#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Pin Definitions
const int pwmPin = 3;       // PWM pin for fan speed
const int tachPin = 2;      // Tachometer pin to read RPM
const int encoderClk = 6;   // Rotary encoder CLK pin
const int encoderDt = 7;    // Rotary encoder DT pin
const int encoderSw = 8;    // Rotary encoder button

// LCD Setup
LiquidCrystal_I2C lcd(0x27, 16, 2);  // LCD address and size (16x2)

// Variables
volatile int tachCount = 0;
unsigned long lastTime = 0;
int fanRPM = 0;
int fanSpeed = 0;  // Speed levels: 0 (off) to 3

// Debounce for Encoder
#define DEBOUNCE_DELAY 5
unsigned long lastDebounceTime = 0;
int lastClkState = HIGH;

// Function for loading animation
void loadingAnimation(LiquidCrystal_I2C &lcd) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Loading...");
  for (int i = 0; i < 16; i++) {  // 16 is the number of columns
    lcd.setCursor(i, 1);
    lcd.write(byte(255));  // Write a filled block (progress bar)
    delay(150);            // Adjust speed as needed
  }
}

void setup() {
  // Pin setup
  pinMode(pwmPin, OUTPUT);
  pinMode(tachPin, INPUT_PULLUP);
  pinMode(encoderClk, INPUT_PULLUP);
  pinMode(encoderDt, INPUT_PULLUP);
  pinMode(encoderSw, INPUT_PULLUP);  // Encoder button with pull-up

  analogWrite(pwmPin, 0);  // Ensure PWM is off initially

  // LCD setup
  lcd.init();
  lcd.backlight();

  // Display loading animation
  loadingAnimation(lcd);

  // Initial LCD display
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Speed: 0");
  lcd.setCursor(0, 1);
  lcd.print("RPM: 0");

  // Tachometer interrupt
  attachInterrupt(digitalPinToInterrupt(tachPin), countTachPulses, FALLING);
}

void loop() {
  // Handle rotary encoder input
  handleEncoder();

  // Calculate RPM every second
  if (millis() - lastTime >= 1000) {
    noInterrupts();
    int count = tachCount;
    tachCount = 0;
    interrupts();

    fanRPM = (count * 60) / 2;  // Calculate RPM (2 pulses per revolution)
    updateLCD();
    lastTime = millis();
  }
}

// Handle rotary encoder with debounce
void handleEncoder() {
  int clkState = digitalRead(encoderClk);
  int dtState = digitalRead(encoderDt);

  if (clkState != lastClkState) {
    if (millis() - lastDebounceTime > DEBOUNCE_DELAY) {
      if (clkState == LOW) {  // Detect step on CLK falling edge
        if (dtState == HIGH) {
          fanSpeed = constrain(fanSpeed + 1, 0, 3);  // Clockwise
        } else {
          fanSpeed = constrain(fanSpeed - 1, 0, 3);  // Counter-clockwise
        }
        updateFanSpeed();
        updateLCD();
      }
      lastDebounceTime = millis();
    }
  }
  lastClkState = clkState;
}

// Update fan speed based on fanSpeed value
void updateFanSpeed() {
  int pwmValue = map(fanSpeed, 0, 3, 0, 255);  // Map speed to PWM range
  analogWrite(pwmPin, pwmValue);  // Set PWM speed
}

// Update the LCD display without flickering
void updateLCD() {
  static int lastFanSpeed = -1;
  static int lastFanRPM = -1;

  // Update only if values have changed
  if (fanSpeed != lastFanSpeed || fanRPM != lastFanRPM) {
    lcd.setCursor(0, 0);
    lcd.print("Speed: ");
    lcd.print(fanSpeed);
    lcd.print(" ");  // Clear leftover characters
    lcd.setCursor(0, 1);
    lcd.print("RPM: ");
    lcd.print(fanRPM);
    lcd.print(" ");  // Clear leftover characters
    lastFanSpeed = fanSpeed;
    lastFanRPM = fanRPM;
  }
}

// Interrupt Service Routine for tachometer
void countTachPulses() {
  tachCount++;
}