//
//  SavedInstancesManager.swift
//  Tusker
//
//  Created by Shadowfacts on 12/19/19.
//  Copyright © 2019 Shadowfacts. All rights reserved.
//

import Foundation

class SavedInstanceManager: Codable {
    private(set) static var shared: SavedInstanceManager = load()
    
    private static var documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    private static var archiveURL = SavedInstanceManager.documentsDirectory.appendingPathComponent("saved_instances").appendingPathExtension("plist")
    
    static func save() {
        DispatchQueue.global(qos: .utility).async {
            let encoder = PropertyListEncoder()
            let data = try? encoder.encode(shared)
            try? data?.write(to: archiveURL, options: .noFileProtection)
        }
    }
    
    static func load() -> SavedInstanceManager {
        let decoder = PropertyListDecoder()
        if let data = try? Data(contentsOf: archiveURL),
            let savedInstanceManager = try? decoder.decode(Self.self, from: data) {
            return savedInstanceManager
        }
        return SavedInstanceManager()
    }
    
    private init() {}
    
    private(set) var savedInstances: [URL] = []
    
    func isSaved(_ url: URL) -> Bool {
        return savedInstances.contains(url)
    }
    
    func add(_ url: URL) {
        if isSaved(url) {
            return
        }
        savedInstances.append(url)
        SavedInstanceManager.save()
        NotificationCenter.default.post(name: .savedInstancesChanged, object: nil)
    }
    
    func remove(_ url: URL) {
        guard isSaved(url) else { return }
        savedInstances.removeAll(where: { $0 == url })
        SavedInstanceManager.save()
        NotificationCenter.default.post(name: .savedInstancesChanged, object: nil)
    }
}

extension Notification.Name {
    static let savedInstancesChanged = Notification.Name("savedInstancesChanged")
}