refactor webhooks (#37)

.golangci.yml

@@ -52,6 +52,7 @@ linters:
   enable-all: true
   # enable some additional linters that are not enabled by default
   disable:
+    - funlen
     - cyclop
     - testpackage
     - prealloc

README.md

@@ -1,5 +1,7 @@
 # whatsapp
 
+NOTE: This is a work in progress. The API is not yet stable and is subject to change.
+
 ## implemented
 - [x] send text message
 - [x] send image message

examples/webhooks/README.txt

@@ -0,0 +1,8 @@
+How to run examples
+
+- Clone the repository
+- Have go 1.22 or higher installed
+- You can use ngrok or similar tools to expose your local server to the internet.
+- Run the example program
+- Follow webhook configuration steps as outlined in Whatsapp Cloud API documentation
+

examples/webhooks/basic/main.go

@@ -0,0 +1,134 @@
+/*
+ * Copyright 2023 Pius Alfred <me.pius1102@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the “Software”), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
+ * LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/piusalfred/whatsapp/webhooks"
+)
+
+type (
+	Middleware func(http.Handler) http.Handler
+
+	Server struct {
+		Logger            *slog.Logger
+		SubscriptionToken string
+		Listener          *webhooks.NotificationListener
+		Endpoint          string
+	}
+)
+
+func main() {
+	if err := ListenAndServe(); err != nil {
+		fmt.Println(err)
+	}
+}
+
+// ListenAndServe starts the server and listens for incoming webhook notifications.
+func ListenAndServe() error {
+	server := NewServer("1234", "/webhook")
+	mux := http.NewServeMux()
+	notificationEndpoint := fmt.Sprintf("POST %s", server.Endpoint)
+	verificationEndpoint := fmt.Sprintf("GET %s", server.Endpoint)
+	notificationHandler := wrapMiddleware(server.LoggingMiddleware, server.Listener.HandleGenericNotification)
+	verificationHandler := wrapMiddleware(server.LoggingMiddleware, server.Listener.HandleSubscriptionVerification)
+
+	mux.HandleFunc(notificationEndpoint, notificationHandler)
+	mux.HandleFunc(verificationEndpoint, verificationHandler)
+
+	return http.ListenAndServe(":8080", mux)
+}
+
+// NewServer returns a new instance of the Server.
+func NewServer(subscriptionToken, endpoint string) *Server {
+	s := &Server{
+		Logger: slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
+			AddSource: true,
+			Level:     slog.LevelDebug,
+		})).WithGroup("webhooks"),
+		SubscriptionToken: subscriptionToken,
+		Endpoint:          endpoint,
+	}
+
+	g := webhooks.GenericNotificationHandler(s.HandleNotification)
+	s.Listener = webhooks.NewGenericNotificationListener(&webhooks.Config{
+		AppSecret:      "",
+		ShouldValidate: false,
+		VerifyToken:    subscriptionToken,
+	}, g)
+
+	return s
+}
+
+// wrapMiddleware wraps the given http.HandlerFunc with the provided middleware.
+// and returns http.HandlerFunc.
+func wrapMiddleware(middleware Middleware, handler http.HandlerFunc) http.HandlerFunc {
+	return middleware(handler).ServeHTTP
+}
+
+// LoggingMiddleware is a middleware that logs incoming requests.
+func (s *Server) LoggingMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		ctx := r.Context()
+
+		s.Logger.LogAttrs(ctx, slog.LevelInfo, "request received",
+			slog.String("method", r.Method),
+			slog.String("path", r.URL.Path),
+			slog.String("remote_addr", r.RemoteAddr),
+			slog.String("user_agent", r.UserAgent()),
+			slog.String("host", r.Host),
+		)
+
+		next.ServeHTTP(w, r)
+
+		s.Logger.LogAttrs(ctx, slog.LevelInfo, "request completed",
+			slog.String("method", r.Method),
+			slog.String("path", r.URL.Path),
+			slog.String("remote_addr", r.RemoteAddr),
+			slog.String("user_agent", r.UserAgent()),
+			slog.String("host", r.Host),
+			slog.Duration("duration", time.Since(start)),
+		)
+	})
+}
+
+// HandleNotification is a handler function that processes incoming webhook notifications.
+func (s *Server) HandleNotification(ctx context.Context, notification *webhooks.Notification) *webhooks.Response {
+	id := notification.Entry[0].ID
+	object := notification.Object
+	product := notification.Entry[0].Changes[0].Value.MessagingProduct
+
+	s.Logger.LogAttrs(ctx, slog.LevelInfo, "notification received",
+		slog.String("id", id),
+		slog.String("object", object),
+		slog.String("product", product),
+	)
+
+	return &webhooks.Response{
+		StatusCode: http.StatusOK,
+	}
+}

go.mod

@@ -1,3 +1,3 @@
 module github.com/piusalfred/whatsapp
 
-go 1.21
+go 1.22