#include <WiFi.h>
#include <PubSubClient.h>

// ----------------------------
// USER CONFIG - EDIT THESE !!!
// ----------------------------
const char* ssid        = "YOUR_WIFI_SSID";      // <-- Replace
const char* password    = "YOUR_WIFI_PASSWORD";  // <-- Replace
const char* student_id  = "3091637K";     // <-- Replace (e.g., "A1234567X")

// MQTT broker (public). You may change to campus broker if provided.
const char* mqtt_server = "mqtt-dashboard.com";   // or "test.mosquitto.org"
const uint16_t mqtt_port = 8884;

// ----------------------------
// PIN ASSIGNMENTS
// ----------------------------
const int RED_LED_PIN    = 23;  // Blink
const int YELLOW_LED_PIN = 22;  // MQTT controlled
const int POT_PIN        = 36;  // VP (ADC1_CH0)

// ----------------------------
// TIMING (ms)
// ----------------------------
const unsigned long BLINK_INTERVAL_MS   = 1000; // toggle every 1s → full cycle 2s
const unsigned long PUBLISH_INTERVAL_MS = 2000; // publish pot every 2s

WiFiClient espClient;
PubSubClient client(espClient);

unsigned long lastBlinkTime   = 0;
unsigned long lastPublishTime = 0;
bool redLedState = false;

// Forward declarations
void setup_wifi();
void reconnect();
void mqttCallback(char* topic, byte* payload, unsigned int length);

void setup() {
  Serial.begin(115200);
  delay(100);
  Serial.println();
  Serial.println("Booting...");

  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(YELLOW_LED_PIN, OUTPUT);
  digitalWrite(RED_LED_PIN, LOW);
  digitalWrite(YELLOW_LED_PIN, LOW);

  // Optional: configure ADC attenuation / width (defaults OK in Wokwi)
  // analogReadResolution(12); // 0-4095
  // analogSetAttenuation(ADC_11db); // full 0-3.3V range typical

  setup_wifi();

  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(mqttCallback);
}

void loop() {
  // Maintain MQTT connection
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  unsigned long now = millis();

  // --- Blink Red LED ---
  if (now - lastBlinkTime >= BLINK_INTERVAL_MS) {
    lastBlinkTime = now;
    redLedState = !redLedState;
    digitalWrite(RED_LED_PIN, redLedState ? HIGH : LOW);
  }

  // --- Publish Pot Value ---
  if (now - lastPublishTime >= PUBLISH_INTERVAL_MS) {
    lastPublishTime = now;
    int potVal = analogRead(POT_PIN); // 0-4095

    char topic[64];
    snprintf(topic, sizeof(topic), "/%s/pot/raw", student_id);

    char payload[16];
    snprintf(payload, sizeof(payload), "%d", potVal);

    bool ok = client.publish(topic, payload, false);
    Serial.printf("Publish %s to %s %s\n", payload, topic, ok ? "OK" : "FAIL");
  }
}

// --------------------------------------------------
// WiFi connect helper
// --------------------------------------------------
void setup_wifi() {
  Serial.printf("Connecting to %s\n", ssid);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  uint8_t dots = 0;
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    dots++;
    if (dots % 10 == 0) {
      Serial.printf(" (status=%d)\n", WiFi.status());
    }
  }
  Serial.println();
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

// --------------------------------------------------
// MQTT message handler
// --------------------------------------------------
void mqttCallback(char* topic, byte* payload, unsigned int length) {
  Serial.print("MQTT msg [");
  Serial.print(topic);
  Serial.print("] ");

  // Copy payload to a small buffer (safe length check)
  char msg[32];
  unsigned int copyLen = (length < sizeof(msg) - 1) ? length : sizeof(msg) - 1;
  memcpy(msg, payload, copyLen);
  msg[copyLen] = '\0';
  Serial.println(msg);

  // Compare topic
  char expected[64];
  snprintf(expected, sizeof(expected), "/%s/y_led", student_id);

  if (strcmp(topic, expected) == 0) {
    if (strcasecmp(msg, "on") == 0) {
      digitalWrite(YELLOW_LED_PIN, HIGH);
      Serial.println("Yellow LED -> ON");
    } else if (strcasecmp(msg, "off") == 0) {
      digitalWrite(YELLOW_LED_PIN, LOW);
      Serial.println("Yellow LED -> OFF");
    } else {
      Serial.println("Unknown payload (expected 'on' or 'off')");
    }
  }
}

// --------------------------------------------------
// MQTT reconnect helper
// --------------------------------------------------
void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a random client ID
    String clientId = String("ESP32-") + String((uint32_t)ESP.getEfuseMac(), HEX);

    // Attempt to connect (no auth)
    if (client.connect(clientId.c_str())) {
      Serial.println("connected");
      // Subscribe
      char topic[64];
      snprintf(topic, sizeof(topic), "/%s/y_led", student_id);
      client.subscribe(topic);
      Serial.print("Subscribed: ");
      Serial.println(topic);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}