Add Compose screen mention, hashtag, emoji completion

Closes #10

Pachyderm/Client.swift

@@ -52,10 +52,11 @@ public class Client {
         self.session = session
     }
     
-    public func run<Result>(_ request: Request<Result>, completion: @escaping Callback<Result>) {
+    @discardableResult
+    public func run<Result>(_ request: Request<Result>, completion: @escaping Callback<Result>) -> URLSessionTask? {
         guard let request = createURLRequest(request: request) else {
             completion(.failure(Error.invalidRequest))
-            return
+            return nil
         }
         
         let task = session.dataTask(with: request) { data, response, error in
@@ -83,6 +84,7 @@ public class Client {
             completion(.success(result, pagination))
         }
         task.resume()
+        return task
     }
     
     func createURLRequest<Result>(request: Request<Result>) -> URLRequest? {
@@ -276,12 +278,12 @@ public class Client {
     }
     
     // MARK: - Search
-    public static func search(query: String, resolve: Bool? = nil, limit: Int? = nil) -> Request<SearchResults> {
+    public static func search(query: String, types: [SearchResultType]? = nil, resolve: Bool? = nil, limit: Int? = nil) -> Request<SearchResults> {
         return Request<SearchResults>(method: .get, path: "/api/v2/search", queryParameters: [
                 "q" => query,
                 "resolve" => resolve,
-                "limit" => limit
+                "limit" => limit,
-            ])
+        ] + "types" => types?.map { $0.rawValue })
     }
     
     // MARK: - Statuses
@@ -314,13 +316,24 @@ public class Client {
     }
     
     
-    // MARK: Bookmarks
+    // MARK: - Bookmarks
     public static func getBookmarks(range: RequestRange = .default) -> Request<[Status]> {
         var request = Request<[Status]>(method: .get, path: "/api/v1/bookmarks")
         request.range = range
         return request
     }
     
+    // MARK: - Trends
+    public static func getTrends(limit: Int? = nil) -> Request<[Hashtag]> {
+        let parameters: [Parameter]
+        if let limit = limit {
+            parameters = ["limit" => limit]
+        } else {
+            parameters = []
+        }
+        return Request<[Hashtag]>(method: .get, path: "/api/v1/trends", queryParameters: parameters)
+    }
+    
 }
 
 extension Client {

Pachyderm/Model/SearchResultType.swift

@@ -0,0 +1,15 @@
+//
+//  SearchResultType.swift
+//  Pachyderm
+//
+//  Created by Shadowfacts on 10/11/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import Foundation
+
+public enum SearchResultType: String {
+    case accounts
+    case hashtags
+    case statuses
+}

Tusker.xcodeproj/project.pbxproj

@@ -263,6 +263,12 @@
 		D6DFC69E242C490400ACC392 /* TrackpadScrollGestureRecognizer.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6DFC69D242C490400ACC392 /* TrackpadScrollGestureRecognizer.swift */; };
 		D6DFC6A0242C4CCC00ACC392 /* WeakArray.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6DFC69F242C4CCC00ACC392 /* WeakArray.swift */; };
 		D6E0DC8E216EDF1E00369478 /* Previewing.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E0DC8D216EDF1E00369478 /* Previewing.swift */; };
+		D6E4267725327FB400C02E1C /* ComposeAutocompleteView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E4267625327FB400C02E1C /* ComposeAutocompleteView.swift */; };
+		D6E426812532814100C02E1C /* MaybeLazyStack.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E426802532814100C02E1C /* MaybeLazyStack.swift */; };
+		D6E4269D2532A3E100C02E1C /* FuzzyMatcher.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E4269C2532A3E100C02E1C /* FuzzyMatcher.swift */; };
+		D6E426AD25334DA500C02E1C /* FuzzyMatcherTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E426AC25334DA500C02E1C /* FuzzyMatcherTests.swift */; };
+		D6E426B325337C7000C02E1C /* CustomEmojiImageView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E426B225337C7000C02E1C /* CustomEmojiImageView.swift */; };
+		D6E426B9253382B300C02E1C /* SearchResultType.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E426B8253382B300C02E1C /* SearchResultType.swift */; };
 		D6E6F26321603F8B006A8599 /* CharacterCounter.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E6F26221603F8B006A8599 /* CharacterCounter.swift */; };
 		D6E6F26521604242006A8599 /* CharacterCounterTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E6F26421604242006A8599 /* CharacterCounterTests.swift */; };
 		D6EBF01523C55C0900AE061B /* UIApplication+Scenes.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6EBF01423C55C0900AE061B /* UIApplication+Scenes.swift */; };
@@ -591,6 +597,12 @@
 		D6DFC69D242C490400ACC392 /* TrackpadScrollGestureRecognizer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TrackpadScrollGestureRecognizer.swift; sourceTree = "<group>"; };
 		D6DFC69F242C4CCC00ACC392 /* WeakArray.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WeakArray.swift; sourceTree = "<group>"; };
 		D6E0DC8D216EDF1E00369478 /* Previewing.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Previewing.swift; sourceTree = "<group>"; };
+		D6E4267625327FB400C02E1C /* ComposeAutocompleteView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposeAutocompleteView.swift; sourceTree = "<group>"; };
+		D6E426802532814100C02E1C /* MaybeLazyStack.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MaybeLazyStack.swift; sourceTree = "<group>"; };
+		D6E4269C2532A3E100C02E1C /* FuzzyMatcher.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FuzzyMatcher.swift; sourceTree = "<group>"; };
+		D6E426AC25334DA500C02E1C /* FuzzyMatcherTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FuzzyMatcherTests.swift; sourceTree = "<group>"; };
+		D6E426B225337C7000C02E1C /* CustomEmojiImageView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CustomEmojiImageView.swift; sourceTree = "<group>"; };
+		D6E426B8253382B300C02E1C /* SearchResultType.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SearchResultType.swift; sourceTree = "<group>"; };
 		D6E4885C24A2890C0011C13E /* Tusker.entitlements */ = {isa = PBXFileReference; lastKnownFileType = text.plist.entitlements; path = Tusker.entitlements; sourceTree = "<group>"; };
 		D6E6F26221603F8B006A8599 /* CharacterCounter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CharacterCounter.swift; sourceTree = "<group>"; };
 		D6E6F26421604242006A8599 /* CharacterCounterTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CharacterCounterTests.swift; sourceTree = "<group>"; };
@@ -753,6 +765,7 @@
 				D61099F82145698900432DC2 /* Relationship.swift */,
 				D61099FA214569F600432DC2 /* Report.swift */,
 				D61099FC21456A1D00432DC2 /* SearchResults.swift */,
+				D6E426B8253382B300C02E1C /* SearchResultType.swift */,
 				D61099FE21456A4C00432DC2 /* Status.swift */,
 				D6285B4E21EA695800FE4B39 /* StatusContentType.swift */,
 				D6109A10214607D500432DC2 /* Timeline.swift */,
@@ -987,6 +1000,7 @@
 				D622757724EE133700B82A16 /* ComposeAssetPicker.swift */,
 				D62275A524F1C81800B82A16 /* ComposeReplyView.swift */,
 				D62275A724F1CA2800B82A16 /* ComposeReplyContentView.swift */,
+				D6E4267625327FB400C02E1C /* ComposeAutocompleteView.swift */,
 			);
 			path = Compose;
 			sourceTree = "<group>";
@@ -1259,6 +1273,8 @@
 				D6C99FC624FACFAB005C74D3 /* ActivityIndicatorView.swift */,
 				D686BBE224FBF8110068E6AA /* WrappedProgressView.swift */,
 				D6B4A4FE2506B81A000C81C1 /* AccountDisplayNameLabel.swift */,
+				D6E426802532814100C02E1C /* MaybeLazyStack.swift */,
+				D6E426B225337C7000C02E1C /* CustomEmojiImageView.swift */,
 				D67C57A721E2649B00C3118B /* Account Detail */,
 				D626494023C122C800612E6E /* Asset Picker */,
 				D61959D0241E842400A37B8E /* Draft Cell */,
@@ -1341,6 +1357,7 @@
 				D64D8CA82463B494006B0BAA /* CachedDictionary.swift */,
 				D60E2F2B24423EAD005F8713 /* LazilyDecoding.swift */,
 				D6CA6A91249FAD8900AD45C1 /* AudioSessionHelper.swift */,
+				D6E4269C2532A3E100C02E1C /* FuzzyMatcher.swift */,
 				D67B506B250B28FF00FAECFB /* Vendor */,
 				D6F1F84E2193B9BE00F5FE67 /* Caching */,
 				D6757A7A2157E00100721E32 /* XCallbackURL */,
@@ -1366,6 +1383,7 @@
 			children = (
 				D6D4DDE4212518A200E1C4BB /* TuskerTests.swift */,
 				D62FF04723D7CDD700909D6E /* AttributedStringHelperTests.swift */,
+				D6E426AC25334DA500C02E1C /* FuzzyMatcherTests.swift */,
 				D6D4DDE6212518A200E1C4BB /* Info.plist */,
 			);
 			path = TuskerTests;
@@ -1696,6 +1714,7 @@
 				D61099CB2144B20500432DC2 /* Request.swift in Sources */,
 				D6109A05214572BF00432DC2 /* Scope.swift in Sources */,
 				D6109A11214607D500432DC2 /* Timeline.swift in Sources */,
+				D6E426B9253382B300C02E1C /* SearchResultType.swift in Sources */,
 				D60E2F3324425374005F8713 /* AccountProtocol.swift in Sources */,
 				D61099E7214561FF00432DC2 /* Attachment.swift in Sources */,
 				D60E2F3124424F1A005F8713 /* StatusProtocol.swift in Sources */,
@@ -1795,6 +1814,7 @@
 				D60E2F2C24423EAD005F8713 /* LazilyDecoding.swift in Sources */,
 				D677284A24ECBDF400C732D3 /* ComposeCurrentAccount.swift in Sources */,
 				D62D2424217ABF3F005076CC /* NSUserActivity+Extensions.swift in Sources */,
+				D6E426812532814100C02E1C /* MaybeLazyStack.swift in Sources */,
 				D646C958213B367000269FB5 /* LargeImageShrinkAnimationController.swift in Sources */,
 				D6A3BC852321F6C100FD64D5 /* AccountListTableViewController.swift in Sources */,
 				D64BC18823C1640A000D0238 /* PinStatusActivity.swift in Sources */,
@@ -1849,6 +1869,7 @@
 				D6B053AB23BD2F1400A066FA /* AssetCollectionViewCell.swift in Sources */,
 				D622757A24EE21D900B82A16 /* ComposeAttachmentRow.swift in Sources */,
 				D6434EB3215B1856001A919A /* XCBRequest.swift in Sources */,
+				D6E4269D2532A3E100C02E1C /* FuzzyMatcher.swift in Sources */,
 				D681E4D3246E2AFF0053414F /* MuteConversationActivity.swift in Sources */,
 				D6969EA0240C8384002843CE /* EmojiLabel.swift in Sources */,
 				D64BC18623C1253A000D0238 /* AssetPreviewViewController.swift in Sources */,
@@ -1910,11 +1931,13 @@
 				D626493F23C101C500612E6E /* AlbumAssetCollectionViewController.swift in Sources */,
 				D68015422401A74600D6103B /* MediaPrefsView.swift in Sources */,
 				D6C99FCB24FADC91005C74D3 /* MainComposeTextView.swift in Sources */,
+				D6E4267725327FB400C02E1C /* ComposeAutocompleteView.swift in Sources */,
 				D6757A7E2157E02600721E32 /* XCBRequestSpec.swift in Sources */,
 				D677284E24ECC01D00C732D3 /* Draft.swift in Sources */,
 				D667E5F12134D5050057A976 /* UIViewController+Delegates.swift in Sources */,
 				D6BC8748219738E1006163F1 /* EnhancedTableViewController.swift in Sources */,
 				D663625F2135C75500C9CBA2 /* ConversationMainStatusTableViewCell.swift in Sources */,
+				D6E426B325337C7000C02E1C /* CustomEmojiImageView.swift in Sources */,
 				D6D4DDD0212518A000E1C4BB /* AppDelegate.swift in Sources */,
 				D6412B0924B0291E00F5412E /* MyProfileViewController.swift in Sources */,
 				D6B053A423BD2C8100A066FA /* AssetCollectionsListViewController.swift in Sources */,
@@ -1928,6 +1951,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				D62FF04823D7CDD700909D6E /* AttributedStringHelperTests.swift in Sources */,
+				D6E426AD25334DA500C02E1C /* FuzzyMatcherTests.swift in Sources */,
 				D6D4DDE5212518A200E1C4BB /* TuskerTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Tusker/Controllers/MastodonController.swift

@@ -44,6 +44,7 @@ class MastodonController: ObservableObject {
     
     @Published private(set) var account: Account!
     @Published private(set) var instance: Instance!
+    private(set) var customEmojis: [Emoji]?
     
     var loggedIn: Bool {
         accountInfo != nil
@@ -56,8 +57,9 @@ class MastodonController: ObservableObject {
         self.transient = transient
     }
     
-    func run<Result>(_ request: Request<Result>, completion: @escaping Client.Callback<Result>) {
+    @discardableResult
-        client.run(request, completion: completion)
+    func run<Result>(_ request: Request<Result>, completion: @escaping Client.Callback<Result>) -> URLSessionTask? {
+        return client.run(request, completion: completion)
     }
     
     func registerApp(completion: @escaping (_ clientID: String, _ clientSecret: String) -> Void) {
@@ -128,4 +130,20 @@ class MastodonController: ObservableObject {
         }
     }
     
+    func getCustomEmojis(completion: @escaping ([Emoji]) -> Void) {
+        if let emojis = self.customEmojis {
+            completion(emojis)
+        } else {
+            let request = Client.getCustomEmoji()
+            run(request) { (response) in
+                if case let .success(emojis, _) = response {
+                    self.customEmojis = emojis
+                    completion(emojis)
+                } else {
+                    completion([])
+                }
+            }
+        }
+    }
+    
 }

Tusker/FuzzyMatcher.swift

@@ -0,0 +1,62 @@
+//
+//  FuzzyMatcher.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 10/10/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import Foundation
+
+struct FuzzyMatcher {
+    
+    private init() {}
+    
+    /// Rudimentary string fuzzy matching algorithm.
+    ///
+    /// Operates on UTF-8 code points, so attempting to match strings which include characters composed of
+    /// multiple code points may produce unexpected results.
+    ///
+    /// Scoring is as follows:
+    /// +2 points for every char in `pattern` that occurs in `str` sequentially
+    /// -2 points for every char in `pattern` that does not occur in `str` sequentially
+    /// -1 point for every char in `str` skipped between matching chars from the `pattern`
+    static func match(pattern: String, str: String) -> (matched: Bool, score: Int) {
+        let pattern = pattern.lowercased()
+        let str = str.lowercased()
+        
+        var patternIndex = pattern.utf8.startIndex
+        var lastStrMatchIndex: String.UTF8View.Index?
+        var strIndex = str.utf8.startIndex
+        
+        var score = 0
+        
+        while patternIndex < pattern.utf8.endIndex && strIndex < str.utf8.endIndex {
+            let patternChar = pattern.utf8[patternIndex]
+            let strChar = str.utf8[strIndex]
+            if patternChar == strChar {
+                let distance = str.utf8.distance(from: lastStrMatchIndex ?? str.utf8.startIndex, to: strIndex)
+                if distance > 1 {
+                    score -= distance - 1
+                }
+                
+                patternIndex = pattern.utf8.index(after: patternIndex)
+                lastStrMatchIndex = strIndex
+                strIndex = str.utf8.index(after: strIndex)
+                
+                score += 2
+            } else {
+                strIndex = str.utf8.index(after: strIndex)
+                
+                if strIndex >= str.utf8.endIndex {
+                    patternIndex = pattern.utf8.index(after: patternIndex)
+                    strIndex = str.utf8.index(after: lastStrMatchIndex ?? str.utf8.startIndex)
+                    score -= 2
+                }
+            }
+        }
+        
+        return (score > 0, score)
+    }
+    
+}

Tusker/Screens/Compose/ComposeAutocompleteView.swift

@@ -0,0 +1,350 @@
+//
+//  ComposeAutocompleteView.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 10/10/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import SwiftUI
+import CoreData
+import Pachyderm
+
+struct ComposeAutocompleteView: View {
+    let autocompleteState: ComposeUIState.AutocompleteState
+    
+    @Environment(\.colorScheme) var colorScheme: ColorScheme
+    
+    private var backgroundColor: Color {
+        Color(white: colorScheme == .light ? 0.98 : 0.15)
+    }
+    
+    private var borderColor: Color {
+        Color(white: colorScheme == .light ? 0.85 : 0.25)
+    }
+    
+    var body: some View {
+        suggestionsView
+            // animate changes of the scroll view items
+            .animation(.default)
+            .background(backgroundColor)
+            .overlay(borderColor.frame(height: 0.5), alignment: .top)
+    }
+    
+    @ViewBuilder
+    private var suggestionsView: some View {
+        switch autocompleteState {
+        case .mention(_):
+            ComposeAutocompleteMentionsView()
+        case .emoji(_):
+            ComposeAutocompleteEmojisView()
+        case .hashtag(_):
+            ComposeAutocompleteHashtagsView()
+        }
+    }
+}
+
+fileprivate extension View {
+    @ViewBuilder
+    func iOS13OnlyPadding() -> some View {
+        // on iOS 13, if the scroll view content's height changes after the view is added to the hierarchy,
+        // it doesn't appear on screen until interactive keyboard dismissal is started and then cancelled :S
+        if #available(iOS 14.0, *) {
+            self
+        } else {
+            self.frame(height: 46)
+        }
+    }
+}
+
+struct ComposeAutocompleteMentionsView: View {
+    @EnvironmentObject private var mastodonController: MastodonController
+    @EnvironmentObject private var uiState: ComposeUIState
+    @ObservedObject private var preferences = Preferences.shared
+    
+    // can't use AccountProtocol because of associated type requirements
+    @State private var accounts: [EitherAccount] = []
+    
+    @State private var searchRequest: URLSessionTask?
+    
+    var body: some View {
+        ScrollView(.horizontal) {
+            // can't use LazyHStack because changing the contents of the ForEach causes the ScrollView to hang
+            HStack(spacing: 8) {
+                ForEach(accounts, id: \.id) { (account) in
+                    Button {
+                        uiState.autocompleteHandler?.autocomplete(with: "@\(account.acct) ")
+                    } label: {
+                        HStack(spacing: 4) {
+                            ComposeAvatarImageView(url: account.avatar)
+                                .frame(width: 30, height: 30)
+                                .cornerRadius(preferences.avatarStyle.cornerRadiusFraction * 30)
+                            
+                            VStack(alignment: .leading) {
+                                switch account {
+                                case let .pachyderm(underlying):
+                                    AccountDisplayNameLabel(account: underlying, fontSize: 14)
+                                        .foregroundColor(Color(UIColor.label))
+                                case let .coreData(underlying):
+                                    AccountDisplayNameLabel(account: underlying, fontSize: 14)
+                                        .foregroundColor(Color(UIColor.label))
+                                }
+                                
+                                Text(verbatim: "@\(account.acct)")
+                                    .font(.system(size: 12))
+                                    .foregroundColor(Color(UIColor.label))
+                            }
+                        }
+                    }
+                    .frame(height: 30)
+                    .padding(.vertical, 8)
+                    .animation(.linear(duration: 0.1))
+                }
+                
+                Spacer()
+            }
+            .padding(.horizontal, 8)
+            .iOS13OnlyPadding()
+        }
+        .onReceive(uiState.$autocompleteState.debounce(for: .milliseconds(250), scheduler: DispatchQueue.main), perform: queryChanged)
+        .onDisappear {
+            searchRequest?.cancel()
+        }
+    }
+    
+    private func queryChanged(_ state: ComposeUIState.AutocompleteState?) {
+        guard case let .mention(query) = state,
+              !query.isEmpty else {
+            accounts = []
+            return
+        }
+        
+        let localSearchWorkItem = DispatchWorkItem {
+            // todo: there's got to be something more efficient than this :/
+            let wildcardedQuery = query.map { "*\($0)" }.joined() + "*"
+            let request: NSFetchRequest<AccountMO> = AccountMO.fetchRequest()
+            request.predicate = NSPredicate(format: "displayName LIKE %@ OR acct LIKE %@", wildcardedQuery, wildcardedQuery)
+            
+            if let results = try? mastodonController.persistentContainer.viewContext.fetch(request) {
+                loadAccounts(results.map { .coreData($0) }, query: query)
+            }
+        }
+        
+        // we only want to search locally if the search API call takes more than .25sec or it fails
+        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(250), execute: localSearchWorkItem)
+        
+        if let oldRequest = searchRequest {
+            oldRequest.cancel()
+        }
+        
+        let apiRequest = Client.searchForAccount(query: query)
+        searchRequest = mastodonController.run(apiRequest) { (response) in
+            guard case let .success(accounts, _) = response else { return }
+            
+            localSearchWorkItem.cancel()
+            
+            // if the query has changed, don't bother loading the now-outdated results
+            if case .mention(query) = uiState.autocompleteState {
+                self.loadAccounts(accounts.map { .pachyderm($0) }, query: query)
+            }
+        }
+    }
+    
+    private func loadAccounts(_ accounts: [EitherAccount], query: String) {
+        // when sorting account suggestions, ignore the domain component of the acct unless the user is typing it themself
+        let ignoreDomain = !query.contains("@")
+        
+        self.accounts =
+            accounts.map { (account: EitherAccount) -> (EitherAccount, (matched: Bool, score: Int)) in
+                let fuzzyStr = ignoreDomain ? String(account.acct.split(separator: "@").first!) : account.acct
+                let res = (account, FuzzyMatcher.match(pattern: query, str: fuzzyStr))
+                return res
+            }
+            .filter(\.1.matched)
+            // todo: it would be nice to prioritize followee/follower accounts, but relationships aren't cached
+            .sorted { $0.1.score > $1.1.score }
+            .map(\.0)
+    }
+    
+    private enum EitherAccount {
+        case pachyderm(Account)
+        case coreData(AccountMO)
+        
+        var id: String {
+            switch self {
+            case let .pachyderm(account):
+                return account.id
+            case let .coreData(account):
+                return account.id
+            }
+        }
+        
+        var acct: String {
+            switch self {
+            case let .pachyderm(account):
+                return account.acct
+            case let .coreData(account):
+                return account.acct
+            }
+        }
+        
+        var avatar: URL {
+            switch self {
+            case let .pachyderm(account):
+                return account.avatar
+            case let .coreData(account):
+                return account.avatar
+            }
+        }
+    }
+}
+
+struct ComposeAutocompleteEmojisView: View {
+    @EnvironmentObject private var mastodonController: MastodonController
+    @EnvironmentObject private var uiState: ComposeUIState
+    
+    @State private var emojis: [Emoji] = []
+    
+    var body: some View {
+        ScrollView(.horizontal) {
+            HStack(spacing: 8) {
+                ForEach(emojis, id: \.shortcode) { (emoji) in
+                    Button {
+                        uiState.autocompleteHandler?.autocomplete(with: ":\(emoji.shortcode): ")
+                    } label: {
+                        HStack(spacing: 4) {
+                            CustomEmojiImageView(emoji: emoji)
+                                .frame(height: 30)
+                            Text(verbatim: ":\(emoji.shortcode):")
+                                .foregroundColor(Color(UIColor.label))
+                        }
+                    }
+                    .frame(height: 30)
+                    .padding(.vertical, 8)
+                    .animation(.linear(duration: 0.1))
+                }
+                
+                Spacer()
+            }
+            .padding(.horizontal, 8)
+            .iOS13OnlyPadding()
+        }
+        .onReceive(uiState.$autocompleteState.debounce(for: .milliseconds(250), scheduler: DispatchQueue.main), perform: queryChanged)
+    }
+    
+    private func queryChanged(_ autocompleteState: ComposeUIState.AutocompleteState?) {
+        guard case let .emoji(query) = autocompleteState,
+              !query.isEmpty else {
+            emojis = []
+            return
+        }
+        
+        mastodonController.getCustomEmojis { (emojis) in
+            guard case .emoji(query) = self.uiState.autocompleteState else { return }
+            
+            self.emojis =
+                emojis.map { (emoji) -> (Emoji, (matched: Bool, score: Int)) in
+                    (emoji, FuzzyMatcher.match(pattern: query, str: emoji.shortcode))
+                }
+                .filter(\.1.matched)
+                .sorted { $0.1.score > $1.1.score }
+                .map(\.0)
+        }
+    }
+}
+
+struct ComposeAutocompleteHashtagsView: View {
+    @EnvironmentObject private var mastodonController: MastodonController
+    @EnvironmentObject private var uiState: ComposeUIState
+    
+    @State private var hashtags: [Hashtag] = []
+    @State private var trendingRequest: URLSessionTask?
+    @State private var searchRequest: URLSessionTask?
+    
+    var body: some View {
+        ScrollView(.horizontal) {
+            HStack(spacing: 8) {
+                ForEach(hashtags, id: \.name) { (hashtag) in
+                    Button {
+                        uiState.autocompleteHandler?.autocomplete(with: "#\(hashtag.name) ")
+                    } label: {
+                        Text(verbatim: "#\(hashtag.name)")
+                            .foregroundColor(Color(UIColor.label))
+                    }
+                    .frame(height: 30)
+                    .padding(.vertical, 8)
+                    .animation(.linear(duration: 0.1))
+                }
+                
+                Spacer()
+            }
+            .padding(.horizontal, 8)
+            .iOS13OnlyPadding()
+        }
+        .onReceive(uiState.$autocompleteState.debounce(for: .milliseconds(250), scheduler: DispatchQueue.main), perform: queryChanged)
+        .onDisappear {
+            trendingRequest?.cancel()
+        }
+    }
+    
+    private func queryChanged(_ autocompleteState: ComposeUIState.AutocompleteState?) {
+        guard case let .hashtag(query) = autocompleteState,
+              !query.isEmpty else {
+            hashtags = []
+            return
+        }
+        
+        let onlySavedTagsWorkItem = DispatchWorkItem {
+            self.updateHashtags(searchResults: [], trendingTags: [], query: query)
+        }
+        
+        // we only want to do the local-only search if the trends API call takes more than .25sec or it fails
+        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(250), execute: onlySavedTagsWorkItem)
+        
+        var trendingTags: [Hashtag] = []
+        var searchedTags: [Hashtag] = []
+        
+        let group = DispatchGroup()
+        
+        group.enter()
+        trendingRequest = mastodonController.run(Client.getTrends()) { (response) in
+            defer { group.leave() }
+            guard case let .success(trends, _) = response else { return }
+            trendingTags = trends
+        }
+        
+        group.enter()
+        searchRequest = mastodonController.run(Client.search(query: "#\(query)", types: [.hashtags])) { (response) in
+            defer { group.leave() }
+            guard case let .success(results, _) = response else { return }
+            searchedTags = results.hashtags
+        }
+        
+        group.notify(queue: .main) {
+            onlySavedTagsWorkItem.cancel()
+            
+            // if the query has changed, don't bother loading the now-outdated results
+            if case .hashtag(query) = self.uiState.autocompleteState {
+                self.updateHashtags(searchResults: searchedTags, trendingTags: trendingTags, query: query)
+            }
+        }
+    }
+    
+    private func updateHashtags(searchResults: [Hashtag], trendingTags: [Hashtag], query: String) {
+        let savedTags = SavedDataManager.shared.sortedHashtags(for: mastodonController.accountInfo!)
+        
+        hashtags = (searchResults + savedTags + trendingTags)
+            .map { (tag) -> (Hashtag, (matched: Bool, score: Int)) in
+                return (tag, FuzzyMatcher.match(pattern: query, str: tag.name))
+            }
+            .filter(\.1.matched)
+            .sorted { $0.1.score > $1.1.score }
+            .map(\.0)
+    }
+}
+
+struct ComposeAutocompleteView_Previews: PreviewProvider {
+    static var previews: some View {
+        ComposeAutocompleteView(autocompleteState: .mention("shadowfacts"))
+    }
+}

Tusker/Screens/Compose/ComposeAvatarImageView.swift

@@ -17,8 +17,6 @@ struct ComposeAvatarImageView: View {
     var body: some View {
         image
             .resizable()
-            .frame(width: 50, height: 50)
-            .cornerRadius(preferences.avatarStyle.cornerRadiusFraction * 50)
             .conditionally(url != nil) {
                 $0.onAppear(perform: self.loadImage)
             }
@@ -27,7 +25,7 @@ struct ComposeAvatarImageView: View {
     
     private var image: Image {
         if let avatarImage = avatarImage {
-            return Image(uiImage: avatarImage)
+            return Image(uiImage: avatarImage).renderingMode(.original)
         } else {
             return placeholderImage
         }

Tusker/Screens/Compose/ComposeCurrentAccount.swift

@@ -11,6 +11,7 @@ import Pachyderm
 
 struct ComposeCurrentAccount: View {
     @EnvironmentObject var mastodonController: MastodonController
+    @ObservedObject private var preferences = Preferences.shared
     
     var account: Account? {
         mastodonController.account
@@ -19,6 +20,8 @@ struct ComposeCurrentAccount: View {
     var body: some View {
         HStack(alignment: .top) {
             ComposeAvatarImageView(url: account?.avatar)
+                .frame(width: 50, height: 50)
+                .cornerRadius(preferences.avatarStyle.cornerRadiusFraction * 50)
                 .accessibility(label: Text(account != nil ? "\(account!.displayName) avatar" : "Avatar"))
             
             if let id = account?.id,

Tusker/Screens/Compose/ComposeHostingController.swift

@@ -164,7 +164,9 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
             let frame = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as! CGRect
             // temporarily reset add'l safe area insets so we can access the default inset
             additionalSafeAreaInsets = .zero
-            keyboardHeight = frame.height - view.safeAreaInsets.bottom - accessoryView.frame.height
+            // there are a few extra points that come from somewhere, it seems to be four
+            // and without it, the autocomplete suggestions are cut off :S
+            keyboardHeight = frame.height - view.safeAreaInsets.bottom - accessoryView.frame.height + 4
             updateAdditionalSafeAreaInsets()
         }
     }

Tusker/Screens/Compose/ComposeReplyView.swift

@@ -15,6 +15,8 @@ struct ComposeReplyView: View {
     
     @State private var contentHeight: CGFloat?
     
+    @ObservedObject private var preferences = Preferences.shared
+    
     private let horizSpacing: CGFloat = 8
     
     var body: some View {
@@ -55,6 +57,8 @@ struct ComposeReplyView: View {
         scrollOffset += stackPadding
         let offset = min(max(scrollOffset, 0), geometry.size.height - 50 - stackPadding)
         return ComposeAvatarImageView(url: status.account.avatar)
+            .frame(width: 50, height: 50)
+            .cornerRadius(preferences.avatarStyle.cornerRadiusFraction * 50)
             .offset(x: 0, y: offset)
     }
     

Tusker/Screens/Compose/ComposeUIState.swift

@@ -27,9 +27,12 @@ class ComposeUIState: ObservableObject {
     @Published var draft: Draft
     @Published var isShowingSaveDraftSheet = false
     @Published var attachmentsMissingDescriptions = Set<UUID>()
+    @Published var autocompleteState: AutocompleteState? = nil
     
     var composeDrawingMode: ComposeDrawingMode?
     
+    weak var autocompleteHandler: ComposeAutocompleteHandler?
+    
     init(draft: Draft) {
         self.draft = draft
     }
@@ -42,3 +45,11 @@ extension ComposeUIState {
         case edit(id: UUID)
     }
 }
+
+extension ComposeUIState {
+    enum AutocompleteState {
+        case mention(String)
+        case emoji(String)
+        case hashtag(String)
+    }
+}

Tusker/Screens/Compose/ComposeView.swift

@@ -65,6 +65,10 @@ struct ComposeView: View {
             
             // can't use SwiftUI.ProgressView because there's no UIProgressView.Style.bar equivalent, see FB8587149
             WrappedProgressView(value: postProgress, total: postTotalProgress)
+            
+            if let state = uiState.autocompleteState {
+                autocompleteSuggestions(state: state)
+            }
         }
         .onAppear(perform: self.didAppear)
         .navigationBarTitle("Compose")
@@ -78,6 +82,24 @@ struct ComposeView: View {
         }
     }
     
+    @ViewBuilder
+    func autocompleteSuggestions(state: ComposeUIState.AutocompleteState) -> some View {
+        // on iOS 13, the transition causes SwiftUI to hang on the main thread when the view appears, so it's disabled
+        if #available(iOS 14.0, *) {
+            VStack(spacing: 0) {
+                Spacer()
+                ComposeAutocompleteView(autocompleteState: state)
+            }
+            .transition(.move(edge: .bottom))
+            .animation(.default)
+        } else {
+            VStack(spacing: 0) {
+                Spacer()
+                ComposeAutocompleteView(autocompleteState: state)
+            }
+        }
+    }
+    
     func mainStack(outerMinY: CGFloat) -> some View {
         VStack(alignment: .leading, spacing: 8) {
             if let id = draft.inReplyToID,

Tusker/Screens/Compose/MainComposeTextView.swift

@@ -66,6 +66,8 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
         textView.textContainer.lineBreakMode = .byWordWrapping
         context.coordinator.textView = textView
         
+        uiState.autocompleteHandler = context.coordinator
+        
         let visibilityAction: Selector?
         if #available(iOS 14.0, *) {
             visibilityAction = nil
@@ -167,7 +169,7 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
         return Coordinator(text: $text, uiState: uiState, didChange: textDidChange)
     }
     
-    class Coordinator: NSObject, UITextViewDelegate {
+    class Coordinator: NSObject, UITextViewDelegate, ComposeAutocompleteHandler {
         weak var textView: UITextView?
         var text: Binding<String>
         var didChange: (UITextView) -> Void
@@ -182,6 +184,8 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
         func textViewDidChange(_ textView: UITextView) {
             text.wrappedValue = textView.text
             didChange(textView)
+            
+            updateAutocompleteState()
         }
         
         @objc func formatButtonPressed(_ sender: UIBarButtonItem) {
@@ -213,5 +217,132 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
         @objc func keyboardDidHide(_ notification: Foundation.Notification) {
             uiState.delegate?.keyboardDidHide(accessoryView: textView!.inputAccessoryView!, notification: notification)
         }
+        
+        func textViewDidEndEditing(_ textView: UITextView) {
+            updateAutocompleteState()
+        }
+        
+        func textViewDidBeginEditing(_ textView: UITextView) {
+            updateAutocompleteState()
+        }
+        
+        func textViewDidChangeSelection(_ textView: UITextView) {
+            updateAutocompleteState()
+        }
+        
+        func autocomplete(with string: String) {
+            guard let textView = textView,
+                  let text = textView.text,
+                  let (lastWordStartIndex, _) = findAutocompleteLastWord() else {
+                return
+            }
+            
+            let characterBeforeCursorIndex = text.utf16.index(text.startIndex, offsetBy: textView.selectedRange.upperBound)
+            
+            textView.text.replaceSubrange(lastWordStartIndex..<characterBeforeCursorIndex, with: string)
+            self.textViewDidChange(textView)
+        }
+        
+        private func updateAutocompleteState() {
+            guard let textView = textView,
+                  let text = textView.text,
+                  let (lastWordStartIndex, foundFirstAtSign) = findAutocompleteLastWord() else {
+                uiState.autocompleteState = nil
+                return
+            }
+            
+            let triggerChars: [Character] = ["@", ":", "#"]
+            if lastWordStartIndex > text.startIndex {
+                // if the character before the "word" beginning is a valid part of a "word",
+                // we aren't able to autocomplete
+                let c = text[text.index(before: lastWordStartIndex)]
+                if isPermittedForAutocomplete(c) || triggerChars.contains(c) {
+                    uiState.autocompleteState = nil
+                    return
+                }
+            }
+            
+            let characterBeforeCursorIndex = text.utf16.index(text.startIndex, offsetBy: textView.selectedRange.upperBound)
+            
+            if lastWordStartIndex >= text.startIndex {
+                let lastWord = text[lastWordStartIndex..<characterBeforeCursorIndex]
+                let exceptFirst = lastWord[lastWord.index(after: lastWord.startIndex)...]
+                
+                // periods are only allowed in mentions in the domain part
+                if lastWord.contains(".") {
+                    if lastWord.first == "@" && foundFirstAtSign {
+                        uiState.autocompleteState = .mention(String(exceptFirst))
+                    } else {
+                        uiState.autocompleteState = nil
+                    }
+                    return
+                }
+                
+                switch lastWord.first {
+                case "@":
+                    uiState.autocompleteState = .mention(String(exceptFirst))
+                case ":":
+                    uiState.autocompleteState = .emoji(String(exceptFirst))
+                case "#":
+                    uiState.autocompleteState = .hashtag(String(exceptFirst))
+                default:
+                    uiState.autocompleteState = nil
+                }
+            } else {
+                uiState.autocompleteState = nil
+            }
+        }
+        
+        private func isPermittedForAutocomplete(_ c: Character) -> Bool {
+            return (c >= "a" && c <= "z") || (c >= "A" && c <= "Z") || (c >= "0" && c <= "9") || c == "_"
+        }
+        
+        private func findAutocompleteLastWord() -> (index: String.Index, foundFirstAtSign: Bool)? {
+            guard let textView = textView,
+                  textView.isFirstResponder,
+                  textView.selectedRange.length == 0,
+                  textView.selectedRange.upperBound > 0,
+                  let text = textView.text,
+                  text.count > 0 else {
+                return nil
+            }
+            
+            let characterBeforeCursorIndex = text.utf16.index(text.startIndex, offsetBy: textView.selectedRange.upperBound)
+            
+            var lastWordStartIndex = text.index(before: characterBeforeCursorIndex)
+            var foundFirstAtSign = false
+            while true {
+                let c = textView.text[lastWordStartIndex]
+                
+                if !isPermittedForAutocomplete(c) {
+                    if foundFirstAtSign {
+                        if c != "@" {
+                            // move the index forward by 1, so that the first char of the substring is the 1st @ instead of whatever comes before it
+                            lastWordStartIndex = text.index(after: lastWordStartIndex)
+                        }
+                        break
+                    } else {
+                        if c == "@" {
+                            foundFirstAtSign = true
+                        } else if c != "." {
+                            // periods are allowed for domain names in mentions
+                            break
+                        }
+                    }
+                }
+                
+                if lastWordStartIndex > text.startIndex {
+                    lastWordStartIndex = text.index(before: lastWordStartIndex)
+                } else {
+                    break
+                }
+            }
+            
+            return (lastWordStartIndex, foundFirstAtSign)
+        }
     }
 }
+
+protocol ComposeAutocompleteHandler: class {
+    func autocomplete(with string: String)
+}

Tusker/Views/AccountDisplayNameLabel.swift

@@ -7,16 +7,17 @@
 //
 
 import SwiftUI
+import Pachyderm
 
 private let emojiRegex = try! NSRegularExpression(pattern: ":(\\w+):", options: [])
 
-struct AccountDisplayNameLabel: View {
+struct AccountDisplayNameLabel<Account: AccountProtocol>: View {
-    let account: AccountMO
+    let account: Account
     let fontSize: Int
     @State var text: Text
     @State var emojiRequests = [ImageCache.Request]()
     
-    init(account: AccountMO, fontSize: Int) {
+    init(account: Account, fontSize: Int) {
         self.account = account
         self.fontSize = fontSize
         self._text = State(initialValue: Text(verbatim: account.displayName))

Tusker/Views/CustomEmojiImageView.swift

@@ -0,0 +1,59 @@
+//
+//  CustomEmojiImageView.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 10/11/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import SwiftUI
+import Pachyderm
+
+struct CustomEmojiImageView: View {
+    let emoji: Emoji
+    @State private var request: ImageCache.Request?
+    @State private var image: UIImage?
+    
+    var body: some View {
+        imageView
+            .onAppear(perform: self.loadImage)
+            .onDisappear(perform: self.cancelRequest)
+    }
+    
+    @ViewBuilder
+    private var imageView: some View {
+        if let image = image {
+            Image(uiImage: image)
+                .renderingMode(.original)
+                .resizable()
+                .aspectRatio(contentMode: .fit)
+        } else {
+            Image(systemName: "smiley.fill")
+        }
+    }
+    
+    private func loadImage() {
+        request = ImageCache.emojis.get(emoji.url) { (data) in
+            if let data = data, let image = UIImage(data: data) {
+                DispatchQueue.main.async {
+                    self.request = nil
+                    self.image = image
+                }
+            } else {
+                DispatchQueue.main.async {
+                    self.request = nil
+                }
+            }
+        }
+    }
+    
+    private func cancelRequest() {
+        request?.cancel()
+    }
+}
+
+//struct CustomEmojiImageView_Previews: PreviewProvider {
+//    static var previews: some View {
+//        CustomEmojiImageView()
+//    }
+//}

Tusker/Views/MaybeLazyStack.swift

@@ -0,0 +1,59 @@
+//
+//  MaybeLazyStack.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 10/10/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import SwiftUI
+
+struct MaybeLazyVStack<Content: View>: View {
+    private let alignment: HorizontalAlignment
+    private let spacing: CGFloat?
+    private let content: Content
+    
+    init(alignment: HorizontalAlignment = .center, spacing: CGFloat? = nil, @ViewBuilder content: () -> Content) {
+        self.alignment = alignment
+        self.spacing = spacing
+        self.content = content()
+    }
+    
+    @ViewBuilder
+    var body: some View {
+        if #available(iOS 14.0, *) {
+            LazyVStack(alignment: alignment, spacing: spacing) {
+                content
+            }
+        } else {
+            VStack(alignment: alignment, spacing: spacing) {
+                content
+            }
+        }
+    }
+}
+
+struct MaybeLazyHStack<Content: View>: View {
+    private let alignment: VerticalAlignment
+    private let spacing: CGFloat?
+    private let content: Content
+    
+    init(alignment: VerticalAlignment = .center, spacing: CGFloat? = nil, @ViewBuilder content: () -> Content) {
+        self.alignment = alignment
+        self.spacing = spacing
+        self.content = content()
+    }
+    
+    @ViewBuilder
+    var body: some View {
+        if #available(iOS 14.0, *) {
+            LazyHStack(alignment: alignment, spacing: spacing) {
+                content
+            }
+        } else {
+            HStack(alignment: alignment, spacing: spacing) {
+                content
+            }
+        }
+    }
+}

TuskerTests/FuzzyMatcherTests.swift

@@ -0,0 +1,25 @@
+//
+//  FuzzyMatcherTests.swift
+//  TuskerTests
+//
+//  Created by Shadowfacts on 10/11/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import XCTest
+@testable import Tusker
+
+class FuzzyMatcherTests: XCTestCase {
+
+    func testExample() throws {
+        XCTAssertEqual(FuzzyMatcher.match(pattern: "foo", str: "foo").score, 6)
+        XCTAssertEqual(FuzzyMatcher.match(pattern: "foo", str: "faoao").score, 4)
+        XCTAssertEqual(FuzzyMatcher.match(pattern: "foo", str: "aaa").score, -6)
+        
+        XCTAssertEqual(FuzzyMatcher.match(pattern: "bar", str: "baz").score, 2)
+        XCTAssertEqual(FuzzyMatcher.match(pattern: "bar", str: "bur").score, 1)
+        
+        XCTAssertGreaterThan(FuzzyMatcher.match(pattern: "sir", str: "sir").score, FuzzyMatcher.match(pattern: "sir", str: "georgespolitzer").score)
+    }
+
+}