Switch to stable, hash-based account IDs

#160

Tusker/LocalData.swift

@@ -8,6 +8,7 @@
 
 import Foundation
 import Combine
+import CryptoKit
 
 class LocalData: ObservableObject {
     
@@ -22,7 +23,6 @@ class LocalData: ObservableObject {
             if ProcessInfo.processInfo.environment.keys.contains("UI_TESTING_LOGIN") {
                 accounts = [
                     UserAccountInfo(
-                        id: UUID().uuidString,
                         instanceURL: URL(string: "http://localhost:8080")!,
                         clientID: "client_id",
                         clientSecret: "client_secret",
@@ -33,23 +33,15 @@ class LocalData: ObservableObject {
         } else {
             defaults = UserDefaults(suiteName: "group.space.vaccor.Tusker")!
         }
+        
+        migrateAccountIDsIfNecessary()
     }
     
     private let accountsKey = "accounts"
-    var accounts: [UserAccountInfo] {
+    private(set) var accounts: [UserAccountInfo] {
         get {
             if let array = defaults.array(forKey: accountsKey) as? [[String: String]] {
-                return array.compactMap { (info) in
+                return array.compactMap(UserAccountInfo.init(userDefaultsDict:))
-                    guard let id = info["id"],
-                        let instanceURL = info["instanceURL"],
-                        let url = URL(string: instanceURL),
-                        let clientId = info["clientID"],
-                        let secret = info["clientSecret"],
-                        let accessToken = info["accessToken"] else {
-                            return nil
-                    }
-                    return UserAccountInfo(id: id, instanceURL: url, clientID: clientId, clientSecret: secret, username: info["username"], accessToken: accessToken)
-                }
             } else {
                 return []
             }
@@ -84,6 +76,41 @@ class LocalData: ObservableObject {
         }
     }
     
+    private let usesAccountIDHashesKey = "usesAccountIDHashes"
+    private var usesAccountIDHashes: Bool {
+        get {
+            return defaults.bool(forKey: usesAccountIDHashesKey)
+        }
+        set {
+            return defaults.set(newValue, forKey: usesAccountIDHashesKey)
+        }
+    }
+    
+    private func migrateAccountIDsIfNecessary() {
+        if usesAccountIDHashes {
+            return
+        }
+        if let mostRecentAccount = getMostRecentAccount() {
+            let hashedMostRecentID = UserAccountInfo.id(instanceURL: mostRecentAccount.instanceURL, username: mostRecentAccount.username)
+            mostRecentAccountID = hashedMostRecentID
+        }
+        if let array = defaults.array(forKey: accountsKey) as? [[String: String]] {
+            accounts = array.compactMap {
+                guard let urlString = $0["instanceURL"],
+                      let url = URL(string: urlString),
+                      let username = $0["username"] else {
+                    return nil
+                }
+                var dict = $0
+                dict["id"] = UserAccountInfo.id(instanceURL: url, username: username)
+                return UserAccountInfo(userDefaultsDict: dict)
+            }
+        }
+        usesAccountIDHashes = true
+    }
+    
+    // MARK: - Account Management
+    
     var onboardingComplete: Bool {
         return !accounts.isEmpty
     }
@@ -93,20 +120,12 @@ class LocalData: ObservableObject {
         if let index = accounts.firstIndex(where: { $0.instanceURL == url && $0.username == username }) {
             accounts.remove(at: index)
         }
-        let id = UUID().uuidString
+        let info = UserAccountInfo(instanceURL: url, clientID: clientID, clientSecret: secret, username: username, accessToken: accessToken)
-        let info = UserAccountInfo(id: id, instanceURL: url, clientID: clientID, clientSecret: secret, username: username, accessToken: accessToken)
         accounts.append(info)
         self.accounts = accounts
         return info
     }
     
-    func setUsername(for info: UserAccountInfo, username: String) {
-        var info = info
-        info.username = username
-        removeAccount(info)
-        accounts.append(info)
-    }
-    
     func removeAccount(_ info: UserAccountInfo) {
         accounts.removeAll(where: { $0.id == info.id })
     }
@@ -138,9 +157,57 @@ extension LocalData {
         let instanceURL: URL
         let clientID: String
         let clientSecret: String
-        fileprivate(set) var username: String!
+        private(set) var username: String!
         let accessToken: String
         
+        fileprivate static let tempAccountID = "temp"
+        
+        fileprivate static func id(instanceURL: URL, username: String?) -> String {
+            // We hash the instance host and username to form the account ID
+            // so that account IDs will match across devices, allowing for data syncing and handoff.
+            var hasher = SHA256()
+            hasher.update(data: instanceURL.host!.data(using: .utf8)!)
+            if let username {
+                hasher.update(data: username.data(using: .utf8)!)
+            }
+            return Data(hasher.finalize()).base64EncodedString()
+        }
+        
+        /// Only to be used for temporary MastodonController needed to fetch own account info and create final UserAccountInfo with real username
+        init(tempInstanceURL instanceURL: URL, clientID: String, clientSecret: String, accessToken: String) {
+            self.id = UserAccountInfo.tempAccountID
+            self.instanceURL = instanceURL
+            self.clientID = clientID
+            self.clientSecret = clientSecret
+            self.accessToken = accessToken
+        }
+        
+        fileprivate init(instanceURL: URL, clientID: String, clientSecret: String, username: String? = nil, accessToken: String) {
+            self.id = UserAccountInfo.id(instanceURL: instanceURL, username: username)
+            self.instanceURL = instanceURL
+            self.clientID = clientID
+            self.clientSecret = clientSecret
+            self.username = username
+            self.accessToken = accessToken
+        }
+        
+        fileprivate init?(userDefaultsDict dict: [String: String]) {
+            guard let id = dict["id"],
+                let instanceURL = dict["instanceURL"],
+                let url = URL(string: instanceURL),
+                let clientID = dict["clientID"],
+                let secret = dict["clientSecret"],
+                let accessToken = dict["accessToken"] else {
+                    return nil
+            }
+            self.id = id
+            self.instanceURL = url
+            self.clientID = clientID
+            self.clientSecret = secret
+            self.username = dict["username"]
+            self.accessToken = accessToken
+        }
+        
         func hash(into hasher: inout Hasher) {
             hasher.combine(id)
         }

Tusker/Screens/Onboarding/OnboardingViewController.swift

@@ -62,7 +62,7 @@ class OnboardingViewController: UINavigationController {
         }
         
         // construct a temporary UserAccountInfo instance for the MastodonController to use to fetch its own account
-        let tempAccountInfo = LocalData.UserAccountInfo(id: "temp", instanceURL: instanceURL, clientID: clientID, clientSecret: clientSecret, username: nil, accessToken: accessToken)
+        let tempAccountInfo = LocalData.UserAccountInfo(tempInstanceURL: instanceURL, clientID: clientID, clientSecret: clientSecret, accessToken: accessToken)
         mastodonController.accountInfo = tempAccountInfo
         
         let ownAccount: Account

Tusker/Screens/Preferences/PreferencesView.swift

@@ -48,7 +48,7 @@ struct PreferencesView: View {
                             indices.remove(index)
                         }
                         
-                        localData.accounts.remove(atOffsets: indices)
+                        indices.forEach { localData.removeAccount(localData.accounts[$0]) }
                         
                         if logoutFromCurrent {
                             self.logoutPressed()