//
//  LaunchScreenScrollView.swift
//  PrivadoVPN
//
//  Created by Lizaveta Malinouskaya on 6/22/21.
//  Copyright © 2021 Privado LLC. All rights reserved.
//

import UIKit

class LaunchScreenScrollView: UITextView {

    enum Constants {

        enum UI {
            static let font = UIFont.primary(size: 13, weight: .medium)
            static let textColor = Colors.basicText.color
            static let bgColor = Colors.Base.primaryDarkBlue.color
            static let insetHorizontal: CGFloat = 32
            static let insetVertical: CGFloat = 60
            static let lineSpacing: CGFloat = 19
        }

        enum LocalizedString {
            static let content = "launch.content"
        }
    }

    private var compactConstraints = [NSLayoutConstraint]()
    private var regularConstraints = [NSLayoutConstraint]()
    private var sharedConstraints = [NSLayoutConstraint]()
    private let isLandscapeModeEmitter = Emitter<Bool>()

    // MARK: - Init

    init() {
        super.init(frame: .zero, textContainer: nil)
        configureUI()
        self.isLandscapeModeEmitter.addReaction { [weak self] isLandscape -> ShouldContinueReceiveNotifications in
            self?.activateLayoutFor(landscape: isLandscape)
            return self.isExist
        }
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    // MARK: - UI
    private func configureUI() {
        
        self.translatesAutoresizingMaskIntoConstraints = false
        self.showsVerticalScrollIndicator = false
        self.showsHorizontalScrollIndicator = false
        self.isEditable = false
        
        self.setContentText(with: self)
        
        // Self apperance
        self.font = Constants.UI.font
        self.textColor = Constants.UI.textColor
        self.backgroundColor = Constants.UI.bgColor
        self.textContainerInset = UIEdgeInsets(top: Constants.UI.insetVertical, left: Constants.UI.insetHorizontal, bottom: Constants.UI.insetVertical, right: Constants.UI.insetHorizontal)
        
        // Self scroll indicator
        self.isScrollEnabled = true
        self.showsVerticalScrollIndicator = true
        self.scrollIndicatorInsets = UIEdgeInsets(top: Constants.UI.insetVertical, left: 0, bottom: Constants.UI.insetVertical, right: 0)
    }

    private func setContentText(with container: UITextView) {
        let text = NSLocalizedString(Constants.LocalizedString.content, comment: "Privacy policy")
        let mutableAttributedString = NSMutableAttributedString(string: text)
        let style = NSMutableParagraphStyle()
        style.lineSpacing = Constants.UI.lineSpacing
        mutableAttributedString.addAttributes([NSAttributedString.Key.paragraphStyle: style], range: NSRange(location: 0, length: mutableAttributedString.length))
        self.attributedText = mutableAttributedString
    }
    
    private func activateLayoutFor(landscape: Bool) {
        if landscape {
            NSLayoutConstraint.deactivate(self.compactConstraints)
            NSLayoutConstraint.activate(self.regularConstraints)
        } else {
            NSLayoutConstraint.deactivate(self.regularConstraints)
            NSLayoutConstraint.activate(self.compactConstraints)
        }
        NSLayoutConstraint.activate(self.sharedConstraints)
    }
}