#Requires -Version 4.0

<#
.SYNOPSIS
    Quickly creates some linked clones
.DESCRIPTION
    Quickly creates one or more linked clone virtual machines on a VMWare 
    vSphere vCenter platform, mostly to be used for development / test purposes
.PARAMETER ServerName
    Specifies the IP address or the DNS name of the vSphere server to which you
    want to connect. You can also specify a server by providing its IPv6
    address enclosed in square brackets, for example [fe80::56ff:feb0:74bd].
.PARAMETER Credential
    Specifies a PSCredential object that contains credentials for
    authenticating with the server.
.PARAMETER VMName
    Specifies the name of the virtual machine which will be worked on.
.PARAMETER SnapshotName
    Specifies the virtual machine's shapshot name. THe snapshot must exist.
.PARAMETER Server
    Specifies a VIServer object to use. You can create a VIServer object using
    VMWare's Connect-VIServer cmdlet.
.PARAMETER Snapshot
    Specifies a Snapshot object to use. Can be created using VMWare's
    Get-Snapshot cmdlet.
.PARAMETER LinkedClone
    Specifies the linked clone(s) which will be created. Can be a string which
    will be used as vm name, an array containing strings, a hashtable 
    containing a key named 'Name' [String] and optionally a key named 'Spec'
    [hashtable]  or an array containing hashtables. Example:

    @(
        @{
            'Name'='adc01'
            'Spec'=@{'MemoryGB'=4;'NumCpu'=2;'CoresPerSocket'=1}
        };
        @{
            'Name'='adc02'
            'Spec'=@{'MemoryGB'=4;'NumCpu'=2;'CoresPerSocket'=1}
        };

    )

    The Spec-key takes every parameter which VMWare's Set-VM cmdlet also takes,
    but be very careful using the -VM and -VMHost parameters as they might have
    strange consequences.
.NOTES
    Author: kurator | lagerhaus128.ch
    Revision 0:
        Initial revision
.EXAMPLE
    Create-LinkedClone -ServerName 172.16.0.10 -Credential $cred -VMName 'mg01'  -SnapshotName '20170607 raw linked clone base' -LinkedClone 'mg02'
    Creates a single linked clone without modifying the vm's specs.
.EXAMPLE
    Create-LinkedClone -ServerName 172.16.0.10 -Credential $cred -VMName 'mg01'  -SnapshotName '20170607 raw linked clone base' -LinkedClone @('mg03','mg04')
    Creates a two linked clone without modifying the vm's specs.
.EXAMPLE
    Create-LinkedClone -ServerName 172.16.0.10 -Credential $cred -VMName 'mg01'  -SnapshotName '20170607 raw linked clone base' -LinkedClone @{'Name'='ap01';'Spec'=@{'MemoryGB'=8}}
    Creates a single linked clone and modifies the vm's memory size to 8GB.
.EXAMPLE
    Create-LinkedClone -ServerName 172.16.0.10 -Credential $cred -VMName 'mg01'  -SnapshotName '20170607 raw linked clone base' -LinkedClone @(@{'Name'='adc01';'Spec'=@{'MemoryGB'=4;'NumCpu'=2;'CoresPerSocket'=1}};@{'Name'='adc02';'Spec'=@{'MemoryGB'=4;'NumCpu'=2;'CoresPerSocket'=1}};@{'Name'='ap02';'Spec'=@{'MemoryGB'=10;'NumCpu'=2;'CoresPerSocket'=2}})
    Creates a two linked clone and modifies the vm's specs.
#>
Function Create-LinkedClone {
    [CmdletBinding()] param(
        [Parameter(ParameterSetName="Strings",Mandatory="true")][String]$ServerName,
        [Parameter(ParameterSetName="Strings",Mandatory="true")][PSCredential]$Credential,
        [Parameter(ParameterSetName="Strings",Mandatory="true")][String]$VMName,
        [Parameter(ParameterSetName="Strings",Mandatory="true")][String]$SnapshotName,
        [Parameter(ParameterSetName="Objects",Mandatory="true")][VMware.VimAutomation.ViCore.Impl.V1.VIServerImpl]$Server,
        [Parameter(ParameterSetName="Objects",Mandatory="true")][VMware.VimAutomation.ViCore.Impl.V1.VM.SnapshotImpl]$Snapshot,
        [Parameter(Mandatory="true")]$LinkedClone
    )
    Try {
        Import-Module VMware.VimAutomation.Core
        if($PSCmdlet.ParameterSetName -eq 'Strings') {
            $Server = Connect-VIServer -Server $ServerName -NotDefault -Credential $Credential
            $Snapshot = (Get-Snapshot -Name $SnapshotName -Server $Server -VM (Get-VM -Name $VMName -Server $Server))
        }
        switch($LinkedClone.GetType()) {
            ('').GetType() {$LinkedClone = @(@{'Name' = $LinkedClone})}
            (@{}).GetType() {$LinkedClone = @($LinkedClone)}
        }
        $LinkedClone | ForEach-Object {
            if($_.GetType() -eq ('').GetType()) {
                $_ = @{'Name' = $_}
            }
            $VMNew = New-VM -Name $_.Name -VM $Snapshot.VM -LinkedClone -ReferenceSnapshot $Snapshot -ResourcePool $Snapshot.VM.ResourcePool -Server $Server -Location $VM.Folder
            if($_.Spec) {
                $Spec = $_.Spec 
                $Spec.Keys | ForEach-Object {
                    Invoke-Expression -Command ('Set-VM -VM $VMNew -Confirm:$false -{0} {1}' -f $_, $Spec.$_ )
                }
                Remove-Variable Spec
            }
        }
        Remove-Variable VMNew
        if($PSCmdlet.ParameterSetName -eq 'Strings') {
            Disconnect-VIServer -Server $Server -Confirm:$false
            Remove-Variable Snapshot,Server
        }
    } Catch {
        Write-Error $_.Exception.Message
    }
}
Export-ModuleMember -Function Create-LinkedClone