package main

import (
	"fmt"
	"math/rand"
	"time"
)

func main() {
	rand.Seed(time.Now().UnixNano())
	start := time.Now()
	results := Google("golang")
	fmt.Println(results)
	fmt.Printf("%s", time.Since(start))
}

type Result string

type Search func(key string) Result

func ResourceSearch(kind string) Search {
	return func(key string) Result {
		time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
		return Result(fmt.Sprintf("<%s from %s server>\n", key, kind))
	}
}

func First(servers []Search, key string) Result {
	result := make(chan Result)
	done := make(chan struct{})
	defer close(done)
	query := func(i int) {
		select {
		case <-done:
			return
		case result <- servers[i](key):
		}
	}
	for i := range servers {
		go query(i)
	}
	return <-result
}

func Google(key string) (results []Result) {
	var images []Search
	var videos []Search
	var voices []Search
	for i := 0; i < 3; i++ {
		images = append(images, ResourceSearch(fmt.Sprintf("image-%d", i)))
		videos = append(videos, ResourceSearch(fmt.Sprintf("video-%d", i)))
		voices = append(voices, ResourceSearch(fmt.Sprintf("voice-%d", i)))
	}
	chanResults := make(chan Result)
	go func() {
		chanResults <- First(images, key)
	}()
	go func() {
		chanResults <- First(videos, key)
	}()
	go func() {
		chanResults <- First(voices, key)
	}()
	after := time.After(80 * time.Millisecond)
	for i := 0; i < 3; i++ {
		select {
		case r := <-chanResults:
			results = append(results, r)
		case <-after:
			fmt.Println("timeout")
			return
		}
	}
	return
}