###############################################################################
#
# BackupVMs.ps1 - alchemy.nodomain.net VM backup script
#
# Copyright 2017 - Josh Moyer <JMoyer@NODOMAIN.NET>, all rights reserved.
#
###############################################################################

# Known Issues:
# - If VMs are using VMDKs in a different directory then the VMDK might get skipped
# - No verbose logging
# - Will start a VM even if it was stopped when the backup started

# Test cases:
# - Disk failure
# - Disk full
# - Disk offline
# - Disk online
# - Disk read only
# - Disk subsystem configuration changes
# - Multiple backup disks connected
# - Multiple script instances started
# - No admin rights
# - VM missing
# - VM powered on 
# - VM powered off

# -5: failed to identify a backup drive
Function CopyVMs () {
    $BackupDrive = ReturnDrive
    $BackupPath = "\"
    $VMDrive = "C:"
    $VMRun = "C:\Program Files (x86)\VMware\VMware Workstation\vmrun.exe"
    $VMPath = "\Virtual Machines\"
    $VMs = "nexus","bliss","mettle","joy","freedom","liberty"
    
    If ($BackupDrive -lt 0) {Return -5} 

    $VMs | ForEach-Object -Process {
        Echo "- Copying $_."
        $DestinationPath = "$BackupDrive$BackupPath"
        $SourcePath = "$VMDrive$VMPath$_"
        $VMXPath = "$VMDrive$VMPath$_\$_.vmx"
        Start-Process $VMRun "suspend `"$VMXPath`"" -NNW -Wait 
        Remove-Item "$DestinationPath$_" -Force -Recurse
        # If robocopy a:\ b:\ /e /b /copyall /sl /r:0 /tee
        Copy-Item "$SourcePath" "$DestinationPath" -Force -Recurse
        Start-Process $VMRun "start `"$VMXPath`"" -NNW -Wait
    }
}

# -4: offline disks was not equal to 1
Function OnlineDrive () {
    $Drives = "list disk" | diskpart | Where {$_ -match "Disk ([0-9]+)\s+Offline"}
    If ($Matches.Count -ne 2) {Return -4}
    $Drive = $Matches[1]
    "select disk $Drive`nattributes disk clear readonly`nonline disk" | diskpart | Out-Null
    $Drive
}

# -3: failed to offline backup drive
Function OfflineDrive ($Drive) {
    "select disk $Drive`noffline disk" | diskpart | Out-Null
}

# -2: backup drive signature not found
Function ReturnDrive () {
$IDFile = "vmbackupdrive.id"
$Drives = Get-WmiObject -Query "SELECT * from win32_logicaldisk WHERE DriveType = 3”
$Drives | ForEach-Object -Process {
            $Drive = $_.DeviceID
            $Candidate = Get-ChildItem "$Drive\$IDFile" -ErrorAction Ignore
            If ($Candidate) {Return}
            }
    If ($Drive -lt 0) {return -2}
    $Drive
}

# -1: failure in main
Function Main () {
    Echo "Bringing drive online."
    $Drive = OnlineDrive
    If ($Drive -lt 0) {Return $Drive}
    Echo "Copying VMs."
    CopyVMs
    Echo "Taking drive offline."
    OfflineDrive($Drive)
}

Main