mastodon-ios/AppShared/UserDefaults.swift

//
//  UserDefaults.swift
//  AppShared
//
//  Created by MainasuK Cirno on 2021-4-27.
//

import UIKit
import CryptoKit

extension UserDefaults {
    public static let shared = UserDefaults(suiteName: AppName.groupID)!
}

extension UserDefaults {
    // always use hash value (SHA256) from accessToken as key
    private static func deriveKey(from accessToken: String, prefix: String) -> String {
        let digest = SHA256.hash(data: Data(accessToken.utf8))
        let bytes = [UInt8](digest)
        let hex = bytes.toHexString()
        let key = prefix + "@" + hex
        return key
    }
    
    private static let notificationCountKeyPrefix = "notification_count"
    
    public func getNotificationCountWithAccessToken(accessToken: String) -> Int {
        let prefix = UserDefaults.notificationCountKeyPrefix
        let key = UserDefaults.deriveKey(from: accessToken, prefix: prefix)
        return integer(forKey: key)
    }
    
    public func setNotificationCountWithAccessToken(accessToken: String, value: Int) {
        let prefix = UserDefaults.notificationCountKeyPrefix
        let key = UserDefaults.deriveKey(from: accessToken, prefix: prefix)
        setValue(value, forKey: key)
    }
    
    public func increaseNotificationCount(accessToken: String) {
        let count = getNotificationCountWithAccessToken(accessToken: accessToken)
        setNotificationCountWithAccessToken(accessToken: accessToken, value: count + 1)
    }
    
}