webbluetooth/src/service.ts

Node.js implementation of the Web Bluetooth Specification

/*
* Node Web Bluetooth
* Copyright (c) 2025 Rob Moran
*
* The MIT License (MIT)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/

import { adapter } from './adapters';
import { BluetoothDeviceImpl } from './device';
import { BluetoothRemoteGATTCharacteristicImpl, CharacteristicEvents } from './characteristic';
import { BluetoothUUID } from './uuid';
import { EventDispatcher, DOMEvent } from './events';

/**
 * @hidden
 */
export interface ServiceEvents extends CharacteristicEvents {
    /**
     * Service added event
     */
    serviceadded: Event;
    /**
     * Service changed event
     */
    servicechanged: Event;
    /**
     * Service removed event
     */
    serviceremoved: Event;
}

/**
 * Bluetooth Remote GATT Service class
 */
export class BluetoothRemoteGATTServiceImpl extends EventDispatcher<ServiceEvents> implements BluetoothRemoteGATTService {

    /**
     * The device the service is related to
     */
    public readonly device: BluetoothDeviceImpl = undefined;

    /**
     * The unique identifier of the service
     */
    public readonly uuid: string = undefined;

    /**
     * Whether the service is a primary one
     */
    public readonly isPrimary: boolean = false;


    /**
     * @hidden
     */
    public _handle: string = undefined;
    private services: Array<BluetoothRemoteGATTService> = undefined;
    private characteristics: Array<BluetoothRemoteGATTCharacteristic> = undefined;

    private _oncharacteristicvaluechanged: (ev: Event) => void;
    public set oncharacteristicvaluechanged(fn: (ev: Event) => void) {
        if (this._oncharacteristicvaluechanged) {
            this.removeEventListener('characteristicvaluechanged', this._oncharacteristicvaluechanged);
            this._oncharacteristicvaluechanged = undefined;
        }
        if (fn) {
            this._oncharacteristicvaluechanged = fn;
            this.addEventListener('characteristicvaluechanged', this._oncharacteristicvaluechanged);
        }
    }

    private _onserviceadded: (ev: Event) => void;
    public set onserviceadded(fn: (ev: Event) => void) {
        if (this._onserviceadded) {
            this.removeEventListener('serviceadded', this._onserviceadded);
            this._onserviceadded = undefined;
        }
        if (fn) {
            this._onserviceadded = fn;
            this.addEventListener('serviceadded', this._onserviceadded);
        }
    }

    private _onservicechanged: (ev: Event) => void;
    public set onservicechanged(fn: (ev: Event) => void) {
        if (this._onservicechanged) {
            this.removeEventListener('servicechanged', this._onservicechanged);
            this._onservicechanged = undefined;
        }
        if (fn) {
            this._onservicechanged = fn;
            this.addEventListener('servicechanged', this._onservicechanged);
        }
    }

    private _onserviceremoved: (ev: Event) => void;
    public set onserviceremoved(fn: (ev: Event) => void) {
        if (this._onserviceremoved) {
            this.removeEventListener('serviceremoved', this._onserviceremoved);
            this._onserviceremoved = undefined;
        }
        if (fn) {
            this._onserviceremoved = fn;
            this.addEventListener('serviceremoved', this._onserviceremoved);
        }
    }

    /**
     * Service constructor
     * @param init A partial class to initialise values
     */
    constructor(init: Partial<BluetoothRemoteGATTServiceImpl>) {
        super();

        this.device = init.device;
        this.uuid = init.uuid;
        this.isPrimary = init.isPrimary;
        this._handle = init._handle;

        this.dispatchEvent(new DOMEvent(this, 'serviceadded'));
        this.device.dispatchEvent(new DOMEvent(this, 'serviceadded'));
        this.device._bluetooth.dispatchEvent(new DOMEvent(this, 'serviceadded'));
    }

    /**
     * Gets a single characteristic contained in the service
     * @param characteristic characteristic UUID
     * @returns Promise containing the characteristic
     */
    public async getCharacteristic(characteristic: BluetoothCharacteristicUUID): Promise<BluetoothRemoteGATTCharacteristic> {
        if (!this.device.gatt.connected) {
            throw new Error('getCharacteristic error: device not connected');
        }

        if (!characteristic) {
            throw new Error('getCharacteristic error: no characteristic specified');
        }

        const characteristics = await this.getCharacteristics(characteristic);
        if (characteristics.length !== 1) {
            throw new Error('getCharacteristic error: characteristic not found');
        }

        return characteristics[0];
    }

    /**
     * Gets a list of characteristics contained in the service
     * @param characteristic characteristic UUID
     * @returns Promise containing an array of characteristics
     */
    public async getCharacteristics(characteristic?: BluetoothCharacteristicUUID): Promise<Array<BluetoothRemoteGATTCharacteristic>> {
        if (!this.device.gatt.connected) {
            throw new Error('getCharacteristics error: device not connected');
        }

        if (!this.characteristics) {
            const characteristics = await adapter.discoverCharacteristics(this._handle);
            this.characteristics = characteristics.map(characteristicInfo => {
                Object.assign(characteristicInfo, {
                    service: this
                });
                return new BluetoothRemoteGATTCharacteristicImpl(characteristicInfo);
            });
        }

        if (!characteristic) {
            return this.characteristics;
        }

        // Canonical-ize characteristic
        characteristic = BluetoothUUID.getCharacteristic(characteristic);

        const filtered = this.characteristics.filter(characteristicObject => characteristicObject.uuid === characteristic);

        if (filtered.length !== 1) {
            throw new Error('getCharacteristics error: characteristic not found');
        }

        return filtered;
    }

    /**
     * Gets a single service included in the service
     * @param service service UUID
     * @returns Promise containing the service
     */
    public async getIncludedService(service: BluetoothServiceUUID): Promise<BluetoothRemoteGATTService> {
        if (!this.device.gatt.connected) {
            throw new Error('getIncludedService error: device not connected');
        }

        if (!service) {
            throw new Error('getIncludedService error: no service specified');
        }

        const services = await this.getIncludedServices(service);
        if (services.length !== 1) {
            throw new Error('getIncludedService error: service not found');
        }

        return services[0];
    }

    /**
     * Gets a list of services included in the service
     * @param service service UUID
     * @returns Promise containing an array of services
     */
    public async getIncludedServices(service?: BluetoothServiceUUID): Promise<Array<BluetoothRemoteGATTService>> {
        if (!this.device.gatt.connected) {
            throw new Error('getIncludedServices error: device not connected');
        }

        if (!this.services) {
            const services = await adapter.discoverIncludedServices(this._handle, this.device._allowedServices);
            this.services = services.map(serviceInfo => {
                Object.assign(serviceInfo, {
                    device: this.device
                });
                return new BluetoothRemoteGATTServiceImpl(serviceInfo);
            });
        }

        if (!service) {
            return this.services;
        }

        const filtered = this.services.filter(serviceObject => serviceObject.uuid === BluetoothUUID.getService(service));

        if (filtered.length !== 1) {
            throw new Error('getIncludedServices error: service not found');
        }

        return filtered;
    }
}