x/build/devapp: support title prefix filtering in HelpWanted handler

A query '/imfeelinghelpful?pkg=net,cmd/go' only redirects to random
issues with the prefix 'net' or 'cmd/go'. This allows individuals to
browse random issues for packages they have specialized in.

Fixes golang/go#20955

Change-Id: I786975fc9f6ea87269176039a3e9233a3500cf06
Reviewed-on: https://go-review.googlesource.com/95275
Reviewed-by: Andrew Bonventre <[email protected]>

Author: urld

devapp/server.go

@@ -31,7 +31,7 @@ type server struct {
 	cMu              sync.RWMutex // Used to protect the fields below.
 	corpus           *maintner.Corpus
 	repo             *maintner.GitHubRepo
-	helpWantedIssues []int32
+	helpWantedIssues []issueData
 	data             pageData
 
 	// GopherCon-specific fields. Must still hold cMu when reading/writing these.
@@ -40,6 +40,11 @@ type server struct {
 	totalPoints int
 }
 
+type issueData struct {
+	id          int32
+	titlePrefix string
+}
+
 type pageData struct {
 	release releaseData
 	reviews reviewsData
@@ -129,17 +134,18 @@ func (s *server) updateHelpWantedIssues() {
 	s.cMu.Lock()
 	defer s.cMu.Unlock()
 
-	var ids []int32
+	var issues []issueData
 	s.repo.ForeachIssue(func(i *maintner.GitHubIssue) error {
 		if i.Closed {
 			return nil
 		}
 		if i.HasLabelID(labelHelpWantedID) {
-			ids = append(ids, i.Number)
+			prefix := strings.SplitN(i.Title, ":", 2)[0]
+			issues = append(issues, issueData{id: i.Number, titlePrefix: prefix})
 		}
 		return nil
 	})
-	s.helpWantedIssues = ids
+	s.helpWantedIssues = issues
 }
 
 func (s *server) handleRandomHelpWantedIssue(w http.ResponseWriter, r *http.Request) {
@@ -149,10 +155,34 @@ func (s *server) handleRandomHelpWantedIssue(w http.ResponseWriter, r *http.Requ
 		http.Redirect(w, r, issuesURLBase, http.StatusSeeOther)
 		return
 	}
-	rid := s.helpWantedIssues[rand.Intn(len(s.helpWantedIssues))]
+	pkgs := r.URL.Query().Get("pkg")
+	var rid int32
+	if pkgs == "" {
+		rid = s.helpWantedIssues[rand.Intn(len(s.helpWantedIssues))].id
+	} else {
+		filtered := s.filteredHelpWantedIssues(strings.Split(pkgs, ",")...)
+		if len(filtered) == 0 {
+			http.Redirect(w, r, issuesURLBase, http.StatusSeeOther)
+			return
+		}
+		rid = filtered[rand.Intn(len(filtered))].id
+	}
 	http.Redirect(w, r, issuesURLBase+strconv.Itoa(int(rid)), http.StatusSeeOther)
 }
 
+func (s *server) filteredHelpWantedIssues(pkgs ...string) []issueData {
+	var issues []issueData
+	for _, i := range s.helpWantedIssues {
+		for _, p := range pkgs {
+			if strings.HasPrefix(i.titlePrefix, p) {
+				issues = append(issues, i)
+				break
+			}
+		}
+	}
+	return issues
+}
+
 func (s *server) handleFavicon(w http.ResponseWriter, r *http.Request) {
 	// Need to specify content type for consistent tests, without this it's
 	// determined from mime.types on the box the test is running on

devapp/server_test.go

@@ -59,7 +59,34 @@ func TestRandomHelpWantedIssue(t *testing.T) {
 	}
 
 	testServer.cMu.Lock()
-	testServer.helpWantedIssues = []int32{42}
+	testServer.helpWantedIssues = []issueData{{id: 42}}
+	testServer.cMu.Unlock()
+	w = httptest.NewRecorder()
+	testServer.ServeHTTP(w, req)
+	if w.Code != http.StatusSeeOther {
+		t.Errorf("w.Code = %d; want %d", w.Code, http.StatusSeeOther)
+	}
+	if g, w := w.Header().Get("Location"), issuesURLBase+"42"; g != w {
+		t.Errorf("Location header = %q; want %q", g, w)
+	}
+}
+
+func TestRandomFilteredHelpWantedIssue(t *testing.T) {
+	req := httptest.NewRequest("GET", "/imfeelinglucky?pkg=foo", nil)
+	w := httptest.NewRecorder()
+	testServer.ServeHTTP(w, req)
+	if w.Code != http.StatusSeeOther {
+		t.Errorf("w.Code = %d; want %d", w.Code, http.StatusSeeOther)
+	}
+	if g, w := w.Header().Get("Location"), issuesURLBase; g != w {
+		t.Errorf("Location header = %q; want %q", g, w)
+	}
+
+	testServer.cMu.Lock()
+	testServer.helpWantedIssues = []issueData{
+		{id: 41, titlePrefix: "not/foo: bar"},
+		{id: 42, titlePrefix: "foo/bar: baz"},
+	}
 	testServer.cMu.Unlock()
 	w = httptest.NewRecorder()
 	testServer.ServeHTTP(w, req)