#!/usr/bin/env python3
"""
Serial loopback test – single file, runs on Pico and ESP32.
Wire TX to RX (Pico: GP0–GP1, ESP32: 17–18), then:
  mpremote run pico/test/test_serial.py

For ESP32→Pico: run test_serial_send.py on ESP32, test_serial_receive.py on Pico; wire ESP32 TX (17) to Pico RX (1).
"""
import time
import sys
from machine import UART, Pin

if "esp32" in sys.platform:
    UART_ID, TX_PIN, RX_PIN, BAUD = 1, 17, 18, 115200
else:
    UART_ID, TX_PIN, RX_PIN, BAUD = 0, 0, 1, 115200

READ_TIMEOUT_MS = 100
LINE_TERM = b"\n"

print("UART loopback: %s UART%d TX=%s RX=%s %d baud" % (sys.platform, UART_ID, TX_PIN, RX_PIN, BAUD))
uart = UART(UART_ID, baudrate=BAUD, tx=Pin(TX_PIN, Pin.OUT), rx=Pin(RX_PIN, Pin.IN))
uart.read()
to_send = [b"hello", b"123", b"{\"v\":\"1\"}"]
errors = []
for msg in to_send:
    uart.write(msg + LINE_TERM)
    time.sleep_ms(20)
    buf = bytearray()
    deadline = time.ticks_add(time.ticks_ms(), READ_TIMEOUT_MS)
    while time.ticks_diff(deadline, time.ticks_ms()) > 0:
        n = uart.any()
        if n:
            buf.extend(uart.read(n))
        if LINE_TERM in buf:
            break
        time.sleep_ms(2)
    got = bytes(buf).strip()
    if got != msg:
        errors.append((msg, got))
uart.deinit()
if errors:
    print("FAIL loopback:", errors)
else:
    print("PASS loopback: sent and received", to_send)