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defmodule WalletIntegrations.ProviderAdapter do |
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@moduledoc """ |
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Port behaviour for external payment provider adapters (ADR 0008). |
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Every provider integration must implement this behaviour. |
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Domain apps call this contract only; they never call provider SDKs or APIs directly. |
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## Contract rules |
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- All operations return `{:ok, AdapterResult.t()}` on success. |
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- All operations return `{:error, AdapterResult.t()}` on failure. |
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- Adapter implementations must handle timeouts and return `AdapterResult` with |
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`status: :unknown` and `retryable: true` for unresolved outcomes. |
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- Provider-specific fields must be isolated in `AdapterResult.metadata`. |
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## Supported operations |
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- `initiate_payment/1` — submit a new payment request to the provider. |
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- `get_payment_status/1` — query current payment status by provider reference. |
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- `cancel_payment/1` — cancel a pending payment (when supported). |
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- `refund_payment/2` — initiate a refund for a completed payment (when supported). |
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""" |
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alias WalletIntegrations.{AdapterRequest, AdapterResult} |
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@doc """ |
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Submit a new payment request to the provider. |
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Returns `{:ok, result}` with `status: :accepted | :pending` when the provider has received |
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the request. Returns `{:error, result}` on failure. |
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""" |
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@callback initiate_payment(request :: AdapterRequest.t()) :: |
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{:ok, AdapterResult.t()} | {:error, AdapterResult.t()} |
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@doc """ |
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Query the current state of a payment by provider reference. |
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Returns `{:ok, result}` with normalized status, or `{:error, result}` on failure. |
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""" |
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@callback get_payment_status(provider_ref :: String.t()) :: |
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{:ok, AdapterResult.t()} | {:error, AdapterResult.t()} |
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@doc """ |
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Cancel a pending payment. Not all providers support this operation. |
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Returns `{:ok, result}` when cancellation is accepted, or `{:error, result}` when |
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unsupported or already terminal. |
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""" |
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@callback cancel_payment(provider_ref :: String.t()) :: |
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{:ok, AdapterResult.t()} | {:error, AdapterResult.t()} |
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@doc """ |
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Initiate a refund for a completed payment. Not all providers support this operation. |
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`amount` is in minor currency units. |
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Returns `{:ok, result}` when refund is accepted, or `{:error, result}` on failure. |
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""" |
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@callback refund_payment(provider_ref :: String.t(), amount :: pos_integer()) :: |
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{:ok, AdapterResult.t()} | {:error, AdapterResult.t()} |
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@doc """ |
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Resolve the adapter module for a given provider atom. |
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Falls back to StubAdapter if not configured. |
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""" |
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@spec for_provider(provider :: atom()) :: module() |
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def for_provider(provider) do |
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configured = |
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Application.get_env(:wallet_integrations, :adapters, %{}) |
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|> Map.get(provider) |
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configured || |
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Application.get_env(:wallet_integrations, :payment_adapter, WalletIntegrations.Adapters.StubAdapter) |
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end |
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end |