package daemon

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"time"

	"dev.mediocregopher.com/mediocre-go-lib.git/mlog"
)

// until keeps trying fn until it returns nil, returning true. If the context is
// canceled then until returns false.
func until(
	ctx context.Context,
	logger *mlog.Logger,
	descr string,
	fn func(context.Context) error,
) bool {
	for {
		logger.Info(ctx, descr)
		err := fn(ctx)
		if err == nil {
			return true
		} else if ctxErr := ctx.Err(); ctxErr != nil {
			return false
		}

		logger.Warn(ctx, descr+" failed, retrying in one second", err)
		time.Sleep(1 * time.Second)
	}
}

func randStr(l int) string {
	b := make([]byte, l)
	if _, err := rand.Read(b); err != nil {
		panic(err)
	}
	return hex.EncodeToString(b)
}