Add an in-process post event bus (#13)

Handlers emit PostCreated and PostUpdated after a successful write. Store writes do not publish, and hidden roots are skipped.

Reviewed-on: #13
Co-authored-by: codegirl-007 <s.raide@gmail.com>

internal/web/server.go

@@ -20,6 +20,7 @@ import (
 	"github.com/go-chi/chi/v5/middleware"
 
 	"plumber/internal/blob"
+	"plumber/internal/events"
 	"plumber/internal/geo"
 	"plumber/internal/mail"
 	"plumber/internal/pacific"
@@ -35,6 +36,8 @@ type Config struct {
 	TrustedProxies []*net.IPNet
 	Blob           blob.Uploader
 	Mail           mail.Notifier
+	Events         events.Publisher
+	BaseURL        string
 }
 
 type Server struct {
@@ -110,6 +113,9 @@ func New(st store.Store, sessionStore scs.Store, templateFS fs.FS, staticFS fs.F
 	if cfg.Mail == nil {
 		cfg.Mail = mail.Nop{}
 	}
+	if cfg.Events == nil {
+		cfg.Events = events.Nop{}
+	}
 	funcMap := template.FuncMap{
 		"voteCtx": func(user *store.User, csrf, view, date string, post *store.Post) voteCtx {
 			return voteCtx{User: user, CSRF: csrf, View: view, Date: date, Post: post}
@@ -371,6 +377,7 @@ func (s *Server) handleSubmit(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "could not save question", http.StatusInternalServerError)
 		return
 	}
+	s.publishPostCreated(post, post, u)
 	http.Redirect(w, r, "/questions/"+url.PathEscape(post.ID), http.StatusSeeOther)
 }