From 28c989a603c891aac71762a05aaddc57d449d304 Mon Sep 17 00:00:00 2001
From: Jordan Orelli <jorelli@etsy.com>
Date: Sun, 23 Jun 2013 15:50:11 -0400
Subject: [PATCH] errors now appear in red in the browser

---
 http.go             | 43 +++++++++++++++++++++++++++++++++++++------
 static/css/home.css |  4 ++++
 static/js/skeam.js  | 26 ++++++++++++++++++++------
 templates/home.html |  8 +++++++-
 4 files changed, 68 insertions(+), 13 deletions(-)

diff --git a/http.go b/http.go
index 0dd4314..b5034fb 100644
--- a/http.go
+++ b/http.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"code.google.com/p/go.net/websocket"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"github.com/jordanorelli/skeam/am"
@@ -40,29 +41,59 @@ func getTemplate(relpath string) (*template.Template, error) {
 	return t, err
 }
 
-type templateHandler string
+type templateHandler struct {
+	path    string
+	context interface{}
+}
 
-func (t templateHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	tpl, err := getTemplate(string(t))
+func (t *templateHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	tpl, err := getTemplate(t.path)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	if err := tpl.Execute(w, nil); err != nil {
+	if err := tpl.Execute(w, t.context); err != nil {
 		fmt.Println(err.Error())
 	}
 }
 
+type wsMessage struct {
+	IsError bool   `json:"is_error"`
+	Message string `json:"message"`
+}
+
+type wsWriter struct {
+	conn *websocket.Conn
+}
+
+func (w wsWriter) Write(b []byte) (int, error) {
+	out, err := json.Marshal(wsMessage{false, string(b)})
+	if err != nil {
+		return 0, err
+	}
+	return w.conn.Write(out)
+}
+
+type wsErrorWriter wsWriter
+
+func (w wsErrorWriter) Write(b []byte) (int, error) {
+	out, err := json.Marshal(wsMessage{true, string(b)})
+	if err != nil {
+		return 0, err
+	}
+	return w.conn.Write(out)
+}
+
 func wsHandler(ws *websocket.Conn) {
 	manager.Add(ws)
 	defer manager.Remove(ws)
 
-	i := newInterpreter(ws, ws, ws)
+	i := newInterpreter(ws, wsWriter{ws}, wsErrorWriter{ws})
 	i.run(universe)
 }
 
 func runHTTPServer() {
-	http.Handle("/", templateHandler("home.html"))
+	http.Handle("/", &templateHandler{"home.html", map[string]interface{}{"ws_path": template.JS("/ws")}})
 	http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir(assets.AbsPath("static")))))
 	http.Handle("/ws", websocket.Handler(wsHandler))
 	http.ListenAndServe(*httpAddr, nil)
diff --git a/static/css/home.css b/static/css/home.css
index c88cec8..e8d3ecd 100644
--- a/static/css/home.css
+++ b/static/css/home.css
@@ -31,3 +31,7 @@ body {
 .message {
 
 }
+
+.error {
+  color: red;
+}
diff --git a/static/js/skeam.js b/static/js/skeam.js
index 39ad42d..bde3f89 100644
--- a/static/js/skeam.js
+++ b/static/js/skeam.js
@@ -39,9 +39,15 @@ InputHandler.prototype.clear = function() {
 // connection handling
 // -----------------------------------------------------------------------------
 
+var buildWsPath = function(wsPath) {
+  if (window.location.port) {
+    return "ws://" + window.location.hostname + ":" + window.location.port + wsPath;
+  }
+  return "ws://" + window.location.hostname + wsPath;
+}
+
 var ConnectionHandler = function(wsPath) {
-  this.path = wsPath;
-  this.c = new WebSocket(wsPath);
+  this.c = new WebSocket(buildWsPath(wsPath));
   this.c.onopen = _.bind(this.onopen, this);
   this.c.onclose = _.bind(this.onclose, this);
   this.c.onerror = _.bind(this.onerror, this);
@@ -79,19 +85,27 @@ ConnectionHandler.prototype.sendMsg = function(message) {
 // response rendering
 // -----------------------------------------------------------------------------
 
-var MessageDisplay = function(selector, templateSelector) {
+var MessageDisplay = function(selector, templateSelector, errorTemplateSelector) {
   this.elem = $(selector);
   this.renderMessage = _.template($(templateSelector).html());
+  this.renderError = _.template($(errorTemplateSelector).html());
 }
 
-MessageDisplay.prototype.addMessage = function(message) {
-  var rendered = this.renderMessage({message: message});
+MessageDisplay.prototype.addMessage = function(rawmessage) {
+  var message = JSON.parse(rawmessage);
+  if (message.is_error) {
+    var rendered = this.renderError(message);
+  } else {
+    var rendered = this.renderMessage(message);
+  }
   this.elem.append(rendered);
 };
 
 var Skeam = function(config) {
   this.inputHandler = new InputHandler(config.inputSelector);
-  this.messageDisplay = new MessageDisplay(config.outputSelector, config.messageTemplateSelector);
+  this.messageDisplay = new MessageDisplay(config.outputSelector,
+                                           config.messageTemplateSelector,
+                                           config.errorTemplateSelector);
   this.conn = new ConnectionHandler(config.wsPath);
   document.addEventListener("sendMsg", _.bind(this.sendMsg, this), false);
   document.addEventListener("receiveResponse", _.bind(this.receiveResponse, this), false);
diff --git a/templates/home.html b/templates/home.html
index 3a38cbb..09f153a 100644
--- a/templates/home.html
+++ b/templates/home.html
@@ -9,13 +9,19 @@
           <pre><%= message %></pre>
         </div>
       </script>
+      <script type="application/template" id="error-template">
+        <div class="error">
+          <pre><%= message %></pre>
+        </div>
+      </script>
       <script>
         $(document).ready(function() {
           var skeam = new Skeam({
             inputSelector: "#txt-repl",
             outputSelector: "#responses",
             messageTemplateSelector: "#message-template",
-            wsPath: "ws://localhost:8000/ws"
+            errorTemplateSelector: "#error-template",
+            wsPath: "{{.ws_path}}"
           });
         });
       </script>