curl --request POST \
  --url https://api.meetcampfire.com/coa/api/v1/invoice/{invoice_id}/calculate-payment \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "transactions": [
    {
      "transaction_id": 123,
      "amount": 0,
      "posted_at": "2023-12-25"
    }
  ],
  "credit_memos": [
    {
      "credit_memo_id": 123,
      "amount": 0,
      "posted_at": "2023-12-25"
    }
  ],
  "empty_transactions": [
    {
      "amount": 0,
      "payment_date": "2023-12-25"
    }
  ]
}
'

{
  "total_due": 0,
  "applied_payments": 0,
  "applied_credits": 0,
  "term_discounts": 0,
  "remaining_due": 0
}