package main

import(
	"fmt"
	"bufio"
	"os"
	"math/rand"
	"sync"
	"time"
)

func main() {
	filename := os.Args[1]
	if filename == "" {
		panic("No filename")
	}
	fh,err := os.Open(filename)
	if err != nil {
		panic(err)
	}
	scanner := bufio.NewScanner(fh)
	c := make(chan string)
	var wg sync.WaitGroup
	for scanner.Scan() {
		line := scanner.Text()
		wg.Add(1)
		go func(l string){
			time.Sleep(time.Duration(rand.Intn(30)) * time.Millisecond)
			c <-  l
			wg.Done()
		}(line)
	}
	go func() {
		wg.Wait()
		close(c)
	}()
	for  {
		myline, ok := <-c
		if !ok {
			return
		}
		fmt.Println(myline)
	}
}