Privado-iOS/iOS/Privado/Sources/Flows/NotificationsFlow/Module/View/NotificationsController.swift

//
//  NotificationsController.swift
//  PrivadoVPN
//
//  Created by Zhandos Bolatbekov on 11.01.2021.
//  Copyright © 2021 Privado LLC. All rights reserved.
//

import Foundation
import UIKit

protocol NotificationsControllerInput: AnyObject {
    func display(notificationCells: [NotificationCellAdapter])
}

protocol NotificationsControllerOutput: AnyObject {
    func viewIsReady()
    func backClick()
}

final class NotificationsController: UIViewController, NotificationsControllerInput {
    
    private enum Constants {
        static let backgroundColor = UIColor(rgb: 0x202864)
        static let statusBarColor = UIColor(red: 18, green: 23, blue: 45)
        
        static let backImage = "navigation_back"
        static let backWidth: CGFloat = 60
        static let backHeight: CGFloat = 40
        static let backLeft: CGFloat = 14
        static let statusBarHeight: CGFloat = UIApplication.shared.statusBarFrame.height
        
        static let estimatedCellHeight: CGFloat = 250
        
        static let emptyLabelTop: CGFloat = 92
    }
    
    private let output: NotificationsControllerOutput
    
    var navigationBar: UIView?
    
    private lazy var notificationsTableViewManager = NotificationsTableViewManager(tableView: self.notificationsTableView)
    private lazy var notificationsTableView: UITableView = {
        let tableView = UITableView()
        tableView.translatesAutoresizingMaskIntoConstraints = false
        tableView.separatorStyle = .none
        tableView.backgroundColor = .clear
        tableView.estimatedRowHeight = Constants.estimatedCellHeight
        tableView.showsVerticalScrollIndicator = true
        tableView.indicatorStyle = .white
        if #available(iOS 11.1, *) {
            tableView.verticalScrollIndicatorInsets = .init(top: 8, left: 0, bottom: 0, right: 8)
        } 
        return tableView
    }()
    private let notificationsEmptyLabel: UILabel = {
        let label = UILabel()
        label.font = UIFont(name: "SFProText-Light", size: 20)
        label.textAlignment = .center
        label.numberOfLines = 0
        label.text = NSLocalizedString("notificationCenter.empty", comment: "There are currently no notifications.")
        label.isHidden = true
        label.translatesAutoresizingMaskIntoConstraints = false
        label.textColor = UIColor(red: 122, green: 134, blue: 190)
        return label
    }()
    
    // MARK: - Init
    
    init(output: NotificationsControllerOutput) {
        self.output = output
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    // MARK: - Lifecycle
    
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .lightContent // .default
    }
    
    override func loadView() {
        let view = UIView(frame: .zero)
        view.autoresizesSubviews = true
        view.backgroundColor = Constants.backgroundColor
        self.view = view
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.configureUI()
        self.output.viewIsReady()
    }
    
    // MARK: - NotificationsControllerInput
    
    func display(notificationCells: [NotificationCellAdapter]) {
        self.notificationsTableViewManager.display(notificationCells: notificationCells)
        if notificationCells.isEmpty {
            self.notificationsTableView.isHidden = true
            self.notificationsEmptyLabel.isHidden = false
        } else {
            self.notificationsTableView.isHidden = false
            self.notificationsEmptyLabel.isHidden = true
        }
    }
    
    // MARK: - UI
    
    private func configureUI() {
        let backButton = self.initializeBackButton()
        self.view.addSubview(backButton)
        NSLayoutConstraint.activate([
            backButton.heightAnchor.constraint(equalToConstant: Constants.backHeight),
            backButton.widthAnchor.constraint(equalToConstant: Constants.backWidth),
            backButton.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: Constants.backLeft),
            backButton.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor)
        ])
        
        // Status bar
        let statusBarView = UIView()
        statusBarView.backgroundColor = Constants.statusBarColor
        statusBarView.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(statusBarView)
        NSLayoutConstraint.activate([
            statusBarView.heightAnchor.constraint(equalToConstant: Constants.statusBarHeight),
            statusBarView.topAnchor.constraint(equalTo: self.view.topAnchor),
            statusBarView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
            statusBarView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor)
        ])
        
        if let navigationBar = navigationBar {
            self.view.addSubview(navigationBar)
            NSLayoutConstraint.activate([
                navigationBar.topAnchor.constraint(equalTo: self.view.safeAreaLayoutGuide.topAnchor),
                navigationBar.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
                navigationBar.trailingAnchor.constraint(equalTo: self.view.trailingAnchor)
            ])
        }
        
        self.view.addSubview(self.notificationsTableView)
        NSLayoutConstraint.activate([
            self.notificationsTableView.topAnchor.constraint(
                equalTo: self.navigationBar?.bottomAnchor ?? self.view.safeAreaLayoutGuide.topAnchor
            ),
            self.notificationsTableView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor),
            self.notificationsTableView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor),
            self.notificationsTableView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor)
        ])
        
        self.view.addSubview(self.notificationsEmptyLabel)
        NSLayoutConstraint.activate([
            self.notificationsEmptyLabel.topAnchor.constraint(
                equalTo: self.navigationBar?.bottomAnchor ?? self.view.safeAreaLayoutGuide.topAnchor,
                constant: Constants.emptyLabelTop
            ),
            self.notificationsEmptyLabel.centerXAnchor.constraint(equalTo: self.view.centerXAnchor)
        ])
    }
    
    private func initializeBackButton() -> UIButton {

        let backButton = UIButton(frame: .zero)
        backButton.translatesAutoresizingMaskIntoConstraints = false
        backButton.addTarget(self, action: #selector(self.backClick), for: .touchUpInside)
        
        let image = UIImage(imageLiteralResourceName: Constants.backImage)
        let imageView = UIImageView(image: image)
        imageView.translatesAutoresizingMaskIntoConstraints = false
        
        backButton.addSubview(imageView)
        NSLayoutConstraint.activate([
            imageView.heightAnchor.constraint(equalToConstant: image.size.height),
            imageView.widthAnchor.constraint(equalToConstant: image.size.width),
            imageView.centerYAnchor.constraint(equalTo: backButton.centerYAnchor),
            imageView.centerXAnchor.constraint(equalTo: backButton.centerXAnchor)
        ])
        return backButton
    }
    
    @objc
    func backClick() {
        self.output.backClick()
    }
}

extension NotificationsController: ViewModuleControllerType { }