teya

defmodule Teya do
  @moduledoc """
  Elixir client for the Teya APIs:

  - **[Online Payments](https://docs.teya.com/apis/online-payments/apis)** —
    hosted checkout, embedded card forms, pay-by-link, and token management
  - **[Payments Gateway](https://docs.teya.com/apis/payments/openapi.yaml)** —
    direct terminal integration for card-present transactions and reversals
  - **[Dynamic Currency Conversion](https://docs.teya.com/apis/dynamic-currency-conversion/openapi.yaml)** —
    unauthenticated BIN eligibility check and real-time exchange rate quotes
  - **[POSLink](https://docs.teya.com/apis/poslink/openapi.yaml)** —
    ePOS middleware for Teya-managed payment terminals

  ## Configuration

  Add to your application config:

      config :teya,
        client_id: "your_client_id",
        client_secret: "your_client_secret",
        token_url: "https://identity.teya.com/connect/token",
        base_url: "https://api.teya.com",
        scopes: [
          # Online Payments
          "checkout/sessions/create",
          "checkout/sessions/id/get",
          "payment-links/create",
          "payment-links/id/get",
          "payment-links/id/update",
          "transactions/online/create",
          "transactions/online/id/get",
          "captures/create",
          "refunds/create",
          "transactions/id/receipts/create",
          "token/delete",
          # Payments Gateway
          "transactions/card-present/create",
          "reversals/create",
          # POSLink
          "poslink/stores/get",
          "poslink/stores/id/terminals/get",
          "poslink/payment-requests/create",
          "poslink/payment-requests/id/get",
          "poslink/payment-requests/id/update",
          "poslink/payment-requests/get",
          "poslink/refunds/create",
          "poslink/receipt-requests/create",
          "poslink/receipt-requests/id/status/get"
        ]

  OAuth tokens are fetched automatically and refreshed before expiry.
  Only request the scopes your application needs.

  ## API modules

  ### Online Payments

  | Module | Purpose |
  |---|---|
  | `Teya.Checkout` | Hosted checkout — redirect customers to Teya's payment page |
  | `Teya.Transaction` | Direct card processing for embedded payment UIs |
  | `Teya.PayByLink` | Generate and manage shareable payment links |
  | `Teya.Capture` | Capture pre-authorised funds |
  | `Teya.Refund` | Refund completed transactions |
  | `Teya.Receipt` | Send digital receipts |
  | `Teya.Token` | Manage saved payment method tokens |

  ### Payments Gateway

  | Module | Purpose |
  |---|---|
  | `Teya.CardPresent` | Card-present transactions with raw EMV/track data |
  | `Teya.Reversal` | Void unsettled transactions |

  ### Dynamic Currency Conversion

  | Module | Purpose |
  |---|---|
  | `Teya.DCC` | BIN eligibility check and exchange rate quote (no OAuth required) |

  ### POSLink

  | Module | Purpose |
  |---|---|
  | `Teya.POSLink.Payment` | Create payment requests and stream status events |
  | `Teya.POSLink.Refund` | Refund a POSLink payment |
  | `Teya.POSLink.Receipt` | Print receipts and stream printer status |
  | `Teya.POSLink.Store` | List stores and terminals |

  ## Error handling

  All functions return `{:ok, response_body}` or `{:error, %Teya.Error{}}`.
  Pattern-match on `%Teya.Error{code: code}` for Teya-specific error codes.

      case Teya.Checkout.create_session(params) do
        {:ok, %{"session_url" => url}} -> redirect(conn, external: url)
        {:error, %Teya.Error{code: "TOO_MANY_REQUESTS"}} -> {:error, :rate_limited}
        {:error, %Teya.Error{} = err} -> {:error, err}
      end

  ## Idempotency

  POST and PATCH requests automatically include a random `Idempotency-Key` header.
  Pass `idempotency_key: "your-key"` in the options to supply your own:

      Teya.Checkout.create_session(params, idempotency_key: order_id)
  """
end