import network

class WiFiUtil:
    def __init__(self):
        self.wlan = network.WLAN(network.STA_IF)
        self.wlan.active(True)

    def scan(self):
        """Scans for networks and returns a list of dictionaries with ssid and rssi."""
        print("Scanning for Wi-Fi networks...")
        networks = self.wlan.scan()
        result = []
        for net in networks:
            # network tuple: (ssid, bssid, channel, RSSI, authmode, hidden)
            try:
                ssid = net[0].decode('utf-8')
            except Exception:
                try:
                    ssid = ''.join(chr(b) if 32 <= b < 127 else '?' for b in net[0])
                except Exception:
                    ssid = "<Unknown SSID>"
            rssi = net[3]
            if ssid: # Filter out hidden/empty SSIDs
                result.append({"ssid": ssid, "rssi": rssi})
        
        # Sort by signal strength (RSSI) descending
        result.sort(key=lambda x: x['rssi'], reverse=True)
        return result