#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>

// ============== CONFIGURATION ==============
const char* ssid = "iot-2GHz";
const char* password = "lesson-greater";

const char* alertTopic = "http://ntfy.sh/ALERT_klubhaus_topic/json?poll=1";
const char* silenceTopic = "http://ntfy.sh/SILENCE_klubhaus_topic/json?poll=1";

const unsigned long POLL_INTERVAL = 15000;
const unsigned long SILENCE_POLL_INTERVAL = 15000;
const unsigned long BLINK_DURATION = 180000;  // 3 minutes
const unsigned long BLINK_PERIOD = 1000;      // 1 second on/off

// Hardware pins
#define BACKLIGHT_PIN 22   // GPIO 22 - backlight control
#define BUTTON_PIN     9   // GPIO 9 - BOOT button

// Backlight brightness levels (0-255)
#define BRIGHTNESS_OFF    0
#define BRIGHTNESS_DIM    50
#define BRIGHTNESS_FULL   255

// ===========================================

// STATE MACHINE
enum State {
  STATE_SILENT,    // Backlight off or dim
  STATE_ALARM      // Backlight blinking full brightness
};

State currentState = STATE_SILENT;

unsigned long lastPoll = 0;
unsigned long lastSilencePoll = 0;
unsigned long blinkStartTime = 0;
bool blinkState = false;  // false = off, true = on

String lastAlertId = "";
String lastSilenceId = "";
bool buttonWasPressed = false;

void setup() {
  Serial.begin(115200);
  delay(3000);
  Serial.println("\n=== BACKLIGHT DOORBELL ===");

  // Initialize backlight PWM
  pinMode(BACKLIGHT_PIN, OUTPUT);
  analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
  Serial.println("Backlight PWM ready on GPIO 22");

  // Initialize button
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  Serial.println("Button ready on GPIO 9");

  // Test sequence: flash backlight to confirm working
  Serial.println("Backlight test sequence...");
  analogWrite(BACKLIGHT_PIN, BRIGHTNESS_FULL);
  delay(200);
  analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
  delay(200);
  analogWrite(BACKLIGHT_PIN, BRIGHTNESS_FULL);
  delay(200);
  analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
  Serial.println("Test complete");

  // Start in silent state
  transitionTo(STATE_SILENT);

  // WiFi
  Serial.println("Connecting WiFi...");
  WiFi.begin(ssid, password);

  int wifiTimeout = 0;
  while (WiFi.status() != WL_CONNECTED && wifiTimeout < 40) {
    delay(500);
    Serial.print(".");
    wifiTimeout++;
  }

  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("\nWiFi FAILED - will retry");
    // Flash error pattern
    for (int i = 0; i < 5; i++) {
      analogWrite(BACKLIGHT_PIN, BRIGHTNESS_FULL);
      delay(100);
      analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
      delay(100);
    }
  } else {
    Serial.println("\nWiFi OK: " + WiFi.localIP().toString());
    // Brief success flash
    analogWrite(BACKLIGHT_PIN, BRIGHTNESS_DIM);
    delay(500);
    analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
  }

  Serial.println("=== SETUP COMPLETE ===");
  Serial.println(String("State: ") + getStateName(currentState));
}

void loop() {
  unsigned long now = millis();
  handleButton();

  switch (currentState) {
    case STATE_SILENT:
      // Check silence topic frequently
      if (now - lastSilencePoll >= SILENCE_POLL_INTERVAL) {
        lastSilencePoll = now;
        checkSilenceTopic();
      }
      // Check alert topic periodically
      if (now - lastPoll >= POLL_INTERVAL) {
        lastPoll = now;
        checkAlertTopic();
      }
      break;

    case STATE_ALARM:
      // Check silence topic for early stop
      if (now - lastSilencePoll >= SILENCE_POLL_INTERVAL) {
        lastSilencePoll = now;
        checkSilenceTopic();
      }
      // Update blinking
      updateBlink(now);
      // Auto-timeout
      if (now - blinkStartTime >= BLINK_DURATION) {
        Serial.println("ALARM TIMEOUT - auto silence");
        transitionTo(STATE_SILENT);
      }
      break;
  }

  delay(10);
}

// ============== STATE MANAGEMENT ==============

void transitionTo(State newState) {
  if (newState == currentState) return;

  Serial.print("STATE: ");
  Serial.print(getStateName(currentState));
  Serial.print(" -> ");
  Serial.println(getStateName(newState));

  currentState = newState;

  switch (currentState) {
    case STATE_SILENT:
      analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
      Serial.println("Backlight OFF");
      break;

    case STATE_ALARM:
      blinkStartTime = millis();
      blinkState = false;
      analogWrite(BACKLIGHT_PIN, BRIGHTNESS_FULL);
      Serial.println("Backlight BLINK started");
      break;
  }
}

const char* getStateName(State s) {
  return (s == STATE_SILENT) ? "SILENT" : "ALARM";
}

// ============== BUTTON HANDLING ==============

void handleButton() {
  bool pressed = (digitalRead(BUTTON_PIN) == LOW);  // Active low

  if (pressed && !buttonWasPressed) {
    // Button just pressed
    Serial.println("BUTTON PRESSED - test mode");
    buttonWasPressed = true;
    analogWrite(BACKLIGHT_PIN, BRIGHTNESS_FULL);
    Serial.println("Backlight FULL (held)");
  }
  else if (!pressed && buttonWasPressed) {
    // Button released
    Serial.println("BUTTON RELEASED");
    buttonWasPressed = false;

    // Restore state
    if (currentState == STATE_SILENT) {
      analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
      Serial.println("Backlight OFF (silent)");
    } else {
      // Let updateBlink handle it on next loop
      Serial.println("Backlight returns to blink mode");
    }
  }
}

// ============== NETWORK FUNCTIONS ==============

void checkAlertTopic() {
  Serial.println("Poll alert...");
  String response = fetchNtfy(alertTopic);

  if (response.length() == 0) {
    Serial.println("  No response");
    return;
  }

  StaticJsonDocument<512> doc;
  DeserializationError error = deserializeJson(doc, response);
  if (error) {
    Serial.print("  JSON error: ");
    Serial.println(error.c_str());
    return;
  }

  String id = doc["id"] | "";
  String message = doc["message"] | "";

  if (id == lastAlertId) {
    Serial.println("  Same ID, skip");
    return;
  }

  lastAlertId = id;
  Serial.print("  New message: ");
  Serial.println(message);

  if (message.equalsIgnoreCase("SILENCE")) {
    Serial.println("  -> SILENCE command");
    transitionTo(STATE_SILENT);
    // Brief green-like flash (dim) to confirm
    analogWrite(BACKLIGHT_PIN, BRIGHTNESS_DIM);
    delay(500);
    analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
  } else {
    Serial.println("  -> TRIGGER ALARM");
    transitionTo(STATE_ALARM);
  }
}

void checkSilenceTopic() {
  String response = fetchNtfy(silenceTopic);
  if (response.length() == 0) return;

  StaticJsonDocument<512> doc;
  DeserializationError error = deserializeJson(doc, response);
  if (error) return;

  String id = doc["id"] | "";
  if (id == lastSilenceId) return;

  lastSilenceId = id;
  Serial.print("Silence topic: ");
  Serial.println((const char*)doc["message"]);

  if (currentState == STATE_ALARM) {
    Serial.println("  -> Stopping alarm");
    transitionTo(STATE_SILENT);
    // Brief dim flash to confirm
    analogWrite(BACKLIGHT_PIN, BRIGHTNESS_DIM);
    delay(500);
    analogWrite(BACKLIGHT_PIN, BRIGHTNESS_OFF);
  }
}

String fetchNtfy(const char* url) {
  HTTPClient http;
  http.begin(url);
  http.setTimeout(5000);

  int code = http.GET();
  Serial.print("  HTTP ");
  Serial.println(code);

  if (code != 200) {
    http.end();
    return "";
  }

  String payload = http.getString();
  http.end();

  int newline = payload.indexOf('\n');
  if (newline > 0) payload = payload.substring(0, newline);

  return payload;
}

// ============== BLINK CONTROL ==============

void updateBlink(unsigned long now) {
  unsigned long elapsed = now - blinkStartTime;
  bool newState = ((elapsed / BLINK_PERIOD) % 2) == 1;

  if (newState != blinkState) {
    blinkState = newState;
    analogWrite(BACKLIGHT_PIN, blinkState ? BRIGHTNESS_FULL : BRIGHTNESS_OFF);
    Serial.println(blinkState ? "BLINK: ON" : "BLINK: OFF");
  }
}