defmodule PaymentGatewayApp do
  @moduledoc """
  PaymentGatewayApp is an independent OTP application for payment processing.
  
  This module provides the public API for payment operations that can be
  called by the main CloudLayer application.
  
  ## Configuration
  
  The Payment Gateway can be configured in your `config.exs`:
  
      config :payment_gateway_app,
        api_provider: PaymentGatewayApp.Providers.MockProvider,
        api_key: System.get_env("PG_API_KEY"),
        api_secret: System.get_env("PG_API_SECRET"),
        api_endpoint: "https://api.payment-provider.com"
  
  ## Usage
  
      # Start a payment
      {:ok, payment} = PaymentGatewayApp.start_payment(100.00, "USD", "user123")
      
      # Check payment status
      {:ok, status} = PaymentGatewayApp.get_payment_status(payment.id)
  """

  alias PaymentGatewayApp.PaymentInitiator
  alias PaymentGatewayApp.StatusChecker

  @doc """
  Initiates a new payment transaction.
  
  ## Parameters
  
    - `amount` - Payment amount as a float or integer
    - `currency` - Currency code (e.g., "USD", "EUR")
    - `user_id` - Unique identifier for the user making the payment
    - `opts` - Additional options (optional)
  
  ## Returns
  
    - `{:ok, payment_data}` - Success with payment details
    - `{:error, reason}` - Failure with error reason
  
  ## Examples
  
      iex> PaymentGatewayApp.start_payment(50.00, "USD", "user_123")
      {:ok, %{id: "pay_123", status: "pending", ...}}
  """
  def start_payment(amount, currency, user_id, opts \\ []) do
    PaymentInitiator.initiate_payment(amount, currency, user_id, opts)
  end

  @doc """
  Retrieves the current status of a payment.
  
  ## Parameters
  
    - `payment_id` - Unique payment transaction identifier
  
  ## Returns
  
    - `{:ok, status_data}` - Success with current status
    - `{:error, reason}` - Failure with error reason
  
  ## Examples
  
      iex> PaymentGatewayApp.get_payment_status("pay_123")
      {:ok, %{status: "completed", ...}}
  """
  def get_payment_status(payment_id) do
    StatusChecker.check_status(payment_id)
  end
end