AppBuilderiOS/appbuilder-ios/NexilisLite/NexilisLite/Source/View/Chat/CustomTextView.swift

//
//  CustomTextView.swift
//  Qmera
//
//  Created by Akhmad Al Qindi Irsyam on 27/09/21.
//

import UIKit

class CustomTextView: UITextView {
    
    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        let menuController = UIMenuController.shared
        if var menuItems = menuController.menuItems,
           (menuItems.map { $0.action }).elementsEqual([#selector(toggleBoldface), #selector(toggleItalics), #selector(toggleUnderline)]) {
            menuItems.append(UIMenuItem(title: "Strikethrough", action: #selector(toggleStrikethrough)))
            menuController.menuItems = menuItems
        }
        return super.canPerformAction(action, withSender: sender)
    }
    
    @objc func toggleStrikethrough(_ sender: Any?) {
        if let range = self.selectedTextRange {
            let startPosition = self.offset(from: self.beginningOfDocument, to: range.start)
            if startPosition == 0 || checkCharBefore(char: self.text.substring(from: startPosition - 1, to: startPosition - 1)) {
                self.replace(self.textRange(from: range.start, to: range.end)!, withText: "~\(self.text(in: range)!)~")
            } else {
                self.replace(self.textRange(from: range.start, to: range.end)!, withText: " ~\(self.text(in: range)!)~")
            }
            UIMenuController.shared.isMenuVisible = false
        }
    }

    override func toggleBoldface(_ sender: Any?) {
        if let range = self.selectedTextRange {
            let startPosition = self.offset(from: self.beginningOfDocument, to: range.start)
            if startPosition == 0 || checkCharBefore(char: self.text.substring(from: startPosition - 1, to: startPosition - 1)) {
                self.replace(self.textRange(from: range.start, to: range.end)!, withText: "*\(self.text(in: range)!)*")
            } else {
                self.replace(self.textRange(from: range.start, to: range.end)!, withText: " *\(self.text(in: range)!)*")
            }
            UIMenuController.shared.isMenuVisible = false
        }
    }
    
    override func toggleUnderline(_ sender: Any?) {
        if let range = self.selectedTextRange {
            let startPosition = self.offset(from: self.beginningOfDocument, to: range.start)
            if startPosition == 0 || checkCharBefore(char: self.text.substring(from: startPosition - 1, to: startPosition - 1)) {
                self.replace(self.textRange(from: range.start, to: range.end)!, withText: "^\(self.text(in: range)!)^")
            } else {
                self.replace(self.textRange(from: range.start, to: range.end)!, withText: " ^\(self.text(in: range)!)^")
            }
            UIMenuController.shared.isMenuVisible = false
        }
    }
    
    override func toggleItalics(_ sender: Any?) {
        if let range = self.selectedTextRange {
            let startPosition = self.offset(from: self.beginningOfDocument, to: range.start)
            if startPosition == 0 || checkCharBefore(char: self.text.substring(from: startPosition - 1, to: startPosition - 1)) {
                self.replace(self.textRange(from: range.start, to: range.end)!, withText: "_\(self.text(in: range)!)_")
            } else {
                self.replace(self.textRange(from: range.start, to: range.end)!, withText: " _\(self.text(in: range)!)_")
            }
            UIMenuController.shared.isMenuVisible = false
        }
    }
    
    func checkCharBefore(char: String) -> Bool {
        return char == " " || char == "\n"
    }
    

}