Allow using subpath as a variable in repo

Author: AlmogBaku

README.md

@@ -120,5 +120,10 @@ paths:
       <td>required if ambiguous</td>
       <td>If the version control system cannot be inferred (e.g. for Bitbucket or a custom domain), then this specifies the version control system as it would appear in <a href="https://golang.org/cmd/go/#hdr-Remote_import_paths"><code>go-import</code> meta tag</a>.  This can be one of <code>git</code>, <code>hg</code>, <code>svn</code>, or <code>bzr</code>.</td>
     </tr>
+    <tr>
+      <th scope="row"><code>wildcard</code></th>
+      <td>optional</td>
+      <td>Boolean. If <code>true</code>, it allows you to use the <code>*</code> placeholder, for the first sub-path inside your <code>repo</code> or <code>display</code></code></td>
+    </tr>
   </tbody>
 </table>

handler.go

@@ -24,6 +24,7 @@ import (
 	"strings"
 
 	"gopkg.in/yaml.v2"
+	"regexp"
 )
 
 type handler struct {
@@ -33,6 +34,7 @@ type handler struct {
 }
 
 type pathConfig struct {
+	wildcard bool
 	path    string
 	repo    string
 	display string
@@ -45,6 +47,7 @@ func newHandler(config []byte) (*handler, error) {
 		CacheAge *int64 `yaml:"cache_max_age,omitempty"`
 		Paths    map[string]struct {
 			Repo    string `yaml:"repo,omitempty"`
+			Wildcard    bool `yaml:"wildcard,omitempty"`
 			Display string `yaml:"display,omitempty"`
 			VCS     string `yaml:"vcs,omitempty"`
 		} `yaml:"paths,omitempty"`
@@ -67,6 +70,7 @@ func newHandler(config []byte) (*handler, error) {
 			repo:    e.Repo,
 			display: e.Display,
 			vcs:     e.VCS,
+			wildcard: e.Wildcard,
 		}
 		switch {
 		case e.Display != "":
@@ -95,7 +99,7 @@ func newHandler(config []byte) (*handler, error) {
 
 func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	current := r.URL.Path
-	pc, subpath := h.paths.find(current)
+	pc, subpath, wildcard := h.paths.find(current)
 	if pc == nil && current == "/" {
 		h.serveIndex(w, r)
 		return
@@ -105,6 +109,11 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	importPath := h.Host(r) + pc.path
+	if wildcard != "" {
+		importPath += "/" + wildcard
+	}
+
 	w.Header().Set("Cache-Control", h.cacheControl)
 	if err := vanityTmpl.Execute(w, struct {
 		Import  string
@@ -113,10 +122,10 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		Display string
 		VCS     string
 	}{
-		Import:  h.Host(r) + pc.path,
+		Import:  importPath,
 		Subpath: subpath,
-		Repo:    pc.repo,
-		Display: pc.display,
+		Repo:    strings.Replace(pc.repo, "*", wildcard, -1),
+		Display: strings.Replace(pc.display, "*", wildcard, -1),
 		VCS:     pc.vcs,
 	}); err != nil {
 		http.Error(w, "cannot render the page", http.StatusInternalServerError)
@@ -184,17 +193,14 @@ func (pset pathConfigSet) Swap(i, j int) {
 	pset[i], pset[j] = pset[j], pset[i]
 }
 
-func (pset pathConfigSet) find(path string) (pc *pathConfig, subpath string) {
+func (pset pathConfigSet) find(path string) (pc *pathConfig, subpath string, wildcard string) {
 	// Fast path with binary search to retrieve exact matches
 	// e.g. given pset ["/", "/abc", "/xyz"], path "/def" won't match.
 	i := sort.Search(len(pset), func(i int) bool {
 		return pset[i].path >= path
 	})
 	if i < len(pset) && pset[i].path == path {
-		return &pset[i], ""
-	}
-	if i > 0 && strings.HasPrefix(path, pset[i-1].path+"/") {
-		return &pset[i-1], path[len(pset[i-1].path)+1:]
+		return &pset[i], "", ""
 	}
 
 	// Slow path, now looking for the longest prefix/shortest subpath i.e.
@@ -214,12 +220,30 @@ func (pset pathConfigSet) find(path string) (pc *pathConfig, subpath string) {
 			// route with equal or greater length is NOT a match.
 			continue
 		}
+
+		if ps.wildcard {
+			p := ps.path
+			if !strings.HasSuffix(p, "/") {
+				p += "/"
+			}
+			regex := "^" + strings.Replace(p, "/", "\\/", -1) + "(.+)=?"
+			r := regexp.MustCompile(regex)
+			finds := r.FindStringSubmatch(path)
+			if finds != nil {
+				parts := strings.SplitN(finds[1], "/", 2)
+				if len(parts) > 1 {
+					return &pset[i], parts[1], parts[0]
+				}
+				return &pset[i], "", parts[0]
+			}
+		}
+
 		sSubpath := strings.TrimPrefix(path, ps.path)
 		if len(sSubpath) < lenShortestSubpath {
 			subpath = sSubpath
 			lenShortestSubpath = len(sSubpath)
 			bestMatchConfig = &pset[i]
 		}
 	}
-	return bestMatchConfig, subpath
+	return bestMatchConfig, subpath, ""
 }

vanity.yaml

@@ -6,3 +6,7 @@ paths:
 
   /launchpad:
     repo: https://github.com/rakyll/launchpad
+
+  /opencensus/:
+    wildcard: true
+    repo: https://github.com/rakyll/opencensus-{subpath}