feat(service): add Mastodon service

go.mod

@@ -80,11 +80,13 @@ require (
 	github.com/leodido/go-urn v1.4.0 // indirect
 	github.com/mattn/go-colorable v0.1.14 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-mastodon v0.0.11 // indirect
 	github.com/oapi-codegen/runtime v1.1.2 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10 // indirect
 	github.com/rs/zerolog v1.34.0 // indirect
 	github.com/spiffe/go-spiffe/v2 v2.6.0 // indirect
+	github.com/tomnomnom/linkheader v0.0.0-20250811210735-e5fe3b51442e // indirect
 	go.mau.fi/util v0.9.5 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
 	go.opentelemetry.io/contrib/detectors/gcp v1.39.0 // indirect

go.sum

@@ -245,6 +245,8 @@ github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/
 github.com/mattn/go-isatty v0.0.19/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/mattn/go-mastodon v0.0.11 h1:Zcvc/8EHpf3os1mwAuUUB5es5VnfVdAeb4ed6ByJnCY=
+github.com/mattn/go-mastodon v0.0.11/go.mod h1:0DcwYEkqigrvknMvjmfKXLP0vYyeYm+vBdUOvoHcczg=
 github.com/mileusna/viber v1.0.1 h1:gWB6/lKoWYVxkH0Jb8jRnGIRZ/9DEM7RBZRJHRfdYWs=
 github.com/mileusna/viber v1.0.1/go.mod h1:Pxu/iPMnYjnHgu+bEp3SiKWHWmlf/kDp/yOX8XUdYrQ=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
@@ -339,6 +341,8 @@ github.com/tidwall/pretty v1.2.1 h1:qjsOFOWWQl+N3RsoF5/ssm1pHmJJwhjlSbZ51I6wMl4=
 github.com/tidwall/pretty v1.2.1/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
 github.com/tidwall/sjson v1.2.5 h1:kLy8mja+1c9jlljvWTlSazM7cKDRfJuR/bOJhcY5NcY=
 github.com/tidwall/sjson v1.2.5/go.mod h1:Fvgq9kS/6ociJEDnK0Fk1cpYF4FIW6ZF7LAe+6jwd28=
+github.com/tomnomnom/linkheader v0.0.0-20250811210735-e5fe3b51442e h1:tD38/4xg4nuQCASJ/JxcvCHNb46w0cdAaJfkzQOO1bA=
+github.com/tomnomnom/linkheader v0.0.0-20250811210735-e5fe3b51442e/go.mod h1:krvJ5AY/MjdPkTeRgMYbIDhbbbVvnPQPzsIsDJO8xrY=
 github.com/ttacon/builder v0.0.0-20170518171403-c099f663e1c2 h1:5u+EJUQiosu3JFX0XS0qTf5FznsMOzTjGqavBGuCbo0=
 github.com/ttacon/builder v0.0.0-20170518171403-c099f663e1c2/go.mod h1:4kyMkleCiLkgY6z8gK5BkI01ChBtxR0ro3I1ZDcGM3w=
 github.com/ttacon/libphonenumber v1.2.1 h1:fzOfY5zUADkCkbIafAed11gL1sW+bJ26p6zWLBMElR4=

service/mastodon/doc.go

@@ -0,0 +1,34 @@
+/*
+Package mastodon provides message notification integration for Mastodon.
+
+Usage:
+
+	package main
+
+	import (
+		"context"
+		"log"
+
+		"github.com/nikoksr/notify"
+		"github.com/nikoksr/notify/service/mastodon"
+	)
+
+	func main() {
+		mastodonSvc := mastodon.New(
+			"https://mastodon.social",
+			"your-client-id",
+			"your-client-secret",
+			"your-access-token",
+		)
+
+		mastodonSvc.AddReceivers("@user@mastodon.social")
+
+		notifier := notify.New()
+		notifier.UseServices(mastodonSvc)
+
+		if err := notifier.Send(context.Background(), "Subject", "Message"); err != nil {
+			log.Fatal(err)
+		}
+	}
+*/
+package mastodon

service/mastodon/mastodon.go

@@ -0,0 +1,69 @@
+package mastodon
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/mattn/go-mastodon"
+)
+
+//go:generate mockery --name=mastodonClient --output=. --case=underscore --inpackage
+type mastodonClient interface {
+	PostStatus(ctx context.Context, toot *mastodon.Toot) (*mastodon.Status, error)
+}
+
+// Compile-time check
+var _ mastodonClient = new(mastodon.Client)
+
+// Mastodon struct holds necessary data to communicate with the Mastodon API.
+type Mastodon struct {
+	client     mastodonClient
+	recipients []string
+}
+
+// New returns a new instance of a Mastodon notification service.
+// serverURL is the Mastodon instance URL (e.g. "https://mastodon.social").
+// clientID, clientSecret, and accessToken are OAuth2 credentials.
+func New(serverURL, clientID, clientSecret, accessToken string) *Mastodon {
+	client := mastodon.NewClient(&mastodon.Config{
+		Server:       serverURL,
+		ClientID:     clientID,
+		ClientSecret: clientSecret,
+		AccessToken:  accessToken,
+	})
+
+	return &Mastodon{
+		client:     client,
+		recipients: []string{},
+	}
+}
+
+// AddReceivers takes Mastodon usernames (e.g. "@user@instance.social") and adds them to the
+// internal recipient list. The Send method will send a direct message to all recipients.
+func (m *Mastodon) AddReceivers(usernames ...string) {
+	m.recipients = append(m.recipients, usernames...)
+}
+
+// Send takes a message subject and a message body and sends them as a direct message
+// to all previously set recipients. Each recipient is mentioned in a separate direct toot.
+func (m Mastodon) Send(ctx context.Context, subject, message string) error {
+	fullMessage := subject + "\n" + message
+
+	for _, recipient := range m.recipients {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+			toot := &mastodon.Toot{
+				Status:     recipient + " " + fullMessage,
+				Visibility: "direct",
+			}
+			_, err := m.client.PostStatus(ctx, toot)
+			if err != nil {
+				return fmt.Errorf("send message to Mastodon recipient %q: %w", recipient, err)
+			}
+		}
+	}
+
+	return nil
+}

service/mastodon/usage.md

@@ -0,0 +1,37 @@
+# Mastodon Usage
+
+Ensure you have a Mastodon account and have created an application
+to obtain your client ID, client secret, and access token.
+
+## Sample Code
+
+```go
+package main
+
+import (
+    "context"
+    "log"
+
+    "github.com/nikoksr/notify"
+    "github.com/nikoksr/notify/service/mastodon"
+)
+
+func main() {
+    mastodonSvc := mastodon.New(
+        "https://mastodon.social",  // Your instance URL
+        "your-client-id",
+        "your-client-secret",
+        "your-access-token",
+    )
+
+    mastodonSvc.AddReceivers("@user@mastodon.social")
+
+    notifier := notify.New()
+    notifier.UseServices(mastodonSvc)
+
+    err := notifier.Send(context.Background(), "Subject", "Message body")
+    if err != nil {
+        log.Fatal(err)
+    }
+}
+```