Privado-macOS/macOS/Privado/Sources/View/UnderlineTextField/UnderlineTextField.swift

//
//  UnderlineTextField.swift
//  PrivadoVPN
//
//  Created by Juraldinio on 1/21/21.
//  Copyright © 2021 Privado LLC. All rights reserved.
//

import Foundation
import AppKit

final class UnderlineTextField: NSTextField, NSTextFieldDelegate {
    
    enum Constants {
        
        static let lineHeight: CGFloat = 2.0
        
        enum Font {
            static let name = PrivadoConstants.Font.regular
            static let size: CGFloat = 14.0
        }
        
        enum Color {
            static let text = NSColor.white
            static let placeholder = NSColor(calibratedRed: 173.0 / 255, green: 179.0 / 255, blue: 210.0 / 255, alpha: 1.0)
            static let neutral = NSColor(calibratedRed: 45.0 / 255, green: 51.0 / 255, blue: 82.0 / 255, alpha: 1.0)
            static let beginEditing = NSColor(red: 40, green: 215, blue: 153)
        }
    }
    
    // MARK: - Properties
    
    private let bottomLineView: NSView
    
    var coloredPlaceHolder: String? {
        get {
            return self.placeholderAttributedString?.string
        }
        set {
            if let value = newValue {
                let attrs = [NSAttributedString.Key.foregroundColor: Constants.Color.placeholder,
                             NSAttributedString.Key.font: NSFont(name: Constants.Font.name, size: Constants.Font.size)]
                self.placeholderAttributedString = NSAttributedString(string: value, attributes: attrs)
            } else {
                self.placeholderAttributedString = nil
            }
        }
    }
    
    func hightlight(with color: NSColor?) {
        self.bottomLineView.viewBackgroundColor = color ?? Constants.Color.neutral
    }
    
    // MARK: - Initializers
    
    override init(frame frameRect: NSRect) {
        
        self.bottomLineView = NSView()
        
        super.init(frame: frameRect)
        self.cell?.isScrollable = true
        self.setupUI()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    // MARK: - Private
    
    private func setupUI() {

        self.isBezeled = false
        self.drawsBackground = false
        self.translatesAutoresizingMaskIntoConstraints = false
        self.focusRingType = .none
        self.usesSingleLineMode = true
        self.textColor = Constants.Color.text
        self.delegate = self
        self.font = NSFont(name: Constants.Font.name, size: Constants.Font.size)
        
        self.bottomLineView.translatesAutoresizingMaskIntoConstraints = false
        self.addSubview(self.bottomLineView)
        
        NSLayoutConstraint.activate([
            self.bottomLineView.heightAnchor.constraint(equalToConstant: Constants.lineHeight),
            self.bottomLineView.leadingAnchor.constraint(equalTo: self.leadingAnchor),
            self.bottomLineView.trailingAnchor.constraint(equalTo: self.trailingAnchor),
            self.bottomLineView.bottomAnchor.constraint(equalTo: self.bottomAnchor)
        ])
        
        self.hightlight(with: nil)
        
    }
    
    private func performEditingKeyEquivalent(with event: NSEvent) -> Bool {
        
        guard event.type == NSEvent.EventType.keyDown else { return false }

        let commandKey = NSEvent.ModifierFlags.command.rawValue
        let commandShiftKey = NSEvent.ModifierFlags.command.rawValue | NSEvent.ModifierFlags.shift.rawValue

        let key = event.modifierFlags.rawValue & NSEvent.ModifierFlags.deviceIndependentFlagsMask.rawValue
        switch key {
        case commandKey: return self.handleCommandKey(keyCode: event.keyCode)
        case commandShiftKey: return self.handleShiftKey(keyCode: event.keyCode)
        default:
            break
        }
        
        return false
    }
    
    private func handleCommandKey(keyCode: UInt16) -> Bool {
        
        switch keyCode {
        case KeyCode.x:
            if NSApp.sendAction(#selector(NSText.cut(_:)), to: nil, from: self) { return true }
        case KeyCode.c:
            if NSApp.sendAction(#selector(NSText.copy(_:)), to: nil, from: self) { return true }
        case KeyCode.v:
            if NSApp.sendAction(#selector(NSText.paste(_:)), to: nil, from: self) { return true }
        case KeyCode.z:
            if NSApp.sendAction(Selector(("undo:")), to: nil, from: self) { return true }
        case KeyCode.a:
            if NSApp.sendAction(#selector(NSResponder.selectAll(_:)), to: nil, from: self) { return true }
        default:
            break
        }
        
        return false
    }
    
    private func handleShiftKey(keyCode: UInt16) -> Bool {
        if keyCode == KeyCode.z {
            if NSApp.sendAction(Selector(("redo:")), to: nil, from: self) { return true }
        }
        
        return false
    }
    
    // MARK: - Lifecycle
    
    // Show edit pointer
    override func viewDidMoveToWindow() {
        if let textView = self.window?.fieldEditor(true, for: self) as? NSTextView {
            textView.insertionPointColor = Constants.Color.text
            textView.alignment = .center
        }
    }
    
    // Allow hotkeys in field
    override func performKeyEquivalent(with event: NSEvent) -> Bool {
        if self.performEditingKeyEquivalent(with: event) {
            return true
        }

        return super.performKeyEquivalent(with: event)
    }
    
    // MARK: - NSTextFieldDelegate
    
    func controlTextDidChange(_ obj: Notification) {
//        self.hightlight(with: nil)
    }
    
    func controlTextDidBeginEditing(_ obj: Notification) {
        self.hightlight(with: Constants.Color.beginEditing)
    }
    
    func controlTextDidEndEditing(_ obj: Notification) {
        self.hightlight(with: nil)
    }
}