/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    This file contains the EnumPickerController class, which is used to control a view containing a UIPickerView.

*/

import UIKit

/// A view controller for a view that contains a picker view for selecting a value in an enum.

class EnumPickerController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {

    // MARK: Properties

    /// The values that can be selected in the picker view.

    var enumValues = [String]()

    /// The index of the currently-selected value.

    var currentValue: Int?

    /// The picker view.

    @IBOutlet weak var enumPicker: UIPickerView!

    /// The title to display for the view.

    var enumTitle: String?

    /// A block to execute when the selected value changes.

    var selectionChangeHandler: (Int) -> Void = { newRow in return }

    // MARK: Interface

    /// Set the enum values to display, the title of the view, the index of the currently-selected value, and a block to execute when the selected value changes.

    func setValues(_ values: [String], title: String, currentSelection: Int?, selectionChanged: @escaping (Int) -> Void) {

        enumValues = values

        enumTitle = title

        currentValue = currentSelection

        selectionChangeHandler = selectionChanged

    }

    // MARK: UIViewController

    /// Handle the event when the view is being displayed.

    override func viewWillAppear(_ animated: Bool) {

        super.viewWillAppear(animated)

        navigationItem.title = enumTitle

        enumPicker.reloadAllComponents()

        if let row = currentValue {

            enumPicker.selectRow(row, inComponent: 0, animated: false)

        }

    }

    // MARK: UIPickerViewDataSource

    /// Return the number of components in the picker, always returns 1.

    func numberOfComponents(in pickerView: UIPickerView) -> Int {

        return 1

    }

    /// Returns the number of enum values.

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {

        return enumValues.count 

    }

    // MARK: UIPickerViewDelegate

    /// Returns the enum value at the given row.

    func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {

        return NSAttributedString(string: enumValues[row])

    }

    /// Handle the user selecting a value in the picker.

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {

        selectionChangeHandler(row)

    }

}