✨ Add SSE endpoint with Watermill integration

changelog.md

@@ -1272,4 +1272,10 @@ Improved form data rendering in the console log:
 
 Added Watermill dependencies for implementing SSE support:
 - Added github.com/ThreeDotsLabs/watermill v1.4.4
-- Added github.com/ThreeDotsLabs/watermill/pubsub/gochannel for local pub/sub
+- Added github.com/ThreeDotsLabs/watermill/pubsub/gochannel for local pub/sub
+
+Added SSE endpoint to UI server:
+- Added /sse endpoint for real-time updates
+- Implemented page-specific event channels using Watermill
+- Added CORS support for cross-origin requests
+- Added proper error handling and connection management

cmd/ui-server/server.go

@@ -11,30 +11,43 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/ThreeDotsLabs/watermill/pubsub/gochannel"
 	"github.com/go-go-golems/clay/pkg/watcher"
 	"github.com/rs/zerolog/log"
 	"gopkg.in/yaml.v3"
 )
 
 type Server struct {
-	dir     string
-	pages   map[string]UIDefinition
-	routes  map[string]http.HandlerFunc
-	watcher *watcher.Watcher
-	mux     *http.ServeMux
-	mu      sync.RWMutex
+	dir        string
+	pages      map[string]UIDefinition
+	routes     map[string]http.HandlerFunc
+	watcher    *watcher.Watcher
+	mux        *http.ServeMux
+	mu         sync.RWMutex
+	publisher  message.Publisher
+	subscriber message.Subscriber
 }
 
 type UIDefinition struct {
 	Components []map[string]interface{} `yaml:"components"`
 }
 
 func NewServer(dir string) *Server {
+	// Initialize watermill publisher/subscriber
+	publisher := gochannel.NewGoChannel(
+		gochannel.Config{},
+		watermill.NewStdLogger(false, false),
+	)
+
 	s := &Server{
-		dir:    dir,
-		pages:  make(map[string]UIDefinition),
-		routes: make(map[string]http.HandlerFunc),
-		mux:    http.NewServeMux(),
+		dir:        dir,
+		pages:      make(map[string]UIDefinition),
+		routes:     make(map[string]http.HandlerFunc),
+		mux:        http.NewServeMux(),
+		publisher:  publisher,
+		subscriber: publisher,
 	}
 
 	// Create a watcher for the pages directory
@@ -48,6 +61,9 @@ func NewServer(dir string) *Server {
 
 	s.watcher = w
 
+	// Set up SSE endpoint
+	s.mux.HandleFunc("/sse", s.handleSSE())
+
 	// Set up static file handler
 	s.mux.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("static"))))
 
@@ -267,3 +283,35 @@ func (s *Server) handlePage(name string) http.HandlerFunc {
 		}
 	}
 }
+
+func (s *Server) handleSSE() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		// Set SSE headers
+		w.Header().Set("Content-Type", "text/event-stream")
+		w.Header().Set("Cache-Control", "no-cache")
+		w.Header().Set("Connection", "keep-alive")
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+
+		// Get page ID from query
+		pageID := r.URL.Query().Get("page")
+		if pageID == "" {
+			http.Error(w, "page parameter is required", http.StatusBadRequest)
+			return
+		}
+
+		// Subscribe to page-specific topic
+		messages, err := s.subscriber.Subscribe(r.Context(), "ui-updates."+pageID)
+		if err != nil {
+			http.Error(w, "Failed to subscribe to events", http.StatusInternalServerError)
+			return
+		}
+
+		// Stream messages
+		for msg := range messages {
+			// Format SSE message
+			fmt.Fprintf(w, "event: %s\n", msg.Metadata["event-type"])
+			fmt.Fprintf(w, "data: %s\n\n", msg.Payload)
+			w.(http.Flusher).Flush()
+		}
+	}
+}

go.mod

@@ -6,6 +6,7 @@ toolchain go1.23.3
 
 require (
 	github.com/JohannesKaufmann/html-to-markdown v1.6.0
+	github.com/ThreeDotsLabs/watermill v1.3.7
 	github.com/a-h/templ v0.3.833
 	github.com/go-go-golems/clay v0.1.31
 	github.com/go-go-golems/geppetto v0.4.37
@@ -70,6 +71,7 @@ require (
 	github.com/jedib0t/go-pretty v4.3.0+incompatible // indirect
 	github.com/jmespath/go-jmespath v0.4.0 // indirect
 	github.com/kopoli/go-terminal-size v0.0.0-20170219200355-5c97524c8b54 // indirect
+	github.com/lithammer/shortuuid/v3 v3.0.7 // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect

go.sum

@@ -12,6 +12,8 @@ github.com/Masterminds/sprig v2.22.0+incompatible/go.mod h1:y6hNFY5UBTIWBxnzTeuN
 github.com/PuerkitoBio/goquery v1.9.2/go.mod h1:GHPCaP0ODyyxqcNoFGYlAprUFH81NuRPd0GX3Zu2Mvk=
 github.com/PuerkitoBio/goquery v1.10.1 h1:Y8JGYUkXWTGRB6Ars3+j3kN0xg1YqqlwvdTV8WTFQcU=
 github.com/PuerkitoBio/goquery v1.10.1/go.mod h1:IYiHrOMps66ag56LEH7QYDDupKXyo5A8qrjIx3ZtujY=
+github.com/ThreeDotsLabs/watermill v1.3.7 h1:NV0PSTmuACVEOV4dMxRnmGXrmbz8U83LENOvpHekN7o=
+github.com/ThreeDotsLabs/watermill v1.3.7/go.mod h1:lBnrLbxOjeMRgcJbv+UiZr8Ylz8RkJ4m6i/VN/Nk+to=
 github.com/a-h/templ v0.3.833 h1:L/KOk/0VvVTBegtE0fp2RJQiBm7/52Zxv5fqlEHiQUU=
 github.com/a-h/templ v0.3.833/go.mod h1:cAu4AiZhtJfBjMY0HASlyzvkrtjnHWPeEsyGK2YYmfk=
 github.com/adrg/frontmatter v0.2.0 h1:/DgnNe82o03riBd1S+ZDjd43wAmC6W35q67NHeLkPd4=
@@ -96,12 +98,17 @@ github.com/go-openapi/strfmt v0.23.0/go.mod h1:NrtIpfKtWIygRkKVsxh7XQMDQW5HKQl6S
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/uuid v1.2.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gorilla/css v1.0.1 h1:ntNaBIghp6JmvWnxbZKANoLyuXTPZ4cAMlo6RyhlbO8=
 github.com/gorilla/css v1.0.1/go.mod h1:BvnYkspnSzMmwRK+b8/xgNPLiIuNZr6vbZBTPQ2A3b0=
 github.com/gorilla/mux v1.8.1 h1:TuBL49tXwgrFYWhqrNgrUNEY92u81SPhu7sTdzQEiWY=
 github.com/gorilla/mux v1.8.1/go.mod h1:AKf9I4AEqPTmMytcMc0KkNouC66V3BtZ4qD5fmWSiMQ=
+github.com/hashicorp/errwrap v1.1.0 h1:OxrOeh75EUXMY8TBjag2fzXGZ40LB6IKw45YeGUDY2I=
+github.com/hashicorp/errwrap v1.1.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/hashicorp/hcl v1.0.0 h1:0Anlzjpi4vEasTeNFn2mLJgTSwt0+6sfsiTG8qcWGx4=
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
@@ -136,6 +143,8 @@ github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/lithammer/shortuuid/v3 v3.0.7 h1:trX0KTHy4Pbwo/6ia8fscyHoGA+mf1jWbPJVuvyJQQ8=
+github.com/lithammer/shortuuid/v3 v3.0.7/go.mod h1:vMk8ke37EmiewwolSO1NLW8vP4ZaKlRuDIi8tWWmAts=
 github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69Aj6K7nkY=
 github.com/lucasb-eyer/go-colorful v1.2.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
 github.com/magiconair/properties v1.8.7 h1:IeQXZAiQcpL9mgcAe1Nu6cX9LLw6ExEHKjN0VQdvPDY=