import fetch, { RequestInit, Response } from 'node-fetch';
import { URL } from 'url';
import * as querystring from 'querystring';

import { AuthorisationTokenRequest } from '../types/request';
import { ErrorData } from '../types/errors';
import { InvalidResponseError } from '../errors';

/**
 * When using some methods in the Subscription service an authorisation token is required.
 * This function gets an authorisation token from the Membership API
 * @param url Should be passed in on initialisation of the service
 * @param sessionToken The 'FT_session_s' value from the user's cookie
 * @param clientId Should be passed in on initialisation of the service
 * @param additionalHeaders any headers to add to the request
 * @returns authorisation token
 *
 */
export async function authorisationTokenRequest({ url, sessionToken, clientId, additionalHeaders = {} }: AuthorisationTokenRequest, fetch: Function): Promise<string> {
	const options: RequestInit = {
		method: 'GET',
		headers: {
			'Cookie': `FTSession_s=${sessionToken}`,
			...additionalHeaders
		},
		redirect: 'manual' // API doesn't follow the redirect and returns an opaque-redirect filtered response which wraps the redirect response.
	};

	const response: Response = await fetch(`${url}?client_id=${clientId}&response_type=token`, options);

	const data: ErrorData = {
		url,
		status: response.status,
		method: options.method
	};
	// Only a redirect is expected from this call
	if (response.status !== 302) {
		throw new InvalidResponseError('Redirect expected', data);
	}

	const location = response.headers.get && response.headers.get('location');

	if (!location) {
		throw new InvalidResponseError('Location header expected', data);
	}

	const { hash } = new URL(location);
	const splitQueryString = querystring.parse(hash.replace(/^#/, ''));
	const accessToken = splitQueryString.access_token;

	if (accessToken && typeof accessToken === 'string') {
		return accessToken;
	}

	// url returns error params: error=invalid_grant&error_description=Invalid%20FT%20user%20session
	if (splitQueryString.error) {
		throw new InvalidResponseError('' + splitQueryString.error_description, data);
	}
	data.location = location;
	throw new InvalidResponseError('Token not found', data);
}