Redirect.swift

private func resolve(url: URL) async -> URL? {
    await withCheckedContinuation { continuation in
        var request = URLRequest(url: url)
        request.httpMethod = "HEAD"

        let task = URLSession.shared.dataTask(with: request) { _, response, error in
            guard let httpResponse = response as? HTTPURLResponse, error == nil else {
                continuation.resume(returning: nil)
                return
            }

            if let location = httpResponse.value(forHTTPHeaderField: "Location"),
               let redirectedURL = URL(string: location) {
                continuation.resume(returning: redirectedURL)
            } else {
                continuation.resume(returning: httpResponse.url)
            }
        }
        task.resume()
    }
}