Build messages page, cache API

cmd/server/api.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/ebosas/microservices/internal/cache"
+	"github.com/go-redis/redis/v8"
+)
+
+// handleAPICache handles an API call for cached messages
+func handleAPICache(cr *redis.Client) func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		data, err := cache.GetCacheJSON(cr)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte("500 - Something happened"))
+
+			log.Printf("get cache json: %s", err)
+			return
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprint(w, data)
+	}
+}

cmd/server/server.go

@@ -9,9 +9,11 @@ import (
 	"net/http"
 	"time"
 
+	"github.com/ebosas/microservices/internal/cache"
 	"github.com/ebosas/microservices/internal/config"
 	"github.com/ebosas/microservices/internal/rabbit"
 	iwebsocket "github.com/ebosas/microservices/internal/websocket"
+	"github.com/go-redis/redis/v8"
 	"github.com/gorilla/websocket"
 	"github.com/streadway/amqp"
 )
@@ -31,30 +33,55 @@ func main() {
 	fmt.Println("[Server]")
 
 	// Establish a Rabbit connection.
-	conn, err := rabbit.GetConn(conf.RabbitURL)
+	connMQ, err := rabbit.GetConn(conf.RabbitURL)
 	if err != nil {
 		log.Fatalf("rabbit connection: %s", err)
 	}
-	defer conn.Close()
+	defer connMQ.Close()
 
-	err = conn.DeclareTopicExchange(conf.Exchange)
+	err = connMQ.DeclareTopicExchange(conf.Exchange)
 	if err != nil {
 		log.Fatalf("declare exchange: %s", err)
 	}
 
+	// Redis connection
+	connR := redis.NewClient(&redis.Options{
+		Addr:     conf.RedisURL,
+		Password: "", // no password set
+		DB:       0,  // use default DB
+	})
+
 	http.Handle("/static/", http.FileServer(http.FS(filesStatic)))
 	http.HandleFunc("/", handleHome)
-	http.HandleFunc("/ws", handleWebsocketConn(conn))
+	http.HandleFunc("/messages", handleMessages(connR))
+	http.HandleFunc("/ws", handleWebsocketConn(connMQ))
+	http.HandleFunc("/api/cache", handleAPICache(connR)) // defined in api.go
 	log.Fatal(http.ListenAndServe(conf.ServerAddr, nil))
 }
 
+// handleHome handles the home page.
 func handleHome(w http.ResponseWriter, r *http.Request) {
 	if r.URL.Path != "/" {
 		handleNotFound(w)
 		return
 	}
-	t, _ := template.ParseFS(filesTempl, "template/template.html")
+	t := template.Must(template.ParseFS(filesTempl, "template/template.html", "template/navbar.html", "template/home.html"))
-	t.Execute(w, nil)
+	t.ExecuteTemplate(w, "layout", nil)
+}
+
+// handleMessages handles the messages page.
+func handleMessages(cr *redis.Client) func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		data, err := cache.GetCache(cr)
+		if err != nil {
+			log.Printf("get cache: %s", err)
+			return
+		}
+
+		funcMap := template.FuncMap{"fdate": formatTime}
+		t := template.Must(template.New("").Funcs(funcMap).ParseFS(filesTempl, "template/template.html", "template/navbar.html", "template/messages.html"))
+		t.ExecuteTemplate(w, "layout", data)
+	}
 }
 
 // handleWebsocketConn passes a Rabbit connection to the Websocket handler.
@@ -145,3 +172,15 @@ func handleNotFound(w http.ResponseWriter) {
 	t, _ := template.ParseFS(filesTempl, "template/404.html")
 	t.Execute(w, nil)
 }
+
+// formatTime returns time formatted for display.
+func formatTime(timestamp int64) string {
+	t := time.Unix(timestamp/1000, 0)
+
+	format := "3:04pm, Jan 2"
+	if t.Day() == time.Now().Day() {
+		format = "3:04pm"
+	}
+
+	return t.Format(format)
+}

cmd/server/template/home.html

@@ -0,0 +1,21 @@
+{{ define "content" }}
+            <div class="container position-relative h-75">
+                <div class="position-absolute bottom-50 start-0 w-100 translate-middle-y">
+                    <div class="row">
+                        <div class="col col-md-8 col-lg-6 mx-auto">
+                            <form>
+                                <div class="input-group">
+                                    <input type="text" class="form-control" placeholder="Enter message" aria-label="Enter message" aria-describedby="button-send" />
+                                    <button class="btn btn-success" type="submit" id="button-send">Send</button>
+                                </div>
+                            </form>
+                        </div>    
+                    </div>
+                </div>
+                <div id="notifications" class="position-absolute top-0 start-0 w-100">
+                    <div class="row">
+                        <div class="col col-md-8 col-lg-6 mx-auto"></div>
+                    </div>
+                </div>
+            </div>
+{{ end }}

cmd/server/template/messages.html

@@ -0,0 +1,27 @@
+{{ define "content" }}
+            <div class="container">
+                <h3 class="my-4 ps-2">Recent messages ({{ .Count }}/{{ .Total }})</h3>
+                <table class="table">
+                    <thead>
+                        <tr>
+                            <th scope="col">Time</th>
+                            <th scope="col">Message</th>
+                            <th scope="col">Source</th>
+                        </tr>
+                    </thead>
+                    <tbody>
+                    {{ range .Messages }}
+                        <tr>
+                            <td>{{ .Time | fdate }}</td>
+                            <td>{{ .Text }}</td>
+                            <td>{{ .Source }}</td>
+                        </tr>
+                    {{ else }}
+                        <tr>
+                            <td colspan="3">No messages</td>
+                        </tr>
+                    {{ end }}
+                    </tbody>
+                </table>
+            </div>
+{{ end }}

cmd/server/template/navbar.html

@@ -0,0 +1,14 @@
+{{ define "navbar" }}
+            <nav class="navbar navbar-expand navbar-light bg-transparent">
+                <div class="container-fluid">
+                    <ul class="navbar-nav">
+                        <li class="nav-item">
+                            <a class="nav-link" href="/">Home</a>
+                        </li>
+                        <li class="nav-item">
+                            <a class="nav-link" href="/messages">Messages</a>
+                        </li>
+                    </ul>
+                </div>
+            </nav>
+{{ end }}

cmd/server/template/template.html

@@ -1,4 +1,4 @@
-<!doctype html>
+{{ define "layout" }}<!doctype html>
 <html lang="en">
     <head>
         <title>Microservices</title>
@@ -8,39 +8,10 @@
     </head>
     <body>
         <div id="root" class="vh-100">
-            <nav class="navbar navbar-expand navbar-light bg-transparent">
+            {{ template "navbar" . }}
-                <div class="container-fluid">
+            {{ template "content" . }}
-                    <ul class="navbar-nav">
-                        <li class="nav-item">
-                            <a class="nav-link" href="/">Home</a>
-                        </li>
-                        <li class="nav-item">
-                            <a class="nav-link" href="/messages">Messages</a>
-                        </li>
-                    </ul>
-                </div>
-            </nav>
-            <div class="container position-relative h-75">
-                <div class="position-absolute bottom-50 start-0 w-100 translate-middle-y">
-                    <div class="row">
-                        <div class="col col-md-8 col-lg-6 mx-auto">
-                            <form>
-                                <div class="input-group">
-                                    <input type="text" class="form-control" placeholder="Enter message" aria-label="Enter message" aria-describedby="button-send" />
-                                    <button class="btn btn-success" type="submit" id="button-send">Send</button>
-                                </div>
-                            </form>
-                        </div>    
-                    </div>
-                </div>
-                <div id="notifications" class="position-absolute top-0 start-0 w-100">
-                    <div class="row">
-                        <div class="col col-md-8 col-lg-6 mx-auto"></div>
-                    </div>
-                </div>
-            </div>
        </div>
        <script src="http://127.0.0.1:8000/index.js"></script>
        <!-- <script src="static/build/index.js"></script> -->
     </body>
-</html>
+</html>{{ end }}

internal/cache/cache.go

@@ -0,0 +1,52 @@
+package cache
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/ebosas/microservices/internal/models"
+	"github.com/go-redis/redis/v8"
+)
+
+// Cache is a data structure for the cache API template.
+type Cache struct {
+	Count    int              `json:"count"`
+	Total    int              `json:"total"`
+	Messages []models.Message `json:"messages"`
+}
+
+// GetCache gets cached messages from Redis by
+// calling GetCacheJSON and unmarshalling the returned JSON.
+func GetCache(c *redis.Client) (*Cache, error) {
+	cacheJSON, err := GetCacheJSON(c)
+	if err != nil {
+		return &Cache{}, fmt.Errorf("get cache json: %v", err)
+	}
+
+	var cache Cache
+	err = json.Unmarshal([]byte(cacheJSON), &cache)
+	if err != nil {
+		return &Cache{}, fmt.Errorf("unmarshal cache: %v", err)
+	}
+
+	return &cache, nil
+}
+
+// GetCacheJSON reads cached messages from Redis, returns JSON.
+func GetCacheJSON(c *redis.Client) (string, error) {
+	messages, err := c.LRange(context.Background(), "messages", 0, -1).Result()
+	if err != nil {
+		return "", fmt.Errorf("lrange redis: %v", err)
+	}
+
+	total, err := c.Get(context.Background(), "count").Result()
+	if err != nil {
+		return "", fmt.Errorf("get redis: %v", err)
+	}
+
+	cacheJSON := "{\"count\":" + fmt.Sprint(len(messages)) + ",\"total\":" + total + ",\"messages\":[" + strings.Join(messages, ",") + "]}"
+
+	return cacheJSON, nil
+}

web/react/src/home.jsx

@@ -71,13 +71,14 @@ function Home() {
                 <div className="row">
                     <div className="col col-md-8 col-lg-6 mx-auto">
                         <Form sendMessage={sendMessage} />
-                    </div>    
+                    </div>
                 </div>
             </div>
             <div id="notifications" className="position-absolute top-0 start-0 w-100">
                 <div className="row">
                     <div className="col col-md-8 col-lg-6 mx-auto">
                         {alerts.map((alert) => (
+                            // TODO: duplicate keys possible
                             <Alert key={alert.time} alert={alert} />
                         ))}
                     </div>

web/react/src/messages.jsx

@@ -1,7 +1,27 @@
 import React from "react";
 
 function Messages() {
-    return (
+    const [error, setError] = React.useState(null);
+    const [isLoaded, setIsLoaded] = React.useState(false);
+    const [items, setItems] = React.useState([]);
+
+    React.useEffect(() => {
+        fetch("/api/cache")
+          .then(res => res.json())
+          .then(
+            (result) => {
+              setIsLoaded(true);
+              setItems(result);
+              console.log(result);
+            },
+            (error) => {
+              setIsLoaded(true);
+              setError(error);
+            }
+          )
+      }, [])
+
+      return (
         <div className="container">
             <h3 className="my-4 ps-2">Recent messages (3/67)</h3>
             <table className="table">