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//
// Copyright (c) 2018 Open Whisper Systems. All rights reserved.
//
import Foundation
@objc(OWSBlockListCacheDelegate)
public protocol BlockListCacheDelegate: class {
func blockListCacheDidUpdate(_ blocklistCache: BlockListCache)
}
/// A performant cache for which contacts/groups are blocked.
///
/// The source of truth for which contacts and groups are blocked is the `blockingManager`, but because
/// those accessors are made to be thread safe, they can be slow in tight loops, e.g. when rendering table
/// view cells.
///
/// Typically you'll want to create a Cache, update it to the latest state while simultaneously being informed
/// of any future changes to block list state.
///
/// class SomeViewController: BlockListCacheDelegate {
/// let blockListCache = BlockListCache()
/// func viewDidLoad() {
/// super.viewDidLoad()
/// blockListCache.startObservingAndSyncState(delegate: self)
/// self.updateAnyViewsWhichDepondOnBlockListCache()
/// }
///
/// func blockListCacheDidUpdate(_ blocklistCache: BlockListCache) {
/// self.updateAnyViewsWhichDepondOnBlockListCache()
/// }
///
/// ...
/// }
///
@objc(OWSBlockListCache)
public class BlockListCache: NSObject {
private var blockedRecipientIds: Set<String> = Set()
private var blockedGroupIds: Set<Data> = Set()
private let serialQueue: DispatchQueue = DispatchQueue(label: "BlockListCache")
weak var delegate: BlockListCacheDelegate?
private var blockingManager: OWSBlockingManager {
return OWSBlockingManager.shared()
}
/// Generally something which wants to use this cache wants to do 3 things
/// 1. get the cache on the latest state
/// 2. update the cache whenever the blockingManager's state changes
/// 3. be notified when the cache updates
/// This method does all three.
@objc
public func startObservingAndSyncState(delegate: BlockListCacheDelegate) {
self.delegate = delegate
NotificationCenter.default.addObserver(self,
selector: #selector(blockListDidChange),
name: NSNotification.Name(rawValue: kNSNotificationName_BlockListDidChange),
object: nil)
updateWithoutNotifyingDelegate()
}
// MARK: -
@objc
func blockListDidChange() {
self.update()
}
@objc(isRecipientIdBlocked:)
public func isBlocked(recipientId: String) -> Bool {
return serialQueue.sync {
blockedRecipientIds.contains(recipientId)
}
}
@objc(isGroupIdBlocked:)
public func isBlocked(groupId: Data) -> Bool {
return serialQueue.sync {
blockedGroupIds.contains(groupId)
}
}
@objc(isThreadBlocked:)
public func isBlocked(thread: TSThread) -> Bool {
switch thread {
case let contactThread as TSContactThread:
return serialQueue.sync {
blockedRecipientIds.contains(contactThread.contactIdentifier())
}
case let groupThread as TSGroupThread:
return serialQueue.sync {
blockedGroupIds.contains(groupThread.groupModel.groupId)
}
default:
owsFailDebug("\(self.logTag) in \(#function) unexpected thread type: \(type(of: thread))")
return false
}
}
// MARK: -
public func update() {
updateWithoutNotifyingDelegate()
DispatchQueue.main.async {
self.delegate?.blockListCacheDidUpdate(self)
}
}
private func updateWithoutNotifyingDelegate() {
let blockedRecipientIds = Set(blockingManager.blockedPhoneNumbers())
let blockedGroupIds = Set(blockingManager.blockedGroupIds)
update(blockedRecipientIds: blockedRecipientIds, blockedGroupIds: blockedGroupIds)
}
private func update(blockedRecipientIds: Set<String>, blockedGroupIds: Set<Data>) {
serialQueue.sync {
self.blockedRecipientIds = blockedRecipientIds
self.blockedGroupIds = blockedGroupIds
}
}
}