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

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

Servo fanServo;
const int BUTTON_PIN = 2;

int speedState = 0; // 0=OFF, 1=LOW, 2=MED, 3=TURBO
String speedNames[] = {"OFF", "LOW", "MED", "TURBO"};

// Live Battery values logic
int batteryLife = 98;
unsigned long lastBatteryTime = 0;
unsigned long lastDisplayTime = 0;

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  fanServo.attach(9); 
  fanServo.write(0); // Rest position at start
  
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    for(;;);
  }
  
  display.clearDisplay();
  updateDisplay();
}

void loop() {
  unsigned long currentMillis = millis();

  // 1. Simple Click Detection Handler
  if (digitalRead(BUTTON_PIN) == LOW) {
    speedState = (speedState + 1) % 4; // Cycles: 0 -> 1 -> 2 -> 3 -> 0
    
    // Position angles dynamically based on speed modes
    if (speedState == 0) fanServo.write(0);
    else if (speedState == 1) fanServo.write(45);
    else if (speedState == 2) fanServo.write(110);
    else if (speedState == 3) fanServo.write(180);
    
    updateDisplay();
    delay(300); // Click stabilization pause (Debounce)
  }

  // 2. Dynamic Battery Consumption Engine
  if (speedState > 0) {
    int drainInterval = 200000 / speedState; // Higher speeds drain battery faster
    if (currentMillis - lastBatteryTime >= drainInterval) {
      if (batteryLife > 0) batteryLife--;
      lastBatteryTime = currentMillis;
    }
  }

  // 3. Auto Refresh Interface Frame every 300ms
  if (currentMillis - lastDisplayTime >= 300) {
    updateDisplay();
    lastDisplayTime = currentMillis;
  }
}

void updateDisplay() {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  
  // Render Current Battery Text Status
  display.setTextSize(1);
  display.setCursor(10, 8);
  display.print("BATTERY: ");
  display.print(batteryLife);
  display.print("% mAh");
  
  // DRAW CORE FIXES HERE: Correct function syntax layout
  // drawRect = Outlined rectangle box frame container
  display.drawRect(10, 22, 100, 10, SSD1306_WHITE);
  
  if(batteryLife > 0) {
    // fillRect = Filled indicator percentage block graphic
    display.fillRect(12, 24, batteryLife, 6, SSD1306_WHITE);
  }
  
  // Render active speed mode texts
  display.setCursor(10, 44);
  display.setTextSize(2);
  display.print(speedNames[speedState]);
  
  display.display();
}