threema-web/src/typeguards.ts

/**
 * This file is part of Threema Web.
 *
 * Threema Web is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero
 * General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Threema Web. If not, see <http://www.gnu.org/licenses/>.
 */

// User defined type guards are small functions that determine the type of an object.
// See https://www.typescriptlang.org/docs/handbook/advanced-types.html#user-defined-type-guards
// for more information.

/**
 * Contact receiver type guard
 */
export function isContactReceiver(
    receiver: threema.BaseReceiver,
): receiver is threema.ContactReceiver {
    return receiver.type === 'contact';
}

/**
 * Group receiver type guard
 */
export function isGroupReceiver(
    receiver: threema.BaseReceiver,
): receiver is threema.GroupReceiver {
    return receiver.type === 'group';
}

/**
 * Distribution list receiver type guard
 */
export function isDistributionListReceiver(
    receiver: threema.BaseReceiver,
): receiver is threema.DistributionListReceiver {
    return receiver.type === 'distributionList';
}

/**
 * Valid receiver types type guard
 */
export function isValidReceiverType(
    receiverType: string,
): receiverType is threema.ReceiverType {
    switch (receiverType) {
        case 'me':
        case 'contact':
        case 'group':
        case 'distributionList':
            return true;
    }
    return false;
}

/**
 * Valid disconnect reasons type guard
 */
export function isValidDisconnectReason(
    reason: string,
): reason is threema.DisconnectReason {
    switch (reason) {
        case 'stop':
        case 'delete':
        case 'disable':
        case 'replace':
            return true;
    }
    return false;
}

/**
 * Text nodes type guard.
 */
export function isTextNode(node: Node): node is Text {
    return node.nodeType === node.TEXT_NODE;
}

/**
 * Element nodes type guard.
 */
export function isElementNode(node: Node): node is HTMLElement {
    return node.nodeType === node.ELEMENT_NODE;
}

/**
 * Emoji info type guard.
 */
export function isEmojiInfo(val: string | threema.EmojiInfo): val is threema.EmojiInfo {
    return typeof val === 'object'
        && val.emojiString !== undefined
        && val.imgPath !== undefined
        && val.codepoint !== undefined;
}

/**
 * Controller model has members.
 *
 * This returns true if the `ControllerModel` also implements the `ControllerModelWithMembers` interface.
 */
export function controllerModelHasMembers<T extends threema.BaseReceiver>(
    cm: threema.ControllerModel<T>,
): cm is threema.ControllerModel<T> & threema.ControllerModelWithMembers {
    return cm.receiverType === 'group' || cm.receiverType === 'distributionList';
}

/**
 * Return whether this event is a keyboard event.
 */
export function isKeyboardEvent(ev: Event): ev is KeyboardEvent {
    return ev.type === 'keydown' || ev.type === 'keypress' || ev.type === 'keyup';
}