//
//  UITextView+isEditableWhenBeingDataDetectable.swift
//  Stories
//
//  Created by Li-Heng Hsu on 15/05/2018.
//  Copyright © 2018 narrativesaw. All rights reserved.
//

import UIKit

extension UITextView {

    @objc private func isTapped(_ sender: UITapGestureRecognizer) {
        let textView = sender.view as! UITextView
        let location = sender.location(in: textView)
        guard let position = textView.closestPosition(to: location) else { return }

        let styleDictionary = textView.textStyling(at: position, in: .forward) ?? [:]
        openURL: if let url = styleDictionary[NSAttributedStringKey.link.rawValue] as? URL {
            let location = offset(from: beginningOfDocument, to: position)
            if delegate?.textView?(self, shouldInteractWith: url, in: NSRange(location: location, length: 0), interaction: .invokeDefaultAction) == false {
                break openURL
            }

            UIApplication.shared.open(url)
        } else if let range = textView.textRange(from: position, to: position) {
            textView.isEditable = true
            textView.becomeFirstResponder()
            textView.selectedTextRange = range
        }
    }

    var isEditableWhenBeingDataDetectable: Bool {
        get {
            return gestureRecognizers?.contains { $0 is LHTextViewEditableWhenBeingDataDetactableHelper } ?? false
        }
        set {
            if newValue {
                if !isEditableWhenBeingDataDetectable {
                    let enabler = LHTextViewEditableWhenBeingDataDetactableHelper(target: self, action: #selector(isTapped))
                    addGestureRecognizer(enabler)
                }
            } else {
                if let enabler = gestureRecognizers?.first(where: { $0 is LHTextViewEditableWhenBeingDataDetactableHelper }) {
                    removeGestureRecognizer(enabler)
                }
            }
        }
    }

}

private class LHTextViewEditableWhenBeingDataDetactableHelper: UITapGestureRecognizer {

    fileprivate override init(target: Any?, action: Selector?) {
        super.init(target: target, action: action)
        delegate = self
        NotificationCenter.default.addObserver(self, selector: #selector(didEndEditing), name: .UITextViewTextDidEndEditing, object: nil)
    }

    deinit {
        NotificationCenter.default.removeObserver(self)
    }

    @objc private func didEndEditing(notification: Notification) {
        guard (notification.object as AnyObject) === view else { return }
        (view as? UITextView)?.isEditable = false
    }

}

extension LHTextViewEditableWhenBeingDataDetactableHelper: UIGestureRecognizerDelegate {

    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        return gestureRecognizer.view?.isFirstResponder == false
    }

}