From f75a6f04dd822c7eb88f66792c663a1f4068a407 Mon Sep 17 00:00:00 2001
From: Valentin Korenjak <valentin@korenjak.si>
Date: Fri, 27 Mar 2026 21:03:46 +0100
Subject: [PATCH] Server-side events (SSE) namesto pollinga #14

---
 projector.py         |  4 +++-
 web/server.py        | 42 +++++++++++++++++++++++++++++++++++++++++-
 web/static/script.js | 23 +++++++++++++++++++----
 3 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/projector.py b/projector.py
index 130a76b..333076c 100755
--- a/projector.py
+++ b/projector.py
@@ -29,7 +29,7 @@ import subprocess
 import sys
 import ctypes
 import tkinter.messagebox as messagebox
-from web.server import start_server_thread
+from web.server import start_server_thread, notify_clients
 import urllib.request
 import tempfile
 from db_schema import create_tables
@@ -476,6 +476,7 @@ class SongProjector:
                 self.song_info_label.lift()
             else:
                 self.song_info_label.config(text="")
+        notify_clients()
 
     # ------------------------------------------------------
     #  Navigacija po straneh
@@ -504,6 +505,7 @@ class SongProjector:
         self.color_frame.config(bg="black", width=self.color_width, height=self.screen_height)
         self.color_frame.place(relx=0.5, rely=0.5, anchor="center")
         self.song_info_label.config(text="")
+        notify_clients()
 
     # ------------------------------------------------------
     #  Iskanje po naslovu
diff --git a/web/server.py b/web/server.py
index cce6bc3..9ba3294 100644
--- a/web/server.py
+++ b/web/server.py
@@ -28,8 +28,10 @@ than being generated inside Python code.
 import threading
 import os
 import json
+import queue
+import time
 
-from flask import Flask, render_template, request, jsonify
+from flask import Flask, render_template, request, jsonify, Response
 
 # create Flask app with proper folders relative to this file
 app = Flask(__name__, static_folder="static", template_folder="templates")
@@ -37,6 +39,17 @@ app = Flask(__name__, static_folder="static", template_folder="templates")
 # Globalna referenca na SongProjector aplikaciju
 _projector_app = None
 
+# List of queues for SSE clients
+_sse_clients = []
+_sse_lock = threading.Lock()
+
+
+def notify_clients():
+    """Notify all connected SSE clients to refresh content"""
+    with _sse_lock:
+        for q in _sse_clients:
+            q.put("refresh content")
+
 
 def set_projector_app(projector_app):
     """Postavi referenco na SongProjector aplikacijo"""
@@ -97,6 +110,26 @@ def get_state():
     })
 
 
+@app.route('/api/events')
+def sse_events():
+    """SSE endpoint for real-time updates"""
+    def event_stream():
+        q = queue.Queue()
+        with _sse_lock:
+            _sse_clients.append(q)
+        try:
+            # Send initial refresh command on connection
+            yield "data: refresh content\n\n"
+            while True:
+                msg = q.get()
+                yield f"data: {msg}\n\n"
+        finally:
+            with _sse_lock:
+                _sse_clients.remove(q)
+
+    return Response(event_stream(), mimetype="text/event-stream")
+
+
 @app.route('/api/load_song', methods=['POST'])
 def load_song():
     """Naloži pesem po številki"""
@@ -111,6 +144,7 @@ def load_song():
         _projector_app.load_song()
         if hasattr(_projector_app, 'show_page'):
             _projector_app.show_page()
+        notify_clients()
 
     return jsonify({'status': 'ok'})
 
@@ -120,6 +154,7 @@ def next_page():
     """Naslednja stran"""
     if _projector_app is not None:
         _projector_app.next_page()
+        notify_clients()
 
     return jsonify({'status': 'ok'})
 
@@ -129,6 +164,7 @@ def prev_page():
     """Prejšnja stran"""
     if _projector_app is not None:
         _projector_app.prev_page()
+        notify_clients()
 
     return jsonify({'status': 'ok'})
 
@@ -138,6 +174,7 @@ def clear_screen():
     """Zatemniti ekran"""
     if _projector_app is not None:
         _projector_app.clear_screen()
+        notify_clients()
 
     return jsonify({'status': 'ok'})
 
@@ -148,6 +185,7 @@ def toggle_caps():
     if _projector_app is not None:
         _projector_app.all_caps_mode = not _projector_app.all_caps_mode
         _projector_app.show_page()
+        notify_clients()
 
     return jsonify({'status': 'ok'})
 
@@ -157,6 +195,7 @@ def toggle_split():
     """Preklop med načinom preloma po kiticah in prostim prelomom"""
     if _projector_app is not None:
         _projector_app.toggle_split_mode()
+        notify_clients()
 
     return jsonify({'status': 'ok'})
 
@@ -283,6 +322,7 @@ def update_song():
         if str(_projector_app.song_number_last) == str(song_id):
             _projector_app.song_number = str(song_id)
             _projector_app.load_song()
+            notify_clients()
 
         return jsonify({'status': 'ok'})
     except Exception as e:
diff --git a/web/static/script.js b/web/static/script.js
index 59a5092..a864c37 100644
--- a/web/static/script.js
+++ b/web/static/script.js
@@ -648,9 +648,24 @@ document.addEventListener('keydown', (e) => {
 updateState(true);
 requestWakeLock();
 
-// osveževanje za sinhronizacijo med več napravami
-setInterval(() => {
-    updateState(false);
-}, 1000);
+// SSE osveževanje za sinhronizacijo med več napravami
+function setupSSE() {
+    const evtSource = new EventSource("/api/events");
+
+    evtSource.onmessage = function(event) {
+        console.log("SSE dogodek:", event.data);
+        if (event.data === "refresh content") {
+            updateState(false);
+        }
+    };
+
+    evtSource.onerror = function(err) {
+        console.error("SSE napaka, ponovni poskus čez 5s...", err);
+        evtSource.close();
+        setTimeout(setupSSE, 5000);
+    };
+}
+
+setupSSE();
 
 console.log('JavaScript inicializacija zaključena');
\ No newline at end of file