@dvsa/appdev-api-common/auth/client-credentials.js

Utils library for common API functionality

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.ClientCredentials = void 0;
const node_querystring_1 = require("node:querystring");
const jose_1 = require("jose");
class ClientCredentials {
    tokenUrl;
    clientId;
    clientSecret;
    scope;
    resource;
    debugMode;
    static accessToken;
    static grantType = "client_credentials";
    /**
     * Create a new instance of the ClientCredentials class
     * @param tokenUrl - The URL to fetch the access token from
     * @param clientId - The client id
     * @param clientSecret - The client secret
     * @param scope - The scope of the access token
     * @param debugMode - Whether to log debug messages
     */
    constructor(tokenUrl, clientId, clientSecret, scope, resource, debugMode = false) {
        this.tokenUrl = tokenUrl;
        this.clientId = clientId;
        this.clientSecret = clientSecret;
        this.scope = scope;
        this.resource = resource;
        this.debugMode = debugMode;
    }
    /**
     * Helper method to perform the client credentials flow and return the access token
     * This method will check for the existence of the token and if it is expired, it will fetch a new one
     * @returns {Promise<string>} - The access token
     */
    async getAccessToken() {
        if (!ClientCredentials.accessToken || this.isAccessTokenExpired()) {
            const { access_token } = await this.fetchClientCredentials();
            if (this.debugMode)
                console.log("[DEBUG] New access token fetched:", access_token);
            ClientCredentials.accessToken = access_token;
        }
        else if (this.debugMode) {
            console.log("[DEBUG] Using existing access token:", ClientCredentials.accessToken);
        }
        return ClientCredentials.accessToken;
    }
    /**
     * Fetch the client credentials from the token URL
     * @returns {Promise<ClientCredentialsResponse>} - The response from the token URL
     * @private
     */
    async fetchClientCredentials() {
        const response = await fetch(this.tokenUrl, {
            method: "POST",
            headers: { "Content-Type": "application/x-www-form-urlencoded" },
            body: (0, node_querystring_1.stringify)({
                grant_type: ClientCredentials.grantType,
                client_id: this.clientId,
                client_secret: this.clientSecret,
                scope: this.scope,
                resource: this.resource,
            }),
        });
        if (!response.ok) {
            console.error("Error fetching client credentials", response);
            throw new Error("Failed to fetch client credentials");
        }
        return (await response.json());
    }
    /**
     * Check if the access token is expired
     * @returns {boolean} - Whether the access token is expired
     * @private
     */
    isAccessTokenExpired() {
        try {
            const decodedAccessToken = (0, jose_1.decodeJwt)(ClientCredentials.accessToken);
            const currentTime = new Date().getTime() / 1000;
            // Check if exp exists before comparing as it can be undefined
            if (!decodedAccessToken?.exp) {
                return true;
            }
            return currentTime > decodedAccessToken.exp;
        }
        catch (err) {
            console.error("Error decoding access token:", err);
            return true;
        }
    }
}
exports.ClientCredentials = ClientCredentials;