#include <Wire.h>
#include <DHT.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// =======================
// DHT22
// =======================
#define DHT_PIN 4
#define DHT_TYPE DHT22
DHT dht(DHT_PIN, DHT_TYPE);

// =======================
// LDR
// =======================
#define LDR_PIN 34

// =======================
// Relay
// =======================
#define RELAY_PIN 5

// =======================
// LEDs
// =======================
#define GREEN_LED 18
#define BLUE_LED 19
#define RED_LED 23

// =======================
// Buzzer
// =======================
#define BUZZER_PIN 32

// =======================
// OLED
// =======================
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_SDA 21
#define OLED_SCL 22
#define OLED_ADDRESS 0x3C

Adafruit_SSD1306 display(
  SCREEN_WIDTH,
  SCREEN_HEIGHT,
  &Wire,
  -1
);

// =======================
// EcoSense settings
// =======================
float HIGH_TEMP = 30.0;
float LIGHT_THRESHOLD = 5000.0;

// =======================
// Setup
// =======================
void setup() {
  Serial.begin(115200);

  dht.begin();

  pinMode(RELAY_PIN, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(BLUE_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  Wire.begin(OLED_SDA, OLED_SCL);

  if (!display.begin(
        SSD1306_SWITCHCAPVCC,
        OLED_ADDRESS
      )) {
    Serial.println("OLED ERROR");
    while (true) {
      delay(100);
    }
  }

  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(2);
  display.setCursor(15, 10);
  display.println("EcoSense");
  display.setTextSize(1);
  display.setCursor(25, 40);
  display.println("Starting...");
  display.display();

  delay(2000);

  // CSV header: column names
  Serial.println(
    "Time_ms,Temperature_C,Humidity_pct,"
    "LightRaw,LightLevel_approx,Fan,Alert,LightState"
  );
}

// =======================
// Loop
// =======================
void loop() {
  // Read sensors
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();
  int lightRaw = analogRead(LDR_PIN);

  // Approximate light index
  float lightLevel = map(
    lightRaw,
    0,
    4095,
    10000,
    0
  );

  // Check DHT22
  if (isnan(temperature) || isnan(humidity)) {
    Serial.println("ERROR: DHT22 reading failed");

    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(BLUE_LED, LOW);
    digitalWrite(RELAY_PIN, LOW);
    noTone(BUZZER_PIN);

    delay(2000);
    return;
  }

  // =======================
  // Decisions
  // =======================
bool highTemperature = temperature >= HIGH_TEMP;
bool lightON = lightLevel >= LIGHT_THRESHOLD;

bool fanON = highTemperature;
bool alert = highTemperature || lightON;

  // =======================
  // Relay
  // =======================
  digitalWrite(RELAY_PIN, fanON ? HIGH : LOW);

  // =======================
  // LEDs
  // =======================
  digitalWrite(RED_LED, alert ? HIGH : LOW);
  digitalWrite(GREEN_LED, alert ? LOW : HIGH);
  digitalWrite(BLUE_LED, lightON ? HIGH : LOW);

  // =======================
  // Buzzer
  // =======================
  if (alert) {
    tone(BUZZER_PIN, 1000);
  } else {
    noTone(BUZZER_PIN);
  }

  // =======================
  // OLED display
  // =======================
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);

  display.setCursor(0, 0);
  display.println("EcoSense");

  display.setCursor(0, 14);
  display.print("Temp: ");
  display.print(temperature, 1);
  display.println(" C");

  display.setCursor(0, 27);
  display.print("Humidity: ");
  display.print(humidity, 1);
  display.println("%");

  display.setCursor(0, 40);
  display.print("Light: ");
  display.print(lightLevel, 0);

  display.setCursor(0, 53);
  display.print("State: ");
  display.print(lightON ? "LIGHT" : "DARK");

  display.display();

  // =======================
  // CSV data logging
  // One row every 2 seconds
  // =======================
  Serial.print(millis());
  Serial.print(",");

  Serial.print(temperature, 2);
  Serial.print(",");

  Serial.print(humidity, 2);
  Serial.print(",");

  Serial.print(lightRaw);
  Serial.print(",");

  Serial.print(lightLevel, 2);
  Serial.print(",");

  Serial.print(fanON ? "ON" : "OFF");
  Serial.print(",");

  Serial.print(alert ? "YES" : "NO");
  Serial.print(",");

  Serial.println(lightON ? "LIGHT" : "DARK");

  delay(2000);
}