Make the speculator serve the spec from drafts branches.

scripts/speculator/main.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"os/exec"
 	"path"
+	"regexp"
 	"strconv"
 	"strings"
 	"sync"
@@ -71,6 +72,8 @@ const (
 	permissionsOwnerFull = 0700
 )
 
+var numericRegex = regexp.MustCompile(`^\d+$`)
+
 func gitClone(url string, shared bool) (string, error) {
 	directory := path.Join("/tmp/matrix-doc", strconv.FormatInt(rand.Int63(), 10))
 	if err := os.MkdirAll(directory, permissionsOwnerFull); err != nil {
@@ -101,17 +104,16 @@ func runGitCommand(path string, args []string) error {
 	return nil
 }
 
-func lookupPullRequest(url url.URL, pathPrefix string) (*PullRequest, error) {
-	if !strings.HasPrefix(url.Path, pathPrefix+"/") {
-		return nil, fmt.Errorf("invalid path passed: %s expect %s/123", url.Path, pathPrefix)
-	}
-	prNumber := strings.Split(url.Path[len(pathPrefix)+1:], "/")[0]
-
+func lookupPullRequest(prNumber string) (*PullRequest, error) {
 	resp, err := http.Get(fmt.Sprintf("%s/%s", pullsPrefix, prNumber))
 	defer resp.Body.Close()
 	if err != nil {
 		return nil, fmt.Errorf("error getting pulls: %v", err)
 	}
+	if resp.StatusCode != 200 {
+		body, _ := ioutil.ReadAll(resp.Body)
+		return nil, fmt.Errorf("error getting pull request %s: %v", prNumber, string(body))
+	}
 	dec := json.NewDecoder(resp.Body)
 	var pr PullRequest
 	if err := dec.Decode(&pr); err != nil {
@@ -120,6 +122,26 @@ func lookupPullRequest(url url.URL, pathPrefix string) (*PullRequest, error) {
 	return &pr, nil
 }
 
+func (s *server) lookupBranch(branch string) (string, error) {
+	err := s.updateBase()
+	if err != nil {
+		log.Printf("Error fetching: %v, will use cached branches")
+	}
+
+	if strings.ToLower(branch) == "head" {
+		branch = "master"
+	}
+	branch = "origin/" + branch
+	sha, err := s.getSHAOf(branch)
+	if err != nil {
+		return "", fmt.Errorf("error getting branch %s: %v", branch, err)
+	}
+	if sha == "" {
+		return "", fmt.Errorf("Unable to get sha for %s", branch)
+	}
+	return sha, nil
+}
+
 func generate(dir string) error {
 	cmd := exec.Command("python", "gendoc.py", "--nodelete")
 	cmd.Dir = path.Join(dir, "scripts")
@@ -193,6 +215,15 @@ func (s *server) getSHAOf(ref string) (string, error) {
 	return strings.TrimSpace(b.String()), nil
 }
 
+// extractPRNumber checks that the path begins with the given base, and returns
+// the following component.
+func extractPRNumber(path, base string) (string, error) {
+	if !strings.HasPrefix(path, base+"/") {
+		return "", fmt.Errorf("invalid path passed: %q expect %s/123", path, base)
+	}
+	return strings.Split(path[len(base)+1:], "/")[0], nil
+}
+
 // extractPath extracts the file path within the gen directory which should be served for the request.
 // Returns one of (file to serve, path to redirect to).
 // path is the actual path being requested, e.g. "/spec/head/client_server.html".
@@ -230,17 +261,45 @@ func (s *server) serveSpec(w http.ResponseWriter, req *http.Request) {
 		return
 	}
 
-	if strings.HasPrefix(strings.ToLower(req.URL.Path), "/spec/head") {
-		// err may be non-nil here but if headSha is non-empty we will serve a possibly-stale result in favour of erroring.
-		// This is to deal with cases like where github is down but we still want to serve the spec.
-		if headSha, err := s.lookupHeadSHA(); headSha == "" {
-			writeError(w, 500, err)
-			return
+	// we use URL.EscapedPath() to get hold of the %-encoded version of the
+	// path, so that we can handle branch names with slashes in.
+	urlPath := req.URL.EscapedPath()
+
+	if urlPath == "/spec" {
+		// special treatment for /spec - redirect to /spec/HEAD/
+		s.redirectTo(w, req, "/spec/HEAD/")
+		return
+	}
+
+	if !strings.HasPrefix(urlPath, "/spec/") {
+		writeError(w, 500, fmt.Errorf("invalid path passed: %q expect /spec/...", urlPath))
+	}
+
+	splits := strings.SplitN(urlPath[6:], "/", 2)
+
+	if len(splits) == 1 {
+		// "/spec/foo" - redirect to "/spec/foo/" (so that relative links from the index work)
+		if splits[0] == "" {
+			s.redirectTo(w, req, "/spec/HEAD/")
 		} else {
-			sha = headSha
+			s.redirectTo(w, req, urlPath+"/")
 		}
-	} else {
-		pr, err := lookupPullRequest(*req.URL, "/spec")
+		return
+	}
+
+	// now we have:
+	//   splits[0] is a PR#, or a branch name
+	//   splits[1] is the file to serve
+
+	branchName, _ := url.QueryUnescape(splits[0])
+	requestedPath, _ := url.QueryUnescape(splits[1])
+	if requestedPath == "" {
+		requestedPath = "index.html"
+	}
+
+	if numericRegex.MatchString(branchName) {
+		// PR number
+		pr, err := lookupPullRequest(branchName)
 		if err != nil {
 			writeError(w, 400, err)
 			return
@@ -253,6 +312,20 @@ func (s *server) serveSpec(w http.ResponseWriter, req *http.Request) {
 			return
 		}
 		sha = pr.Head.SHA
+		log.Printf("Serving pr %s (%s)\n", branchName, sha)
+	} else if strings.ToLower(branchName) == "head" ||
+		branchName == "master" ||
+		strings.HasPrefix(branchName, "drafts/") {
+		branchSHA, err := s.lookupBranch(branchName)
+		if err != nil {
+			writeError(w, 400, err)
+			return
+		}
+		sha = branchSHA
+		log.Printf("Serving branch %s (%s)\n", branchName, sha)
+	} else {
+		writeError(w, 404, fmt.Errorf("invalid branch name"))
+		return
 	}
 
 	var cache = specCache
@@ -299,11 +372,6 @@ func (s *server) serveSpec(w http.ResponseWriter, req *http.Request) {
 		cache.Add(sha, pathToContent)
 	}
 
-	requestedPath, redirect := extractPath(req.URL.Path, "/spec/")
-	if redirect != "" {
-		s.redirectTo(w, req, redirect)
-		return
-	}
 	if b, ok := pathToContent[requestedPath]; ok {
 		w.Write(b)
 		return
@@ -319,31 +387,11 @@ func (s *server) serveSpec(w http.ResponseWriter, req *http.Request) {
 	w.Write([]byte("Not found"))
 }
 
-func (s *server) redirectTo(w http.ResponseWriter, req *http.Request, path string) {
-	req.URL.Path = path
-	w.Header().Set("Location", req.URL.String())
+func (s *server) redirectTo(w http.ResponseWriter, _ *http.Request, path string) {
+	w.Header().Set("Location", path)
 	w.WriteHeader(302)
 }
 
-// lookupHeadSHA looks up what origin/master's HEAD SHA is.
-// It attempts to `git fetch` before doing so.
-// If this fails, it may still return a stale sha, but will also return an error.
-func (s *server) lookupHeadSHA() (sha string, retErr error) {
-	retErr = s.updateBase()
-	if retErr != nil {
-		log.Printf("Error fetching: %v, attempting to fall back to current known value", retErr)
-	}
-	originHead, err := s.getSHAOf("origin/master")
-	if err != nil {
-		retErr = err
-	}
-	sha = originHead
-	if retErr != nil && originHead != "" {
-		log.Printf("Successfully fell back to possibly stale sha: %s", sha)
-	}
-	return
-}
-
 func checkAuth(pr *PullRequest) error {
 	if !pr.User.IsTrusted() {
 		return fmt.Errorf("%q is not a trusted pull requester", pr.User.Login)
@@ -352,7 +400,12 @@ func checkAuth(pr *PullRequest) error {
 }
 
 func (s *server) serveRSTDiff(w http.ResponseWriter, req *http.Request) {
-	pr, err := lookupPullRequest(*req.URL, "/diff/rst")
+	prNumber, err := extractPRNumber(req.URL.Path, "/diff/rst")
+	if err != nil {
+		writeError(w, 400, err)
+		return
+	}
+	pr, err := lookupPullRequest(prNumber)
 	if err != nil {
 		writeError(w, 400, err)
 		return
@@ -390,7 +443,12 @@ func (s *server) serveRSTDiff(w http.ResponseWriter, req *http.Request) {
 }
 
 func (s *server) serveHTMLDiff(w http.ResponseWriter, req *http.Request) {
-	pr, err := lookupPullRequest(*req.URL, "/diff/html")
+	prNumber, err := extractPRNumber(req.URL.Path, "/diff/html")
+	if err != nil {
+		writeError(w, 400, err)
+		return
+	}
+	pr, err := lookupPullRequest(prNumber)
 	if err != nil {
 		writeError(w, 400, err)
 		return
@@ -450,21 +508,54 @@ func findHTMLDiffer() (string, error) {
 	return "", fmt.Errorf("unable to find htmldiff.pl")
 }
 
-func listPulls(w http.ResponseWriter, req *http.Request) {
+func getPulls() ([]PullRequest, error) {
 	resp, err := http.Get(pullsPrefix)
 	if err != nil {
-		writeError(w, 500, err)
-		return
+		return nil, err
 	}
 	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		body, _ := ioutil.ReadAll(resp.Body)
+		return nil, fmt.Errorf("error getting pull requests: %v", string(body))
+	}
 	dec := json.NewDecoder(resp.Body)
 	var pulls []PullRequest
-	if err := dec.Decode(&pulls); err != nil {
-		writeError(w, 500, err)
-		return
+	err = dec.Decode(&pulls)
+	return pulls, err
+}
+
+// getBranches returns a list of the upstream branch names.
+// It attempts to `git fetch` before doing so.
+func (s *server) getBranches() ([]string, error) {
+	err := s.updateBase()
+	if err != nil {
+		log.Printf("Error fetching: %v, will use cached branches")
 	}
-	if len(pulls) == 0 {
-		io.WriteString(w, "No pull requests found")
+
+	cmd := exec.Command("git", "branch", "-r")
+	cmd.Dir = path.Join(s.matrixDocCloneURL)
+	var b bytes.Buffer
+	cmd.Stdout = &b
+	s.mu.Lock()
+	err = cmd.Run()
+	s.mu.Unlock()
+	if err != nil {
+		return nil, fmt.Errorf("Error reading branch names: %v. Output from git:\n%v", err, b.String())
+	}
+	branches := []string{}
+	for _, b := range strings.Split(b.String(), "\n") {
+		b = strings.TrimSpace(b)
+		if strings.HasPrefix(b, "origin/") {
+			branches = append(branches, b[7:])
+		}
+	}
+	return branches, nil
+}
+
+func (srv *server) makeIndex(w http.ResponseWriter, req *http.Request) {
+	pulls, err := getPulls()
+	if err != nil {
+		writeError(w, 500, err)
 		return
 	}
 	s := "<body><ul>"
@@ -472,10 +563,31 @@ func listPulls(w http.ResponseWriter, req *http.Request) {
 		s += fmt.Sprintf(`<li>%d: <a href="%s">%s</a>: <a href="%s">%s</a>: <a href="spec/%d/">spec</a> <a href="diff/html/%d/">spec diff</a> <a href="diff/rst/%d/">rst diff</a></li>`,
 			pull.Number, pull.User.HTMLURL, pull.User.Login, pull.HTMLURL, pull.Title, pull.Number, pull.Number, pull.Number)
 	}
-	s += `</ul><div><a href="spec/head/">View the spec at head</a></div></body>`
-	if *includesDir != "" {
-		s += `</ul><div><a href="spec/head/?matrixdotorgstyle=1">View the spec at head styled like matrix.org</a></div></body>`
+	s += "</ul>"
+
+	branches, err := srv.getBranches()
+	if err != nil {
+		writeError(w, 500, err)
+		return
+	}
+
+	s += `<div>View the spec at:<ul>`
+	branchNames := []string{}
+	for _, branch := range branches {
+		if strings.HasPrefix(branch, "drafts/") {
+			branchNames = append(branchNames, branch)
+		}
+	}
+	branchNames = append(branchNames, "HEAD")
+	for _, branch := range branchNames {
+		href := "spec/"+url.QueryEscape(branch)+"/"
+		s += fmt.Sprintf(`<li><a href="%s">%s</a></li>`, href, branch)
+		if *includesDir != "" {
+			s += fmt.Sprintf(`<li><a href="%s?matrixdotorgstyle=1">%s, styled like matrix.org</a></li>`,
+				href, branch)
+		}
 	}
+	s += "</ul></div></body>"
 
 	io.WriteString(w, s)
 }
@@ -521,7 +633,7 @@ func main() {
 	http.HandleFunc("/diff/rst/", s.serveRSTDiff)
 	http.HandleFunc("/diff/html/", forceHTML(s.serveHTMLDiff))
 	http.HandleFunc("/healthz", serveText("ok"))
-	http.HandleFunc("/", forceHTML(listPulls))
+	http.HandleFunc("/", forceHTML(s.makeIndex))
 
 	fmt.Printf("Listening on port %d\n", *port)
 	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", *port), nil))