#include "Wire.h" // Emulated Wire.h library
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// Pin Definitions
#define TEMP_SENSOR_PIN A0
#define SLIDER_PIN A1 // Analog pin for sliding potentiometer
#define POWER_MODE_PIN 4
#define SWITCH_PIN 2 // Pin for the switch
#define CONDENSER_FAN_PIN 5
#define EVAPORATOR_FAN_PIN 6
#define COMPRESSOR_PIN 7

// Power Modes
#define OFF_MODE 0
#define ON_MODE 1
#define AUTO_MODE 2

// Temperature Constants
#define MIN_TEMP 50 // Minimum temperature (in Fahrenheit)
#define MAX_TEMP 99 // Maximum temperature (in Fahrenheit)

// Timing Constants (in milliseconds)
#define FAN_DELAY 3000 // 3 seconds delay between turning on fans
#define COMPRESSOR_DELAY 6000 // 6 seconds delay before turning on compressor
#define COOLING_CYCLE_INTERVAL 1800000 // 30 minutes interval before cooling cycle starts again in ON mode
#define AUTO_MODE_DELAY 600000 // 10 minutes delay before turning on again in AUTO mode

// Global Variables
float currentTemperature = 0.0;
float setPointTemperature = 75.0; // Initial set point temperature
int powerMode = OFF_MODE;
unsigned long lastCoolingStartTime = 0;

// Initialize OLED Display
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Button State Variables
int sliderValue = 0; // Slider value from the potentiometer

void setup() {
  // Initialize Serial Communication
  Serial.begin(9600);

  // Initialize I2C communication
  Wire.begin();

  // Initialize pins
  pinMode(POWER_MODE_PIN, INPUT_PULLUP);
  pinMode(SWITCH_PIN, INPUT_PULLUP); // Set the switch pin as input with internal pull-up resistor
  pinMode(CONDENSER_FAN_PIN, OUTPUT);
  pinMode(EVAPORATOR_FAN_PIN, OUTPUT);
  pinMode(COMPRESSOR_PIN, OUTPUT);

  // Initialize OLED display
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;)
      ;
  }
  display.display();
  delay(2000);
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.print("Thermostat");
  display.setCursor(0, 10); // Set cursor to the second line
  display.print("Initialized");
  display.display();
  delay(2000);
  display.clearDisplay();
}

void loop() {
  // Read temperature
  currentTemperature = readTemperature();

  // Read slider value
  sliderValue = analogRead(SLIDER_PIN);

  // Map slider value to set point temperature range
  setPointTemperature = map(sliderValue, 0, 1023, MIN_TEMP, MAX_TEMP);

  // Check the state of the switch
  bool switchState = digitalRead(SWITCH_PIN);

  // Update power mode based on switch state
  if (switchState == LOW) {
    powerMode = ON_MODE;
  } else {
    powerMode = OFF_MODE;
  }

  // Control air conditioner based on power mode
  switch (powerMode) {
    case OFF_MODE:
      turnOffAC();
      break;
    case ON_MODE:
      if (currentTemperature > setPointTemperature) {
        turnOnAC();
      } else if (millis() - lastCoolingStartTime >= COOLING_CYCLE_INTERVAL) {
        turnOffAC();
      }
      break;
    case AUTO_MODE:
      if (currentTemperature > setPointTemperature) {
        if (millis() - lastCoolingStartTime >= COOLING_CYCLE_INTERVAL) {
          turnOnAC();
        }
      } else if (currentTemperature <= setPointTemperature - 3) {
        turnOffAC();
      }
      break;
  }

  // Display temperature readings
  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.print("Set Point: ");
  display.print((int)setPointTemperature); // Cast setPointTemperature to int to display only the whole number part
  display.setCursor(0, 10);
  display.print("Current Temp: ");
  display.print((int)currentTemperature); // Cast currentTemperature to int to display only the whole number part
  display.print(" °F"); // Display the °F symbol for Fahrenheit
  display.setCursor(0, 20);
  display.print("Power Mode: ");
  switch (powerMode) {
    case OFF_MODE:
      display.print("Off");
      break;
    case ON_MODE:
      display.print("On");
      break;
    case AUTO_MODE:
      display.print("Auto");
      break;
  }
  display.display();
  delay(100); // Add a small delay to prevent excessive display updating
}

float readTemperature() {
  const float BETA = 3950; // Beta Coefficient of the thermistor

  // Read the analog value from the temperature sensor
  int analogValue = analogRead(TEMP_SENSOR_PIN);

  // Calculate temperature in Celsius
  float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;

  // Convert Celsius to Fahrenheit
  float fahrenheit = celsius * 9 / 5 + 32;

  return fahrenheit;
}

void turnOnAC() {
  digitalWrite(CONDENSER_FAN_PIN, HIGH);
  delay(FAN_DELAY);
  digitalWrite(EVAPORATOR_FAN_PIN, HIGH);
  delay(FAN_DELAY);
  digitalWrite(COMPRESSOR_PIN, HIGH);
  delay(COMPRESSOR_DELAY);
  lastCoolingStartTime = millis();
}

void turnOffAC() {
  digitalWrite(CONDENSER_FAN_PIN, LOW);
   delay(FAN_DELAY);
  digitalWrite(EVAPORATOR_FAN_PIN, LOW);
  delay(FAN_DELAY);
  digitalWrite(COMPRESSOR_PIN, LOW);
}