implement custom welcome message (#820)

* implement custom welcome message

This change adds logic for handling custom welcome messages.

* trim welcome message string on POST

Instead of trimming the welcome message every time we are going to send to send
a welcome message, we just trim once when the message is posted from the admin.

controllers/admin/config.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"path/filepath"
 	"reflect"
+	"strings"
 
 	"github.com/owncast/owncast/controllers"
 	"github.com/owncast/owncast/core"
@@ -120,6 +121,25 @@ func SetServerSummary(w http.ResponseWriter, r *http.Request) {
 	controllers.WriteSimpleResponse(w, true, "changed")
 }
 
+// SetServerWelcomeMessage will handle the web config request to set the welcome message text.
+func SetServerWelcomeMessage(w http.ResponseWriter, r *http.Request) {
+	if !requirePOST(w, r) {
+		return
+	}
+
+	configValue, success := getValueFromRequest(w, r)
+	if !success {
+		return
+	}
+
+	if err := data.SetServerWelcomeMessage(strings.TrimSpace(configValue.Value.(string))); err != nil {
+		controllers.WriteSimpleResponse(w, false, err.Error())
+		return
+	}
+
+	controllers.WriteSimpleResponse(w, true, "changed")
+}
+
 // SetExtraPageContent will handle the web config request to set the page markdown content.
 func SetExtraPageContent(w http.ResponseWriter, r *http.Request) {
 	if !requirePOST(w, r) {