// Gate Controller — ESP32 + PIR + Pushbutton + Servo
// Uses ESP32Servo.h | Non-blocking timing | Debounced button

#include <ESP32Servo.h>

// ── Pin definitions ────────────────────────────────────────────
#define PIR_PIN       13    // PIR sensor signal pin
#define BUTTON_PIN    27    // Pushbutton (active LOW with INPUT_PULLUP)
#define SERVO_PIN     14   // Servo signal pin

// ── Servo positions ────────────────────────────────────────────
#define SERVO_CLOSED   0    // degrees — gate closed
#define SERVO_OPEN    90    // degrees — gate open

// ── Timing constants ──────────────────────────────────────────
#define GATE_OPEN_MS       10000UL   // 10 seconds open duration
#define DEBOUNCE_MS           50UL  // 50 ms button debounce window
#define PIR_RESAMPLE_MS      200UL  // re-check PIR every 200 ms

// ── Objects ───────────────────────────────────────────────────
Servo gateServo;

// ── State variables ───────────────────────────────────────────
bool gateOpen = false;                    // is the gate currently open?
unsigned long gateOpenedAt = 0;           // millis() when gate last opened/extended

// Button debounce state
bool lastButtonReading   = HIGH;          // last raw pin read
bool buttonState         = HIGH;          // confirmed (debounced) state
unsigned long lastDebounceTime = 0;

// PIR previous state (for edge detection)
bool lastPirState = LOW;

// ── Helper: open the gate (or extend its timer) ────────────────
void openGate(const char* reason) {
  if (!gateOpen) {
    gateServo.write(SERVO_OPEN);
    gateOpen = true;
    Serial.print("[GATE OPENED] Triggered by: ");
    Serial.println(reason);
  } else {
    Serial.print("[GATE EXTENDED] Triggered by: ");
    Serial.println(reason);
  }
  gateOpenedAt = millis();   // reset / extend the timer
}

// ── Helper: close the gate ─────────────────────────────────────
void closeGate() {
  gateServo.write(SERVO_CLOSED);
  gateOpen = false;
  Serial.println("[GATE CLOSED] Auto-close after timeout.");
}

// ── Setup ──────────────────────────────────────────────────────
void setup() {
  Serial.begin(115200);
  Serial.println("=== Gate Controller Starting ===");

  pinMode(PIR_PIN,    INPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);   // internal pull-up — avoids floating input

  // Allocate a timer channel and attach servo
  ESP32PWM::allocateTimer(0);
  gateServo.setPeriodHertz(50);        // standard 50 Hz servo
  gateServo.attach(SERVO_PIN, 500, 2400);  // pulse range µs (typical SG90)

  gateServo.write(SERVO_CLOSED);       // ensure gate starts closed
  Serial.println("Gate initialised — CLOSED.");
  Serial.println("Waiting for motion or button press...\n");
}

// ── Main loop ─────────────────────────────────────────────────
void loop() {
  unsigned long now = millis();

  // ── 1. Read & debounce pushbutton ─────────────────────────
  bool reading = digitalRead(BUTTON_PIN);

  if (reading != lastButtonReading) {
    lastDebounceTime = now;            // reset the debounce timer on any change
  }
  lastButtonReading = reading;

  if ((now - lastDebounceTime) >= DEBOUNCE_MS) {
    // State has been stable for DEBOUNCE_MS
    if (reading != buttonState) {
      buttonState = reading;
      if (buttonState == LOW) {        // active LOW — button pressed
        openGate("PUSHBUTTON");
      }
    }
  }

  // ── 2. Read PIR (rising-edge only — triggers once per detection) ──
  bool pirNow = digitalRead(PIR_PIN);
  if (pirNow == HIGH && lastPirState == LOW) {
    openGate("PIR MOTION");
  }
  lastPirState = pirNow;

  // ── 3. Auto-close check ───────────────────────────────────
  if (gateOpen && (now - gateOpenedAt >= GATE_OPEN_MS)) {
    closeGate();
  }
}