/*
 * JoystickBridge.ino  —  Arduino Uno <-> Godot (ArduinoGodot/Main.gd)
 *
 * Talks plain serial lines to the UDP<->serial bridge process, which forwards
 * telemetry to Godot on UDP 4242 and relays LED commands from UDP 4243.
 *
 * PROTOCOL (must match Main.gd)
 *   OUT (Uno -> host):  "x,y,btn\n"   raw 10-bit ADC, e.g. "512,498,1"
 *                       btn = 1 when the stick's push-button is pressed.
 *   IN  (host -> Uno):  "L1" = LED on, "L0" = LED off  (newline optional)
 *
 * WIRING (KY-023 2-axis analog joystick + external LED)
 *   Joystick  +5V / VCC  -> 5V
 *   Joystick  GND        -> GND
 *   Joystick  VRx        -> A0
 *   Joystick  VRy        -> A1
 *   Joystick  SW         -> D2   (uses internal pull-up; pressed = LOW)
 *
 *   LED:  D13 -> 220 ohm resistor -> LED anode (+, long leg)
 *         LED cathode (-, short leg) -> GND
 *   (D13 is also the Uno's onboard LED, so it flashes during every upload —
 *    a free "is this pin alive" check. 220-330 ohm keeps it near ~15 mA.)
 */

const uint8_t PIN_VRX = A0;   // joystick X axis
const uint8_t PIN_VRY = A1;   // joystick Y axis
const uint8_t PIN_SW  = 2;    // joystick push-button (active LOW)
const uint8_t PIN_LED = 13;   // external LED through a 220 ohm resistor (also onboard LED)

const unsigned long BAUD      = 115200;  // must match the bridge process
const unsigned long SEND_MS   = 16;      // ~60 Hz telemetry

unsigned long lastSend = 0;
char cmdBuf[8];
uint8_t cmdLen = 0;

void setup() {
  Serial.begin(BAUD);
  pinMode(PIN_SW, INPUT_PULLUP);
  pinMode(PIN_LED, OUTPUT);
  digitalWrite(PIN_LED, LOW);
}

void loop() {
  handleCommands();

  unsigned long now = millis();
  if (now - lastSend >= SEND_MS) {
    lastSend = now;
    int x = analogRead(PIN_VRX);           // 0..1023
    int y = analogRead(PIN_VRY);           // 0..1023
    int btn = (digitalRead(PIN_SW) == LOW) // pull-up: LOW == pressed
              ? 1 : 0;                     // Godot wants 1 = pressed

    // "x,y,btn\n"
    Serial.print(x);
    Serial.print(',');
    Serial.print(y);
    Serial.print(',');
    Serial.println(btn);
  }
}

// Parse newline-terminated commands. Recognizes "L1" / "L0".
void handleCommands() {
  while (Serial.available() > 0) {
    char c = Serial.read();
    if (c == '\n' || c == '\r') {
      if (cmdLen >= 2 && cmdBuf[0] == 'L') {
        digitalWrite(PIN_LED, cmdBuf[1] == '1' ? HIGH : LOW);
      }
      cmdLen = 0;
    } else if (cmdLen < sizeof(cmdBuf) - 1) {
      cmdBuf[cmdLen++] = c;
    } else {
      cmdLen = 0;  // overflow guard: drop the runt line
    }
  }
}