import React from 'react';
import { Redirect, generatePath } from 'react-router-dom';
import { isExpired } from 'react-jwt';

const UserContext = React.createContext();

class Login extends React.Component {
	constructor(props) {
		super(props);
		this.state = {};
	}
	async componentDidMount() {
		let url = await this.get_oauth_url();
		this.setState({url: url});
		window.location = url;
	}
	render() {
		if (this.state.url) {
			return <div>Redirecting to <a href={this.state.url}>{this.state.url}</a></div>;
		}
		return <div>Logging in…</div>;
	}
	async get_oauth_url() {
		let redirect_uri = window.location.origin + generatePath('/oauth-callback');
		let response = await fetch('/api/auth/request', {
			method: 'POST',
			headers: {
				'Content-Type': 'application/x-www-form-urlencoded',
			},
			body: 'redirect_uri=' + encodeURIComponent(redirect_uri),
		});
		let data = await response.json();
		if (response.ok && data.url) {
			return data.url;
		}
	}
}

class Logout extends React.Component {
	static contextType = UserContext;
	constructor(props) {
		super(props);
		this.state = {done: false};
	}
	async componentDidMount() {
		await this.context.logout();
		this.setState({done: true});
	}
	render() {
		if (this.state.done) {
			return <Redirect to='/' />;
		}
		return <div>Logging out…</div>;
	}
}

class OauthCallback extends React.Component {
	static contextType = UserContext;
	constructor(props) {
		super(props);
		this.state = {
			error: null,
			done: false,
		};
	}
	async componentDidMount() {
		this.setState({error: null});
		let params = new URLSearchParams(this.props.location.search);
		let error = params.get('error');
		if (error) {
			this.setState({error: params.get('error_description')});
			return;
		}
		let redirect_uri = window.location.origin + generatePath('/oauth-callback');
		let response = await fetch('/api/auth/response', {
			method: 'POST',
			headers: {
				'Content-Type': 'application/x-www-form-urlencoded',
			},
			body: 'code=' + encodeURIComponent(params.get('code')) + '&state=' + encodeURIComponent(params.get('state'))
				+ '&redirect_uri=' + encodeURIComponent(redirect_uri),
		});
		let data = await response.json();
		if (!response.ok) {
			this.setState({error: data.message});
			return;
		}
		const user = await this.context.get_user();
		if (user) {
			this.setState({error: null, done: true});
			window.flash({header: 'Logged in', text: 'You are now logged in as ' + user.username + '.'});
		} else {
			window.flash({header: 'Login failed', text: 'Something failed during authentication.'});
		}
	}
	render() {
		if (this.state.error) {
			return this.state.error;
		}
		if (this.state.done) {
			return <Redirect to='/' />;
		}
		return 'Logging in…';
	}
}

class AuthenticationProvider extends React.Component {
	constructor(props) {
		super(props);
		this.state = {
			username: null,
			is_logged_in: false,
			access_token: null,
		};
		this.logout = this.logout.bind(this);
		this.get_user = this.get_user.bind(this);
		this.get_token = this.get_token.bind(this);
	}
	async componentDidMount() {
		await this.get_user();
	}
	render() {
		return <UserContext.Provider value={{
				username: this.state.username,
				is_logged_in: this.state.is_logged_in,
				get_user: this.get_user,
				logout: this.logout,
				get_token: this.get_token}}>
			{this.props.children}
		</UserContext.Provider>;
	}
	async logout() {
		const was_logged_in = this.state.is_logged_in;
		await fetch('/api/auth/logout', {
			method: 'POST',
		});
		this.setState({username: null, is_logged_in: false, access_token: null});
		if (was_logged_in) {
			window.flash({header: 'Logged out', text: 'You are now logged out.'});
		}
	}
	async get_user() {
		let token = await this.get_token();
		if (!token) {
			return;
		}
		let response = await fetch('/api/user',{
			headers: {
				Authorization: 'Bearer ' + token,
			}
		});
		if (response.ok) {
			let data = await response.json();
			this.setState({username: data.username, is_logged_in: true});
			return data;
		} else {
			await this.logout();
		}
	}
	async refresh() {
		let response = await fetch('/api/auth/refresh', {
			method: 'POST',
			credentials: 'include',
			headers: {
				'Content-Type': 'application/x-www-form-urlencoded',
			},
			body: '',
		});
		if (response.ok) {
			let data = await response.json();
			return data.access_token;
		}
	}
	async get_token() {
		let access_token = this.state.access_token;
		let is_expired = !access_token || isExpired(access_token);
		if (is_expired) {
			access_token = await this.refresh();
			this.setState({access_token: access_token});
		}
		return access_token;
	}
}

export { UserContext, Login, Logout, OauthCallback, AuthenticationProvider };