feat(espnow): add espnow-sender utility

Co-authored-by: Cursor <cursoragent@cursor.com>

espnow-sender/main.py

@@ -0,0 +1,120 @@
+import asyncio
+import json
+
+from microdot import Microdot
+from microdot.websocket import WebSocketError, with_websocket
+
+import espnow
+import network
+from util import format_mac, parse_mac
+
+
+app = Microdot()
+_esp = None
+_known_peers = set()
+_ws_clients = set()
+
+
+def _init_espnow():
+    global _esp
+    sta = network.WLAN(network.STA_IF)
+    sta.active(True)
+    _esp = espnow.ESPNow()
+    _esp.active(True)
+
+
+def _validate_envelope(obj):
+    if obj.get("v") != "1":
+        raise ValueError("message.v must be '1'")
+    devices = obj["devices"]
+    for address in devices.keys():
+        parse_mac(address)
+    return obj
+
+
+def _send_espnow(address, payload):
+    if _esp is None:
+        raise ValueError("espnow is not initialized")
+    mac = parse_mac(address)
+    msg = json.dumps(payload, separators=(",", ":")).encode("utf-8")
+    if mac not in _known_peers:
+        _esp.add_peer(mac)
+        _known_peers.add(mac)
+    _esp.send(mac, msg)
+    return mac, len(msg)
+
+
+async def _broadcast_ws(obj):
+    text = json.dumps(obj)
+    dead = []
+    for client in list(_ws_clients):
+        try:
+            await client.send(text)
+        except Exception:
+            dead.append(client)
+    for client in dead:
+        _ws_clients.discard(client)
+
+
+async def _espnow_receive_loop():
+    while True:
+        host, msg = _esp.recv(0)
+        if not host:
+            await asyncio.sleep(0.01)
+            continue
+        await _broadcast_ws(
+            {
+                "from": format_mac(host),
+                "payload": msg.decode("utf-8"),
+            }
+        )
+
+
+@app.route("/ws")
+@with_websocket
+async def ws(request, ws):
+    _ws_clients.add(ws)
+    while True:
+        try:
+            raw = await ws.receive()
+        except WebSocketError:
+            break
+
+        if not raw:
+            break
+
+        try:
+            parsed = json.loads(raw)
+            env = _validate_envelope(parsed)
+            sent = []
+            for address, payload in env["devices"].items():
+                mac, payload_size = _send_espnow(address, payload)
+                sent.append(
+                    {
+                        "address": format_mac(mac),
+                        "bytes": payload_size,
+                    }
+                )
+        except (ValueError, TypeError) as e:
+            await ws.send(json.dumps({"ok": False, "error": str(e)}))
+            continue
+
+        await ws.send(
+            json.dumps(
+                {
+                    "ok": True,
+                    "sent": sent,
+                }
+            )
+        )
+    _ws_clients.discard(ws)
+
+
+async def main(port=80):
+    _init_espnow()
+    asyncio.create_task(_espnow_receive_loop())
+    await app.start_server(host="0.0.0.0", port=port)
+
+
+if __name__ == "__main__":
+    asyncio.run(main(port=80))