rxpoweredup/src/messenger/outbound-messenger/channel/channel.js

A Typescript RxJS-based library for controlling LEGO Powered UP hubs & peripherals.

export class Channel {
    characteristic;
    packetBuilder;
    messageMiddleware;
    queue = Promise.resolve();
    constructor(characteristic, packetBuilder, messageMiddleware) {
        this.characteristic = characteristic;
        this.packetBuilder = packetBuilder;
        this.messageMiddleware = messageMiddleware;
    }
    sendMessage(message, beforeSend) {
        const p = this.queue.then(() => {
            const resultingMessage = this.messageMiddleware.reduce((acc, middleware) => middleware.handle(acc), message);
            const packet = this.packetBuilder.buildPacket(resultingMessage);
            if (beforeSend) {
                beforeSend();
            }
            return this.characteristic.writeValueWithoutResponse(packet);
        });
        this.queue = p.catch(() => void 0);
        return p;
    }
}