autocomplete polishing

* suppress autocomplete when navigating through history
* only search for slashcommands if in the first block of the editor
* handle suffix returns from providers correctly
* fix SelectionRange typing in the providers
* fix bugs when pressing ctrl-a, typing and then tab to complete a replacement by collapsing selection to anchor when inserting a completion in the editor
* fix https://github.com/vector-im/riot-web/issues/4762

src/autocomplete/AutocompleteProvider.js

@@ -20,13 +20,19 @@ import React from 'react';
 import type {Completion, SelectionRange} from './Autocompleter';
 
 export default class AutocompleteProvider {
-    constructor(commandRegex?: RegExp) {
+    constructor(commandRegex?: RegExp, forcedCommandRegex?: RegExp) {
         if (commandRegex) {
             if (!commandRegex.global) {
                 throw new Error('commandRegex must have global flag set');
             }
             this.commandRegex = commandRegex;
         }
+        if (forcedCommandRegex) {
+            if (!forcedCommandRegex.global) {
+                throw new Error('forcedCommandRegex must have global flag set');
+            }
+            this.forcedCommandRegex = forcedCommandRegex;
+        }
     }
 
     destroy() {
@@ -36,11 +42,11 @@ export default class AutocompleteProvider {
     /**
      * Of the matched commands in the query, returns the first that contains or is contained by the selection, or null.
      */
-    getCurrentCommand(query: string, selection: {start: number, end: number}, force: boolean = false): ?string {
+    getCurrentCommand(query: string, selection: SelectionRange, force: boolean = false): ?string {
         let commandRegex = this.commandRegex;
 
         if (force && this.shouldForceComplete()) {
-            commandRegex = /\S+/g;
+            commandRegex = this.forcedCommandRegex || /\S+/g;
         }
 
         if (commandRegex == null) {

src/autocomplete/Autocompleter.js

@@ -27,6 +27,7 @@ import NotifProvider from './NotifProvider';
 import Promise from 'bluebird';
 
 export type SelectionRange = {
+    beginning: boolean,
     start: number,
     end: number
 };
@@ -77,12 +78,12 @@ export default class Autocompleter {
             // Array of inspections of promises that might timeout. Instead of allowing a
             // single timeout to reject the Promise.all, reflect each one and once they've all
             // settled, filter for the fulfilled ones
-            this.providers.map((provider) => {
-                return provider
+            this.providers.map(provider =>
+                provider
                     .getCompletions(query, selection, force)
                     .timeout(PROVIDER_COMPLETION_TIMEOUT)
-                    .reflect();
-            }),
+                    .reflect()
+            ),
         );
 
         return completionsList.filter(

src/autocomplete/CommandProvider.js

@@ -21,6 +21,7 @@ import { _t, _td } from '../languageHandler';
 import AutocompleteProvider from './AutocompleteProvider';
 import FuzzyMatcher from './FuzzyMatcher';
 import {TextualCompletion} from './Components';
+import type {SelectionRange} from './Autocompleter';
 
 // TODO merge this with the factory mechanics of SlashCommands?
 // Warning: Since the description string will be translated in _t(result.description), all these strings below must be in i18n/strings/en_EN.json file
@@ -123,8 +124,9 @@ export default class CommandProvider extends AutocompleteProvider {
         });
     }
 
-    async getCompletions(query: string, selection: {start: number, end: number}) {
+    async getCompletions(query: string, selection: SelectionRange) {
         let completions = [];
+        if (!selection.beginning) return completions;
         const {command, range} = this.getCurrentCommand(query, selection);
         if (command) {
             completions = this.matcher.match(command[0]).map((result) => {

src/autocomplete/DuckDuckGoProvider.js

@@ -22,6 +22,7 @@ import AutocompleteProvider from './AutocompleteProvider';
 import 'whatwg-fetch';
 
 import {TextualCompletion} from './Components';
+import type {SelectionRange} from './Autocompleter';
 
 const DDG_REGEX = /\/ddg\s+(.+)$/g;
 const REFERRER = 'vector';
@@ -36,7 +37,7 @@ export default class DuckDuckGoProvider extends AutocompleteProvider {
          + `&format=json&no_redirect=1&no_html=1&t=${encodeURIComponent(REFERRER)}`;
     }
 
-    async getCompletions(query: string, selection: {start: number, end: number}) {
+    async getCompletions(query: string, selection: SelectionRange) {
         const {command, range} = this.getCurrentCommand(query, selection);
         if (!query || !command) {
             return [];

src/autocomplete/NotifProvider.js

@@ -20,6 +20,7 @@ import { _t } from '../languageHandler';
 import MatrixClientPeg from '../MatrixClientPeg';
 import {PillCompletion} from './Components';
 import sdk from '../index';
+import type {SelectionRange} from './Autocompleter';
 
 const AT_ROOM_REGEX = /@\S*/g;
 
@@ -29,7 +30,7 @@ export default class NotifProvider extends AutocompleteProvider {
         this.room = room;
     }
 
-    async getCompletions(query: string, selection: {start: number, end: number}, force = false) {
+    async getCompletions(query: string, selection: SelectionRange, force = false) {
         const RoomAvatar = sdk.getComponent('views.avatars.RoomAvatar');
 
         const client = MatrixClientPeg.get();

src/autocomplete/RoomProvider.js

@@ -26,6 +26,7 @@ import {getDisplayAliasForRoom} from '../Rooms';
 import sdk from '../index';
 import _sortBy from 'lodash/sortBy';
 import {makeRoomPermalink} from "../matrix-to";
+import type {SelectionRange} from './Autocompleter';
 
 const ROOM_REGEX = /(?=#)(\S*)/g;
 
@@ -46,15 +47,9 @@ export default class RoomProvider extends AutocompleteProvider {
         });
     }
 
-    async getCompletions(query: string, selection: {start: number, end: number}, force = false) {
+    async getCompletions(query: string, selection: SelectionRange, force = false) {
         const RoomAvatar = sdk.getComponent('views.avatars.RoomAvatar');
 
-        // Disable autocompletions when composing commands because of various issues
-        // (see https://github.com/vector-im/riot-web/issues/4762)
-        if (/^(\/join|\/leave)/.test(query)) {
-            return [];
-        }
-
         const client = MatrixClientPeg.get();
         let completions = [];
         const {command, range} = this.getCurrentCommand(query, selection, force);

src/autocomplete/UserProvider.js

@@ -28,18 +28,21 @@ import _sortBy from 'lodash/sortBy';
 import MatrixClientPeg from '../MatrixClientPeg';
 
 import type {Room, RoomMember} from 'matrix-js-sdk';
+import type {SelectionRange} from './Autocompleter';
 import {makeUserPermalink} from "../matrix-to";
 
 const USER_REGEX = /@\S*/g;
 
+// used when you hit 'tab' - we allow some separator chars at the beginning
+// to allow you to tab-complete /mat into /(matthew)
+const FORCED_USER_REGEX = /[^/,:; \t\n]\S*/g;
+
 export default class UserProvider extends AutocompleteProvider {
     users: Array<RoomMember> = null;
     room: Room = null;
 
     constructor(room) {
-        super(USER_REGEX, {
-            keys: ['name'],
-        });
+        super(USER_REGEX, FORCED_USER_REGEX);
         this.room = room;
         this.matcher = new FuzzyMatcher([], {
             keys: ['name', 'userId'],
@@ -87,15 +90,9 @@ export default class UserProvider extends AutocompleteProvider {
         this.users = null;
     }
 
-    async getCompletions(query: string, selection: {start: number, end: number}, force = false) {
+    async getCompletions(query: string, selection: SelectionRange, force = false) {
         const MemberAvatar = sdk.getComponent('views.avatars.MemberAvatar');
 
-        // Disable autocompletions when composing commands because of various issues
-        // (see https://github.com/vector-im/riot-web/issues/4762)
-        if (/^(\/ban|\/unban|\/op|\/deop|\/invite|\/kick|\/verify)/.test(query)) {
-            return [];
-        }
-
         // lazy-load user list into matcher
         if (this.users === null) this._makeUsers();
 
@@ -114,7 +111,7 @@ export default class UserProvider extends AutocompleteProvider {
                     // relies on the length of the entity === length of the text in the decoration.
                     completion: user.rawDisplayName.replace(' (IRC)', ''),
                     completionId: user.userId,
-                    suffix: range.start === 0 ? ': ' : ' ',
+                    suffix: (selection.beginning && range.start === 0) ? ': ' : ' ',
                     href: makeUserPermalink(user.userId),
                     component: (
                         <PillCompletion