export type PurchaseRequest = {
  items: {
    product: Product;
    negotiation?: Negotiation;
  }[];
  customer: Customer;
  status: string;
  validationDate?: DateTime;
}

export type Negotiation = {
  type: 'percentage' | 'fixed';
  value: number;
}

type Color = "♣︎" | "♥︎" | "♦︎" | "♠︎";
type Rank = "A" | "K" | "Q"  // ...

export type Customer = {
  id: CustomerId;
  email: Email;
  address: string;
};

export type Negotiation = {
  type: "percentage" | "fixed" | "free";
  value: number;
};

export type Product = SaasProduct | PhysicalProduct;

type SaasProduct = {
  id: ProductId;
  name: string;
  type: "saas";
  unitPrice: number;
  details: { 
    saasId: SaasId, 
    subscriptionEnd: PlainDate, 
    billingQuarter: BillingQuarter 
  };
};

type PhysicalProduct = {
  id: ProductId;
  name: string;
  type: "physical";
  unitPrice: number;
  details: { itemId: ItemId; count: number };
};

export type PurchaseRequest = DraftPurchaseRequest 
  | SentPurchaseRequest | ValidatedPurchaseRequest;

type DraftPurchaseRequest = {
  items: PurchaseRequestItem[];
  customer?: {
    email: string;
    address: string;
  };
  status: "draft";
};

type SentPurchaseRequest = {
  items: NonEmptyArray<PurchaseRequestItem>;
  customer: Customer;
  status: "sent";
};

type ValidatedPurchaseRequest = {
  // ...
  validationDate: DateTime;
};

export type Currency = "USD" | "EUR";

export type Price<T extends Currency> = { 
  value: number; 
  currency: T 
};