SynchroneHTTPRequest.swift

// A simple network stack I use for my command line tools written in Swift.
// The dataTask here work only for GET operations.

protocol Operation {
    associatedtype T: Codable
  
    enum HTTPMethod {
        case GET
        case POST
        case PUT
        case DELETE
    }
  
    var url: URL { get set }
    var method: HTTPMethod { get }
    var params: [String : Any]? { get set }
    var completion: (T?, OperationResponse?) -> () { get }
}

struct OperationResponse {
    var statusCode: Int
    var error: Error?
}

struct Network {
    static func start<Op: Operation>(_ operation: Op) {
        var keepAlive = true
        URLSession.shared.dataTask(with: operation.url) { (data, res, err) in
            Network.handleResponse(data, (res as? HTTPURLResponse), err, operation)
            keepAlive = false
        }.resume()
        while keepAlive {
            RunLoop.current.run(until: Date().addingTimeInterval(0.1))
        }
    }
    
    private static func handleResponse<Op: Operation>(_ data: Data?, _ response: HTTPURLResponse?, _ error: Error?, _ operation: Op) {
        let res = OperationResponse(statusCode: (response?.statusCode ?? -1), error: error)
        
        func failed(response: OperationResponse) {
            operation.completion(nil, res)
        }
        
        guard let data = data else { failed(response: res) ; return }
        
        let decoded = try? JSONDecoder().decode(Op.T.self, from: data)
        operation.completion(decoded, res)
    }
}