VandyHacks/vaken

import { Strategy, VerifyCallback as GVerifyCallback } from 'passport-google-oauth20';
import processOAuthCallback from './processOAuthCallback';
import { Models } from '../models';

const {
    GOOGLE_CLIENT_ID: clientID,
    GOOGLE_CLIENT_SECRET: clientSecret,
    GOOGLE_CALLBACK_URL: callbackURL,
} = process.env;

if (!clientID) {
    throw new Error('GOOGLE_CLIENT_ID not set');
}
if (!clientSecret) {
    throw new Error('GOOGLE_CLIENT_SECRET not set');
}
if (!callbackURL) {
    throw new Error('GOOGLE_CALLBACK_URL not set');
}

export const strategy = (models: Models): Strategy =>
    new Strategy(
        {
            callbackURL,
            clientID,
            clientSecret,
            passReqToCallback: false,
            scope: ['openid', 'profile', 'email'],
        },
        // explicitly typing done to clarify the difference in the two VerifyCallback signatures
        (_, __, profile, done: GVerifyCallback) => {
            void processOAuthCallback(models, profile, (err, user, info) => {
                // the Google verifyCallback function has a *slightly* different call signature for the first param
                // the way we call this function uses Error | null | undefined
                // Google wants Error | string | undefined because of course it does
                // we just need to take care of the difference between null/undefined and we're fine
                // I want to note here that passport and the google passport library are made by the same ****ing person
                let coercedErr: Error | string | undefined;

                if (err == null) coercedErr = undefined;
                else coercedErr = err;

                return done(coercedErr, user, info);
            });
        }
    );