/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    This file contains the StringListController class, which controls a list of strings.

*/

import UIKit

/// A view controller of a view that displays an editable list of strings.

class StringListController: ListViewController {

    // MARK: Properties

    /// The current list of strings.

    var targetStrings = [String]()

    /// The text to display in the "add a string" text field.

    var addText: String?

    /// The title to display for the list.

    var listTitle: String?

    /// The block to execute when the list of strings changes.

    var stringsChangedHandler: ([String]) -> Void = { strings in return }

    /// A table view cell containing a text field used to enter new strings to be added to the list.

    @IBOutlet weak var addStringCell: TextFieldCell!

    /// The number of strings in the list.

    override var listCount: Int {

        return targetStrings.count 

    }

    /// Returns UITableViewCellSelectionStyle.None

    override var listCellSelectionStyle: UITableViewCellSelectionStyle {

        return .none

    }

    // MARK: UIViewController

    /// Handle the event when the view is loaded into memory.

    override func viewDidLoad() {

        isAddEnabled = true

        isAlwaysEditing = true

        addStringCell.valueChanged = {

            guard let enteredText = self.addStringCell.textField.text else { return }

            self.targetStrings.append(enteredText)

            self.listInsertItemAtIndex(self.targetStrings.count - 1)

            self.addStringCell.textField.text = ""

            self.stringsChangedHandler(self.targetStrings)

        }

        // Set addStringCell as a custom "add a new item" cell.

        addCell = addStringCell

        super.viewDidLoad()

    }

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

    override func viewWillAppear(_ animated: Bool) {

        super.viewWillAppear(animated)

        addStringCell.textField.placeholder = addText

        navigationItem.title = listTitle

    }

    // MARK: ListViewController

    /// Return the string at the given index.

    override func listTextForItemAtIndex(_ index: Int) -> String {

        return targetStrings[index] 

    }

    /// Remove the string at the given index.

    override func listRemoveItemAtIndex(_ index: Int) {

        targetStrings.remove(at: index)

        stringsChangedHandler(targetStrings)

    }

    // MARK: Interface

    /// Set the list of strings, the title to display for the list, the text used to prompt the user for a new string, and a block to execute when the list of strings changes.

    func setTargetStrings(_ strings: [String]?, title: String, addTitle: String, saveHandler: @escaping ([String]) -> Void) {

        targetStrings = strings ?? [String]()

        listTitle = title

        addText = addTitle

        stringsChangedHandler = saveHandler

    }

}