package main

import (
	"context"
	"github.com/oklog/run"
	"log"
	"syscall"
	"time"
)

func main() {
	group := new(run.Group)
	ctx := context.Background()

	// add signal handler to the run group
	group.Add(run.SignalHandler(ctx, syscall.SIGINT, syscall.SIGTERM))

	// execute async fns with timeout
	// play with these values to trigger errors
	group.Add(sleepWithTimeout(ctx, 1 * time.Second, 3 * time.Second))

	log.Println("Running...")

	err := group.Run()
	if err != nil {
		log.Fatal("Program exit: ", err)
	}

	log.Println("Done")
}

func sleepWithTimeout(ctx context.Context, sleep time.Duration, timeout time.Duration) (execute func() error, interrupt func(error)) {
	ctx, cancel := context.WithTimeout(ctx, timeout)

	execute = func() error {
		err := sleepContext(ctx, sleep)
		return err
	}

	interrupt = func(err error) {
		cancel()
	}

	return execute, interrupt
}

func sleepContext(ctx context.Context, delay time.Duration) error {
	select {
	case <-ctx.Done():
		return ctx.Err()
	case <-time.After(delay):
		return ctx.Err()
	}
}