// Copyright 2020 The OPA Authors.  All rights reserved.
// Use of this source code is governed by an Apache2
// license that can be found in the LICENSE file.

package util

import (
	"fmt"
	"time"
)

// WaitFunc will call passed function at an interval and return nil
// as soon this function returns true.
// If timeout is reached before the passed in function returns true
// an error is returned.
func WaitFunc(fun func() bool, interval, timeout time.Duration) error {
	if fun() {
		return nil
	}
	ticker := time.NewTicker(interval)
	timer := time.NewTimer(timeout)
	defer ticker.Stop()
	defer timer.Stop()
	for {
		select {
		case <-timer.C:
			return fmt.Errorf("timeout")
		case <-ticker.C:
			if fun() {
				return nil
			}
		}
	}
}