import { get } from 'https';
import Router from 'express';
import bodyParser from 'body-parser';
import fetch from 'node-fetch';
import jwt from 'jsonwebtoken';
import jwkToPem from 'jwk-to-pem';

import { WebError, UnknownError, UnauthenticatedError, NotFoundError, InvalidCredentialsError, BadRequestError } from './errors';

export default class API {
	constructor(database) {
		this.database = database;

		// Binds
		this.auth = this.auth.bind(this);

		// Router

		this.router = Router({
			strict: true,
		});

		this.router.use(bodyParser.json());

		// Routes

		this.router.get('/', (req, res) => {
			res.end('API v1');
		});

		// Schools
		this.router.get('/schools/', (req, res, next) => {
			this.database.getSchools()
			.then((data) => {
				res.json(data);
			})
			.catch(next);
		});
		this.router.get('/schools/:school', (req, res, next) => {
			this.database.getSchoolWithAuth(req.params.school)
			.then((data) => {
				res.json(Object.assign(data, {
					auth: data.auth.map(a => Object.assign(a, { oid_csecret: undefined })),
				}));
			})
			.catch(next);
		});
		this.router.get('/schools/:school/oid/.well-known/openid-configuration', (req, res, next) => {
			this.database.getSchoolWithAuth(req.params.school)
			.then((data) => {
				// assume auth[0] exists
				const url = data.auth[0].oid_meta;
				if (url) {
					get(url, (d) => {
						d.pipe(res);
					});
				}
			})
			.catch(next);
		});

		// Login
		this.router.post('/schools/:school/login', (req, res, next) => {
			this.checkLogin(req.params.school, req.body)
			.then((l) => {
				res.json(l);
				// Generate and return token
			})
			.catch(next);
		});

		// Users
		this.router.get('/schools/:school/users/', this.auth, (req, res, next) => {
			this.database.getUsers(req.params.school)
			.then((data) => {
				res.json(data);
			})
			.catch(next);
		});
		this.router.get('/schools/:school/users/:id', this.auth, (req, res, next) => {
			this.database.getUserWithSchool(req.params.school, req.params.id)
			.then((data) => {
				res.json(Object.assign(data, {
					pwd: undefined,
					oid_id: undefined,
				}));
			})
			.catch(next);
		});

		this.router.use('/*', (req, res, next) => {
			next(new NotFoundError());
		});
		this.router.use(API.error);
	}

	auth(req, res, next) {
		// res.end('not implemented');
		if (this.validate(req.get('FakeAuth'))) {
			req.user = {
				id: req.get('FakeID'),
			};
			return next();
		}
		return next(new UnauthenticatedError());
	}

	// eslint-disable-next-line class-methods-use-this
	validate(token) {
		return !!token;
	}

	async checkLogin(school, options) {
		const checkLoginPassword = async () => {
			// TODO
			throw new InvalidCredentialsError('Not implemented');
		};
		const checkLoginToken = async (sch, token) => {
			// do
			// - get school
			// then
			// - fetch school private key
			// then
			// - verify jwt
			const s = await this.database.getSchoolWithAuth(sch);
			const oidUrl = s.auth[0].oid_meta;
			if (!oidUrl) {
				throw new Error();
			}
			const o = await fetch(oidUrl).then(res => res.json());
			const jwksUrl = o.jwks_uri;
			const k = await fetch(jwksUrl).then(res => res.json());
			const keys = k.keys;
			const verified = keys.reduce((a, key) => {
				try {
					return jwt.verify(token, jwkToPem(key), {
						algorithms: ['RS256', 'RS384', 'RS512', 'ES256', 'ES384', 'ES512'],
						ignoreExpiration: true,
					});
				} catch (e) {
					return a;
				}
			}, null);
			if (!verified) {
				throw new InvalidCredentialsError('Token not verifiable');
			}
			return verified;
		};
		if (options.type === 'PWD') { // not used
			return this.database.getUserByEmail(options.email)
			.then(data => checkLoginPassword(data.pwd_hash, options.pwd) && data);
		} else if (options.type === 'OID') {
			return checkLoginToken(school, options.id_token)
			.then(data => this.database.getUserByEmail(data.upn));
		}
		return new BadRequestError();
	}

	// eslint-disable-next-line no-unused-vars
	static error(err, req, res, next) {
		if (err instanceof WebError) {
			err.responseTo(res);
		} else if (err) {
			console.error(err);
			new UnknownError().responseTo(res);
		}
		next();
	}
}