// SPDX-License-Identifier: Apache-2.0
// Copyright (c) 2012-2024 Scott Penrose <scottp@dd.com.au> and WII5 Buoy contributors
//
// This file is part of WII5 Buoy firmware.
// See LICENSE for full terms.

/**
 * @file wii5_passthrough.ino
 * @brief Minimal firmware: keeps the Maths CPU powered on and provides
 *        bidirectional raw serial passthrough to the Iridium modem.
 *
 * The AVR becomes a transparent bridge between the USB console and the
 * Iridium 9602/9603 modem (Serial3 @ 19200 baud). AT commands typed on
 * the console go directly to the modem; modem responses are echoed back.
 *
 * Maths CPU (Raspberry Pi) is kept alive indefinitely via the hold timer
 * and the MATHS_RETURNLINE hardware signal.
 *
 * Build (PlatformIO):
 *   pio run -e wii5_passthrough
 */

#include <Arduino.h>
#include <WII5.h>

elapsedMillis wdtWait;
elapsedMillis holdCheckWait;

void setup() {
  wii5Setup.beginSafe();
  wii5Setup.setupConsole();

  // Maths CPU — start and hold on indefinitely
  wii5Maths.begin();
  wii5Maths.start(WII5MATHSMODE_COMMS);
  wii5Maths.setHold(MATHS_MAXHOLD);
  wii5Maths.setReturnLine();

  // Iridium modem — initialise, then power on with passthrough
  wii5Iridium.begin();
  wii5Iridium.setPassthrough(true);
  wii5Iridium.powerOn(true);

  wdtWait = 0;
  holdCheckWait = 0;
}

void loop() {
  // ---- external watchdog ----
#ifdef WDT_RESET
  if (wdtWait > 5100) {
    digitalWrite(WDT_RESET, LOW);
    wdtWait = 0;
  } else if (wdtWait > 5000) {
    digitalWrite(WDT_RESET, HIGH);
  }
#endif

  // ---- Maths CPU keep-alive ----
  wii5Maths.loop();
  if (holdCheckWait > 30000) {
    holdCheckWait = 0;
    if (wii5Maths.remainingHold() < 600) {
      wii5Maths.setHold(MATHS_MAXHOLD);
    }
    wii5Maths.setReturnLine();
  }

  // ---- Modem → Console (passthrough echo) ----
  wii5Iridium.WII5SerialManager::loop();

  // ---- Console → Modem (raw forwarding) ----
  while (SerialConsole.available()) {
    SerialComms.write(SerialConsole.read());
  }
}