import UIKit

class SigninViewController: UIViewController {

    @IBOutlet weak var userNameTextFeild: UITextField!
    @IBOutlet weak var userPasswordTextField: UITextField!

    @IBAction func loginInButtonTapped(_ sender: Any) {
        print("log in button tapped")

        //Read values from text field
        let userName = userNameTextFeild.text
        let userPassword = userPasswordTextField.text

        // Check if required fields are not empty
        if (userName?.isEmpty)! || (userPassword?.isEmpty)! {
            // Display alert message here
            print("User name (String(describing: userName)) or password (String(describing: userPassword)) is empty")
            displayMessage(userMessage: "One of the required fields is missing")

            return
        }

        //Create Activity Indicator
        let myActivityIndicator = UIActivityIndicatorView(activityIndicatorStyle: UIActivityIndicatorViewStyle.gray)

        // Position Activity Indicator in the center of the main view
        myActivityIndicator.center = view.center

        // If needed, you can prevent Acivity Indicator from hiding when stopAnimating() is called
        myActivityIndicator.hidesWhenStopped = false

        // Start Activity Indicator
        myActivityIndicator.startAnimating()

        view.addSubview(myActivityIndicator)

        //Send HTTP Request to perform Sign in
        let myUrl = URL(string: "http://198.162.8.80:50000/login/")
        var request = URLRequest(url:myUrl!)
        request.httpMethod = "POST"// Compose a query string
        request.addValue("application/json", forHTTPHeaderField: "content-type")
        request.addValue("application/json", forHTTPHeaderField: "Accept")

        let postString = ["userName": userName!, "userPassword": userPassword!] as [String: String]

        do {
            request.httpBody = try JSONSerialization.data(withJSONObject: postString, options: .prettyPrinted)
        } catch let error {
            print(error.localizedDescription)
            displayMessage(userMessage: "Something went wrong...")
            return
        }

        let task = URLSession.shared.dataTask(with: request) { (data: Data?, response: URLResponse?, error: Error?) in
            self.removeActivityIndicator(activityIndicator: myActivityIndicator)

            if error != nil {
                self.displayMessage(userMessage: "Could not successfully perform this request. Please try again later")
                print("error=(String(describing: error))")
                return
            }

            //Let's convert response sent from a server side code to a NSDictionary object:
            do {
                let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary

                if let parseJSON = json {

                    if parseJSON["errorMessageKey"] != nil {
                        self.displayMessage(userMessage: parseJSON["errorMessage"] as! String)
                        return
                    }

                    DispatchQueue.main.async {
                        let homePage = self.storyboard?.instantiateViewController(withIdentifier: "dashboardViewController") as! dashboardViewController
                        let appDelegate = UIApplication.shared.delegate
                        appDelegate?.window??.rootViewController = homePage
                    }
                } else {
                    //Display an Alert dialog with a friendly error message
                    self.displayMessage(userMessage: "Could not successfully perform this request. Please try again later")
                }

            } catch {
                self.removeActivityIndicator(activityIndicator: myActivityIndicator)

                // Display an Alert dialog with a friendly error message
                self.displayMessage(userMessage: "Could not successfully perform this request. Please try again later")
                print(error)
            }
        }
        task.resume()
    }

    @IBAction func registerNewAccountButtonTapped(_ sender: Any) {
        print("Register account button tapped")

        let registerViewController = self.storyboard?.instantiateViewController(withIdentifier: "registerViewController") as! registerViewController
        self.present(registerViewController, animated: true)
    }

    func displayMessage(userMessage:String) -> Void {
        DispatchQueue.main.async {
                let alertController = UIAlertController(title: "Alert", message: userMessage, preferredStyle: .alert)
                let OKAction = UIAlertAction(title: "OK", style: .default) { (action:UIAlertAction!) in
                    // Code in this block will trigger when OK button tapped.
                    print("Ok button tapped")
                    DispatchQueue.main.async {
                        self.dismiss(animated: true, completion: nil)
                    }
                }
                alertController.addAction(OKAction)
                self.present(alertController, animated: true, completion:nil)
        }
    }

    func removeActivityIndicator(activityIndicator: UIActivityIndicatorView) {
        DispatchQueue.main.async{
            activityIndicator.stopAnimating()
            activityIndicator.removeFromSuperview()
        }
    }
}