Get-AbsenceData.ps1

# General Settings
$exportDir = "$env:workspace\uploadArtifacts\"
$exportFile = "AbsenceExport.csv"
$exportPath = "$exportDir\$exportFile"

# AAD Credentials
$ClientSecret = $env:aadSecret
$ClientId = $env:aadId
$TenantId = $env:tenantId
$groupName = $env:aadGroup

#region Azure AD (Graph) Authentication
$Body = @{
    'tenant' = $TenantId
    'client_id' = $ClientId
    'scope' = 'https://graph.microsoft.com/.default'
    'client_secret' = $ClientSecret
    'grant_type' = 'client_credentials'
}
$Params = @{
    'Uri' = "https://login.microsoftonline.com/$TenantId/oauth2/v2.0/token"
    'Method' = 'Post'
    'Body' = $Body
    'ContentType' = 'application/x-www-form-urlencoded'
}

$AuthResponse = Invoke-RestMethod @Params
$Headers = @{
    'Authorization' = "Bearer $($AuthResponse.access_token)"
}
#endregion

function Get-GraphApiResult {

    param (
        [parameter(Mandatory = $true)]
        $ClientID,

        [parameter(Mandatory = $true)]
        $ClientSecret,

        [parameter(Mandatory = $true)]
        $TenantName,

        [parameter(Mandatory = $true)]
        $Uri
    )

    # Graph API URLs.
    $LoginUrl = "https://login.microsoft.com"
    $resourceUrl = "https://graph.microsoft.com"

    # Compose REST request.
    $Body = @{ grant_type = "client_credentials"; resource = $resourceUrl; client_id = $ClientID; client_secret = $ClientSecret }     
    $OAuth = Invoke-RestMethod -Method Post -Uri $LoginUrl/$TenantName/oauth2/token?api-version=1.0 -Body $Body

    # Check if authentication was successfull.
    if ($OAuth.access_token) {
        # Format headers.
        $HeaderParams = @{
            'Content-Type'  = "application\json"
            'Authorization' = "$($OAuth.token_type) $($OAuth.access_token)"
        }

        # Create an empty array to store the result.
        $QueryResults = @()
        
        # Invoke REST method and fetch data until there are no pages left.
        do {
            $Results = Invoke-RestMethod -Headers $HeaderParams -Uri $Uri -UseBasicParsing -Method "GET" -ContentType "application/json"
            if ($Results.value) {
                $QueryResults += $Results.value
            }
            else {
                $QueryResults += $Results
            }
            $uri = $Results.'@odata.nextlink'
        } until (!($uri))

        # Return the result.
        $QueryResults
    }
    else {
        Write-Error "No Access Token"
    }
}

#region Get Azure AD Group
$groupId = Get-GraphApiResult -ClientID $ClientId -ClientSecret $ClientSecret -TenantName $TenantId -Uri "https://graph.microsoft.com/v1.0/groups?`$filter=displayname+eq+'$groupName'&`$select=id,displayname" | Select-Object -ExpandProperty Id
#endregion
if(!$groupId){
    Write-Error("[$(Get-Date)] Safety Check: groupId not found, breaking!")
    exit 1;
}
#endregion

$funcDef = ${function:Get-GraphApiResult}.ToString()

if($members = Get-GraphApiResult -ClientID $ClientId -ClientSecret $ClientSecret -TenantName $TenantId -Uri "https://graph.microsoft.com/v1.0/groups/$groupId/members?`$select=onPremisesSamAccountName,userPrincipalName,id"){
    $entries = $members | ForEach-Object -ThrottleLimit 15 -Parallel {
        $user = $_
        try{
            ${function:Get-GraphApiResult} = $using:funcDef
            $res = Get-GraphApiResult -ClientID $using:ClientId -ClientSecret $using:ClientSecret -TenantName $using:TenantId -Uri "https://graph.microsoft.com/v1.0/users/$($user.id)/mailboxSettings/automaticRepliesSetting" -ErrorAction Stop
            
            if(
                $res -and
                $res.status -ne "disabled"
            ){
                [PSCustomObject]@{
                    userPrincipalName = $user.UserPrincipalName
                    sAMAccountName = $user.onPremisesSamAccountName
                    AzureADID = $user.id
                    Status = $res.Status
                    StartTime = ($res.scheduledStartDateTime.dateTime | Get-Date -Format "yyyy\/MM\/dd HH:mm:ss")
                    StartTimeTimeZone = $res.scheduledStartDateTime.timeZone
                    EndTime = ($res.scheduledEndDateTime.dateTime | Get-Date -Format "yyyy\/MM\/dd HH:mm:ss")
                    EndTimeTimeZone = $res.scheduledEndDateTime.timeZone
                }
            }
        }catch{
            if($_.ErrorDetails.Message -and $_.ErrorDetails.Message.Contains("REST API is not yet supported for this mailbox")){
                Write-Host($user.userPrincipalName + ": Not a cloud mailbox user (REST API is not yet supported for this mailbox).")
            }elseif($_.Exception -and $_.Exception.Message -and $_.Exception.Message.Contains("404")){
                Write-Host($user.userPrincipalName + ": Not a cloud mailbox user (404).")
            }else{
                Write-Error("[$(Get-Date)] Could not get recipient details for $($user.userPrincipalName), error: $_")
            }
        }
    }

    if(
        $entries -and
        $entries.Count -gt 10
    ){
        if(Test-Path -Path $exportPath -ErrorAction SilentlyContinue){
            Write-Host("[$(Get-Date)] Removing Export at `"$exportPath`"..")
            Remove-Item -Path $exportPath -Confirm:$false
        }
        if(Test-Path -Path $exportDir -ErrorAction SilentlyContinue){
            Write-Host("[$(Get-Date)] Removing Directory at `"$exportDir`"..")
            Remove-item -Path $exportDir -Recurse -Confirm:$false
        }
        $null = New-Item -Path $exportDir -ItemType 'Directory' -Force

        Write-Host("[$(Get-Date)] Exporting Results to `"$exportPath`"..")
        $entries | Export-Csv -Path $exportPath -Encoding 'UTF8' -NoClobber -NoTypeInformation
    }
}else{
    Write-Error("[$(Get-Date)] Safety Check: Group members empty, breaking!")
    exit 1;
}