Login.php

<?php

class Login {

	public function hook(){
		add_filter( 'determine_current_user', [ $this, 'login_via_token' ], 20 );
		add_action( 'rest_api_init', [ $this, 'register_routes' ], 10 );
	}
  
	public function register_routes(){
		register_rest_route( 'auth/v1', '/login/', [
			'methods'  => 'POST',
			'callback' => [ $this, 'basic_auth_handler' ],
		] );
	}
  
	public function basic_auth_handler( \WP_REST_Request $request ){
		if ( ! isset( $_SERVER[ 'PHP_AUTH_USER' ] ) ) {
			return new \WP_Error( 'no_user', __( 'No User Passed' ), [ 'status' => 201 ] );
		}

		$username = $_SERVER[ 'PHP_AUTH_USER' ];
		$password = $_SERVER[ 'PHP_AUTH_PW' ];

		$user = wp_authenticate( $username, $password );

		if ( is_wp_error( $user ) ){
			return $user;
		}

		return $this->get_valid_authenticated_response( $user );
	}
  
	private function get_valid_authenticated_response( $user ) {
		$columns = [
			'user_id' => $user->ID,
			'token'   => wp_hash_password( $user->user_email . time() ),
			'expires' => gmdate( 'Y-m-d H:i:s', strtotime( '+1 week' ) ),
		];
		AuthTable::instance()->add_token( $columns );

		$response = new \WP_REST_Response( $columns );
		$response->set_status( 200 );

		return $response;
  }

}