package main

import (
    "fmt"
    "io/ioutil"
    "log"
    "net/http"
    "regexp"
    "time"
)

var user_id = 345058277
var number_doc = 449613314

func MakeRequest(url string, ch chan<- string) {
    resp, err := http.Get(url)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        log.Fatal("Error reading HTTP body. ", err)
    }

    re := regexp.MustCompile(`<img src=".*?" class="can_zoom".*?/>`)
    findtag := re.FindAllStringSubmatch(string(body), -1)
    stringArray := findtag
    justString := fmt.Sprint(stringArray)
    if findtag == nil {
        ch <- "n"
    } else {
        ch <- justString
    }

}

func main() {
    for j := 0; j < 100; j++ {
        var arrurls [1000]string
        ch := make(chan string)
        for i := 0; i < 1000; i++ {
            number_doc++
            raw_url := fmt.Sprintf("https://vk.com/doc%d_%d", user_id, number_doc)
            arrurls[i] = raw_url
        }
        fmt.Println(number_doc)
        start := time.Now()
        for _, url := range arrurls {
            go MakeRequest(url, ch)
        }
        for range arrurls {
            d := <-ch
            if d != "n" {
                fmt.Println(d)
            }
        }
        elapsed := time.Since(start)
        fmt.Println(elapsed)
    }
}