func MaybeDownload()

in httputil/httputil.go [243:278]
31 lines of code
8 McCabe index (conditional complexity)

func MaybeDownload(bazeliskHome, url, filename, description, auth string, merger ContentMerger) ([]byte, error) {
	cachePath := filepath.Join(bazeliskHome, filename)
	if cacheStat, err := os.Stat(cachePath); err == nil {
		if time.Since(cacheStat.ModTime()).Hours() < 1 {
			res, err := ioutil.ReadFile(cachePath)
			if err != nil {
				return nil, fmt.Errorf("could not read %s: %v", cachePath, err)
			}
			return res, nil
		}
	}

	contents := make([][]byte, 0)
	nextURL := url
	for nextURL != "" {
		// We could also use go-github here, but I can't get it to build with Bazel's rules_go and it pulls in a lot of dependencies.
		body, headers, err := ReadRemoteFile(nextURL, auth)
		if err != nil {
			return nil, fmt.Errorf("could not download %s: %v", description, err)
		}
		contents = append(contents, body)
		nextURL = getNextURL(headers)
	}

	merged, err := merger(contents)
	if err != nil {
		return nil, fmt.Errorf("failed to merge %d chunks from %s: %v", len(contents), url, err)
	}

	err = ioutil.WriteFile(cachePath, merged, 0666)
	if err != nil {
		return nil, fmt.Errorf("could not create %s: %v", cachePath, err)
	}

	return merged, nil
}