import axios, { AxiosError, AxiosInstance, AxiosRequestConfig } from 'axios';
import { WithMicroserviceContext } from '../with-microservice';
import { AuthAdapter } from './auth-adapter';

export interface BearerTokenAuthOptions {}

export class BearerTokenAuth implements AuthAdapter {
    private authAbortController?: AbortController;
    private authToken: string = '';
    private authURL: string;
    private axios: AxiosInstance;

    constructor(context: WithMicroserviceContext, _options?: BearerTokenAuthOptions) {
        this.authURL = context.authURL ?? `${context.baseURL}/auth`;
        this.axios = axios.create();
    }

    onDestroy() {
        this.abortAuthRequest();
    }

    authenticate() {
        this.authAbortController = new AbortController();
        return this.axios
            .get<string>(this.authURL, {
                signal: this.authAbortController.signal,
            })
            .then(response => {
                this.authToken = response.data;
            })
            .catch((error: AxiosError) => {
                this.authToken = '';
                return Promise.reject(error);
            })
            .finally(() => {
                this.authAbortController = undefined;
            });
    }

    interceptRequest(config: AxiosRequestConfig) {
        config.headers = {
            ...config.headers,
            ...this.getAuthHeader(),
        };
    }

    didAuthenticationHappenWhileRequestInFlight(config: AxiosRequestConfig) {
        /**
         * Check if auth token got updated while the request was in flight to avoid unnecessary extra auth request
         * For example, if two requests requiring authentication happen at the same time
         *   - the first takes 5 seconds to get a 401 response, then runs authenticate and sets the auth token
         *   - the second takes 10 seconds to get a 401 response, then we don't want to do an auth request because we
         *     already have an auth token
         */
        return (
            this.getAuthHeader().Authorization !== config.headers?.Authorization &&
            this.authToken !== ''
        );
    }

    abortAuthRequest() {
        if (this.authAbortController) {
            this.authAbortController.abort();
            this.authAbortController = undefined;
        }
    }

    getAuthHeader() {
        return {
            Authorization: `Bearer ${this.authToken}`,
        };
    }
}