hydrogen-web/src/matrix/room/timeline/PendingAnnotation.js

/*
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 class PendingAnnotation {
    constructor() {
        // TODO: use simple member for reaction and redaction as we can't/shouldn't really have more than 2 entries
        // this contains both pending annotation entries, and pending redactions of remote annotation entries 
        this._entries = [];
    }

    get firstTimestamp() {
        return this._entries.reduce((ts, e) => {
            if (e.isRedaction) {
                return ts;
            }
            return Math.min(e.timestamp, ts);
        }, Number.MAX_SAFE_INTEGER);
    }

    get annotationEntry() {
        return this._entries.find(e => !e.isRedaction);
    }

    get redactionEntry() {
        return this._entries.find(e => e.isRedaction);
    }

    get count() {
        return this._entries.reduce((count, e) => {
            return count + (e.isRedaction ? -1 : 1);
        }, 0);
    }

    add(entry) {
        this._entries.push(entry);
    }

    remove(entry) {
        const idx = this._entries.indexOf(entry);
        if (idx === -1) {
            return false;
        }
        this._entries.splice(idx, 1);
        return true;
    }

    get willAnnotate() {
        const lastEntry = this._entries.reduce((lastEntry, e) => {
            if (!lastEntry || e.pendingEvent.queueIndex > lastEntry.pendingEvent.queueIndex) {
                return e;
            }
            return lastEntry;
        }, null);
        if (lastEntry) {
            return !lastEntry.isRedaction;
        }
        return false;
    }

    get isEmpty() {
        return this._entries.length === 0;
    }
}