#!/usr/bin/env python3
"""UART Diagnostic - finds the correct serial port for Quectel M66."""
import glob
import time

try:
    import serial
except ImportError:
    print("ERROR: pyserial not installed. Run: pip install pyserial")
    exit(1)

# Discover all serial ports
ports = sorted(glob.glob("/dev/ttyS*") + glob.glob("/dev/ttyAMA*") + glob.glob("/dev/serial*"))
print(f"Available serial ports: {ports}\n")

baudrates = [9600, 115200, 19200, 38400, 57600, 4800]

for port in ports:
    for baud in baudrates:
        try:
            ser = serial.Serial(port, baud, timeout=1.5)
            ser.reset_input_buffer()
            ser.write(b"AT\r\n")
            time.sleep(0.5)
            response = b""
            while ser.in_waiting:
                response += ser.read(ser.in_waiting)
                time.sleep(0.1)
            ser.close()
            resp_text = response.decode("ascii", errors="ignore").strip()
            if resp_text:
                status = "OK" if "OK" in resp_text else "RESPONSE"
                print(f"  ✅ {port} @ {baud} -> {status}: {repr(resp_text)}")
            else:
                print(f"  ❌ {port} @ {baud} -> No response")
        except Exception as e:
            print(f"  ⚠️  {port} @ {baud} -> Error: {e}")

print("\n--- Done ---")
print("If no port responded, check:")
print("  1. Modem power (M66 needs stable 3.8V-4.2V VBAT)")
print("  2. TX/RX wiring (Pi TX -> M66 RX, Pi RX -> M66 TX)")
print("  3. GND connection between Pi and M66")
print("  4. On Pi 5: add 'dtoverlay=uart0-pi5' to /boot/firmware/config.txt")