URLBuilder.swift

/// JavaのStringBuilder的なインターフェースを想定
final class URLBuilder {
    private var components: URLComponents

    init?(string: String) {
        guard let components = URLComponents(string: string) else {
            return nil
        }
        self.components = components
    }

    @discardableResult
    func append(_ queryItem: URLQueryItem) -> URLBuilder {
        var newItems = components.queryItems ?? []
        newItems.append(queryItem)
        components.queryItems = newItems
        return self
    }

    func build() -> URL? {
        components.url
    }
}