#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_LED   18  // Visual reference for IR Sensor activity
#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;

// --- THRESHOLDS & VARIABLES ---
const int MIN_ALCOHOL_LEVEL = 1000; 
bool cycleComplete = false;

void setup() {
  pinMode(PIN_STEP, OUTPUT);
  pinMode(PIN_DIR, OUTPUT);
  pinMode(PIN_BUZZER, OUTPUT);
  pinMode(PIN_IR_LED, OUTPUT); // The IR status light
  pinMode(PIN_LED_R, OUTPUT);
  pinMode(PIN_LED_G, OUTPUT);
  pinMode(PIN_LED_B, OUTPUT);
  
  digitalWrite(PIN_BUZZER, LOW);
  digitalWrite(PIN_IR_LED, LOW);
  setRGB(0, 0, 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("IR SENSOR ACTIVE");
  delay(2000);
}

void loop() {
  if (!cycleComplete) {
    // 3-Station Sequence
    for (int station = 1; station <= 3; station++) {
      handleMovement(station, true);
      beepArrival();
      handleProcessing(station);
    }
    
    // Return to Start
    handleMovement(1, false);
    
    // Final State
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("CYCLE SUCCESSFUL");
    lcd.setCursor(0, 1);
    lcd.print("SYSTEM AT HOME");
    setRGB(0, 0, 0); 
    digitalWrite(PIN_IR_LED, LOW);
    cycleComplete = true; 
  }
}

// ==========================================
// MOVEMENT: IR Status LED is ON here
// ==========================================
void handleMovement(int station, bool forward) {
  lcd.clear();
  setRGB(0, 255, 0);         // Green for Stepper Moving
  digitalWrite(PIN_IR_LED, HIGH); // IR Sensor LED ON (Searching)
  
  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(1000);
    digitalWrite(PIN_STEP, LOW);
    delayMicroseconds(1000);
  }
  
  digitalWrite(PIN_IR_LED, LOW); // IR Sensor LED OFF (Arrived)
}

// ==========================================
// PROCESSING: IR Status LED is OFF here
// ==========================================
void handleProcessing(int station) {
  float currentTemp = (station == 1) ? 22.5 : (station == 2) ? 23.1 : 62.0;

  // --- STAGE: IMMERSION (15s) ---
  setRGB(255, 0, 0); // Red LED
  liftServo.write(90); 
  updateDisplay(station, "Immersion", currentTemp);
  monitorAndDelay(15000);

  // --- STAGE: LIFTING (8s) ---
  setRGB(0, 0, 255); // Blue LED
  liftServo.write(0); 
  updateDisplay(station, "Lifting  ", currentTemp);
  monitorAndDelay(8000);

  // --- STAGE: PURGING (7s) ---
  updateDisplay(station, "Purging  ", currentTemp);
  monitorAndDelay(7000);
}

// ==========================================
// HELPERS
// ==========================================
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);
    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); 
  }
}

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(150);
  digitalWrite(PIN_BUZZER, LOW);
}