A way to standardize logging.

Write-Log.ps1

Function Write-Log {
    <#
    .SYNOPSIS
        Standard Event Log entry writer
    .DESCRIPTION
        Writes an entry to the local system's Event Log in a predictable and dependable way.
    .INPUTS
        None
    .OUTPUTS
        None
    .NOTES
        Version:        1.0
        Author:         Spyingwind
        License:        MIT or use how you like
        Creation Date:  3/16/2017
        Updated Date:   5/27/2003
        Changes:
            Initial Event Log Writer
            Implimented file logging
    .EXAMPLE
        Write-Log -Method Console -Level Info -Message "Did task" -EventID 0
        Logs to console
    .EXAMPLE
        Write-Log -Level Info -Message "Did task" -EventID 0
        Logs to Event Log
    .EXAMPLE
        Write-Log -Level Warn -Message "Did bad task" -EventID 1
        Logs to Event Log with warning
    .EXAMPLE
        Write-Log -Method LogFile -File "C:\Temp\MyLog.log" -Level Info -Message "Did task" -EventID 0
        Logs to a log file with event id
    .EXAMPLE
        Write-Log -Method LogFile -File "C:\Temp\MyLog.log" -Level Info -Message "Did task"
        Logs to a log file
    .EXAMPLE
        Write-Log -Method LogFile -File "C:\Temp\MyLog.log" -Level Info -Message "Did task" -UseUtc
        Logs to a log file with dates in UTC time
    #>
    Param(
        [Parameter(Mandatory = $true, ParameterSetName = "EventLog")]
        [Parameter(Mandatory = $true, ParameterSetName = "Console")]
        [Parameter(Mandatory = $true, ParameterSetName = "LogFile")]
        [ValidateNotNullOrEmpty()]
        [string]
        # The information that you wish to convey to the log
        $Message,
        [Parameter(Mandatory = $true, ParameterSetName = "EventLog")]
        [Parameter(Mandatory = $true, ParameterSetName = "Console")]
        [Parameter(Mandatory = $false, ParameterSetName = "LogFile")]
        [ValidateNotNullOrEmpty()]
        [ValidateCount(0, 65535)]
        [int]
        # The Event ID of this log entry
        $EventID,
        [Parameter(Mandatory = $false, ParameterSetName = "EventLog")]
        [Parameter(Mandatory = $false, ParameterSetName = "Console")]
        [Parameter(Mandatory = $false, ParameterSetName = "LogFile")]
        [ValidateSet("Error", "Warn", "Warning", "Info", "Information", "Fatal", "Debug", "Verbose")]
        [Alias("EntryType")]
        [string]
        # Sets the what type of entry this is
        $Level = "Info",
        [Parameter(Mandatory = $false, ParameterSetName = "EventLog")]
        [Parameter(Mandatory = $false, ParameterSetName = "Console")]
        [Parameter(Mandatory = $false, ParameterSetName = "LogFile")]
        [ValidateSet("EventLog", "Console", "LogFile")]
        [string]
        # Method of logging
        $Method = "EventLog",
        [Parameter(Mandatory = $true, ParameterSetName = "LogFile")]
        [ValidateScript(
            {
                if ($(Split-Path -Path $_ -Parent | Test-Path)) { $true }
                else { throw "Folder ($(Split-Path -Path $_ -Parent)) does not exist." }
            }
        )]
        [string]
        # Log file to write to
        $File,
        [Parameter(Mandatory = $true, ParameterSetName = "LogFile")]
        [switch]
        # Uses UTC time
        $UseUtc
    )

    switch ($Method) {
        'EventLog' {
            $Message = "{0}: {1}" -f $Level, $Message
            switch ($Level) {
                'Error' { Write-EventLog -LogName "Application" -Source $ScriptName -EntryType FailureAudit -EventId $EventID -Message $Message }
                'Warn' { Write-EventLog -LogName "Application" -Source $ScriptName -EntryType Warning -EventId $EventID -Message $Message }
                'Warning' { Write-EventLog -LogName "Application" -Source $ScriptName -EntryType Warning -EventId $EventID -Message $Message }
                'Info' { Write-EventLog -LogName "Application" -Source $ScriptName -EntryType Information -EventId $EventID -Message $Message }
                'Information' { Write-EventLog -LogName "Application" -Source $ScriptName -EntryType Information -EventId $EventID -Message $Message }
                'Fatal' { Write-EventLog -LogName "Application" -Source $ScriptName -EntryType Error -EventId $EventID -Message $Message }
                'Debug' { Write-EventLog -LogName "Application" -Source $ScriptName -EntryType Information -EventId $EventID -Message $Message }
                'Verbose' { Write-EventLog -LogName "Application" -Source $ScriptName -EntryType SuccessAudit -EventId $EventID -Message $Message }
            }
        }
        'Console' {
            switch ($Level) {
                'Error' { Write-Error -Message "$Message" -ErrorId $EventID }
                'Warn' { Write-Warning "Warning $EventID : $Message" }
                'Warning' { Write-Warning "Warning $EventID : $Message" }
                'Info' { Write-Information "$EventID : $Message" -ForegroundColor White }
                'Information' { Write-Information "$EventID : $Message" -ForegroundColor White }
                'Fatal' { Write-Error -Message "$Message" -ErrorId $EventID }
                'Debug' { Write-Debug -Message "$EventID : $Message" }
                'Verbose' { Write-Verbose "$EventID : $Message" }
            }
        }
        'LogFile' {
            if (-not $(Test-Path -Path $File -ErrorAction SilentlyContinue)) {
                try {
                    New-Item $File -ErrorAction Stop
                }
                catch {
                    Write-Error -Message "Could not create file." -TargetObject $File
                }
            }
            $LogLevel = switch ($Level) {
                'Error' { "[Error]" }
                'Warn' { "[Warn]" }
                'Warning' { "[Warn]" }
                'Info' { "[Info]" }
                'Information' { "[Info]" }
                'Fatal' { "[Fatal]" }
                'Debug' { "[Debug]" }
                'Verbose' { "[Verbose]" }
            }

            $Date = if ($UseUtc) {
                $(Get-Date).ToUniversalTime().ToString("o")
            }
            else {
                $(Get-Date).ToString("o")
            }

            if ($EventID) {
                "{0} {1}: {2,9} {3:n} {4}" -f $Date, $ScriptName, $LogLevel, $EventID, $Message | Add-Content -Path $File
            }
            else {
                "{0} {1}: {2,9} {3}" -f $Date, $ScriptName, $LogLevel, $Message | Add-Content -Path $File
            }
        }
    }
}