/*
  Greenhouse IoT System - Core Driver
  Platform: ESP32 (Wokwi Simulation)
  
  Features:
  - Auto Watering (Based on Soil Moisture & Water Tank Level)
  - Auto Ventilation (Based on Air Temperature)
  - Tank Level Display (LED Bar)
  - Status Display (I2C LCD)
*/

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

// ================= Pin Definitions =================
#define PIN_DHT         15
#define PIN_TRIG        5
#define PIN_ECHO        18
#define PIN_RELAY_PUMP  4
#define PIN_SOIL        34 // Analog Input
#define PIN_STEP        19
#define PIN_DIR         23

// LED Bar Pins (Low Level to High Level)
const int ledPins[5] = {13, 12, 14, 27, 26};

// ================= Configuration =================
#define DHTTYPE DHT22
const float DIST_TANK_HEIGHT = 20.0; // cm (Tank depth)
const float DIST_EMPTY_THRESH = 15.0; // cm (Distance > 15cm means water is low)

// Thresholds
const int SOIL_DRY_THRESH = 30; // % (Start watering if < 30%)
const int SOIL_WET_THRESH = 70; // % (Stop watering if > 70%)
const float TEMP_HOT_THRESH = 30.0; // C (Open fan/window if > 30C)
const float TEMP_COOL_THRESH = 25.0; // C (Close fan/window if < 25C)

// ================= Global Objects =================
DHT dht(PIN_DHT, DHTTYPE);
LiquidCrystal_I2C lcd(0x27, 16, 2);

// ================= Variables =================
float airTemp = 0;
float airHum = 0;
int soilMoisturePercent = 0;
float waterLevelCm = 0; // Calculated water height
float distanceCm = 0;   // Raw ultrasonic distance

bool isWatering = false;
bool isVentOpen = false;
bool tankEmpty = false;

// Timer variables (Non-blocking)
unsigned long lastSensorTime = 0;
unsigned long lastScreenTime = 0;
const long SENSOR_INTERVAL = 2000; // Read sensors every 2s
const long SCREEN_INTERVAL = 1000; // Update screen every 1s

// ================= Setup =================
void setup() {
  Serial.begin(115200);
  
  // Pin Modes
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
  pinMode(PIN_RELAY_PUMP, OUTPUT);
  pinMode(PIN_STEP, OUTPUT);
  pinMode(PIN_DIR, OUTPUT);
  digitalWrite(PIN_RELAY_PUMP, LOW); // Assume HIGH trigger or init state

  for(int i=0; i<5; i++) {
    pinMode(ledPins[i], OUTPUT);
    digitalWrite(ledPins[i], LOW);
  }

  // Init Components
  dht.begin();
  lcd.init();
  lcd.backlight();
  
  lcd.setCursor(0,0);
  lcd.print("Greenhouse Sys");
  lcd.setCursor(0,1);
  lcd.print("Initializing...");
  delay(1500);
  lcd.clear();
}

// ================= Main Loop =================
void loop() {
  unsigned long currentMillis = millis();

  // 1. Task: Read Sensors
  if (currentMillis - lastSensorTime >= SENSOR_INTERVAL) {
    lastSensorTime = currentMillis;
    readSensors();
    controlSystem(); // Run logic after reading
  }

  // 2. Task: Update LCD
  if (currentMillis - lastScreenTime >= SCREEN_INTERVAL) {
    lastScreenTime = currentMillis;
    updateDisplay();
  }
}

// ================= Functions =================

void readSensors() {
  // --- DHT22 ---
  airTemp = dht.readTemperature();
  airHum = dht.readHumidity();

  // --- Soil Moisture (Simulated) ---
  // Potentiometer gives 0-4095. Map to 0-100%
  int rawSoil = analogRead(PIN_SOIL);
  soilMoisturePercent = map(rawSoil, 0, 4095, 0, 100);

  // --- Ultrasonic (Water Level) ---
  digitalWrite(PIN_TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);
  long duration = pulseIn(PIN_ECHO, HIGH);
  distanceCm = duration * 0.034 / 2;
  
  // Calculate Water Height (Tank Height - Distance to water surface)
  waterLevelCm = DIST_TANK_HEIGHT - distanceCm;
  if (waterLevelCm < 0) waterLevelCm = 0; 
  
  // Safety Check
  if (distanceCm >= DIST_EMPTY_THRESH) {
    tankEmpty = true;
  } else {
    tankEmpty = false;
  }
  
  // Update LED Bar (Visual Water Level)
  // Map water level (0 to 20cm) to 0 to 5 LEDs
  int ledLevel = map((int)waterLevelCm, 0, (int)DIST_TANK_HEIGHT, 0, 5);
  for(int i=0; i<5; i++) {
    if (i < ledLevel) digitalWrite(ledPins[i], HIGH);
    else digitalWrite(ledPins[i], LOW);
  }
}

void controlSystem() {
  // --- Watering Logic ---
  // If Tank is Empty -> STOP PUMP immediately (Protection)
  if (tankEmpty) {
    digitalWrite(PIN_RELAY_PUMP, LOW); // OFF (Adjust if Relay is Active LOW)
    isWatering = false;
  } 
  else {
    // Tank has water, check Soil
    if (!isWatering && soilMoisturePercent < SOIL_DRY_THRESH) {
      digitalWrite(PIN_RELAY_PUMP, HIGH); // Turn ON Pump
      isWatering = true;
    } 
    else if (isWatering && soilMoisturePercent > SOIL_WET_THRESH) {
      digitalWrite(PIN_RELAY_PUMP, LOW); // Turn OFF Pump
      isWatering = false;
    }
  }

  // --- Ventilation Logic (Stepper) ---
  // Simple logic: If hot, open window (move stepper). If cool, close.
  // Note: A4988 needs pulses.
  if (!isVentOpen && airTemp > TEMP_HOT_THRESH) {
    // Open Window (Rotate CW)
    moveStepper(true, 200); // 200 steps
    isVentOpen = true;
  }
  else if (isVentOpen && airTemp < TEMP_COOL_THRESH) {
    // Close Window (Rotate CCW)
    moveStepper(false, 200); // 200 steps back
    isVentOpen = false;
  }
}

// Helper to move stepper (Blocking slightly, but short duration for demo)
// For best IoT performance, use AccelStepper non-blocking in future
void moveStepper(bool dir, int steps) {
  digitalWrite(PIN_DIR, dir ? HIGH : LOW);
  for(int i=0; i<steps; i++) {
    digitalWrite(PIN_STEP, HIGH);
    delayMicroseconds(1000); // Speed control
    digitalWrite(PIN_STEP, LOW);
    delayMicroseconds(1000);
  }
}

void updateDisplay() {
  // Rotate display info
  static int page = 0;
  page = !page; // Toggle 0 and 1

  lcd.setCursor(0, 0);
  if (page == 0) {
    // Page 1: Environment
    lcd.print("T:"); lcd.print((int)airTemp); lcd.print("C ");
    lcd.print("H:"); lcd.print((int)airHum); lcd.print("%   ");
    
    lcd.setCursor(0, 1);
    lcd.print("Soil:"); lcd.print(soilMoisturePercent); lcd.print("% ");
    lcd.print(isWatering ? "P:ON " : "P:OFF");
  } else {
    // Page 2: System Status
    lcd.print("Tank Lvl: "); 
    if(tankEmpty) lcd.print("EMPTY!"); 
    else { lcd.print((int)waterLevelCm); lcd.print("cm "); }

    lcd.setCursor(0, 1);
    lcd.print("Vent: ");
    lcd.print(isVentOpen ? "OPEN " : "SHUT ");
  }
  
  // Debug to Serial
  Serial.printf("T:%.1f H:%.1f Soil:%d%% Tank:%.1fcm Pump:%d Vent:%d\n", 
    airTemp, airHum, soilMoisturePercent, waterLevelCm, isWatering, isVentOpen);
}