refactor(packageHandler): Don't retain configuration (#85)

This patch removes the need to retain the configuration in the
packageHandler struct.
Instead, it retains only the fields that are required for the
handler to function.

This also allows us to pre-compute the canonical import path
rather than calculating it on the request path.

1 files changed, 40 insertions, 20 deletions

diff --git a/handler.go b/handler.go
index 08c3e4b..5144caf 100644
--- a/handler.go
+++ b/handler.go
@@ -22,15 +22,11 @@ func CreateHandler(config *Config) http.Handler {
 
 	mux.Handle("/", &indexHandler{config: config})
 	for name, pkg := range config.Packages {
-		handle := packageHandler{
-			pkgName: name,
-			pkg:     pkg,
-			config:  config,
-		}
+		handler := newPackageHandler(config, name, pkg)
 		// Double-register so that "/foo"
 		// does not redirect to "/foo/" with a 300.
-		mux.Handle("/"+name, &handle)
-		mux.Handle("/"+name+"/", &handle)
+		mux.Handle("/"+name, handler)
+		mux.Handle("/"+name+"/", handler)
 	}
 
 	return mux
@@ -54,9 +50,38 @@ func (h *indexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 type packageHandler struct {
-	pkg     PackageConfig
-	pkgName string
-	config  *Config
+	// Hostname of the godoc server, e.g. "godoc.org".
+	godocHost string
+
+	// Name of the package relative to the vanity base URL.
+	// For example, "zap" for "go.uber.org/zap".
+	name string
+
+	// Path at which the Git repository is hosted.
+	// For example, "github.com/uber-go/zap".
+	gitURL string
+
+	// Default branch of the Git repository.
+	defaultBranch string
+
+	// Canonical import path for the package.
+	canonicalURL string
+}
+
+func newPackageHandler(cfg *Config, name string, pkg PackageConfig) *packageHandler {
+	baseURL := cfg.URL
+	if pkg.URL != "" {
+		baseURL = pkg.URL
+	}
+	canonicalURL := fmt.Sprintf("%s/%s", baseURL, name)
+
+	return &packageHandler{
+		godocHost:     cfg.Godoc.Host,
+		name:          name,
+		canonicalURL:  canonicalURL,
+		gitURL:        pkg.Repo,
+		defaultBranch: pkg.Branch,
+	}
 }
 
 func (h *packageHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -68,23 +93,18 @@ func (h *packageHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Extract the relative path to subpackages, if any.
 	//	"/foo/bar" => "/bar"
 	//	"/foo" => ""
-	relPath := strings.TrimPrefix(r.URL.Path, "/"+h.pkgName)
+	relPath := strings.TrimPrefix(r.URL.Path, "/"+h.name)
 
-	baseURL := h.config.URL
-	if h.pkg.URL != "" {
-		baseURL = h.pkg.URL
-	}
-	canonicalURL := fmt.Sprintf("%s/%s", baseURL, h.pkgName)
 	data := struct {
 		Repo         string
 		Branch       string
 		CanonicalURL string
 		GodocURL     string
 	}{
-		Repo:         h.pkg.Repo,
-		Branch:       h.pkg.Branch,
-		CanonicalURL: canonicalURL,
-		GodocURL:     fmt.Sprintf("https://%s/%s%s", h.config.Godoc.Host, canonicalURL, relPath),
+		Repo:         h.gitURL,
+		Branch:       h.defaultBranch,
+		CanonicalURL: h.canonicalURL,
+		GodocURL:     fmt.Sprintf("https://%s/%s%s", h.godocHost, h.canonicalURL, relPath),
 	}
 	if err := packageTemplate.Execute(w, data); err != nil {
 		http.Error(w, err.Error(), 500)