// Copyright (C) 2014-2021 Goodrain Co., Ltd.
// RAINBOND, Application Management Platform

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version. For any non-GPL usage of Rainbond,
// one or multiple Commercial Licenses authorized by Goodrain Co., Ltd.
// must be obtained first.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.

package retryutil

import (
	"fmt"
	"time"
)

//RetryError -
type RetryError struct {
	n int
}

func (e *RetryError) Error() string {
	return fmt.Sprintf("still failing after %d retries", e.n)
}

//IsRetryFailure -
func IsRetryFailure(err error) bool {
	_, ok := err.(*RetryError)
	return ok
}

//ConditionFunc -
type ConditionFunc func() (bool, error)

// Retry retries f every interval until after maxRetries.
// The interval won't be affected by how long f takes.
// For example, if interval is 3s, f takes 1s, another f will be called 2s later.
// However, if f takes longer than interval, it will be delayed.
func Retry(interval time.Duration, maxRetries int, f ConditionFunc) error {
	if maxRetries <= 0 {
		return fmt.Errorf("maxRetries (%d) should be > 0", maxRetries)
	}
	tick := time.NewTicker(interval)
	defer tick.Stop()

	for i := 0; ; i++ {
		ok, err := f()
		if err != nil {
			return err
		}
		if ok {
			return nil
		}
		if i == maxRetries {
			break
		}
		<-tick.C
	}
	return &RetryError{maxRetries}
}