#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <ESP32Servo.h>

// --- PIN DEFINITIONS ---
#define PIN_STEP     27
#define PIN_DIR      26
#define PIN_SERVO    32
#define PIN_BUZZER   25
#define PIN_POT      34  
#define PIN_IR_STAT  18  // Corrected to Pin 18 as per your instruction
#define PIN_LED_R    14
#define PIN_LED_G    12
#define PIN_LED_B    13

// --- SYSTEM OBJECTS ---
LiquidCrystal_I2C lcd(0x27, 20, 4); 
Servo liftServo;

const int MIN_ALCOHOL_LEVEL = 1000; 
const int STEP_DELAY = 1000; // Real-world NEMA 17 pulse timing
bool cycleComplete = false;

void setup() {
  pinMode(PIN_STEP, OUTPUT);
  pinMode(PIN_DIR, OUTPUT);
  pinMode(PIN_BUZZER, OUTPUT);
  pinMode(PIN_IR_STAT, OUTPUT); 
  pinMode(PIN_LED_R, OUTPUT);
  pinMode(PIN_LED_G, OUTPUT);
  pinMode(PIN_LED_B, OUTPUT);
  
  digitalWrite(PIN_IR_STAT, LOW);
  setRGB(0, 0, 0); 

  // Required for Servo response on ESP32
  ESP32PWM::allocateTimer(0);
  liftServo.setPeriodHertz(50);
  liftServo.attach(PIN_SERVO, 500, 2400);
  liftServo.write(0); 

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("TISSUE PROCESSOR");
  lcd.setCursor(0, 1);
  lcd.print("READY TO START");
  delay(2000);
}

void loop() {
  if (!cycleComplete) {
    for (int station = 1; station <= 3; station++) {
      // 1. MOVEMENT: Green LED ON, Status LED 18 OFF
      handleMovement(station, true);
      
      // 2. ARRIVAL: Status LED 18 ON, Single Beep
      digitalWrite(PIN_IR_STAT, HIGH);
      beepArrival();
      
      // 3. PROCESSING: Red/Blue LEDs, Servo Action, 30s Total
      handleProcessing(station);
    }
    
    // RETURN HOME (Back to Station 1)
    handleMovement(1, false);
    
    // FINAL SHUTDOWN
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Cycle successful");
    setRGB(0, 0, 0); 
    digitalWrite(PIN_IR_STAT, LOW);
    cycleComplete = true; 
  }
}

// ==========================================
// TRANSITION: Stepper Rotation (10 Seconds)
// ==========================================
void handleMovement(int station, bool forward) {
  lcd.clear();
  setRGB(0, 255, 0);              // Green LED ON for movement
  digitalWrite(PIN_IR_STAT, LOW); // Status LED OFF during travel
  
  lcd.setCursor(0, 0);
  if (forward) {
    lcd.print("Moving to station ");
    lcd.print(station);
    digitalWrite(PIN_DIR, HIGH);
  } else {
    lcd.print("Returning Home...");
    digitalWrite(PIN_DIR, LOW);
  }

  unsigned long startMove = millis();
  while (millis() - startMove < 10000) { 
    digitalWrite(PIN_STEP, HIGH);
    delayMicroseconds(STEP_DELAY);
    digitalWrite(PIN_STEP, LOW);
    delayMicroseconds(STEP_DELAY);
  }
}

// ==========================================
// TRANSITION: Station Processing (30 Seconds)
// ==========================================
void handleProcessing(int station) {
  // Presentation data
  float temp = (station == 1) ? 22.5 : (station == 2) ? 23.1 : 62.0;

  // --- STAGE 1: Immersion (15s) ---
  setRGB(255, 0, 0);   // Red LED ON
  liftServo.write(90); // Servo DOWN
  updateDisplay(station, "Immersion", temp);
  monitorAndDelay(15000);

  // --- STAGE 2: Lifting (8s) ---
  setRGB(0, 0, 255);   // Blue LED ON
  liftServo.write(0);  // Servo UP
  updateDisplay(station, "Lifting  ", temp);
  monitorAndDelay(8000);

  // --- STAGE 3: Purging (7s) ---
  // Blue LED stays ON (represents blower fan carryover mitigation)
  updateDisplay(station, "Purging  ", temp);
  monitorAndDelay(7000);
}

// ==========================================
// HELPERS: Display & Safety
// ==========================================
void updateDisplay(int st, String stage, float temp) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("STATION: "); lcd.print(st);
  lcd.setCursor(0, 1);
  lcd.print("STAGE:   "); lcd.print(stage);
  lcd.setCursor(0, 2);
  lcd.print("TEMP:    "); lcd.print(temp, 1); lcd.print(" C");
}

void monitorAndDelay(unsigned long waitTime) {
  unsigned long startTime = millis();
  while (millis() - startTime < waitTime) {
    int alc = analogRead(PIN_POT);
    // Beep and display alarm if concentration drops
    if (alc < MIN_ALCOHOL_LEVEL) {
      digitalWrite(PIN_BUZZER, HIGH);
      lcd.setCursor(0, 3);
      lcd.print("!! LOW ALCOHOL !!");
    } else {
      digitalWrite(PIN_BUZZER, LOW);
      lcd.setCursor(0, 3);
      lcd.print("                 ");
    }
    delay(100); 
  }
  digitalWrite(PIN_BUZZER, LOW);
}

void setRGB(int r, int g, int b) {
  analogWrite(PIN_LED_R, r);
  analogWrite(PIN_LED_G, g);
  analogWrite(PIN_LED_B, b);
}

void beepArrival() {
  digitalWrite(PIN_BUZZER, HIGH);
  delay(200);
  digitalWrite(PIN_BUZZER, LOW);
}