Copy-Diff.ps1

 
<#
Verify contents between two tree structures and copy newer or missing files from the source to the destination
#>
　
function Global:Copy-Diff{
    param($SourcePath,$DestinationPath,[switch]$Informational,[switch]$Force)

    # Variable setup...
    # Verify paths & normalize path names
    $sourceExists = Test-Path $SourcePath
    $destinationExists  = Test-Path $DestinationPath
    If((-not $sourceExists) -or (-not $destinationExists)){Return}
    Else{
        $SourcePath = Get-Item $SourcePath | Select -ExpandProperty FullName
        $DestinationPath = Get-Item $DestinationPath | Select -ExpandProperty FullName
    }

    # Get tree of source path.  Add properties for source path and relative path to each item.
    $sourceTree = Get-ChildItem $SourcePath -Recurse -Force |
        Add-Member -MemberType ScriptProperty -Name 'RootLocation' -Force -PassThru `
                -Value {$SourcePath} |
        Add-Member -MemberType ScriptProperty -Name 'RelativePath' -Force -PassThru `
            -Value {$this.FullName -replace ('.*' + [regex]::escape($SourcePath + '\'))} |
        Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
            -Value {'Source object.'}  
    # Get tree of destination path.  Add properties for source path and relative path to each item. 
    $destinationTree = Get-ChildItem $DestinationPath -Recurse -Force |
        Add-Member -MemberType ScriptProperty -Name 'RootLocation' -Force -PassThru `
                -Value {$DestinationPath} |
        Add-Member -MemberType ScriptProperty -Name 'RelativePath' -Force -PassThru `
            -Value {$this.FullName -replace ('.*' + [regex]::escape($DestinationPath + '\'))} |
        Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
            -Value {'Destination object.'}  

    # declare work arrays
    $workInfoDestIsDifferent = @()
    $workCompareEqualFiles = @()
    $workCopyToDestination = @()

    $DiffTree = Compare $SourceTree $DestinationTree -IncludeEqual

　
    # Sort each diff object out into appropriate work arrays.
    ForEach ($diff in $DiffTree){
        Switch ($diff.SideIndicator){
            '=>' { # Present in destination only.
                $workInfoDestIsDifferent += $diff.InputObject |
                    Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
                        -Value {'Present only at destination.'}  
            }
            '<=' { # Present in source only.
                $workCopyToDestination += $diff.InputObject |
                    Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
                        -Value {'Present only at source.'}  
            }
            '==' { # Present in both source & destination.
                $workCompareEqualFiles += $diff.InputObject |
                    Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
                        -Value {'Present at both locations.'}  
            }
            default {Write-Error -Message ('Found crazy SideIndicator. File ' + $diff.InputObject.FullName)}
        } # End Switch
    } # End sorting foreach

　
    # Compare hashes of '==' objects
    ForEach ($sameObject in $workCompareEqualFiles) {
        # ***".InputObject" should always be the source item when side indicator is '=='

        If ($sameObject.PSIsContainer -eq $true){
            $sameObject = $sameObject |
                Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
                    -Value {'Folder present in both locations.'}
        }
        Else{
            # Get source object.  Add hash as property.
            $objSource = Get-Item $sameObject.FullName |
                Add-Member -MemberType ScriptProperty -Name 'FileHash' -Force -PassThru `
                    -Value {$this | Get-FileHash | Select -ExpandProperty Hash}

            # Get destination object.  Add hash as property.
            $uncObjDest = ($DestinationPath + '\' + $sameObject.RelativePath)
            $objDest = Get-Item $uncObjDest |
                Add-Member -MemberType ScriptProperty -Name 'FileHash' -Force -PassThru `
                    -Value {$this | Get-FileHash | Select -ExpandProperty Hash}
        
            # If hashes don't match...
            If ($objSource.FileHash -ne $objDest.FileHash) {
                # If destination object was modified most recently...
                If ($objSource.LastWriteTime -lt $objDest.LastWriteTime){
                    $workInfoDestIsDifferent += Get-Item $objDest.FullName |
                        Add-Member -MemberType ScriptProperty -Name 'RootLocation' -Force -PassThru `
                            -Value {$DestinationPath} |
                        Add-Member -MemberType ScriptProperty -Name 'RelativePath' -Force -PassThru `
                            -Value {$this.FullName -replace ('.*' + [regex]::escape($DestinationPath + '\'))} |
                        Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
                            -Value {'Present only at destination.'}
                }
                Else{
                    $workCopyToDestination += $sameObject |
                        Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
                            -Value {'Newer copy at source.'}  
                }
            } # End if hashed don't match
        } # End Else if
    } # End foreach hash compare

　
    # Prompt for write if -Force isn't used
    If ((-not $Force) -and (-not $Informational)){
        Write-Host 'Comparisons finished.  Begin copy/overwrite?'
        $userAnswer = Read-Host '(y/n)'

        Switch ($userAnswer){
            'y'{Write-Host 'Starting copy process...'}
            'n'{$Informational = $true}
            deafult{
                $Informational = $true
                Write-Host 'Invalid selection.  Returning information only.  (accpets only "y" or "n")'
                Pause
            }
        }
    }

　
    # Process copies or return information only
    If ($Informational){
        $returnArray = ($workCopyToDestination += $workInfoDestIsDifferent) |
            Select Name,FullName,Info,PSIsContainer,Length,LastWriteTime,RootLocation,RelativePath
        Return $returnArray
    }
    Else{
        $returnArray = @()
        ForEach ($workObject in $workCopyToDestination) {
            $from = ($workObject.FullName)
            $to = ($workObject.FullName -replace [regex]::Escape($workObject.RootLocation),$DestinationPath)

            # DO WORK!
            Copy-Item $from $to -Force > $null
            
            $newInfoText = ($workObject.Info + '  Object Copied.')
            $returnArray += $workObject |
                Add-Member -MemberType ScriptProperty -Name 'Info' -Force -PassThru `
                    -Value {$newInfoText}
        }

        $returnArray = $returnArray |
            Select Name,FullName,Info,PSIsContainer,Length,LastWriteTime
        Return $returnArray
    }
}