defmodule ArcadiaCloud.Sync.BillingHistoryWorker do
  @moduledoc """
  Daily discovery of new invoices via `/v2/customers/my/billing_history`.

  Upserts an invoice header per row and enqueues an InvoiceIngestWorker
  job for any invoice not yet ingested (CSV parse + line-item write +
  resource match). Idempotent — re-running re-enqueues nothing new.
  """

  use Oban.Worker, queue: :cloud_billing, max_attempts: 3

  alias ArcadiaCloud.Billing
  alias ArcadiaCloud.DigitalOcean.Client
  alias ArcadiaCloud.Sync.InvoiceIngestWorker

  @impl Oban.Worker
  def perform(_job) do
    with {:ok, history} <- Client.list_billing_history() do
      Enum.each(history, fn item ->
        case extract_invoice_attrs(item) do
          {:ok, attrs} ->
            {:ok, invoice} = Billing.upsert_invoice(attrs)

            if is_nil(invoice.lines_ingested_at) do
              %{invoice_id: invoice.id}
              |> InvoiceIngestWorker.new()
              |> Oban.insert!()
            end

          :skip ->
            :ok
        end
      end)

      :ok
    end
  end

  # DO billing_history items have shape:
  #   {"type" => "Invoice", "description" => "Invoice for September 2024",
  #    "amount" => "-100.00", "date" => "2024-10-01T00:00:00Z",
  #    "invoice_id" => "uuid-here", "invoice_uuid" => "uuid-here"}
  # We only care about Invoice rows (skip Payment, Credit, etc).
  defp extract_invoice_attrs(%{"type" => "Invoice"} = item) do
    case item["invoice_uuid"] || item["invoice_id"] do
      nil ->
        :skip

      uuid ->
        {:ok,
         %{
           provider: "digitalocean",
           provider_invoice_id: uuid,
           invoice_period: derive_period(item["date"]),
           amount_cents: dollars_to_cents_abs(item["amount"]),
           status: "issued",
           issued_at: parse_iso(item["date"]),
           raw: item
         }}
    end
  end

  defp extract_invoice_attrs(_), do: :skip

  # Invoice dated YYYY-MM-01 covers the previous month. Derive period as
  # first-of-the-previous-month.
  defp derive_period(nil), do: Date.utc_today() |> Date.add(-30) |> first_of_month()

  defp derive_period(iso) do
    case DateTime.from_iso8601(iso) do
      {:ok, dt, _} -> dt |> DateTime.to_date() |> Date.add(-1) |> first_of_month()
      _ -> Date.utc_today() |> first_of_month()
    end
  end

  defp first_of_month(%Date{year: y, month: m}), do: Date.new!(y, m, 1)

  defp dollars_to_cents_abs(nil), do: nil

  defp dollars_to_cents_abs(value) when is_binary(value) do
    case Float.parse(value) do
      {float, _} -> abs(round(float * 100))
      :error -> nil
    end
  end

  defp dollars_to_cents_abs(value) when is_number(value), do: abs(round(value * 100))

  defp parse_iso(nil), do: nil

  defp parse_iso(str) when is_binary(str) do
    case DateTime.from_iso8601(str) do
      {:ok, dt, _} -> DateTime.truncate(dt, :second)
      _ -> nil
    end
  end
end