {
            if (0,6 -notcontains (Get-Date($startingDate)).AddDays($i).DayOfWeek)
            {
                $NumberOfDays++
            }
        }                
        $NumberOfDays -= $Holidays

        # Create a custom object to hold the results
        $results = "" | Select-Object `
            Name, `
            Days, `
            Hours_Total, `
            Hours_Per_Day
        $results.Name = $ComputerName 
        $results.Days = $NumberOfDays
        $results.Hours_Total = "{0:n0}" -f ($uptime.TotalMinutes/60)
        $results.Hours_Per_Day = (Get-Date("00:00:00")).AddMinutes($uptime.TotalMinutes/$NumberOfDays).toString("HH:mm")
                
        Write-Output $results | Format-List        

        Write-Output "Press any key to continue..."
        [void][System.Console]::ReadKey($true)

    } # end Process

#*=============================================================================
#* END OF SCRIPT
#*=============================================================================