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

// Define pin connections and initialize LCD display
const int fanPin = 3;        // PWM control pin for fan
const int switch1Pin = 4;    // Pin for switch 1 (100%)
const int switch2Pin = 5;    // Pin for switch 2 (50%)
const int switch3Pin = 6;    // Pin for switch 3 (0%)
const int emergencyStopPin = 7; // Pin for emergency stop switch
const int tachPin = 2;       // Pin for tachometer signal

LiquidCrystal_I2C lcd(0x27, 16, 2); // Adjust address and size for your I2C module

// Variable declarations for RPM calculation and debouncing
volatile int rpmCount = 0;
unsigned int rpm = 0;
unsigned long lastRPMCalc = 0;
unsigned long lastDebounceTime1 = 0;
unsigned long lastDebounceTime2 = 0;
unsigned long lastDebounceTime3 = 0;
unsigned long lastDebounceTime4 = 0;
unsigned long debounceDelay = 50;

int fanState = 128; // Start with 50% speed
int lastSwitchState1 = HIGH;
int lastSwitchState2 = HIGH;
int lastSwitchState3 = HIGH;
int lastEmergencyStopState = HIGH;
int currentSwitchState1 = HIGH;
int currentSwitchState2 = HIGH;
int currentSwitchState3 = HIGH;

void rpmInterrupt() {
  rpmCount++;
}

void setup() {
  // Set pin modes
  pinMode(fanPin, OUTPUT);
  pinMode(switch1Pin, INPUT_PULLUP);
  pinMode(switch2Pin, INPUT_PULLUP);
  pinMode(switch3Pin, INPUT_PULLUP);
  pinMode(emergencyStopPin, INPUT_PULLUP);
  pinMode(tachPin, INPUT_PULLUP);

  // Attach interrupt for tachometer
  attachInterrupt(digitalPinToInterrupt(tachPin), rpmInterrupt, FALLING);

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

  // Set initial fan state
  analogWrite(fanPin, fanState);
  lastRPMCalc = millis();
}

void loop() {
  // Read switch states
  int reading1 = digitalRead(switch1Pin);
  int reading2 = digitalRead(switch2Pin);
  int reading3 = digitalRead(switch3Pin);
  int emergencyStopReading = digitalRead(emergencyStopPin);

  // Handle emergency stop
  if (emergencyStopReading != lastEmergencyStopState) {
    lastDebounceTime4 = millis();
  }

  if ((millis() - lastDebounceTime4) > debounceDelay) {
    if (emergencyStopReading == LOW) {
      setFanSpeed(0); // Immediately stop the fan
      displayState("EMERGENCY STOP");
    }
  }

  // Handle switch 1 (100% speed)
  if (reading1 != lastSwitchState1) {
    lastDebounceTime1 = millis();
  }
  if ((millis() - lastDebounceTime1) > debounceDelay && emergencyStopReading == HIGH) {
    if (reading1 == LOW && currentSwitchState1 == HIGH) {
      setFanSpeed(255); // Soft start to 100% speed
      displayState("100%");
      currentSwitchState1 = LOW;
      currentSwitchState2 = HIGH;
      currentSwitchState3 = HIGH;
    }
  }

  // Handle switch 2 (50% speed)
  if (reading2 != lastSwitchState2) {
    lastDebounceTime2 = millis();
  }
  if ((millis() - lastDebounceTime2) > debounceDelay && emergencyStopReading == HIGH) {
    if (reading2 == LOW && currentSwitchState2 == HIGH) {
      setFanSpeed(128); // Soft start to 50% speed
      displayState("50%");
      currentSwitchState1 = HIGH;
      currentSwitchState2 = LOW;
      currentSwitchState3 = HIGH;
    }
  }

  // Handle switch 3 (0% speed/off)
  if (reading3 != lastSwitchState3) {
    lastDebounceTime3 = millis();
  }
  if ((millis() - lastDebounceTime3) > debounceDelay && emergencyStopReading == HIGH) {
    if (reading3 == LOW && currentSwitchState3 == HIGH) {
      setFanSpeed(0); // Soft start to 0% speed (off)
      displayState("OFF");
      currentSwitchState1 = HIGH;
      currentSwitchState2 = HIGH;
      currentSwitchState3 = LOW;
    }
  }

  // Update last states
  lastSwitchState1 = reading1;
  lastSwitchState2 = reading2;
  lastSwitchState3 = reading3;
  lastEmergencyStopState = emergencyStopReading;

  // Calculate RPM every second
  if (millis() - lastRPMCalc >= 1000) {
    rpm = (rpmCount * 60) / 4; // Convert to RPM (4 pulses per revolution)
    rpmCount = 0;
    lastRPMCalc = millis();
    displayRPM(rpm);
  }
}

void setFanSpeed(int targetSpeed) {
  int currentSpeed = analogRead(fanPin); // Read the current PWM value
  int step = (targetSpeed > currentSpeed) ? 1 : -1;
  while (currentSpeed != targetSpeed) {
    currentSpeed += step;
    analogWrite(fanPin, currentSpeed);
    delay(10); // Adjust delay for smoother or faster transitions
  }
}

void displayState(const char* state) {
  lcd.setCursor(0, 0);
  lcd.print("State: ");
  lcd.print(state);
  lcd.print("    "); // Clear any remaining characters
}

void displayRPM(unsigned int rpm) {
  lcd.setCursor(0, 1);
  lcd.print("RPM: ");
  lcd.print(rpm);
  lcd.print("    "); // Clear any remaining characters
}