### Copyright (c) 2014, Svendsen Tech
### Author: Joakim Svendsen
### Get-MountPointData v1.1

# "Change history": 1.0 -> 1.1 = -Credential, -PromptForCredentials and -NoFormat (the latter allows math operations)

# Convert from one device ID format to another.
function Get-DeviceIDFromMP {
    
    param([Parameter(Mandatory=$true)][string] $VolumeString,
          [Parameter(Mandatory=$true)][string] $Directory)
    
    if ($VolumeString -imatch '^\s*Win32_Volume\.DeviceID="([^"]+)"\s*$') {
        # Return it in the wanted format.
        $Matches[1] -replace '\\{2}', '\'
    }
    else {
        # Return a presumably unique hashtable key if there's no match.
        "Unknown device ID for " + $Directory
    }
    
}

function Get-MountPointData {
    
    param(
        [Parameter(Mandatory=$true)][string[]] $ComputerName,
        [switch] $PromptForCredentials,
        [System.Management.Automation.Credential()] $Credential = [System.Management.Automation.PSCredential]::Empty,
        [switch] $IncludeRootDrives,
        [switch] $NoFormat
    )
    
    foreach ($Computer in $ComputerName) {
        
        $WmiHash = @{
            ComputerName = $Computer
            ErrorAction  = 'Stop'
        }

        if ($PromptForCredentials -and $Credential.Username) {
            Write-Warning "You specified both -PromptForCredentials and -Credential. Prompting overrides."
        }
        if ($PromptForCredentials) {
            $WmiHash.Credential = Get-Credential
        }
        elseif ($Credential) {
            $WmiHash.Credential = $Credential
        }

        try {
            
            # Collect mount point device IDs and populate a hashtable with IDs as keys
            $MountPointData = @{}
            Get-WmiObject @WmiHash -Class Win32_MountPoint | 
                Where {
                    if ($IncludeRootDrives) {
                        $true
                    }
                    else {
                        $_.Directory -NotMatch '^\s*Win32_Directory\.Name="[a-z]:\\{2}"\s*$'
                    }
                } |
                ForEach-Object {
                    $MountPointData.(Get-DeviceIDFromMP $_.Volume $_.Directory) = $_.Directory
            }
            
            $Volumes = Get-WmiObject @WmiHash -Class Win32_Volume | Where {
                    if ($IncludeRootDrives) { $true } else { -not $_.DriveLetter }
                } | 
                Select-Object Label, Caption, Capacity, FreeSpace, FileSystem, DeviceID, @{n='Computer';e={$Computer}}
            
        }
        
        catch {
            
            Write-Error "${Computer}: Terminating WMI error (skipping): $_"
            continue
            
        }
        
        if (-not $Volumes) {
            Write-Error "${Computer}: No mount points found. Skipping."
            continue
        }
        
        $Volumes | ForEach-Object {
            
            if ($MountPointData.ContainsKey($_.DeviceID)) {
                
                if ($_.Capacity) { $PercentFree = $_.FreeSpace*100/$_.Capacity }
                else { $PercentFree = 0 }
                
                $_ | Select-Object Computer, Label, Caption, FileSystem, @{n='Size (GB)';e={$_.Capacity/1GB}},
                    @{n='Free space';e={$_.FreeSpace/1GB}}, @{n='Percent free';e={$PercentFree}}
                
            }
            
        } | Sort-Object -Property 'Percent free', @{Descending=$true;e={$_.'Size (GB)'}}, Label, Caption |
            Select-Object -Property $(if ($NoFormat) {
                @{n='ComputerName'; e={$_.Computer}},
                @{n='Label';        e={$_.Label}},
                @{n='Caption';      e={$_.Caption}},
                @{n='FileSystem';   e={$_.FileSystem}},
                @{n='Size (GB)';    e={$_.'Size (GB)'}},
                @{n='Free space';   e={$_.'Free space'}},
                @{n='Percent free'; e={$_.'Percent free'}}
            }
            else {
                @{n='ComputerName'; e={$_.Computer}},
                @{n='Label';        e={$_.Label}},
                @{n='Caption';      e={$_.Caption}},
                @{n='FileSystem';   e={$_.FileSystem}},
                @{n='Size (GB)';    e={$_.'Size (GB)'.ToString('N')}},
                @{n='Free space';   e={$_.'Free space'.ToString('N')}},
                @{n='Percent free'; e={$_.'Percent free'.ToString('N')}}
           })
        
    }
    
}