Separate index and GitHub OAuth callback handlers.

Also switch to gorilla/mux for the router and fix some variable names to be
mixedCase.

app/githop.go

@@ -1,61 +1,80 @@
 package githop
 
 import (
+	"encoding/base64"
 	"encoding/json"
 	"html/template"
 	"io/ioutil"
+	"log"
 	"net/http"
+	"net/url"
 
 	"appengine"
 	"appengine/urlfetch"
 
 	"code.google.com/p/goauth2/oauth"
 	"github.com/google/go-github/github"
+	"github.com/gorilla/mux"
 )
 
+var router *mux.Router
+var githubOauthConfig oauth.Config
+
+func initGithubOAuthConfig() {
+	path := "config/github-oauth"
+	if appengine.IsDevAppServer() {
+		path += "-dev"
+	}
+	path += ".json"
+	configBytes, err := ioutil.ReadFile(path)
+	if err != nil {
+		log.Panicf("Could not read GitHut OAuth config from %s: %s", path, err.Error())
+	}
+	err = json.Unmarshal(configBytes, &githubOauthConfig)
+	if err != nil {
+		log.Panicf("Could not parse GitHut OAuth %s", err.Error())
+	}
+	githubOauthConfig.Scope = "repo"
+	githubOauthConfig.AuthURL = "https://github.com/login/oauth/authorize"
+	githubOauthConfig.TokenURL = "https://github.com/login/oauth/access_token"
+}
+
 func init() {
-	http.HandleFunc("/", index)
+	initGithubOAuthConfig()
+
+	router = mux.NewRouter()
+	router.HandleFunc("/", indexHandler).Name("index")
+	router.HandleFunc("/github/callback", githubOAuthCallbackHandler)
+	http.Handle("/", router)
 }
 
 var indexTemplate = template.Must(template.ParseFiles("templates/index.html"))
 
-func index(w http.ResponseWriter, r *http.Request) {
-	// TODO: Don't do this every request
-	github_oauth_config_path := "config/github-oauth"
-	if appengine.IsDevAppServer() {
-		github_oauth_config_path += "-dev"
+func indexHandler(w http.ResponseWriter, r *http.Request) {
+	tokenEncoded := r.FormValue("token")
+	if tokenEncoded == "" {
+		http.Redirect(w, r, githubOauthConfig.AuthCodeURL(""), http.StatusFound)
+		return
 	}
-	github_oauth_config_path += ".json"
-	github_oauth_config_bytes, err := ioutil.ReadFile(github_oauth_config_path)
+	tokenBytes, err := base64.URLEncoding.DecodeString(tokenEncoded)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	var github_oauth_config oauth.Config
-	err = json.Unmarshal(github_oauth_config_bytes, &github_oauth_config)
+	var token oauth.Token
+	err = json.Unmarshal(tokenBytes, &token)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	github_oauth_config.Scope = "repo"
-	github_oauth_config.AuthURL = "https://github.com/login/oauth/authorize"
-	github_oauth_config.TokenURL = "https://github.com/login/oauth/access_token"
-
-	code := r.FormValue("code")
-	if code == "" {
-		http.Redirect(w, r, github_oauth_config.AuthCodeURL(""), http.StatusFound)
-		return
+	appengineContext := appengine.NewContext(r)
+	oauthTransport := &oauth.Transport{
+		Config:    &githubOauthConfig,
+		Transport: &urlfetch.Transport{Context: appengineContext},
+		Token:     &token,
 	}
-	appengine_context := appengine.NewContext(r)
-	oauth_transport := &oauth.Transport{
-		Config:    &github_oauth_config,
-		Transport: &urlfetch.Transport{Context: appengine_context},
-	}
-	token, _ := oauth_transport.Exchange(code)
-	oauth_transport.Token = token
-
-	github_client := github.NewClient(oauth_transport.Client())
-	events, _, err := github_client.Activity.ListEventsPerformedByUser("mihaip", false, nil)
+	githubClient := github.NewClient(oauthTransport.Client())
+	events, _, err := githubClient.Activity.ListEventsPerformedByUser("mihaip", false, nil)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -64,3 +83,28 @@ func index(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 	}
 }
+
+func githubOAuthCallbackHandler(w http.ResponseWriter, r *http.Request) {
+	code := r.FormValue("code")
+	appengineContext := appengine.NewContext(r)
+	oauthTransport := &oauth.Transport{
+		Config:    &githubOauthConfig,
+		Transport: &urlfetch.Transport{Context: appengineContext},
+	}
+	token, err := oauthTransport.Exchange(code)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	tokenBytes, err := json.Marshal(token)
+	tokenEncoded := base64.StdEncoding.EncodeToString(tokenBytes)
+	redirectUrl, err := router.GetRoute("index").URL()
+	redirectParams := url.Values{}
+	redirectParams.Add("token", tokenEncoded)
+	redirectUrl.RawQuery = redirectParams.Encode()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	http.Redirect(w, r, redirectUrl.String(), http.StatusFound)
+}