func()

in internal/frontend/unit.go [95:222]

• 97 lines of code
• 20 McCabe index (conditional complexity)

func (s *Server) serveUnitPage(ctx context.Context, w http.ResponseWriter, r *http.Request,
	ds internal.DataSource, info *urlPathInfo) (err error) {
	defer derrors.Wrap(&err, "serveUnitPage(ctx, w, r, ds, %v)", info)
	defer middleware.ElapsedStat(ctx, "serveUnitPage")()

	tab := r.FormValue("tab")
	if tab == "" {
		// Default to details tab when there is no tab param.
		tab = tabMain
	}
	// Redirect to clean URL path when tab param is invalid.
	if _, ok := unitTabLookup[tab]; !ok {
		http.Redirect(w, r, r.URL.Path, http.StatusFound)
		return nil
	}

	um, err := ds.GetUnitMeta(ctx, info.fullPath, info.modulePath, info.requestedVersion)
	if err != nil {
		if !errors.Is(err, derrors.NotFound) {
			return err
		}
		return s.servePathNotFoundPage(w, r, ds, info.fullPath, info.modulePath, info.requestedVersion)
	}

	// Use GOOS and GOARCH query parameters to create a build context, which
	// affects the documentation and synopsis. Omitting both results in an empty
	// build context, which will match the first (and preferred) build context.
	// It's also okay to provide just one (e.g. GOOS=windows), which will select
	// the first doc with that value, ignoring the other one.
	bc := internal.BuildContext{GOOS: r.FormValue("GOOS"), GOARCH: r.FormValue("GOARCH")}
	var getVulnEntries vulnEntriesFunc
	if s.vulnClient != nil {
		getVulnEntries = s.vulnClient.GetByModule
	}
	d, err := fetchDetailsForUnit(ctx, r, tab, ds, um, info.requestedVersion, bc, getVulnEntries)
	if err != nil {
		return err
	}
	if s.shouldServeJSON(r) {
		return s.serveJSONPage(w, r, d)
	}

	recordVersionTypeMetric(ctx, info.requestedVersion)
	if _, ok := internal.DefaultBranches[info.requestedVersion]; ok {
		// Since path@master is a moving target, we don't want it to be stale.
		// As a result, we enqueue every request of path@master to the frontend
		// task queue, which will initiate a fetch request depending on the
		// last time we tried to fetch this module version.
		//
		// Use a separate context here to prevent the context from being canceled
		// elsewhere before a task is enqueued.
		go func() {
			ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
			defer cancel()
			log.Infof(ctx, "serveUnitPage: Scheduling %q@%q to be fetched", um.ModulePath, info.requestedVersion)
			if _, err := s.queue.ScheduleFetch(ctx, um.ModulePath, info.requestedVersion, nil); err != nil {
				log.Errorf(ctx, "serveUnitPage(%q): scheduling fetch for %q@%q: %v",
					r.URL.Path, um.ModulePath, info.requestedVersion, err)
			}
		}()
	}

	if !isValidTabForUnit(tab, um) {
		// Redirect to clean URL path when tab param is invalid for the unit
		// type.
		http.Redirect(w, r, r.URL.Path, http.StatusFound)
		return nil
	}

	// If we've already called GetUnitMeta for an unknown module path and the latest version, pass
	// it to GetLatestInfo to avoid a redundant call.
	var latestUnitMeta *internal.UnitMeta
	if info.modulePath == internal.UnknownModulePath && info.requestedVersion == version.Latest {
		latestUnitMeta = um
	}
	latestInfo := s.GetLatestInfo(ctx, um.Path, um.ModulePath, latestUnitMeta)
	var redirectPath string
	redirectPath, err = cookie.Extract(w, r, cookie.AlternativeModuleFlash)
	if err != nil {
		// Don't fail, but don't display a banner either.
		log.Errorf(ctx, "extracting AlternativeModuleFlash cookie: %v", err)
	}
	title := pageTitle(um)
	basePage := s.newBasePage(r, title)
	tabSettings := unitTabLookup[tab]
	basePage.AllowWideContent = true
	if tabSettings.Name == "" {
		basePage.UseResponsiveLayout = true
	}
	lv := linkVersion(um.ModulePath, info.requestedVersion, um.Version)
	page := UnitPage{
		basePage:              basePage,
		Unit:                  um,
		Breadcrumb:            displayBreadcrumb(um, info.requestedVersion),
		Title:                 title,
		SelectedTab:           tabSettings,
		URLPath:               constructUnitURL(um.Path, um.ModulePath, info.requestedVersion),
		CanonicalURLPath:      canonicalURLPath(um.Path, um.ModulePath, info.requestedVersion, um.Version),
		DisplayVersion:        displayVersion(um.ModulePath, info.requestedVersion, um.Version),
		LinkVersion:           lv,
		LatestURL:             constructUnitURL(um.Path, um.ModulePath, version.Latest),
		LatestMinorClass:      latestMinorClass(lv, latestInfo),
		LatestMajorVersionURL: latestInfo.MajorUnitPath,
		PageLabels:            pageLabels(um),
		PageType:              pageType(um),
		RedirectedFromPath:    redirectPath,
	}

	// Show the banner if there was no error getting the latest major version,
	// and it is different from the major version of the current module path.
	latestMajor := internal.MajorVersionForModule(latestInfo.MajorModulePath)
	if latestMajor != "" && latestMajor != internal.MajorVersionForModule(um.ModulePath) {
		page.LatestMajorVersion = latestMajor
	}

	page.Details = d
	main, ok := d.(*MainDetails)
	if ok {
		page.MetaDescription = metaDescription(main.DocSynopsis)
	}

	// Get vulnerability information.
	if s.vulnClient != nil && experiment.IsActive(ctx, internal.ExperimentVulns) {
		page.Vulns = VulnsForPackage(um.ModulePath, um.Version, um.Path, s.vulnClient.GetByModule)
	}
	s.servePage(ctx, w, tabSettings.TemplateName, page)
	return nil
}