Add M0 server skeleton with SQLite store, SSE events, worktrees, and tailscale service

internal/server/sse.go

@@ -0,0 +1,91 @@
+package server
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"g.fc.run/misc/byre/internal/api"
+)
+
+const backfillPage = 500
+
+func (s *Server) StreamEvents(w http.ResponseWriter, r *http.Request, params api.StreamEventsParams) {
+	last := int64(0)
+	if params.After != nil {
+		last = *params.After
+	}
+	if params.LastEventID != nil {
+		last = *params.LastEventID
+	}
+
+	rc := http.NewResponseController(w)
+	w.Header().Set("Content-Type", "text/event-stream")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.WriteHeader(http.StatusOK)
+
+	live := s.hub.subscribe()
+	defer s.hub.unsubscribe(live)
+
+	for {
+		events, err := s.store.EventsAfter(r.Context(), last, backfillPage)
+		if err != nil {
+			return
+		}
+		for _, ev := range events {
+			if !writeEvent(w, ev) {
+				return
+			}
+			last = ev.Seq
+		}
+		if len(events) < backfillPage {
+			break
+		}
+	}
+
+	if rc.Flush() != nil {
+		return
+	}
+
+	ping := time.NewTicker(30 * time.Second)
+	defer ping.Stop()
+
+	for {
+		select {
+		case ev, ok := <-live:
+			if !ok {
+				return
+			}
+			if ev.Seq <= last {
+				continue
+			}
+			if !writeEvent(w, ev) {
+				return
+			}
+			last = ev.Seq
+
+		case <-ping.C:
+			_, err := fmt.Fprint(w, ": ping\n\n")
+			if err != nil {
+				return
+			}
+
+		case <-r.Context().Done():
+			return
+		}
+
+		if rc.Flush() != nil {
+			return
+		}
+	}
+}
+
+func writeEvent(w http.ResponseWriter, ev api.Event) bool {
+	data, err := json.Marshal(ev)
+	if err != nil {
+		return false
+	}
+	_, err = fmt.Fprintf(w, "id: %d\ndata: %s\n\n", ev.Seq, data)
+	return err == nil
+}