package main

import (
	"flag"
	"fmt"
	"sync"
	"time"
)

type Ball struct{ hits int }

func main() {
	numSecs := flag.Int("s", 1, "Number of seconds game should last")
	flag.Parse()

	game(*numSecs)
}

func game(numSecs int) {
	var wg sync.WaitGroup
	done := make(chan struct{})
	p0 := make(chan Ball)

	p1 := player(1, &wg, done, p0)
	p2 := player(2, &wg, done, p1)
	t := time.Tick(time.Duration(numSecs) * time.Second)

	p0 <- Ball{}

loop:
	for b := range p2 {
		select {
		case p0 <- b:
		case <-t:
			break loop
		}
	}

	close(p0)

	wg.Wait()
	fmt.Println("Done for now")
}

func player(id int, wg *sync.WaitGroup, done <-chan struct{}, input <-chan Ball) <-chan Ball {
	out := make(chan Ball)

	wg.Go(func() {
		defer func() {
			close(out)
			fmt.Printf("(%d) finished\n", id)
		}()

		fmt.Printf("(%d) started\n", id)
	loop:
		for b := range input {
			b.hits++
			fmt.Printf("(%d) %d\n", id, b.hits)
			time.Sleep(100 * time.Millisecond)

			select {
			case out <- b:
			case <-done:
				break loop
			}
		}
	})

	return out
}