<#
.SYNOPSIS
PowerShell script to get Exchange Calendar permissions report.

.DESCRIPTION
The script gets Calendar permissions report within your Exchange organization. It also can get a report from Office 365.

.PARAMETER Version
Mandatory parameter. Select between Exchange Versions. It can be 2010, 2013-2016 or O365.

.PARAMETER File
Optional parameter. Exports the results to file.

.EXAMPLE
.\Get-CalendarPermissionsReport.ps1 -Version 2010 -File FileName.csv
Gets calendar permissions report for Exchange 2010 and exports the results to FileName.csv file.

.EXAMPLE
.\Get-CalendarPermissionsReport.ps1 -Version 2013-2016 -File FileName.csv
Gets calendar permissions report for Exchange 2013 or 2016 and exports the results to FileName.csv file.

.EXAMPLE
 .\Get-CalendarPermissionsReport.ps1 -Version O365 -File FileName.csv
Gets calendar permissions report for Exchange Online and exports the results to FileName.csv file. It will ask an Office 365 admin credentials.

.EXAMPLE
.\Get-CalendarPermissionsReport.ps1 -Version O365
Connects to Exchange Online and prints calendar permissions to console.

.LINK
Script author Slava Fedenko - http://blog.fedenko.info
#>

[CmdletBinding()]
Param(
    [Parameter(Mandatory = $True)]
    [ValidateSet('2010', '2013-2016', 'O365')]
    [String]$Version,

    [Parameter(Mandatory = $False)]
    [ValidateNotNull()]
    [String]$File

)

if ($Version -like "2010") {
    $Out = @()
    $mbxs = Get-Mailbox | Where-Object { $_.WindowsEmailAddress -like '*pepcoservices*' }
    foreach ($mbx in $mbxs) {
        $id = $mbx.alias
        $id = $id + ":\Calendar"
        $perms = Get-MailboxFolderPermission -Identity $id | Where-Object { $_.User -notlike "Anonymous" -and $_.User -notlike "Default" }
        foreach ($perm in $perms) {
            if (!$perm) { break }
            $Properties = @{
                "Mailbox"      = $mbx.DisplayName;
                "Email"        = $mbx.windowsemailaddress;
                "User"         = $perm.User;
                "AccessRights" = $perm.AccessRights -join ','
            }
            $Obj = New-Object -TypeName PSObject -Property $Properties

            if (!$File) {
                Write-Output $Obj | Select-Object Mailbox, Email, User, AccessRights
            }
            $Out += $Obj
        }

    }
    if ($File) {
        $Out | Select-Object Mailbox, Email, User, AccessRights | Export-Csv -NoTypeInformation $File
    }
}


if ($Version -like "2013-2016") {
    if (!$File) {
        Get-Mailbox | ForEach-Object { Get-MailboxFolderPermission -Identity "$($_.alias):\Calendar" | Where-Object { $_.User -notlike "Anonymous" -and $_.User -notlike "Default" } } | Select-Object Identity, User, @{name = 'AccessRights'; expression = { $_.AccessRights -join ',' } }
    }
    if ($File) {
        Get-Mailbox | ForEach-Object { Get-MailboxFolderPermission -Identity "$($_.alias):\Calendar" | Where-Object { $_.User -notlike "Anonymous" -and $_.User -notlike "Default" } } | Select-Object Identity, User, @{name = 'AccessRights'; expression = { $_.AccessRights -join ',' } } | Export-Csv -NoTypeInformation $File
    }
}

if ($Version -like "O365") {
    $UserCredential = Get-Credential
    $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
    Import-PSSession $Session

    if (!$File) {
        Get-Mailbox | ForEach-Object { Get-MailboxFolderPermission -Identity "$($_.alias):\Calendar" | Where-Object { $_.User -notlike "Anonymous" -and $_.User -notlike "Default" } } | Select-Object Identity, User, @{name = 'AccessRights'; expression = { $_.AccessRights -join ',' } }
    }
    if ($file) {
        Get-Mailbox | ForEach-Object { Get-MailboxFolderPermission -Identity "$($_.alias):\Calendar" | Where-Object { $_.User -notlike "Anonymous" -and $_.User -notlike "Default" } } | Select-Object Identity, User, @{name = 'AccessRights'; expression = { $_.AccessRights -join ',' } } | Export-Csv -NoTypeInformation $File
    }
    Remove-PSSession $Session
}