func (h *HTTP) Fetch() (io.Reader, error) {
	//delay fetches after first
	if h.delay {
		time.Sleep(h.Interval)
	}
	h.delay = true
	//status check using HEAD
	resp, err := http.Head(h.URL)
	if err != nil {
		return nil, fmt.Errorf("HEAD request failed (%s)", err)
	}
	resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("HEAD request failed (status code %d)", resp.StatusCode)
	}
	//if all headers match, skip update
	matches, total := 0, 0
	for _, header := range h.CheckHeaders {
		if curr := resp.Header.Get(header); curr != "" {
			if last, ok := h.lasts[header]; ok && last == curr {
				matches++
			}
			h.lasts[header] = curr
			total++
		}
	}
	if matches == total {
		return nil, nil //skip, file match
	}
	//binary fetch using GET
	resp, err = http.Get(h.URL)
	if err != nil {
		return nil, fmt.Errorf("GET request failed (%s)", err)
	}
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("GET request failed (status code %d)", resp.StatusCode)
	}
	//extract gz files
	if strings.HasSuffix(h.URL, ".gz") && resp.Header.Get("Content-Encoding") != "gzip" {
		return gzip.NewReader(resp.Body)
	}
	//success!
	return resp.Body, nil
}
func (h *HTTP) Fetch() (io.Reader, error) {
	
	if h.delay {
		time.Sleep(h.Interval)
	}
	h.delay = true
	
	resp, err := http.Head(h.URL)
	if err != nil {
		return nil, fmt.Errorf("HEAD request failed (%s)", err)
	}
	resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("HEAD request failed (status code %d)", resp.StatusCode)
	}
	
	matches, total := 0, 0
	for _, header := range h.CheckHeaders {
		if curr := resp.Header.Get(header); curr != "" {
			if last, ok := h.lasts[header]; ok && last == curr {
				matches++
			}
			h.lasts[header] = curr
			total++
		}
	}
	if matches == total {
		return nil, nil 
	}
	
	resp, err = http.Get(h.URL)
	if err != nil {
		return nil, fmt.Errorf("GET request failed (%s)", err)
	}
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("GET request failed (status code %d)", resp.StatusCode)
	}
	
	if strings.HasSuffix(h.URL, ".gz") && resp.Header.Get("Content-Encoding") != "gzip" {
		return gzip.NewReader(resp.Body)
	}
	
	return resp.Body, nil
}
func ( h * HTTP ) Fetch ( ) ( io . Reader , error ) { //delay fetches after first if h . delay { time . Sleep ( h . Interval ) } h . delay = true //status check using HEAD resp , err := http . Head ( h . URL ) if err != nil { return nil , fmt . Errorf ( " " , err ) } resp . Body . Close ( ) if resp . StatusCode != http . StatusOK { return nil , fmt . Errorf ( " " , resp . StatusCode ) } //if all headers match, skip update matches , total := 0 , 0 for _ , header := range h . CheckHeaders { if curr := resp . Header . Get ( header ) ; curr != " " { if last , ok := h . lasts [ header ] ; ok && last == curr { matches ++ } h . lasts [ header ] = curr total ++ } } if matches == total { return nil , nil //skip, file match } //binary fetch using GET resp , err = http . Get ( h . URL ) if err != nil { return nil , fmt . Errorf ( " " , err ) } if resp . StatusCode != http . StatusOK { return nil , fmt . Errorf ( " " , resp . StatusCode ) } //extract gz files if strings . HasSuffix ( h . URL , " " ) && resp . Header . Get ( " " ) != " " { return gzip . NewReader ( resp . Body ) } //success! return resp . Body , nil }
// Fetch the binary from the provided URL
Fetch the binary from the provided URL