refactor: migration Negroni from codegangsta to urfave

vendor/github.com/urfave/negroni/static.go

@@ -0,0 +1,88 @@
+package negroni
+
+import (
+	"net/http"
+	"path"
+	"strings"
+)
+
+// Static is a middleware handler that serves static files in the given
+// directory/filesystem. If the file does not exist on the filesystem, it
+// passes along to the next middleware in the chain. If you desire "fileserver"
+// type behavior where it returns a 404 for unfound files, you should consider
+// using http.FileServer from the Go stdlib.
+type Static struct {
+	// Dir is the directory to serve static files from
+	Dir http.FileSystem
+	// Prefix is the optional prefix used to serve the static directory content
+	Prefix string
+	// IndexFile defines which file to serve as index if it exists.
+	IndexFile string
+}
+
+// NewStatic returns a new instance of Static
+func NewStatic(directory http.FileSystem) *Static {
+	return &Static{
+		Dir:       directory,
+		Prefix:    "",
+		IndexFile: "index.html",
+	}
+}
+
+func (s *Static) ServeHTTP(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
+	if r.Method != "GET" && r.Method != "HEAD" {
+		next(rw, r)
+		return
+	}
+	file := r.URL.Path
+	// if we have a prefix, filter requests by stripping the prefix
+	if s.Prefix != "" {
+		if !strings.HasPrefix(file, s.Prefix) {
+			next(rw, r)
+			return
+		}
+		file = file[len(s.Prefix):]
+		if file != "" && file[0] != '/' {
+			next(rw, r)
+			return
+		}
+	}
+	f, err := s.Dir.Open(file)
+	if err != nil {
+		// discard the error?
+		next(rw, r)
+		return
+	}
+	defer f.Close()
+
+	fi, err := f.Stat()
+	if err != nil {
+		next(rw, r)
+		return
+	}
+
+	// try to serve index file
+	if fi.IsDir() {
+		// redirect if missing trailing slash
+		if !strings.HasSuffix(r.URL.Path, "/") {
+			http.Redirect(rw, r, r.URL.Path+"/", http.StatusFound)
+			return
+		}
+
+		file = path.Join(file, s.IndexFile)
+		f, err = s.Dir.Open(file)
+		if err != nil {
+			next(rw, r)
+			return
+		}
+		defer f.Close()
+
+		fi, err = f.Stat()
+		if err != nil || fi.IsDir() {
+			next(rw, r)
+			return
+		}
+	}
+
+	http.ServeContent(rw, r, file, fi.ModTime(), f)
+}