package main

import (
    "encoding/json"
    "fmt"
    "log"
    "net/http"
    "sync"
)

const (
    storiesURL = "https://hacker-news.firebaseio.com/v0/topstories.json"
    itemURL    = "https://hacker-news.firebaseio.com/v0/item"
)

type (
    story struct {
        Title string `json:"title"`
    }

    storyID int
)

func main() {
    resp, err := http.Get(storiesURL)
    if err != nil {
        log.Fatalln(err)
    }
    defer resp.Body.Close()

    var ids []storyID
    if err := json.NewDecoder(resp.Body).Decode(&ids); err != nil {
        log.Fatalln(err)
    }

    workChan := make(chan storyID, len(ids))
    wg := sync.WaitGroup{}

    for i := 0; i < 8; i++ {
        wg.Add(1)
        go func() (err error) {
            defer wg.Done()

            for id := range workChan {
                url := fmt.Sprintf("%s/%d.json", itemURL, id)

                resp, err := http.Get(url)
                if err != nil {
                    return err
                }
                defer resp.Body.Close()

                var story story
                if err := json.NewDecoder(resp.Body).Decode(&story); err != nil {
                    return err
                }

                fmt.Println(story.Title)
            }

            return nil
        }()
    }

    for _, id := range ids {
        workChan <- id
    }
    close(workChan)

    wg.Wait()
}