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package fetcher
import (
"context"
"fmt"
"io"
"net/http"
"strings"
"time"
"go.alanpearce.eu/searchix/internal/config"
"github.com/andybalholm/brotli"
"github.com/pkg/errors"
"go.alanpearce.eu/x/log"
)
type brotliReadCloser struct {
src io.ReadCloser
*brotli.Reader
}
func newBrotliReader(src io.ReadCloser) *brotliReadCloser {
return &brotliReadCloser{
src: src,
Reader: brotli.NewReader(src),
}
}
func (r *brotliReadCloser) Close() error {
return errors.Wrap(r.src.Close(), "failed to call close on underlying reader")
}
func fetchFileIfNeeded(
ctx context.Context,
log *log.Logger,
mtime time.Time,
url string,
) (body io.ReadCloser, newMtime time.Time, err error) {
var ifModifiedSince string
if !mtime.IsZero() {
ifModifiedSince = strings.Replace(mtime.UTC().Format(time.RFC1123), "UTC", "GMT", 1)
}
req, err := http.NewRequestWithContext(ctx, "GET", url, http.NoBody)
if err != nil {
err = errors.WithMessagef(err, "could not create HTTP request for %s", url)
return
}
req.Header.Set("User-Agent", fmt.Sprintf("Searchix %s", config.Version))
if ifModifiedSince != "" {
req.Header.Set("If-Modified-Since", ifModifiedSince)
}
res, err := http.DefaultClient.Do(req)
if err != nil {
err = errors.WithMessagef(err, "could not make HTTP request to %s", url)
return
}
switch res.StatusCode {
case http.StatusNotModified:
newMtime = mtime
return
case http.StatusOK:
newMtime, err = time.Parse(time.RFC1123, res.Header.Get("Last-Modified"))
if err != nil {
log.Warn(
"could not parse Last-Modified header from response",
"value",
res.Header.Get("Last-Modified"),
)
newMtime = time.Now()
}
switch ce := res.Header.Get("Content-Encoding"); ce {
case "br":
log.Debug("using brotli encoding")
body = newBrotliReader(res.Body)
case "", "identity", "gzip":
body = res.Body
default:
err = fmt.Errorf("cannot handle a body with content-encoding %s", ce)
}
default:
err = fmt.Errorf("got response code %d, don't know what to do", res.StatusCode)
}
return
}
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