/*

See LICENSE folder for this sample’s licensing information.

Abstract:

An example demonstrating setup of an accessibility rotor to search for fruit buttons.

*/

import Cocoa

// Note: To test UIAccessibilityCustomRotor, focus on the CustomRotorsContainerView, and type control+option+u

@available(OSX 10.13, *)

class CustomRotorsElementViewController: NSViewController,

            NSAccessibilityCustomRotorItemSearchDelegate,

            NSAccessibilityElementLoading,

            CustomRotorsElementViewDelegate {

    static let SearchableItemsID = "searchable"

    static let CustomRotorFruitButtonsName = "Fruit Buttons"

    static let MaxPageIndex = 2

    var displayPageIndex = 0

    @IBOutlet var containerView: CustomRotorsContainerView!

    @IBOutlet var pageView1: CustomRotorsPageView!

    @IBOutlet var pageView2: CustomRotorsPageView!

    @IBOutlet var pageView3: CustomRotorsPageView!

    @IBOutlet var contentView1: NSView!

    @IBOutlet var contentView2: NSView!

    @IBOutlet var contentView3: NSView!

    // MARK: - View Controller Lifecycle

    override func viewDidLoad() {

        super.viewDidLoad()

        displayPageIndex = 0

        containerView.delegate = self

        pageView1.contentView = contentView1

        pageView2.contentView = contentView2

        pageView3.contentView = contentView3

        pageView1.addSubview(pageView1.contentView)

        pageView2.addSubview(pageView2.contentView)

        pageView3.addSubview(pageView3.contentView)

        pageView2.contentView.isHidden = true

        pageView3.contentView.isHidden = true

        pageView1.setAccessibilityLabel(NSLocalizedString("Page 1", comment: ""))

        pageView2.setAccessibilityLabel(NSLocalizedString("Page 2", comment: ""))

        pageView3.setAccessibilityLabel(NSLocalizedString("Page 3", comment: ""))

    }

    // Given a fruit name, display the page containing that fruit onscreen and return the button corresponding to that fruit.

    func showFruit(fruit: String) -> NSAccessibilityElementProtocol {

        var fruitButtonAccessibilityElement: NSAccessibilityElementProtocol?

        for pageView in containerView.subviews {

            if let pageCheck = pageView as? CustomRotorsPageView {

                for subView in pageCheck.contentView.subviews where subView is NSButton {

                    if let button = subView as? NSButton {

                        if button.cell?.title == fruit {

                            fruitButtonAccessibilityElement = NSAccessibilityUnignoredDescendant(button) as? NSAccessibilityElementProtocol

                            displayPageIndex = pageIndexForPageView(pageView: pageCheck)

                            updateViews()

                            break

                        }

                    }

                }

            }

        }

        return fruitButtonAccessibilityElement!

    }

    // MARK: Page Management

    fileprivate func pageIndexForPageView(pageView: CustomRotorsPageView) -> Int {

        var pageIndex = 0

        if pageView == pageView3 {

            pageIndex = 2

        } else if pageView == pageView2 {

            pageIndex = 1

        }

        return pageIndex

    }

    fileprivate func pageViewforPageIndex(pageIndex: Int) -> CustomRotorsPageView {

        var pageView: CustomRotorsPageView?

        switch pageIndex {

        case 0:

            pageView = pageView1

        case 1:

            pageView = pageView2

        case 2:

            pageView = pageView3

        default: break

        }

        return pageView!

    }

    fileprivate func updateViews() {

        let currentFocusedViewIndex = displayPageIndex

        for i in 0...CustomRotorsElementViewController.MaxPageIndex {

            let pageView = pageViewforPageIndex(pageIndex: i)

            if i == currentFocusedViewIndex {

                pageView.contentView.isHidden = false

            } else {

                pageView.contentView.isHidden = true

            }

        }

    }

    // MARK: - Actions

    @IBAction func nextPage(_ sender: Any) {

        if displayPageIndex < CustomRotorsElementViewController.MaxPageIndex {

            displayPageIndex += 1

        }

        updateViews()

    }

    @IBAction func previousPage(_ sender: Any) {

        if displayPageIndex > 0 {

            displayPageIndex -= 1

        }

        updateViews()

    }

    var fruitElements: [NSButton] {

        var fruitList = [NSButton]()

        for pageView in containerView.subviews {

            if let pageCheck = pageView as? CustomRotorsPageView {

                for subView in pageCheck.contentView.subviews where subView is NSButton {

                    if let button = subView as? NSButton {

                        fruitList.append(button)

                    }

                }

            }

        }

        return fruitList

    }

    // MARK: - NSAccessibilityElementLoading Token

    func accessibilityElement(withToken token: NSAccessibilityLoadingToken) -> NSAccessibilityElementProtocol? {

        let fruitToken = token as! CustomRotorsElementLoadingToken

        let fruitName = fruitToken.uniqueIdentifier

        return showFruit(fruit: fruitName)

    }

    // MARK: - CustomRotorsElementViewDelegate

    func createCustomRotors() -> [NSAccessibilityCustomRotor] {

        // Create the fruit rotor.

        let buttonRotor =

            NSAccessibilityCustomRotor(label: CustomRotorsElementViewController.CustomRotorFruitButtonsName,

                                       itemSearchDelegate: self as NSAccessibilityCustomRotorItemSearchDelegate)

        buttonRotor.itemLoadingDelegate = self

        return [buttonRotor]

    }

    // MARK: - NSAccessibilityCustomRotorItemSearchDelegate

    public func rotor(_ rotor: NSAccessibilityCustomRotor,

                      resultFor searchParameters: NSAccessibilityCustomRotor.SearchParameters) -> NSAccessibilityCustomRotor.ItemResult? {

        var searchResult: NSAccessibilityCustomRotor.ItemResult?

        let currentItemResult = searchParameters.currentItem

        let direction = searchParameters.searchDirection

        let filterText = searchParameters.filterString

        let currentItem = currentItemResult?.targetElement

        let children = NSAccessibilityUnignoredChildren(fruitElements)

        _ = children.filter {

            if let obj = $0 as? NSButtonCell {

                return filterText.isEmpty || // Filter based on filter string

                    (obj.accessibilityTitle()?.localizedCaseInsensitiveContains(filterText))!

            } else if let obj = $0 as? NSTextFieldCell {

                return filterText.isEmpty || // Filter based on filter string

                    (obj.accessibilityTitle()?.localizedCaseInsensitiveContains(filterText))!

            } else {

                return false

            }

        }

        var currentElementIndex = NSNotFound

        var targetElement : Any?

        let loadingToken = currentItemResult?.itemLoadingToken

        if currentItem == nil && loadingToken != nil {

            // Find out the corresponding hidden button of the current search position, in order to find the next/previous button.

            let elementLoadingToken = loadingToken as? CustomRotorsElementLoadingToken

            if let currentItemIdentifier = elementLoadingToken?.uniqueIdentifier {

                for case let child as NSButtonCell in children where child.title == currentItemIdentifier {

                    currentElementIndex = (children as NSArray).index(of: child)

                }

            }

        } else if currentItem != nil {

            currentElementIndex = (children as NSArray).index(of: currentItem!)

        }

        if currentElementIndex == NSNotFound {

            // Fetch the first element.

            if direction == NSAccessibilityCustomRotor.SearchDirection.next {

                targetElement = children.first

            }

                // Fetch the last element.

            else if direction == NSAccessibilityCustomRotor.SearchDirection.previous {

                targetElement = children.last

            }

        } else {

            if direction ==

                NSAccessibilityCustomRotor.SearchDirection.previous && currentElementIndex != 0 {

                targetElement = children[currentElementIndex - 1]

            } else if direction ==

                NSAccessibilityCustomRotor.SearchDirection.next && currentElementIndex < (children.count - 1) {

                targetElement = children[currentElementIndex + 1]

            }

        }

        if targetElement != nil {

            if let targetButtonCell = targetElement as? NSCell {

                if let controlView = targetButtonCell.controlView as? NSControl {

                    if controlView.isHiddenOrHasHiddenAncestor {

                        let label = targetButtonCell.title

                        let token = CustomRotorsElementLoadingToken(identifier: label)

                        searchResult =

                            NSAccessibilityCustomRotor.ItemResult(itemLoadingToken: token as NSAccessibilityLoadingToken, customLabel: label)

                    } else {

                        searchResult = NSAccessibilityCustomRotor.ItemResult(targetElement: targetElement as! NSAccessibilityElementProtocol)

                    }

                }

            }

        }

        return searchResult

    }

}