PurchaseEndpoints.swift

enum PurchaseEndpoint: String {
    private var baseURL: String { return "https://www.purchase.com" }

    case product = "/product"
    case user = "/user"
    case store = "/store"
    case payment = "/payment"
    
    var url: URL {
        guard let url = URL(string: baseURL) else {
            preconditionFailure("The url used in \(PurchaseEndpoint.self) is not valid")
        }
        return url.appendingPathComponent(self.rawValue)
    }
}