$bullingPeriodStartDay = "06" #Start day bulling period
$clientid = "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"
$clientsecret = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
$subscriptionid = "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"
$tenantid = "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"

$resource = "https://management.azure.com/"
$tokenendpoint = "https://login.microsoftonline.com/$tenantid/oauth2/token"
$body = @{
    grant_type    = "client_credentials"
    resource      = $resource
    client_id     = $clientid
    client_secret = $clientsecret
}
$tokenresponse = Invoke-RestMethod -Method Post -Uri $tokenendpoint -Body $body -ContentType "application/x-www-form-urlencoded"
$accesstoken = $tokenresponse.access_token

$headers = @{
    'Authorization' = "Bearer $accesstoken"
    'Content-Type'  = 'application/json'
}

$bullingPeriodToday = (get-date -format "dd")
if ([int]$bullingPeriodToday -ge [int]$bullingPeriodStartDay) {
  $bullingPeriodCurrentStart = (Get-Date -format "yyyy-MM-$bullingPeriodStartDay")
  $bullingPeriod = (Get-Date((get-date).AddDays(30)) -format "yyyyMM")
} else {
  $bullingPeriodCurrentStart = (Get-Date((get-date).AddDays(30)) -format "yyyy-MM-$bullingPeriodStartDay")
  $bullingPeriod = (get-date -format "yyyyMM")
}
$dateEnd = Get-Date
$dateEnd = (Get-Date).ToString("s")
$dateStart = $bullingPeriodCurrentStart + "T00:00:00.0000000Z"

$requesturi = "https://management.azure.com/subscriptions/$subscriptionid/providers/Microsoft.Billing/billingPeriods/$bullingPeriod/providers/Microsoft.Consumption/usageDetails?api-version=2019-01-01&$filter=properties/usageStart ge '$dateStart' and properties/usageEnd le '$dateEnd'"

$ret = (Invoke-RestMethod -Uri $requesturi -Headers $headers -Method Get)
$usageCost = $ret.value.properties.pretaxCost|measure-object -Sum
$usageCost = [Math]::Round($usageCost.Sum)
Write-Output $usageCost