MaritUpdateSharePointCalendarURLs.ps1

[cmdletbinding(SupportsShouldProcess=$true,ConfirmImpact="High")]
Param(
  [parameter(Mandatory=$True,Position=1)]
  [String]
    $currentWebApplicationURL,
  [parameter(Mandatory=$True,Position=2)]
  [String]
    $oldWebApplicationURL
)
PROCESS {
[bool]$do = $pscmdlet.ShouldProcess($currentWebApplicationURL);
if((Get-PSSnapin -Name Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue) -eq $null){
  $ver = $host | select version
  if ($ver.Version.Major -gt 1) {$Host.Runspace.ThreadOptions = "ReuseThread"}
  Add-PsSnapin Microsoft.SharePoint.PowerShell
  Set-location $home
}
if($do){
  write-host "Updating CalendarSettings..."
  $gc = Start-SPAssignment
  $views = $gc | get-spwebapplication $currentWebApplicationURL | get-spsite -limit all | get-spweb -limit all | % { $_.Lists | % { $_.Views | ? { $_.CalendarSettings -ne $null -and $_.CalendarSettings -like '*'+$oldWebApplicationURL+'*' } }}
  $views | % { $_.CalendarSettings = $_.CalendarSettings.Replace($oldWebApplicationURL, $currentWebApplicationURL); $_.Update() }
  write-host $views.Count "views updated.";
  Stop-SPAssignment -SemiGlobal $gc
} else {
  write-host "Operation cancelled."
}
}