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

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

int sensorPin = A0; // Analog input pin for the potentiometer (hydration sensor)
int ledPin = 13;    // Digital output pin for the built-in LED

int readings[10];     // Array to store the last 10 hydration readings
int currentIndex = 0; // Current index in the readings array
int total = 0;        // Running total of hydration readings
int average = 0;      // Calculated average hydration level

void setup() {
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);

  // Initialize OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.display();
  delay(2000);  // Pause for 2 seconds
  display.clearDisplay();

  // Initialize readings array
  for (int i = 0; i < 10; i++) {
    readings[i] = 0;
  }
}

void loop() {
  int sensorValue = analogRead(sensorPin); // Read the simulated hydration level from the potentiometer

  // Map the sensor value to a hydration level (0-100%)
  int hydrationLevel = map(sensorValue, 0, 1023, 0, 100);
  
  // Subtract the last reading from the total
  total = total - readings[currentIndex];
  
  // Add the current reading to the total
  readings[currentIndex] = hydrationLevel;
  total = total + readings[currentIndex];
  
  // Advance to the next position in the array
  currentIndex = currentIndex + 1;

  // If we're at the end of the array, wrap around to the beginning
  if (currentIndex >= 10) {
    currentIndex = 0;
  }
  
  // Calculate the average
  average = total / 10;

  // Print the hydration level and average to the serial monitor
  Serial.print("Hydration Level: ");
  Serial.println(hydrationLevel);
  Serial.print("Average Hydration: ");
  Serial.println(average);

  // Display the hydration level and average on the OLED
  display.clearDisplay();
  display.setTextSize(1);             // Display text size
  display.setTextColor(SSD1306_WHITE); // Display text color
  display.setCursor(0,10);            // Display text starting position
  display.print("Hydration: ");
  display.print(hydrationLevel);
  display.print("%");
  display.setCursor(0, 30);
  display.print("Average: ");
  display.print(average);
  display.print("%");
  
  // If hydration level is below the average, indicate on the display and turn on the LED
  if (hydrationLevel < average) {
    display.setCursor(0, 50);
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.print("Hydration Low!");
    
    digitalWrite(ledPin, HIGH); // Turn on the LED
  } else {
    display.setCursor(0, 50);
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.print("Hydration Normal");
    
    digitalWrite(ledPin, LOW); // Turn off the LED
  }

  display.display();                  // Show the display

  delay(1000); // Delay for 1 second before next reading
}