feat(SPV-848): webhook subscribe

examples/Taskfile.yml

@@ -66,3 +66,8 @@ tasks:
     cmds:
       - echo "running generate_totp..."
       - go run ./generate_totp/generate_totp.go
+  webhooks:
+    desc: "running webhooks..."
+    cmds:
+      - echo "running webhooks..."
+      - go run ./webhooks/webhooks.go

examples/webhooks/webhooks.go

@@ -0,0 +1,41 @@
+/*
+Package main - send_op_return example
+*/
+package main
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"time"
+
+	walletclient "github.com/bitcoin-sv/spv-wallet-go-client"
+	"github.com/bitcoin-sv/spv-wallet-go-client/examples"
+)
+
+func main() {
+	defer examples.HandlePanic()
+
+	client := walletclient.NewWithAdminKey("http://localhost:3003/v1", examples.ExampleAdminKey)
+	wh := walletclient.NewWebhook(client, "http://localhost:5005/notification", "", "")
+	err := wh.Subscribe(context.Background())
+	if err != nil {
+		panic(err)
+	}
+
+	http.Handle("/notification", wh.HTTPHandler())
+
+	go func() {
+		for {
+			select {
+			case event := <-wh.Channel:
+				time.Sleep(100 * time.Millisecond) // simulate processing time
+				fmt.Println(event)
+			case <-context.Background().Done():
+				return
+			}
+		}
+	}()
+
+	http.ListenAndServe(":5005", nil)
+}

http.go

@@ -1128,3 +1128,21 @@ func (wc *WalletClient) SendToRecipients(ctx context.Context, recipients []*Reci
 
 	return wc.RecordTransaction(ctx, hex, draft.ID, metadata)
 }
+
+func (wc *WalletClient) AdminSubscribeWebhook(ctx context.Context, webhookURL, tokenHeader, tokenValue string) ResponseError {
+	requestModel := struct {
+		URL         string `json:"url"`
+		TokenHeader string `json:"tokenHeader"`
+		TokenValue  string `json:"tokenValue"`
+	}{
+		URL:         webhookURL,
+		TokenHeader: tokenHeader,
+		TokenValue:  tokenValue,
+	}
+	rawJSON, err := json.Marshal(requestModel)
+	if err != nil {
+		return WrapError(nil)
+	}
+	err = wc.doHTTPRequest(ctx, http.MethodPost, "/admin/webhooks/subscribe", rawJSON, wc.adminXPriv, true, nil)
+	return WrapError(err)
+}

webhook.go

@@ -0,0 +1,62 @@
+package walletclient
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+)
+
+const (
+	eventBufferLength = 100
+)
+
+type Event any
+
+type Webhook struct {
+	URL         string
+	TokenHeader string
+	TokenValue  string
+	Channel     chan Event
+
+	client *WalletClient
+}
+
+func NewWebhook(client *WalletClient, url, tokenHeader, tokenValue string) *Webhook {
+	return &Webhook{
+		URL:         url,
+		TokenHeader: tokenHeader,
+		TokenValue:  tokenValue,
+		Channel:     make(chan Event, eventBufferLength),
+		client:      client,
+	}
+}
+
+func (w *Webhook) Subscribe(ctx context.Context) ResponseError {
+	return w.client.AdminSubscribeWebhook(ctx, w.URL, w.TokenHeader, w.TokenValue)
+}
+
+func (w *Webhook) HTTPHandler() http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		var events []Event
+		if err := json.NewDecoder(r.Body).Decode(&events); err != nil {
+			http.Error(rw, err.Error(), http.StatusBadRequest)
+			return
+		}
+		fmt.Printf("Received: %v\n", events)
+		for _, event := range events {
+			select {
+			case w.Channel <- event:
+				// event sent
+			case <-r.Context().Done():
+				// context cancelled
+				return
+			case <-time.After(1 * time.Second):
+				// timeout, most probably the channel is full
+				// TODO: log this
+			}
+		}
+		rw.WriteHeader(http.StatusOK)
+	})
+}