Wire up drag-drop file uploads for the thread view (#7860)

res/css/_components.scss

@@ -10,6 +10,7 @@
 @import "./structures/_ContextualMenu.scss";
 @import "./structures/_CreateRoom.scss";
 @import "./structures/_CustomRoomTagPanel.scss";
+@import "./structures/_FileDropTarget.scss";
 @import "./structures/_FilePanel.scss";
 @import "./structures/_GenericErrorPage.scss";
 @import "./structures/_GroupFilterPanel.scss";
@@ -141,11 +142,11 @@
 @import "./views/elements/_Dropdown.scss";
 @import "./views/elements/_EditableItemList.scss";
 @import "./views/elements/_ErrorBoundary.scss";
-@import "./views/elements/_GenericEventListSummary.scss";
 @import "./views/elements/_EventTilePreview.scss";
 @import "./views/elements/_ExternalLink.scss";
 @import "./views/elements/_FacePile.scss";
 @import "./views/elements/_Field.scss";
+@import "./views/elements/_GenericEventListSummary.scss";
 @import "./views/elements/_ImageView.scss";
 @import "./views/elements/_InfoTooltip.scss";
 @import "./views/elements/_InlineSpinner.scss";
@@ -183,9 +184,9 @@
 @import "./views/messages/_CallEvent.scss";
 @import "./views/messages/_CreateEvent.scss";
 @import "./views/messages/_DateSeparator.scss";
-@import "./views/messages/_JumpToDatePicker.scss";
 @import "./views/messages/_EventTileBubble.scss";
 @import "./views/messages/_HiddenBody.scss";
+@import "./views/messages/_JumpToDatePicker.scss";
 @import "./views/messages/_MEmoteBody.scss";
 @import "./views/messages/_MFileBody.scss";
 @import "./views/messages/_MImageBody.scss";

res/css/structures/_FileDropTarget.scss

@@ -0,0 +1,65 @@
+/*
+Copyright 2015, 2016 OpenMarket Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+@keyframes mx_FileDropTarget_animation {
+    from {
+        opacity: 0;
+    }
+    to {
+        opacity: 0.95;
+    }
+}
+
+.mx_FileDropTarget {
+    min-width: 0;
+    width: 100%;
+    height: 100%;
+
+    font-size: $font-18px;
+    text-align: center;
+
+    pointer-events: none;
+
+    background-color: $background;
+    opacity: 0.95;
+
+    position: absolute;
+    z-index: 3000;
+
+    display: flex;
+    flex-direction: column;
+    justify-content: center;
+    align-items: center;
+
+    animation: mx_FileDropTarget_animation;
+    animation-duration: 0.5s;
+}
+
+@keyframes mx_FileDropTarget_image_animation {
+    from {
+        transform: scaleX(0);
+    }
+    to {
+        transform: scaleX(1);
+    }
+}
+
+.mx_FileDropTarget_image {
+    width: 32px;
+    animation: mx_FileDropTarget_image_animation;
+    animation-duration: 0.5s;
+    margin-bottom: 16px;
+}

res/css/structures/_RoomView.scss

@@ -32,56 +32,6 @@ limitations under the License.
     position: relative;
 }
 
-@keyframes mx_RoomView_fileDropTarget_animation {
-    from {
-        opacity: 0;
-    }
-    to {
-        opacity: 0.95;
-    }
-}
-
-.mx_RoomView_fileDropTarget {
-    min-width: 0px;
-    width: 100%;
-    height: 100%;
-
-    font-size: $font-18px;
-    text-align: center;
-
-    pointer-events: none;
-
-    background-color: $background;
-    opacity: 0.95;
-
-    position: absolute;
-    z-index: 3000;
-
-    display: flex;
-    flex-direction: column;
-    justify-content: center;
-    align-items: center;
-
-    animation: mx_RoomView_fileDropTarget_animation;
-    animation-duration: 0.5s;
-}
-
-@keyframes mx_RoomView_fileDropTarget_image_animation {
-    from {
-        transform: scaleX(0);
-    }
-    to {
-        transform: scaleX(1);
-    }
-}
-
-.mx_RoomView_fileDropTarget_image {
-    width: 32px;
-    animation: mx_RoomView_fileDropTarget_image_animation;
-    animation-duration: 0.5s;
-    margin-bottom: 16px;
-}
-
 .mx_RoomView_auxPanel {
     min-width: 0px;
     width: 100%;

res/css/views/right_panel/_ThreadPanel.scss

@@ -106,11 +106,18 @@ limitations under the License.
         padding-right: 16px;
     }
 
-    &.mx_ThreadView .mx_AutoHideScrollbar {
+    &.mx_ThreadView .mx_ThreadView_timelinePanelWrapper {
         /* the scrollbar is 8px wide, and we want a 12px gap with the side of the
         panel. Hence the magic number, 8+4=12 */
         width: calc(100% - 4px);
         padding-right: 4px;
+        position: relative;
+        min-height: 0; // don't displace the composer
+        flex-grow: 1;
+
+        .mx_FileDropTarget {
+            border-radius: 8px;
+        }
     }
 
     .mx_RoomView_MessageList {

src/@types/groups.ts

@@ -0,0 +1,59 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+export const CreateEventField = "io.element.migrated_from_community";
+
+export interface IGroupRoom {
+    displayname: string;
+    name?: string;
+    roomId: string;
+    canonicalAlias?: string;
+    avatarUrl?: string;
+    topic?: string;
+    numJoinedMembers?: number;
+    worldReadable?: boolean;
+    guestCanJoin?: boolean;
+    isPublic?: boolean;
+}
+
+/* eslint-disable camelcase */
+export interface IGroupSummary {
+    profile: {
+        avatar_url?: string;
+        is_openly_joinable?: boolean;
+        is_public?: boolean;
+        long_description: string;
+        name: string;
+        short_description: string;
+    };
+    rooms_section: {
+        rooms: unknown[];
+        categories: Record<string, unknown>;
+        total_room_count_estimate: number;
+    };
+    user: {
+        is_privileged: boolean;
+        is_public: boolean;
+        is_publicised: boolean;
+        membership: string;
+    };
+    users_section: {
+        users: unknown[];
+        roles: Record<string, unknown>;
+        total_user_count_estimate: number;
+    };
+}
+/* eslint-enable camelcase */

src/ContentMessages.tsx

@@ -447,7 +447,7 @@ export default class ContentMessages {
     public async sendContentListToRoom(
         files: File[],
         roomId: string,
-        relation: IEventRelation | null,
+        relation: IEventRelation | undefined,
         matrixClient: MatrixClient,
         context = TimelineRenderingType.Room,
     ): Promise<void> {
@@ -566,7 +566,7 @@ export default class ContentMessages {
     private sendContentToRoom(
         file: File,
         roomId: string,
-        relation: IEventRelation,
+        relation: IEventRelation | undefined,
         matrixClient: MatrixClient,
         promBefore: Promise<any>,
     ) {

src/HtmlUtils.tsx

@@ -32,9 +32,9 @@ import { IExtendedSanitizeOptions } from './@types/sanitize-html';
 import SettingsStore from './settings/SettingsStore';
 import { tryTransformPermalinkToLocalHref } from "./utils/permalinks/Permalinks";
 import { getEmojiFromUnicode } from "./emoji";
-import ReplyChain from "./components/views/elements/ReplyChain";
 import { mediaFromMxc } from "./customisations/Media";
 import { ELEMENT_URL_PATTERN, options as linkifyMatrixOptions } from './linkify-matrix';
+import { stripHTMLReply, stripPlainReply } from './utils/Reply';
 
 // Anything outside the basic multilingual plane will be a surrogate pair
 const SURROGATE_PAIR_PATTERN = /([\ud800-\udbff])([\udc00-\udfff])/;
@@ -501,8 +501,8 @@ export function bodyToHtml(content: IContent, highlights: string[], opts: IOpts
         let formattedBody = typeof content.formatted_body === 'string' ? content.formatted_body : null;
         const plainBody = typeof content.body === 'string' ? content.body : "";
 
-        if (opts.stripReplyFallback && formattedBody) formattedBody = ReplyChain.stripHTMLReply(formattedBody);
+        if (opts.stripReplyFallback && formattedBody) formattedBody = stripHTMLReply(formattedBody);
-        strippedBody = opts.stripReplyFallback ? ReplyChain.stripPlainReply(plainBody) : plainBody;
+        strippedBody = opts.stripReplyFallback ? stripPlainReply(plainBody) : plainBody;
 
         bodyHasEmoji = mightContainEmoji(isFormattedBody ? formattedBody : plainBody);
 

src/components/structures/FileDropTarget.tsx

@@ -0,0 +1,120 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React, { useEffect, useState } from "react";
+
+import { _t } from "../../languageHandler";
+
+interface IProps {
+    parent: HTMLElement;
+    onFileDrop(dataTransfer: DataTransfer): void;
+}
+
+interface IState {
+    dragging: boolean;
+    counter: number;
+}
+
+const FileDropTarget: React.FC<IProps> = ({ parent, onFileDrop }) => {
+    const [state, setState] = useState<IState>({
+        dragging: false,
+        counter: 0,
+    });
+
+    useEffect(() => {
+        if (!parent || parent.ondrop) return;
+
+        const onDragEnter = (ev: DragEvent) => {
+            ev.stopPropagation();
+            ev.preventDefault();
+
+            setState(state => ({
+                // We always increment the counter no matter the types, because dragging is
+                // still happening. If we didn't, the drag counter would get out of sync.
+                counter: state.counter + 1,
+                // See:
+                // https://docs.w3cub.com/dom/datatransfer/types
+                // https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API/Recommended_drag_types#file
+                dragging: (
+                    ev.dataTransfer.types.includes("Files") ||
+                    ev.dataTransfer.types.includes("application/x-moz-file")
+                ) ? true : state.dragging,
+            }));
+        };
+
+        const onDragLeave = (ev: DragEvent) => {
+            ev.stopPropagation();
+            ev.preventDefault();
+
+            setState(state => ({
+                counter: state.counter - 1,
+                dragging: state.counter <= 1 ? false : state.dragging,
+            }));
+        };
+
+        const onDragOver = (ev: DragEvent) => {
+            ev.stopPropagation();
+            ev.preventDefault();
+
+            ev.dataTransfer.dropEffect = "none";
+
+            // See:
+            // https://docs.w3cub.com/dom/datatransfer/types
+            // https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API/Recommended_drag_types#file
+            if (ev.dataTransfer.types.includes("Files") || ev.dataTransfer.types.includes("application/x-moz-file")) {
+                ev.dataTransfer.dropEffect = "copy";
+            }
+        };
+
+        const onDrop = (ev: DragEvent) => {
+            ev.stopPropagation();
+            ev.preventDefault();
+            onFileDrop(ev.dataTransfer);
+
+            setState(state => ({
+                dragging: false,
+                counter: state.counter - 1,
+            }));
+        };
+
+        parent.addEventListener("drop", onDrop);
+        parent.addEventListener("dragover", onDragOver);
+        parent.addEventListener("dragenter", onDragEnter);
+        parent.addEventListener("dragleave", onDragLeave);
+
+        return () => {
+            // disconnect the D&D event listeners from the room view. This
+            // is really just for hygiene - we're going to be
+            // deleted anyway, so it doesn't matter if the event listeners
+            // don't get cleaned up.
+            parent.removeEventListener("drop", onDrop);
+            parent.removeEventListener("dragover", onDragOver);
+            parent.removeEventListener("dragenter", onDragEnter);
+            parent.removeEventListener("dragleave", onDragLeave);
+        };
+    }, [parent, onFileDrop]);
+
+    if (state.dragging) {
+        return <div className="mx_FileDropTarget">
+            <img src={require("../../../res/img/upload-big.svg")} className="mx_FileDropTarget_image" alt="" />
+            { _t("Drop file here to upload") }
+        </div>;
+    }
+
+    return null;
+};
+
+export default FileDropTarget;

src/components/structures/LegacyCommunityPreview.tsx

@@ -20,7 +20,6 @@ import MatrixClientContext from "../../contexts/MatrixClientContext";
 import { _t } from "../../languageHandler";
 import AccessibleButton from "../views/elements/AccessibleButton";
 import ErrorBoundary from "../views/elements/ErrorBoundary";
-import { IGroupSummary } from "../views/dialogs/CreateSpaceFromCommunityDialog";
 import { useAsyncMemo } from "../../hooks/useAsyncMemo";
 import Spinner from "../views/elements/Spinner";
 import GroupAvatar from "../views/avatars/GroupAvatar";
@@ -28,6 +27,7 @@ import { linkifyElement } from "../../HtmlUtils";
 import defaultDispatcher from "../../dispatcher/dispatcher";
 import { Action } from "../../dispatcher/actions";
 import { UserTab } from "../views/dialogs/UserSettingsDialog";
+import { IGroupSummary } from "../../@types/groups";
 
 interface IProps {
     groupId: string;

src/components/structures/LoggedInView.tsx

@@ -396,8 +396,7 @@ class LoggedInView extends React.Component<IProps, IState> {
             inputableElement.focus();
         } else {
             const inThread = !!document.activeElement.closest(".mx_ThreadView");
-            // refocusing during a paste event will make the
+            // refocusing during a paste event will make the paste end up in the newly focused element,
-            // paste end up in the newly focused element,
             // so dispatch synchronously before paste happens
             dis.dispatch({
                 action: Action.FocusSendMessageComposer,

src/components/structures/RoomView.tsx

@@ -19,7 +19,6 @@ limitations under the License.
 
 // TODO: This component is enormous! There's several things which could stand-alone:
 //  - Search results component
-//  - Drag and drop
 
 import React, { createRef } from 'react';
 import classNames from 'classnames';
@@ -104,6 +103,7 @@ import { KeyBindingAction } from "../../accessibility/KeyboardShortcuts";
 import { ViewRoomPayload } from "../../dispatcher/payloads/ViewRoomPayload";
 import { JoinRoomPayload } from "../../dispatcher/payloads/JoinRoomPayload";
 import { DoAfterSyncPreparedPayload } from '../../dispatcher/payloads/DoAfterSyncPreparedPayload';
+import FileDropTarget from './FileDropTarget';
 
 const DEBUG = false;
 let debuglog = function(msg: string) {};
@@ -153,7 +153,6 @@ export interface IRoomState {
     isInitialEventHighlighted?: boolean;
     replyToEvent?: MatrixEvent;
     numUnreadMessages: number;
-    draggingFile: boolean;
     searching: boolean;
     searchTerm?: string;
     searchScope?: SearchScope;
@@ -205,7 +204,6 @@ export interface IRoomState {
     rejectError?: Error;
     hasPinnedWidgets?: boolean;
     mainSplitContentType?: MainSplitContentType;
-    dragCounter: number;
     // whether or not a spaces context switch brought us here,
     // if it did we don't want the room to be marked as read as soon as it is loaded.
     wasContextSwitch?: boolean;
@@ -242,7 +240,6 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
             shouldPeek: true,
             membersLoaded: !llMembers,
             numUnreadMessages: 0,
-            draggingFile: false,
             searching: false,
             searchResults: null,
             callState: null,
@@ -272,7 +269,6 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
             showDisplaynameChanges: true,
             matrixClientIsReady: this.context && this.context.isInitialSyncComplete(),
             mainSplitContentType: MainSplitContentType.Timeline,
-            dragCounter: 0,
             timelineRenderingType: TimelineRenderingType.Room,
             liveTimeline: undefined,
         };
@@ -670,16 +666,6 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
     }
 
     componentDidUpdate() {
-        if (this.roomView.current) {
-            const roomView = this.roomView.current;
-            if (!roomView.ondrop) {
-                roomView.addEventListener('drop', this.onDrop);
-                roomView.addEventListener('dragover', this.onDragOver);
-                roomView.addEventListener('dragenter', this.onDragEnter);
-                roomView.addEventListener('dragleave', this.onDragLeave);
-            }
-        }
-
         // Note: We check the ref here with a flag because componentDidMount, despite
         // documentation, does not define our messagePanel ref. It looks like our spinner
         // in render() prevents the ref from being set on first mount, so we try and
@@ -714,17 +700,6 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         // stop tracking room changes to format permalinks
         this.stopAllPermalinkCreators();
 
-        if (this.roomView.current) {
-            // disconnect the D&D event listeners from the room view. This
-            // is really just for hygiene - we're going to be
-            // deleted anyway, so it doesn't matter if the event listeners
-            // don't get cleaned up.
-            const roomView = this.roomView.current;
-            roomView.removeEventListener('drop', this.onDrop);
-            roomView.removeEventListener('dragover', this.onDragOver);
-            roomView.removeEventListener('dragenter', this.onDragEnter);
-            roomView.removeEventListener('dragleave', this.onDragLeave);
-        }
         dis.unregister(this.dispatcherRef);
         if (this.context) {
             this.context.removeListener("Room", this.onRoom);
@@ -813,11 +788,15 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
                 this.jumpToReadMarker();
                 handled = true;
                 break;
-            case KeyBindingAction.UploadFile:
+            case KeyBindingAction.UploadFile: {
-                dis.dispatch({ action: "upload_file" }, true);
+                dis.dispatch({
+                    action: "upload_file",
+                    context: TimelineRenderingType.Room,
+                }, true);
                 handled = true;
                 break;
             }
+        }
 
         if (handled) {
             ev.stopPropagation();
@@ -1311,65 +1290,6 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         this.updateTopUnreadMessagesBar();
     };
 
-    private onDragEnter = ev => {
-        ev.stopPropagation();
-        ev.preventDefault();
-
-        // We always increment the counter no matter the types, because dragging is
-        // still happening. If we didn't, the drag counter would get out of sync.
-        this.setState({ dragCounter: this.state.dragCounter + 1 });
-
-        // See:
-        // https://docs.w3cub.com/dom/datatransfer/types
-        // https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API/Recommended_drag_types#file
-        if (ev.dataTransfer.types.includes("Files") || ev.dataTransfer.types.includes("application/x-moz-file")) {
-            this.setState({ draggingFile: true });
-        }
-    };
-
-    private onDragLeave = ev => {
-        ev.stopPropagation();
-        ev.preventDefault();
-
-        this.setState({
-            dragCounter: this.state.dragCounter - 1,
-        });
-
-        if (this.state.dragCounter === 0) {
-            this.setState({
-                draggingFile: false,
-            });
-        }
-    };
-
-    private onDragOver = ev => {
-        ev.stopPropagation();
-        ev.preventDefault();
-
-        ev.dataTransfer.dropEffect = 'none';
-
-        // See:
-        // https://docs.w3cub.com/dom/datatransfer/types
-        // https://developer.mozilla.org/en-US/docs/Web/API/HTML_Drag_and_Drop_API/Recommended_drag_types#file
-        if (ev.dataTransfer.types.includes("Files") || ev.dataTransfer.types.includes("application/x-moz-file")) {
-            ev.dataTransfer.dropEffect = 'copy';
-        }
-    };
-
-    private onDrop = ev => {
-        ev.stopPropagation();
-        ev.preventDefault();
-        ContentMessages.sharedInstance().sendContentListToRoom(
-            ev.dataTransfer.files, this.state.room.roomId, null, this.context,
-        );
-        dis.fire(Action.FocusSendMessageComposer);
-
-        this.setState({
-            draggingFile: false,
-            dragCounter: this.state.dragCounter - 1,
-        });
-    };
-
     private injectSticker(url: string, info: object, text: string, threadId: string | null) {
         if (this.context.isGuest()) {
             dis.dispatch({ action: 'require_registration' });
@@ -1802,6 +1722,14 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         });
     }
 
+    private onFileDrop = (dataTransfer: DataTransfer) => ContentMessages.sharedInstance().sendContentListToRoom(
+        Array.from(dataTransfer.files),
+        this.state.room?.roomId ?? this.state.roomId,
+        null,
+        this.context,
+        TimelineRenderingType.Room,
+    );
+
     render() {
         if (!this.state.room) {
             const loading = !this.state.matrixClientIsReady || this.state.roomLoading || this.state.peekLoading;
@@ -1902,19 +1830,6 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
             }
         }
 
-        let fileDropTarget = null;
-        if (this.state.draggingFile) {
-            fileDropTarget = (
-                <div className="mx_RoomView_fileDropTarget">
-                    <img
-                        src={require("../../../res/img/upload-big.svg")}
-                        className="mx_RoomView_fileDropTarget_image"
-                    />
-                    { _t("Drop file here to upload") }
-                </div>
-            );
-        }
-
         // We have successfully loaded this room, and are not previewing.
         // Display the "normal" room view.
 
@@ -2171,7 +2086,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         let mainSplitBody = <React.Fragment>
             { auxPanel }
             <div className={timelineClasses}>
-                { fileDropTarget }
+                <FileDropTarget parent={this.roomView.current} onFileDrop={this.onFileDrop} />
                 { topUnreadMessagesBar }
                 { jumpToBottom }
                 { messagePanel }

src/components/structures/SpaceRoomView.tsx

@@ -74,7 +74,6 @@ import { BetaPill } from "../views/beta/BetaCard";
 import { UserTab } from "../views/dialogs/UserSettingsDialog";
 import { EffectiveMembership, getEffectiveMembership } from "../../utils/membership";
 import { SpaceFeedbackPrompt } from "../views/spaces/SpaceCreateMenu";
-import { CreateEventField, IGroupSummary } from "../views/dialogs/CreateSpaceFromCommunityDialog";
 import { useAsyncMemo } from "../../hooks/useAsyncMemo";
 import Spinner from "../views/elements/Spinner";
 import GroupAvatar from "../views/avatars/GroupAvatar";
@@ -85,6 +84,7 @@ import { UIComponent } from "../../settings/UIFeature";
 import { UPDATE_EVENT } from "../../stores/AsyncStore";
 import PosthogTrackers from "../../PosthogTrackers";
 import { ViewRoomPayload } from "../../dispatcher/payloads/ViewRoomPayload";
+import { CreateEventField, IGroupSummary } from "../../@types/groups";
 
 interface IProps {
     space: Room;

src/components/structures/ThreadView.tsx

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React from 'react';
+import React, { createRef, KeyboardEvent } from 'react';
 import { Thread, ThreadEvent } from 'matrix-js-sdk/src/models/thread';
 import { RelationType } from 'matrix-js-sdk/src/@types/event';
 import { Room } from 'matrix-js-sdk/src/models/room';
@@ -46,6 +46,9 @@ import ThreadListContextMenu from '../views/context_menus/ThreadListContextMenu'
 import RightPanelStore from '../../stores/right-panel/RightPanelStore';
 import SettingsStore from "../../settings/SettingsStore";
 import { ViewRoomPayload } from "../../dispatcher/payloads/ViewRoomPayload";
+import FileDropTarget from "./FileDropTarget";
+import { getKeyBindingsManager } from "../../KeyBindingsManager";
+import { KeyBindingAction } from "../../accessibility/KeyboardShortcuts";
 
 interface IProps {
     room: Room;
@@ -68,9 +71,11 @@ interface IState {
 @replaceableComponent("structures.ThreadView")
 export default class ThreadView extends React.Component<IProps, IState> {
     static contextType = RoomContext;
+    public context!: React.ContextType<typeof RoomContext>;
 
     private dispatcherRef: string;
-    private timelinePanelRef: React.RefObject<TimelinePanel> = React.createRef();
+    private timelinePanelRef = createRef<TimelinePanel>();
+    private cardRef = createRef<HTMLDivElement>();
     private readonly layoutWatcherRef: string;
 
     constructor(props: IProps) {
@@ -206,6 +211,27 @@ export default class ThreadView extends React.Component<IProps, IState> {
         }
     };
 
+    private onKeyDown = (ev: KeyboardEvent) => {
+        let handled = false;
+
+        const action = getKeyBindingsManager().getRoomAction(ev);
+        switch (action) {
+            case KeyBindingAction.UploadFile: {
+                dis.dispatch({
+                    action: "upload_file",
+                    context: TimelineRenderingType.Thread,
+                }, true);
+                handled = true;
+                break;
+            }
+        }
+
+        if (handled) {
+            ev.stopPropagation();
+            ev.preventDefault();
+        }
+    };
+
     private renderThreadViewHeader = (): JSX.Element => {
         return <div className="mx_ThreadPanel__header">
             <span>{ _t("Thread") }</span>
@@ -240,18 +266,32 @@ export default class ThreadView extends React.Component<IProps, IState> {
         return timelineWindow.paginate(direction, limit);
     };
 
-    public render(): JSX.Element {
+    private onFileDrop = (dataTransfer: DataTransfer) => {
-        const highlightedEventId = this.props.isInitialEventHighlighted
+        ContentMessages.sharedInstance().sendContentListToRoom(
-            ? this.props.initialEvent?.getId()
+            Array.from(dataTransfer.files),
-            : null;
+            this.props.mxEvent.getRoomId(),
+            this.threadRelation,
+            MatrixClientPeg.get(),
+            TimelineRenderingType.Thread,
+        );
+    };
 
-        const threadRelation: IEventRelation = {
+    private get threadRelation(): IEventRelation {
+        return {
             "rel_type": RelationType.Thread,
             "event_id": this.state.thread?.id,
             "m.in_reply_to": {
                 "event_id": this.state.lastThreadReply?.getId() ?? this.state.thread?.id,
             },
         };
+    }
+
+    public render(): JSX.Element {
+        const highlightedEventId = this.props.isInitialEventHighlighted
+            ? this.props.initialEvent?.getId()
+            : null;
+
+        const threadRelation = this.threadRelation;
 
         const messagePanelClassNames = classNames(
             "mx_RoomView_messagePanel",
@@ -272,8 +312,11 @@ export default class ThreadView extends React.Component<IProps, IState> {
                     onClose={this.props.onClose}
                     withoutScrollContainer={true}
                     header={this.renderThreadViewHeader()}
+                    ref={this.cardRef}
+                    onKeyDown={this.onKeyDown}
                 >
-                    { this.state.thread && (
+                    { this.state.thread && <div className="mx_ThreadView_timelinePanelWrapper">
+                        <FileDropTarget parent={this.cardRef.current} onFileDrop={this.onFileDrop} />
                         <TimelinePanel
                             ref={this.timelinePanelRef}
                             showReadReceipts={false} // Hide the read receipts
@@ -297,7 +340,7 @@ export default class ThreadView extends React.Component<IProps, IState> {
                             onUserScroll={this.onScroll}
                             onPaginationRequest={this.onPaginationRequest}
                         />
-                    ) }
+                    </div> }
 
                     { ContentMessages.sharedInstance().getCurrentUploads(threadRelation).length > 0 && (
                         <UploadBar room={this.props.room} relation={threadRelation} />

src/components/views/dialogs/CreateSpaceFromCommunityDialog.tsx

@@ -43,6 +43,7 @@ import TagOrderActions from "../../../actions/TagOrderActions";
 import { inviteUsersToRoom } from "../../../RoomInvite";
 import ProgressBar from "../elements/ProgressBar";
 import { ViewRoomPayload } from "../../../dispatcher/payloads/ViewRoomPayload";
+import { CreateEventField, IGroupRoom, IGroupSummary } from "../../../@types/groups";
 
 interface IProps {
     matrixClient: MatrixClient;
@@ -50,50 +51,6 @@ interface IProps {
     onFinished(spaceId?: string): void;
 }
 
-export const CreateEventField = "io.element.migrated_from_community";
-
-interface IGroupRoom {
-    displayname: string;
-    name?: string;
-    roomId: string;
-    canonicalAlias?: string;
-    avatarUrl?: string;
-    topic?: string;
-    numJoinedMembers?: number;
-    worldReadable?: boolean;
-    guestCanJoin?: boolean;
-    isPublic?: boolean;
-}
-
-/* eslint-disable camelcase */
-export interface IGroupSummary {
-    profile: {
-        avatar_url?: string;
-        is_openly_joinable?: boolean;
-        is_public?: boolean;
-        long_description: string;
-        name: string;
-        short_description: string;
-    };
-    rooms_section: {
-        rooms: unknown[];
-        categories: Record<string, unknown>;
-        total_room_count_estimate: number;
-    };
-    user: {
-        is_privileged: boolean;
-        is_public: boolean;
-        is_publicised: boolean;
-        membership: string;
-    };
-    users_section: {
-        users: unknown[];
-        roles: Record<string, unknown>;
-        total_user_count_estimate: number;
-    };
-}
-/* eslint-enable camelcase */
-
 enum Progress {
     NotStarted,
     ValidatingInputs,

src/components/views/elements/ReplyChain.tsx

@@ -17,11 +17,8 @@ limitations under the License.
 
 import React from 'react';
 import classNames from 'classnames';
-import { IEventRelation, MatrixEvent } from 'matrix-js-sdk/src/models/event';
+import { MatrixEvent } from 'matrix-js-sdk/src/models/event';
-import escapeHtml from "escape-html";
-import sanitizeHtml from "sanitize-html";
 import { Room } from 'matrix-js-sdk/src/models/room';
-import { RelationType } from 'matrix-js-sdk/src/@types/event';
 import { Relations } from 'matrix-js-sdk/src/models/relations';
 
 import { _t } from '../../../languageHandler';
@@ -32,12 +29,12 @@ import { Layout } from "../../../settings/enums/Layout";
 import MatrixClientContext from "../../../contexts/MatrixClientContext";
 import { getUserNameColorClass } from "../../../utils/FormattingUtils";
 import { Action } from "../../../dispatcher/actions";
-import { PERMITTED_URL_SCHEMES } from "../../../HtmlUtils";
 import { replaceableComponent } from "../../../utils/replaceableComponent";
 import Spinner from './Spinner';
 import ReplyTile from "../rooms/ReplyTile";
 import Pill from './Pill';
 import { ButtonEvent } from './AccessibleButton';
+import { getParentEventId } from '../../../utils/Reply';
 
 /**
  * This number is based on the previous behavior - if we have message of height
@@ -97,174 +94,6 @@ export default class ReplyChain extends React.Component<IProps, IState> {
         this.room = this.context.getRoom(this.props.parentEv.getRoomId());
     }
 
-    public static getParentEventId(ev: MatrixEvent): string | undefined {
-        if (!ev || ev.isRedacted()) return;
-        if (ev.replyEventId) {
-            return ev.replyEventId;
-        }
-    }
-
-    // Part of Replies fallback support
-    public static stripPlainReply(body: string): string {
-        // Removes lines beginning with `> ` until you reach one that doesn't.
-        const lines = body.split('\n');
-        while (lines.length && lines[0].startsWith('> ')) lines.shift();
-        // Reply fallback has a blank line after it, so remove it to prevent leading newline
-        if (lines[0] === '') lines.shift();
-        return lines.join('\n');
-    }
-
-    // Part of Replies fallback support
-    public static stripHTMLReply(html: string): string {
-        // Sanitize the original HTML for inclusion in <mx-reply>.  We allow
-        // any HTML, since the original sender could use special tags that we
-        // don't recognize, but want to pass along to any recipients who do
-        // recognize them -- recipients should be sanitizing before displaying
-        // anyways.  However, we sanitize to 1) remove any mx-reply, so that we
-        // don't generate a nested mx-reply, and 2) make sure that the HTML is
-        // properly formatted (e.g. tags are closed where necessary)
-        return sanitizeHtml(
-            html,
-            {
-                allowedTags: false, // false means allow everything
-                allowedAttributes: false,
-                // we somehow can't allow all schemes, so we allow all that we
-                // know of and mxc (for img tags)
-                allowedSchemes: [...PERMITTED_URL_SCHEMES, 'mxc'],
-                exclusiveFilter: (frame) => frame.tag === "mx-reply",
-            },
-        );
-    }
-
-    // Part of Replies fallback support
-    public static getNestedReplyText(
-        ev: MatrixEvent,
-        permalinkCreator: RoomPermalinkCreator,
-    ): { body: string, html: string } | null {
-        if (!ev) return null;
-
-        let { body, formatted_body: html } = ev.getContent();
-        if (this.getParentEventId(ev)) {
-            if (body) body = this.stripPlainReply(body);
-        }
-
-        if (!body) body = ""; // Always ensure we have a body, for reasons.
-
-        if (html) {
-            // sanitize the HTML before we put it in an <mx-reply>
-            html = this.stripHTMLReply(html);
-        } else {
-            // Escape the body to use as HTML below.
-            // We also run a nl2br over the result to fix the fallback representation. We do this
-            // after converting the text to safe HTML to avoid user-provided BR's from being converted.
-            html = escapeHtml(body).replace(/\n/g, '<br/>');
-        }
-
-        // dev note: do not rely on `body` being safe for HTML usage below.
-
-        const evLink = permalinkCreator.forEvent(ev.getId());
-        const userLink = makeUserPermalink(ev.getSender());
-        const mxid = ev.getSender();
-
-        // This fallback contains text that is explicitly EN.
-        switch (ev.getContent().msgtype) {
-            case 'm.text':
-            case 'm.notice': {
-                html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
-                    + `<br>${html}</blockquote></mx-reply>`;
-                const lines = body.trim().split('\n');
-                if (lines.length > 0) {
-                    lines[0] = `<${mxid}> ${lines[0]}`;
-                    body = lines.map((line) => `> ${line}`).join('\n') + '\n\n';
-                }
-                break;
-            }
-            case 'm.image':
-                html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
-                    + `<br>sent an image.</blockquote></mx-reply>`;
-                body = `> <${mxid}> sent an image.\n\n`;
-                break;
-            case 'm.video':
-                html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
-                    + `<br>sent a video.</blockquote></mx-reply>`;
-                body = `> <${mxid}> sent a video.\n\n`;
-                break;
-            case 'm.audio':
-                html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
-                    + `<br>sent an audio file.</blockquote></mx-reply>`;
-                body = `> <${mxid}> sent an audio file.\n\n`;
-                break;
-            case 'm.file':
-                html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
-                    + `<br>sent a file.</blockquote></mx-reply>`;
-                body = `> <${mxid}> sent a file.\n\n`;
-                break;
-            case 'm.emote': {
-                html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> * `
-                    + `<a href="${userLink}">${mxid}</a><br>${html}</blockquote></mx-reply>`;
-                const lines = body.trim().split('\n');
-                if (lines.length > 0) {
-                    lines[0] = `* <${mxid}> ${lines[0]}`;
-                    body = lines.map((line) => `> ${line}`).join('\n') + '\n\n';
-                }
-                break;
-            }
-            default:
-                return null;
-        }
-
-        return { body, html };
-    }
-
-    public static makeReplyMixIn(ev: MatrixEvent, renderIn?: string[]) {
-        if (!ev) return {};
-
-        const mixin: any = {
-            'm.relates_to': {
-                'm.in_reply_to': {
-                    'event_id': ev.getId(),
-                },
-            },
-        };
-
-        if (renderIn) {
-            mixin['m.relates_to']['m.in_reply_to']['m.render_in'] = renderIn;
-        }
-
-        /**
-         * If the event replied is part of a thread
-         * Add the `m.thread` relation so that clients
-         * that know how to handle that relation will
-         * be able to render them more accurately
-         */
-        if (ev.isThreadRelation) {
-            mixin['m.relates_to'] = {
-                ...mixin['m.relates_to'],
-                rel_type: RelationType.Thread,
-                event_id: ev.threadRootId,
-            };
-        }
-
-        return mixin;
-    }
-
-    public static shouldDisplayReply(event: MatrixEvent, renderTarget?: string): boolean {
-        const parentExist = Boolean(ReplyChain.getParentEventId(event));
-
-        const relations = event.getRelation();
-        const renderIn = relations?.["m.in_reply_to"]?.["m.render_in"] ?? [];
-
-        const shouldRenderInTarget = !renderTarget || (renderIn.includes(renderTarget));
-
-        return parentExist && shouldRenderInTarget;
-    }
-
-    public static getRenderInMixin(relation?: IEventRelation): string[] | undefined {
-        if (relation?.rel_type === RelationType.Thread) {
-            return [RelationType.Thread];
-        }
-    }
-
     componentDidMount() {
         this.initialize();
         this.trySetExpandableQuotes();
@@ -296,7 +125,7 @@ export default class ReplyChain extends React.Component<IProps, IState> {
     private async initialize(): Promise<void> {
         const { parentEv } = this.props;
         // at time of making this component we checked that props.parentEv has a parentEventId
-        const ev = await this.getEvent(ReplyChain.getParentEventId(parentEv));
+        const ev = await this.getEvent(getParentEventId(parentEv));
 
         if (this.unmounted) return;
 
@@ -314,7 +143,7 @@ export default class ReplyChain extends React.Component<IProps, IState> {
 
     private async getNextEvent(ev: MatrixEvent): Promise<MatrixEvent> {
         try {
-            const inReplyToEventId = ReplyChain.getParentEventId(ev);
+            const inReplyToEventId = getParentEventId(ev);
             return await this.getEvent(inReplyToEventId);
         } catch (e) {
             return null;
@@ -399,7 +228,7 @@ export default class ReplyChain extends React.Component<IProps, IState> {
                 }
             </blockquote>;
         } else if (this.props.forExport) {
-            const eventId = ReplyChain.getParentEventId(this.props.parentEv);
+            const eventId = getParentEventId(this.props.parentEv);
             header = <p className="mx_ReplyChain_Export">
                 { _t("In reply to <a>this message</a>",
                     {},

src/components/views/messages/MessageActionBar.tsx

@@ -42,6 +42,7 @@ import ReplyChain from '../elements/ReplyChain';
 import ReactionPicker from "../emojipicker/ReactionPicker";
 import { CardContext } from '../right_panel/BaseCard';
 import { showThread } from "../../../dispatcher/dispatch-actions/threads";
+import { shouldDisplayReply } from '../../../utils/Reply';
 
 interface IOptionsButtonProps {
     mxEvent: MatrixEvent;
@@ -375,7 +376,7 @@ export default class MessageActionBar extends React.PureComponent<IMessageAction
                 toolbarOpts.push(cancelSendingButton);
             }
 
-            if (this.props.isQuoteExpanded !== undefined && ReplyChain.shouldDisplayReply(this.props.mxEvent)) {
+            if (this.props.isQuoteExpanded !== undefined && shouldDisplayReply(this.props.mxEvent)) {
                 const expandClassName = classNames({
                     'mx_MessageActionBar_maskButton': true,
                     'mx_MessageActionBar_expandMessageButton': !this.props.isQuoteExpanded,

src/components/views/messages/TextualBody.tsx

@@ -28,7 +28,6 @@ import { _t } from '../../../languageHandler';
 import * as ContextMenu from '../../structures/ContextMenu';
 import { ChevronFace, toRightOf } from '../../structures/ContextMenu';
 import SettingsStore from "../../../settings/SettingsStore";
-import ReplyChain from "../elements/ReplyChain";
 import { pillifyLinks, unmountPills } from '../../../utils/pillify';
 import { IntegrationManagers } from "../../../integrations/IntegrationManagers";
 import { isPermalinkHost, tryTransformPermalinkToLocalHref } from "../../../utils/permalinks/Permalinks";
@@ -48,6 +47,7 @@ import { IBodyProps } from "./IBodyProps";
 import RoomContext from "../../../contexts/RoomContext";
 import AccessibleButton from '../elements/AccessibleButton';
 import { options as linkifyOpts } from "../../../linkify-matrix";
+import { getParentEventId } from '../../../utils/Reply';
 
 const MAX_HIGHLIGHT_LENGTH = 4096;
 
@@ -557,7 +557,7 @@ export default class TextualBody extends React.Component<IBodyProps, IState> {
         let isEmote = false;
 
         // only strip reply if this is the original replying event, edits thereafter do not have the fallback
-        const stripReply = !mxEvent.replacingEvent() && !!ReplyChain.getParentEventId(mxEvent);
+        const stripReply = !mxEvent.replacingEvent() && !!getParentEventId(mxEvent);
         let body;
         if (SettingsStore.isEnabled("feature_extensible_events")) {
             const extev = this.props.mxEvent.unstableExtensibleEvent as MessageEvent;

src/components/views/right_panel/BaseCard.tsx

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { ReactNode } from 'react';
+import React, { forwardRef, ReactNode, KeyboardEvent, Ref } from 'react';
 import classNames from 'classnames';
 
 import AutoHideScrollbar from "../../structures/AutoHideScrollbar";
@@ -32,7 +32,9 @@ interface IProps {
     closeLabel?: string;
     onClose?(ev: ButtonEvent): void;
     onBack?(ev: ButtonEvent): void;
+    onKeyDown?(ev: KeyboardEvent): void;
     cardState?: any;
+    ref?: Ref<HTMLDivElement>;
 }
 
 interface IGroupProps {
@@ -47,7 +49,7 @@ export const Group: React.FC<IGroupProps> = ({ className, title, children }) =>
     </div>;
 };
 
-const BaseCard: React.FC<IProps> = ({
+const BaseCard: React.FC<IProps> = forwardRef<HTMLDivElement, IProps>(({
     closeLabel,
     onClose,
     onBack,
@@ -56,7 +58,8 @@ const BaseCard: React.FC<IProps> = ({
     footer,
     withoutScrollContainer,
     children,
-}) => {
+    onKeyDown,
+}, ref) => {
     let backButton;
     const cardHistory = RightPanelStore.instance.roomPhaseHistory;
     if (cardHistory.length > 1) {
@@ -87,7 +90,7 @@ const BaseCard: React.FC<IProps> = ({
 
     return (
         <CardContext.Provider value={{ isCard: true }}>
-            <div className={classNames("mx_BaseCard", className)}>
+            <div className={classNames("mx_BaseCard", className)} ref={ref} onKeyDown={onKeyDown}>
                 <div className="mx_BaseCard_header">
                     { backButton }
                     { closeButton }
@@ -98,6 +101,6 @@ const BaseCard: React.FC<IProps> = ({
             </div>
         </CardContext.Provider>
     );
-};
+});
 
 export default BaseCard;

src/components/views/rooms/EventTile.tsx

@@ -78,6 +78,7 @@ import { copyPlaintext } from '../../../utils/strings';
 import { DecryptionFailureTracker } from '../../../DecryptionFailureTracker';
 import RedactedBody from '../messages/RedactedBody';
 import { ViewRoomPayload } from "../../../dispatcher/payloads/ViewRoomPayload";
+import { shouldDisplayReply } from '../../../utils/Reply';
 
 export type GetRelationsForEvent = (eventId: string, relationType: string, eventType: string) => Relations;
 
@@ -1390,8 +1391,7 @@ export default class EventTile extends React.Component<IProps, IState> {
             ? RelationType.Thread
             : undefined;
 
-        const replyChain = haveTileForEvent(this.props.mxEvent)
+        const replyChain = haveTileForEvent(this.props.mxEvent) && shouldDisplayReply(this.props.mxEvent, renderTarget)
-            && ReplyChain.shouldDisplayReply(this.props.mxEvent, renderTarget)
             ? <ReplyChain
                 parentEv={this.props.mxEvent}
                 onHeightChanged={this.props.onHeightChanged}

src/components/views/rooms/MessageComposerButtons.tsx

@@ -17,7 +17,7 @@ limitations under the License.
 import classNames from 'classnames';
 import { IEventRelation } from "matrix-js-sdk/src/models/event";
 import { M_POLL_START } from "matrix-events-sdk";
-import React, { createContext, ReactElement, useContext } from 'react';
+import React, { createContext, ReactElement, useContext, useRef } from 'react';
 import { Room } from 'matrix-js-sdk/src/models/room';
 import { MatrixClient } from 'matrix-js-sdk/src/client';
 import { RelationType } from 'matrix-js-sdk/src/@types/event';
@@ -33,10 +33,10 @@ import LocationButton from '../location/LocationButton';
 import Modal from "../../../Modal";
 import PollCreateDialog from "../elements/PollCreateDialog";
 import { MatrixClientPeg } from '../../../MatrixClientPeg';
-import { ActionPayload } from '../../../dispatcher/payloads';
 import ContentMessages from '../../../ContentMessages';
 import MatrixClientContext from '../../../contexts/MatrixClientContext';
 import RoomContext from '../../../contexts/RoomContext';
+import { useDispatcher } from "../../../hooks/useDispatcher";
 
 interface IProps {
     addEmoji: (emoji: string) => boolean;
@@ -189,50 +189,37 @@ interface IUploadButtonProps {
     relation?: IEventRelation | null;
 }
 
-class UploadButton extends React.Component<IUploadButtonProps> {
+const UploadButton = ({ roomId, relation }: IUploadButtonProps) => {
-    private uploadInput = React.createRef<HTMLInputElement>();
+    const cli = useContext(MatrixClientContext);
-    private dispatcherRef: string;
+    const roomContext = useContext(RoomContext);
+    const overflowMenuCloser = useContext(OverflowMenuContext);
+    const uploadInput = useRef<HTMLInputElement>();
 
-    constructor(props: IUploadButtonProps) {
+    const onUploadClick = () => {
-        super(props);
+        if (cli.isGuest()) {
-
-        this.dispatcherRef = dis.register(this.onAction);
-    }
-
-    componentWillUnmount() {
-        dis.unregister(this.dispatcherRef);
-    }
-
-    private onAction = (payload: ActionPayload) => {
-        if (payload.action === "upload_file") {
-            this.onUploadClick();
-        }
-    };
-
-    private onUploadClick = () => {
-        if (MatrixClientPeg.get().isGuest()) {
             dis.dispatch({ action: 'require_registration' });
             return;
         }
-        this.uploadInput.current?.click();
+        uploadInput.current?.click();
+        overflowMenuCloser?.(); // close overflow menu
     };
 
-    private onUploadFileInputChange = (ev: React.ChangeEvent<HTMLInputElement>) => {
+    useDispatcher(dis, payload => {
+        if (roomContext.timelineRenderingType === payload.context && payload.action === "upload_file") {
+            onUploadClick();
+        }
+    });
+
+    const onUploadFileInputChange = (ev: React.ChangeEvent<HTMLInputElement>) => {
         if (ev.target.files.length === 0) return;
 
-        // take a copy so we can safely reset the value of the form control
+        // Take a copy, so we can safely reset the value of the form control
-        // (Note it is a FileList: we can't use slice or sensible iteration).
-        const tfiles = [];
-        for (let i = 0; i < ev.target.files.length; ++i) {
-            tfiles.push(ev.target.files[i]);
-        }
-
         ContentMessages.sharedInstance().sendContentListToRoom(
-            tfiles,
+            Array.from(ev.target.files),
-            this.props.roomId,
+            roomId,
-            this.props.relation,
+            relation,
-            MatrixClientPeg.get(),
+            cli,
-            this.context.timelineRenderingType,
+            roomContext.timelineRenderingType,
         );
 
         // This is the onChange handler for a file form control, but we're
@@ -242,24 +229,22 @@ class UploadButton extends React.Component<IUploadButtonProps> {
         ev.target.value = '';
     };
 
-    render() {
     const uploadInputStyle = { display: 'none' };
     return <>
         <CollapsibleButton
             className="mx_MessageComposer_button mx_MessageComposer_upload"
-                onClick={this.onUploadClick}
+            onClick={onUploadClick}
             title={_t('Attachment')}
         />
         <input
-                ref={this.uploadInput}
+            ref={uploadInput}
             type="file"
             style={uploadInputStyle}
             multiple
-                onChange={this.onUploadFileInputChange}
+            onChange={onUploadFileInputChange}
         />
     </>;
-    }
+};
-}
 
 function showStickersButton(props: IProps): ReactElement {
     return (

src/components/views/rooms/SendMessageComposer.tsx

@@ -36,7 +36,6 @@ import {
 } from '../../../editor/serialize';
 import BasicMessageComposer, { REGEX_EMOTICON } from "./BasicMessageComposer";
 import { CommandPartCreator, Part, PartCreator, SerializedPart } from '../../../editor/parts';
-import ReplyChain from "../elements/ReplyChain";
 import { findEditableEvent } from '../../../utils/EventUtils';
 import SendHistoryManager from "../../../SendHistoryManager";
 import { CommandCategories } from '../../../SlashCommands';
@@ -58,6 +57,7 @@ import { ComposerType } from "../../../dispatcher/payloads/ComposerInsertPayload
 import { getSlashCommand, isSlashCommand, runSlashCommand, shouldSendAnyway } from "../../../editor/commands";
 import { KeyBindingAction } from "../../../accessibility/KeyboardShortcuts";
 import { PosthogAnalytics } from "../../../PosthogAnalytics";
+import { getNestedReplyText, getRenderInMixin, makeReplyMixIn } from '../../../utils/Reply';
 
 interface IAddReplyOpts {
     permalinkCreator?: RoomPermalinkCreator;
@@ -72,13 +72,13 @@ function addReplyToMessageContent(
         includeLegacyFallback: true,
     },
 ): void {
-    const replyContent = ReplyChain.makeReplyMixIn(replyToEvent, opts.renderIn);
+    const replyContent = makeReplyMixIn(replyToEvent, opts.renderIn);
     Object.assign(content, replyContent);
 
     if (opts.includeLegacyFallback) {
         // Part of Replies fallback support - prepend the text we're sending
         // with the text we're replying to
-        const nestedReply = ReplyChain.getNestedReplyText(replyToEvent, opts.permalinkCreator);
+        const nestedReply = getNestedReplyText(replyToEvent, opts.permalinkCreator);
         if (nestedReply) {
             if (content.formatted_body) {
                 content.formatted_body = nestedReply.html + content.formatted_body;
@@ -132,7 +132,7 @@ export function createMessageContent(
         addReplyToMessageContent(content, replyToEvent, {
             permalinkCreator,
             includeLegacyFallback: true,
-            renderIn: ReplyChain.getRenderInMixin(relation),
+            renderIn: getRenderInMixin(relation),
         });
     }
 
@@ -384,7 +384,7 @@ export class SendMessageComposer extends React.Component<ISendMessageComposerPro
                         addReplyToMessageContent(content, replyToEvent, {
                             permalinkCreator: this.props.permalinkCreator,
                             includeLegacyFallback: true,
-                            renderIn: ReplyChain.getRenderInMixin(this.props.relation),
+                            renderIn: getRenderInMixin(this.props.relation),
                         });
                     }
                 } else {

src/components/views/settings/tabs/user/PreferencesUserSettingsTab.tsx

@@ -32,13 +32,13 @@ import dis from "../../../../../dispatcher/dispatcher";
 import GroupActions from "../../../../../actions/GroupActions";
 import MatrixClientContext from "../../../../../contexts/MatrixClientContext";
 import { useDispatcher } from "../../../../../hooks/useDispatcher";
-import { CreateEventField, IGroupSummary } from "../../../dialogs/CreateSpaceFromCommunityDialog";
 import { createSpaceFromCommunity } from "../../../../../utils/space";
 import Spinner from "../../../elements/Spinner";
 import { UserTab } from "../../../dialogs/UserSettingsDialog";
 import { OpenToTabPayload } from "../../../../../dispatcher/payloads/OpenToTabPayload";
 import { Action } from "../../../../../dispatcher/actions";
 import { ViewRoomPayload } from "../../../../../dispatcher/payloads/ViewRoomPayload";
+import { CreateEventField, IGroupSummary } from '../../../../../@types/groups';
 
 interface IProps {
     closeSettingsFn(success: boolean): void;

src/contexts/RoomContext.ts

@@ -35,7 +35,6 @@ const RoomContext = createContext<IRoomState>({
     shouldPeek: true,
     membersLoaded: false,
     numUnreadMessages: 0,
-    draggingFile: false,
     searching: false,
     guestsCanJoin: false,
     canPeek: false,
@@ -62,7 +61,6 @@ const RoomContext = createContext<IRoomState>({
     showAvatarChanges: true,
     showDisplaynameChanges: true,
     matrixClientIsReady: false,
-    dragCounter: 0,
     timelineRenderingType: TimelineRenderingType.Room,
     threadId: undefined,
     liveTimeline: undefined,

src/i18n/strings/en_EN.json

@@ -2985,6 +2985,7 @@
     "Pause": "Pause",
     "Play": "Play",
     "Couldn't load page": "Couldn't load page",
+    "Drop file here to upload": "Drop file here to upload",
     "You must <a>register</a> to use this functionality": "You must <a>register</a> to use this functionality",
     "You must join the room to see its files": "You must join the room to see its files",
     "No files visible in this room": "No files visible in this room",
@@ -3127,7 +3128,6 @@
     "Server may be unavailable, overloaded, or search timed out :(": "Server may be unavailable, overloaded, or search timed out :(",
     "No more results": "No more results",
     "Failed to reject invite": "Failed to reject invite",
-    "Drop file here to upload": "Drop file here to upload",
     "You have %(count)s unread notifications in a prior version of this room.|other": "You have %(count)s unread notifications in a prior version of this room.",
     "You have %(count)s unread notifications in a prior version of this room.|one": "You have %(count)s unread notification in a prior version of this room.",
     "Joining": "Joining",

src/stores/GroupFilterOrderStore.js

@@ -23,7 +23,7 @@ import Analytics from '../Analytics';
 import * as RoomNotifs from "../RoomNotifs";
 import { MatrixClientPeg } from '../MatrixClientPeg';
 import SettingsStore from "../settings/SettingsStore";
-import { CreateEventField } from "../components/views/dialogs/CreateSpaceFromCommunityDialog";
+import { CreateEventField } from "../@types/groups";
 
 const INITIAL_STATE = {
     orderedTags: null,

src/stores/room-list/previews/MessageEventPreview.ts

@@ -20,8 +20,8 @@ import { IPreview } from "./IPreview";
 import { TagID } from "../models";
 import { _t, sanitizeForTranslation } from "../../../languageHandler";
 import { getSenderName, isSelf, shouldPrefixMessagesIn } from "./utils";
-import ReplyChain from "../../../components/views/elements/ReplyChain";
 import { getHtmlText } from "../../../HtmlUtils";
+import { stripHTMLReply, stripPlainReply } from "../../../utils/Reply";
 
 export class MessageEventPreview implements IPreview {
     public getTextFor(event: MatrixEvent, tagId?: TagID, isThread?: boolean): string {
@@ -44,13 +44,12 @@ export class MessageEventPreview implements IPreview {
         }
 
         // XXX: Newer relations have a getRelation() function which is not compatible with replies.
-        const mRelatesTo = event.getWireContent()['m.relates_to'];
+        if (event.getWireContent()['m.relates_to']?.['m.in_reply_to']) {
-        if (mRelatesTo && mRelatesTo['m.in_reply_to']) {
             // If this is a reply, get the real reply and use that
             if (hasHtml) {
-                body = (ReplyChain.stripHTMLReply(body) || '').trim();
+                body = (stripHTMLReply(body) || '').trim();
             } else {
-                body = (ReplyChain.stripPlainReply(body) || '').trim();
+                body = (stripPlainReply(body) || '').trim();
             }
             if (!body) return null; // invalid event, no preview
         }

src/utils/Reply.ts

@@ -0,0 +1,191 @@
+/*
+Copyright 2021 Šimon Brandner <simon.bra.ag@gmail.com>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { IEventRelation, MatrixEvent } from "matrix-js-sdk/src/models/event";
+import { RelationType } from "matrix-js-sdk/src/@types/event";
+import sanitizeHtml from "sanitize-html";
+import escapeHtml from "escape-html";
+
+import { PERMITTED_URL_SCHEMES } from "../HtmlUtils";
+import { makeUserPermalink, RoomPermalinkCreator } from "./permalinks/Permalinks";
+
+export function getParentEventId(ev: MatrixEvent): string | undefined {
+    if (!ev || ev.isRedacted()) return;
+    if (ev.replyEventId) {
+        return ev.replyEventId;
+    }
+}
+
+// Part of Replies fallback support
+export function stripPlainReply(body: string): string {
+    // Removes lines beginning with `> ` until you reach one that doesn't.
+    const lines = body.split('\n');
+    while (lines.length && lines[0].startsWith('> ')) lines.shift();
+    // Reply fallback has a blank line after it, so remove it to prevent leading newline
+    if (lines[0] === '') lines.shift();
+    return lines.join('\n');
+}
+
+// Part of Replies fallback support
+export function stripHTMLReply(html: string): string {
+    // Sanitize the original HTML for inclusion in <mx-reply>.  We allow
+    // any HTML, since the original sender could use special tags that we
+    // don't recognize, but want to pass along to any recipients who do
+    // recognize them -- recipients should be sanitizing before displaying
+    // anyways.  However, we sanitize to 1) remove any mx-reply, so that we
+    // don't generate a nested mx-reply, and 2) make sure that the HTML is
+    // properly formatted (e.g. tags are closed where necessary)
+    return sanitizeHtml(
+        html,
+        {
+            allowedTags: false, // false means allow everything
+            allowedAttributes: false,
+            // we somehow can't allow all schemes, so we allow all that we
+            // know of and mxc (for img tags)
+            allowedSchemes: [...PERMITTED_URL_SCHEMES, 'mxc'],
+            exclusiveFilter: (frame) => frame.tag === "mx-reply",
+        },
+    );
+}
+
+// Part of Replies fallback support
+export function getNestedReplyText(
+    ev: MatrixEvent,
+    permalinkCreator: RoomPermalinkCreator,
+): { body: string, html: string } | null {
+    if (!ev) return null;
+
+    let { body, formatted_body: html } = ev.getContent();
+    if (getParentEventId(ev)) {
+        if (body) body = stripPlainReply(body);
+    }
+
+    if (!body) body = ""; // Always ensure we have a body, for reasons.
+
+    if (html) {
+        // sanitize the HTML before we put it in an <mx-reply>
+        html = stripHTMLReply(html);
+    } else {
+        // Escape the body to use as HTML below.
+        // We also run a nl2br over the result to fix the fallback representation. We do this
+        // after converting the text to safe HTML to avoid user-provided BR's from being converted.
+        html = escapeHtml(body).replace(/\n/g, '<br/>');
+    }
+
+    // dev note: do not rely on `body` being safe for HTML usage below.
+
+    const evLink = permalinkCreator.forEvent(ev.getId());
+    const userLink = makeUserPermalink(ev.getSender());
+    const mxid = ev.getSender();
+
+    // This fallback contains text that is explicitly EN.
+    switch (ev.getContent().msgtype) {
+        case 'm.text':
+        case 'm.notice': {
+            html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
+                + `<br>${html}</blockquote></mx-reply>`;
+            const lines = body.trim().split('\n');
+            if (lines.length > 0) {
+                lines[0] = `<${mxid}> ${lines[0]}`;
+                body = lines.map((line) => `> ${line}`).join('\n') + '\n\n';
+            }
+            break;
+        }
+        case 'm.image':
+            html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
+                + `<br>sent an image.</blockquote></mx-reply>`;
+            body = `> <${mxid}> sent an image.\n\n`;
+            break;
+        case 'm.video':
+            html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
+                + `<br>sent a video.</blockquote></mx-reply>`;
+            body = `> <${mxid}> sent a video.\n\n`;
+            break;
+        case 'm.audio':
+            html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
+                + `<br>sent an audio file.</blockquote></mx-reply>`;
+            body = `> <${mxid}> sent an audio file.\n\n`;
+            break;
+        case 'm.file':
+            html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> <a href="${userLink}">${mxid}</a>`
+                + `<br>sent a file.</blockquote></mx-reply>`;
+            body = `> <${mxid}> sent a file.\n\n`;
+            break;
+        case 'm.emote': {
+            html = `<mx-reply><blockquote><a href="${evLink}">In reply to</a> * `
+                + `<a href="${userLink}">${mxid}</a><br>${html}</blockquote></mx-reply>`;
+            const lines = body.trim().split('\n');
+            if (lines.length > 0) {
+                lines[0] = `* <${mxid}> ${lines[0]}`;
+                body = lines.map((line) => `> ${line}`).join('\n') + '\n\n';
+            }
+            break;
+        }
+        default:
+            return null;
+    }
+
+    return { body, html };
+}
+
+export function makeReplyMixIn(ev: MatrixEvent, renderIn?: string[]) {
+    if (!ev) return {};
+
+    const mixin: any = {
+        'm.relates_to': {
+            'm.in_reply_to': {
+                'event_id': ev.getId(),
+            },
+        },
+    };
+
+    if (renderIn) {
+        mixin['m.relates_to']['m.in_reply_to']['m.render_in'] = renderIn;
+    }
+
+    /**
+     * If the event replied is part of a thread
+     * Add the `m.thread` relation so that clients
+     * that know how to handle that relation will
+     * be able to render them more accurately
+     */
+    if (ev.isThreadRelation) {
+        mixin['m.relates_to'] = {
+            ...mixin['m.relates_to'],
+            rel_type: RelationType.Thread,
+            event_id: ev.threadRootId,
+        };
+    }
+
+    return mixin;
+}
+
+export function shouldDisplayReply(event: MatrixEvent, renderTarget?: string): boolean {
+    const parentExist = Boolean(getParentEventId(event));
+
+    const relations = event.getRelation();
+    const renderIn = relations?.["m.in_reply_to"]?.["m.render_in"] ?? [];
+
+    const shouldRenderInTarget = !renderTarget || (renderIn.includes(renderTarget));
+
+    return parentExist && shouldRenderInTarget;
+}
+
+export function getRenderInMixin(relation?: IEventRelation): string[] | undefined {
+    if (relation?.rel_type === RelationType.Thread) {
+        return [RelationType.Thread];
+    }
+}

test/components/views/elements/ReplyChain-test.js

@@ -1,6 +1,22 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
 import "../../../skinned-sdk";
 import * as testUtils from '../../../test-utils';
-import ReplyChain from '../../../../src/components/views/elements/ReplyChain';
+import { getParentEventId } from "../../../../src/utils/Reply";
 
 describe("ReplyChain", () => {
     describe('getParentEventId', () => {
@@ -21,7 +37,7 @@ describe("ReplyChain", () => {
                 room: "room_id",
             });
 
-            expect(ReplyChain.getParentEventId(originalEventWithRelation))
+            expect(getParentEventId(originalEventWithRelation))
                 .toStrictEqual('$qkjmFBTEc0VvfVyzq1CJuh1QZi_xDIgNEFjZ4Pq34og');
         });
 
@@ -65,7 +81,7 @@ describe("ReplyChain", () => {
             originalEventWithRelation.makeReplaced(editEvent);
 
             // The relation should be pulled from the original event
-            expect(ReplyChain.getParentEventId(originalEventWithRelation))
+            expect(getParentEventId(originalEventWithRelation))
                 .toStrictEqual('$qkjmFBTEc0VvfVyzq1CJuh1QZi_xDIgNEFjZ4Pq34og');
         });
 
@@ -109,7 +125,7 @@ describe("ReplyChain", () => {
             originalEvent.makeReplaced(editEvent);
 
             // The relation should be pulled from the edit event
-            expect(ReplyChain.getParentEventId(originalEvent))
+            expect(getParentEventId(originalEvent))
                 .toStrictEqual('$qkjmFBTEc0VvfVyzq1CJuh1QZi_xDIgNEFjZ4Pq34og');
         });
 
@@ -158,7 +174,7 @@ describe("ReplyChain", () => {
             originalEventWithRelation.makeReplaced(editEvent);
 
             // The relation should be pulled from the edit event
-            expect(ReplyChain.getParentEventId(originalEventWithRelation)).toStrictEqual('$999');
+            expect(getParentEventId(originalEventWithRelation)).toStrictEqual('$999');
         });
 
         it('able to clear relation reply from original event by providing empty relation field', () => {
@@ -203,7 +219,7 @@ describe("ReplyChain", () => {
             originalEventWithRelation.makeReplaced(editEvent);
 
             // The relation should be pulled from the edit event
-            expect(ReplyChain.getParentEventId(originalEventWithRelation)).toStrictEqual(undefined);
+            expect(getParentEventId(originalEventWithRelation)).toStrictEqual(undefined);
         });
     });
 });

test/components/views/rooms/MessageComposerButtons-test.tsx

@@ -148,7 +148,6 @@ function createRoomState(room: Room): IRoomState {
         shouldPeek: true,
         membersLoaded: false,
         numUnreadMessages: 0,
-        draggingFile: false,
         searching: false,
         guestsCanJoin: false,
         canPeek: false,
@@ -175,7 +174,6 @@ function createRoomState(room: Room): IRoomState {
         showAvatarChanges: true,
         showDisplaynameChanges: true,
         matrixClientIsReady: false,
-        dragCounter: 0,
         timelineRenderingType: TimelineRenderingType.Room,
         liveTimeline: undefined,
     };

test/components/views/rooms/SendMessageComposer-test.tsx

@@ -45,7 +45,6 @@ describe('<SendMessageComposer/>', () => {
         shouldPeek: true,
         membersLoaded: false,
         numUnreadMessages: 0,
-        draggingFile: false,
         searching: false,
         guestsCanJoin: false,
         canPeek: false,
@@ -72,7 +71,6 @@ describe('<SendMessageComposer/>', () => {
         showAvatarChanges: true,
         showDisplaynameChanges: true,
         matrixClientIsReady: false,
-        dragCounter: 0,
         timelineRenderingType: TimelineRenderingType.Room,
         liveTimeline: undefined,
     };