# In order to run script for SharePoint 2019 OnPremise set $SharePointVersion = "2019".
$SharePointVersion = "Online" #Possible options: Online, 2019

Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy RemoteSigned

function New-Folder-Name( [Microsoft.SharePoint.Client.ListItem]$mainItem, [Microsoft.SharePoint.Client.ListItem]$folder ){    
    $newFolderName = $mainItem["Title"] + "-" + $mainItem.Id
    #Replaces special symbols that are not allowed to be used in folder name
    $newFolderName = $newFolderName -replace '[:*"?|%#<>\\/]|^~|(_vti_)|^(?:aux|con|clock\$|nul|prn|com[1-9]|lpt[1-9]|forms)$/gi', '_'
    return $newFolderName
}

function Install-PnP-Module{   
	if($SharePointVersion -eq "Online"){
		Write-Host "Checking for PnP.Powershell module..."
		if (-not (Get-Module -ListAvailable -Name PnP.Powershell)) 
		{
			Write-Host "Installing PnP.Powershell module..."
			Install-Module -Name PnP.Powershell -Scope CurrentUser -Repository PSGallery -AllowClobber        
			Write-Host "PnP.Powershell module has been installed"
		}
		else{
			Write-Host "PnP.Powershell module is installed"
		}
		Import-Module -Name PnP.Powershell
	}
	else{
		Write-Host "Checking for SharePointPnPPowerShell2019 module..."
		if (-not (Get-Module -ListAvailable -Name SharePointPnPPowerShell2019)) 
		{
			Write-Host "Installing SharePointPnPPowerShell2019 module..."
			Install-Module -Name SharePointPnPPowerShell2019 -Scope CurrentUser -Repository PSGallery -AllowClobber        
			Write-Host "SharePointPnPPowerShell2019 module has been installed"
		}
		else{
			Write-Host "SharePointPnPPowerShell2019 module is installed"
		}
		Import-Module -Name SharePointPnPPowerShell2019
	}
}

function Connect-SharePoint-Site{
    $SiteURL = Read-Host 'Enter Site URL' # Site URL which contains main list and sub-library
    Write-Host ("connecting to '"+$SiteURL+"' site")
    
    if($SharePointVersion -eq "Online"){
	    $connection = Connect-PnPOnline -Url $SiteURL -ReturnConnection -Interactive -ForceAuthentication
    }
    else{
        $cred = Get-Credential -Message "Enter credentials to SharePoint site"
	    $connection = Connect-PnPOnline -Url $SiteURL -ReturnConnection -Credentials $cred
    }

    if( !$connection ){
        Write-Error -Message "Failed to connect to SharePoint site." -ErrorAction Continue
        Read-Host -Prompt "Press Enter to quit..."
        exit 0
    }
}

function Process-Folders($folders){
    $filterByIDs = $folders | ForEach-Object {'<Value Type="Integer">'+$_[$LookupFieldName].LookupId+'</Value>'}
    $camlFilter = "<View Scope='Recursive'>
                        <Query>
                            <Where> 
                                <In>
                                    <FieldRef Name='ID'/>
                                    <Values>"+$filterByIDs+"</Values>                            
                                </In>
                            </Where>
                        </Query>
                    </View>"
    $mainitems = Get-PnPListItem -List $mainList.Id -Query $camlFilter
    
	if($SharePointVersion -eq "Online"){
		$batch = New-PnPBatch
		foreach ($folder in $folders) {
			[Microsoft.SharePoint.Client.ListItem]$mainItem = $mainitems | Where-Object -FilterScript { $_.Id -eq $folder[$LookupFieldName].LookupId }
			if(!$mainitem){
				Write-Error -Message ("Cannot load main item for '"+$folder.FileLeafRef+"' folder. Main Item ID: " + $folder[$LookupFieldName].LookupId ) -ErrorAction Continue
			}
			else{
				[String]$folderName = New-Folder-Name -mainItem $mainItem -folder $folder
				Write-Host $folder["FileLeafRef"] --> $folderName            
				Set-PnPListItem -List $lib.Id -Identity $folder.Id -Values @{ "FileLeafRef" = $folderName } -UpdateType SystemUpdate -Batch $batch
			}
		}
		Invoke-PnPBatch -Batch $batch
	}
	else{
		foreach ($folder in $folders) {
			[Microsoft.SharePoint.Client.ListItem]$mainItem = $mainitems | Where-Object -FilterScript { $_.Id -eq $folder[$LookupFieldName].LookupId }
			if(!$mainitem){
				Write-Error -Message ("Cannot load main item for '"+$folder.FileLeafRef+"' folder. Main Item ID: " + $folder[$LookupFieldName].LookupId ) -ErrorAction Continue
			}
			else{
				[String]$folderName = New-Folder-Name -mainItem $mainItem -folder $folder
				Write-Host $folder["FileLeafRef"] --> $folderName            
				Set-PnPListItem -List $lib.Id -Identity $folder.Id -Values @{ "FileLeafRef" = $folderName }
			}
		}
	}
}

#------------------------------------------------------------------------------------------------------------------------------------
Install-PnP-Module
Write-Host "-------------------------------------------------------------------" -ForegroundColor White
Connect-SharePoint-Site

$LibraryName = Read-Host "Enter sub-library ID or Name"
$lib = Get-PnPList -Identity $LibraryName
if( !$lib ){
    Write-Error -Message "Cannot load the library." -ErrorAction Continue
    Read-Host -Prompt "Press Enter to quit..."
    exit 0
}

$LookupFieldName = Read-Host ("Enter Internal name of lookup column from '"+$lib.Title+"' library") # Lookup column in sub-library
$lookupfield = Get-PnPField -List $lib.Id -Identity $LookupFieldName
if( !$lookupfield ){
    Write-Error -Message ("Cannot load find '"+$LookupFieldName+"' lookup column in '"+$lib.Title+"' the library.") -ErrorAction Continue
    Read-Host -Prompt "Press Enter to quit..."
    exit 0
}
[xml]$schemaXml=$lookupField.SchemaXml
$mainListId = $schemaXml.Field.Attributes["List"].Value
$mainList = Get-PnPList -Identity $mainListId

if( !$mainList ){
    Write-Error -Message "Cannot load main list." -ErrorAction Continue
    Read-Host -Prompt "Press Enter to quit..."
    exit 0
}

Write-Host ("Loading main folders from '" + $lib.Title + "' library...")


$queryMainFolders= "
        <View>
            <Query>
                <Where>
                    <And>
                        <Eq>
                            <FieldRef Name='FSObjType'/>
                            <Value Type='Integer'>1</Value>
                        </Eq>
                        <IsNotNull>
                            <FieldRef Name='"+$LookupFieldName+"'/>                            
                        </IsNotNull>
                    </And>
                </Where>
            </Query>
        </View>"
[Microsoft.SharePoint.Client.ListItem[]]$mainfolders = Get-PnPListItem -List $LibraryName -PageSize 500 -Query $queryMainFolders | Where-Object {$_[$LookupFieldName] -ne $null}

$choices  = '&Yes', '&No'
$decision = $Host.UI.PromptForChoice('Confirmation', "'"+$lib.Title+" library contains "+$mainfolders.Count+" main folders. Are you sure you want to rename them?", $choices, 1)
if ($decision -eq 1) {
    Write-Error -Message "The process has been cancelled." -ErrorAction Continue
    Read-Host -Prompt "Press Enter to quit..."
    exit 0    
}

Write-Host "Renaming folders...."
$batchsize = 100;
$folderscount = $mainfolders.Count
$mainItemIDs = [System.Collections.ArrayList]::new()

for( $idx = 0; $idx -lt $folderscount / $batchsize; $idx++)
{
    $idxStart = $idx * $batchsize
    $idxEnd = [math]::Min( ($idx + 1 )*$batchsize - 1, $folderscount - 1 )

    $folders = $mainfolders[$idxStart..$idxEnd]

    Process-Folders -folders $folders    
}

Write-Host "The process has been finished."
Read-Host -Prompt "Press Enter to quit..."
exit 0