Compare current time with DateTime object

doc/31-Changelog.md

@@ -14,6 +14,8 @@ Released closed milestones can be found on [GitHub](https://github.com/Icinga/ic
 ### Enhancements
 
 * [#136](https://github.com/Icinga/icinga-powershell-framework/pull/136) Adds support to ignore empty check packages and return `Ok` instead of `Unknown` if `-IgnoreEmptyPackage` is set on `New-IcingaCheckPackage`
+* [#137](https://github.com/Icinga/icinga-powershell-framework/issues/137) Adds Cmdlet to compare a DateTime object with the current DateTime and return the offset as Integer in seconds
+
 
 ### Bugfixes
 

lib/core/tools/Compare-IcingaUnixTimeWithDateTime.psm1

@@ -0,0 +1,27 @@
+<#
+.SYNOPSIS
+    Compare-IcingaUnixTimeWithDateTime compares a DateTime-Object with the current DateTime and returns the offset between these values as Integer
+.DESCRIPTION
+    Compare-IcingaUnixTimeWithDateTime compares a DateTime-Object with the current DateTime and returns the offset between these values as Integer
+.PARAMETER DateTime
+    DateTime object you want to compare with the Universal Time
+.INPUTS
+    System.DateTime
+.OUTPUTS
+    System.Int64
+#>
+function Compare-IcingaUnixTimeWithDateTime() {
+    param (
+        [datetime]$DateTime
+    );
+
+    # This is when the computer starts counting time
+    $UnixEpochStart = (New-Object DateTime 1970, 1, 1, 0, 0, 0, ([DateTimeKind]::Utc));
+    # We convert the creation and current time to seconds
+    $CreationTime   = [long][System.Math]::Floor((($DateTime.ToUniversalTime() - $UnixEpochStart).Ticks / [timespan]::TicksPerSecond));
+    $CurrentTime    = Get-IcingaUnixTime;
+
+    # To find out, from the snapshot creation time to the current time, how many seconds are,
+    # you have to subtract from the (Current Time in s) the (Creation Time in s)
+    return ($CurrentTime - $CreationTime);
+}