elpha-ios/elpha-ios/AlertManager.swift

//
//  AlertManager.swift
//  elpha-ios
//
//  Created by Dwayne Harris on 10/30/18.
//  Copyright © 2018 Elpha. All rights reserved.
//

import UIKit

enum AlertCategory {
    case normal, newStatuses, favorited, boosted, toot, noConnection, error
}

class Alert {
    let category: AlertCategory
    let message: String
    
    init(category: AlertCategory, message: String) {
        self.category = category
        self.message = message
    }
}

class AlertManager {
    static let shared = AlertManager()
    static let alertStartPosition: CGFloat = 100.0
    static let alertEndPosition: CGFloat = -80.0
    
    var done: Bool = true
    var alertView: AlertView?
    var bottomLayoutConstraint: NSLayoutConstraint?
    var alerts: [Alert] = []
    
    func createAlertView() {
        guard alertView == nil else {
            return
        }
        
        alertView = AlertView()
        alertView!.translatesAutoresizingMaskIntoConstraints = false
        
        let blurEffectView = UIVisualEffectView(effect: UIBlurEffect(style: UIBlurEffect.Style.prominent))
        blurEffectView.translatesAutoresizingMaskIntoConstraints = false
        blurEffectView.contentView.addSubview(alertView!)
        blurEffectView.layer.cornerRadius = 10
        blurEffectView.layer.masksToBounds = true
        
        NSLayoutConstraint.activate([
            alertView!.leadingAnchor.constraint(equalTo: blurEffectView.leadingAnchor),
            alertView!.trailingAnchor.constraint(equalTo: blurEffectView.trailingAnchor),
            alertView!.topAnchor.constraint(equalTo: blurEffectView.topAnchor),
            alertView!.bottomAnchor.constraint(equalTo: blurEffectView.bottomAnchor),
        ])
        
        let view = UIApplication.shared.keyWindow!
        
        view.addSubview(blurEffectView)
        
        bottomLayoutConstraint = blurEffectView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: AlertManager.alertStartPosition)
        
        NSLayoutConstraint.activate([
            blurEffectView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20),
            blurEffectView.widthAnchor.constraint(equalToConstant: 220),
            blurEffectView.heightAnchor.constraint(equalToConstant: 50),
            bottomLayoutConstraint!,
        ])
    }
    
    private func start() {
        guard done else {
            return
        }
        
        if alertView == nil {
            createAlertView()
        }
        
        let view = UIApplication.shared.keyWindow!
        
        done = false
        self.alertView?.setAlert(self.alerts.first!)
        
        view.layoutIfNeeded()
        
        UIView.animate(withDuration: 0.2, delay: 0.0, options: .curveEaseInOut, animations: {
            self.bottomLayoutConstraint?.constant = AlertManager.alertEndPosition
            view.layoutIfNeeded()
        }) { _ in
            DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
                UIView.animate(withDuration: 0.2, delay: 0.0, options: .curveEaseInOut, animations: {
                    self.bottomLayoutConstraint?.constant = AlertManager.alertStartPosition
                    view.layoutIfNeeded()
                }) { _ in
                    self.done = true
                    _ = self.alerts.remove(at: 0)
                    
                    if self.alerts.count > 0 {
                        DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
                            self.start()
                        }
                    }
                }
            }
        }
    }
    
    func show(message: String, category: AlertCategory = .normal) {
        if let alert = alerts.last {
            if alert.category == category {
                return
            }
        }
        
        print("Alert: \(message)")
        
        alerts.append(Alert(category: category, message: message))
        start()
    }
}