@type promotion() :: %{
  optional(:coupon) => String.t() | nil,
  optional(:type) => String.t() | nil,
  optional(String.t()) => term()
}

• coupon - If promotion type is coupon, the coupon for this promotion code. Max length: 5000.
• type - Specifies the type of promotion. Possible values: coupon.

@type restrictions() :: %{
  optional(:currency_options) =>
    %{required(String.t()) => restrictions_currency_options()} | nil,
  optional(:first_time_transaction) => boolean() | nil,
  optional(:minimum_amount) => integer() | nil,
  optional(:minimum_amount_currency) => String.t() | nil,
  optional(String.t()) => term()
}

• currency_options - Promotion codes defined in each available currency option. Each key must be a three-letter ISO currency code and a supported currency.
• first_time_transaction - A Boolean indicating if the Promotion Code should only be redeemed for Customers without any successful payments or invoices
• minimum_amount - Minimum amount required to redeem this Promotion Code into a Coupon (e.g., a purchase must be $100 or more to work).
• minimum_amount_currency - Three-letter ISO code for minimum_amount Format: ISO 4217 currency code.

@type restrictions_currency_options() :: %{
  optional(:minimum_amount) => integer() | nil,
  optional(String.t()) => term()
}

• minimum_amount - Minimum amount required to redeem this Promotion Code into a Coupon (e.g., a purchase must be $100 or more to work).

@type t() :: %Stripe.Params.PromotionCodeCreateParams{
  active: boolean() | nil,
  code: String.t() | nil,
  customer: String.t() | nil,
  customer_account: String.t() | nil,
  expand: [String.t()] | nil,
  expires_at: integer() | nil,
  max_redemptions: integer() | nil,
  metadata: %{required(String.t()) => String.t()} | nil,
  promotion: promotion(),
  restrictions: restrictions() | nil
}

• active - Whether the promotion code is currently active.
• code - The customer-facing code. Regardless of case, this code must be unique across all active promotion codes for a specific customer. Valid characters are lower case letters (a-z), upper case letters (A-Z), and digits (0-9).

If left blank, we will generate one automatically. Max length: 500.

• customer - The customer who can use this promotion code. If not set, all customers can use the promotion code. Max length: 5000.
• customer_account - The account representing the customer who can use this promotion code. If not set, all customers can use the promotion code. Max length: 5000.
• expand - Specifies which fields in the response should be expanded.
• expires_at - The timestamp at which this promotion code will expire. If the coupon has specified a redeems_by, then this value cannot be after the coupon's redeems_by. Format: Unix timestamp.
• max_redemptions - A positive integer specifying the number of times the promotion code can be redeemed. If the coupon has specified a max_redemptions, then this value cannot be greater than the coupon's max_redemptions.
• metadata - Set of key-value pairs that you can attach to an object. This can be useful for storing additional information about the object in a structured format. Individual keys can be unset by posting an empty value to them. All keys can be unset by posting an empty value to metadata.
• promotion - The promotion referenced by this promotion code.
• restrictions - Settings that restrict the redemption of the promotion code.