#include <DHT.h>
#include <PID_v1.h>


// --- PIN DEFINITIONS ---

#define DHT22_1PIN 4    // PID Control Sensor 1
#define DHT22_2PIN 2    // Safety Protection Sensor 2
#define HEATER_CONTROL_PIN 16   // PID control to Heater MOSFET (PWM)
#define HEATER_SAFETY_PIN 17   // Safety protection (on/off depending on temp/humid hihi)
#define DHTTYPE DHT22

// --- EC11 Rotary Encoder Pins ---
// #define ENCODER_A 13       // CLK pin (usually labeled A or CLK)
// #define ENCODER_B 14       // DT pin (usually labeled B or DT)
// #define ENCODER_SW 15      // SW pin (push button)

// --- ROTARY ENCODER SETTINGS ---

// #define SETPOINT_MIN 20.0   // Minimum setpoint (°C)
// #define SETPOINT_MAX 50.0   // Maximum setpoint (°C)
// #define SETPOINT_STEP 0.5   // Step size (°C)

// ### SENSOR SETTINGS ###

// --- SENSOR 1: PID CONTROL SETTIGNS ---

#define DHT22_1SETPOINT 20.0    // FIXED Temperature setpoint
#define DHT22_1HIGH_ALARM 25.0  // Temp: High alarm (alarm only to cloud and phone)
#define DHT22_1LOW_ALARM 15.0   // Temp: Low alarm (alarm only to cloud and phone)

// --- SENSOR 2: SAFETY PROTECTION SETTINGS---

#define DHT22_2TEMP_HIHI 35.0   // Temperature HiHi - CUT OFF heater
#define DHT22_2HUMID_HIHI 70.0  // Humidity HiHi - TURN ON heater

// --- PID Variables ---
double pidSetpoint, pidInput, pidOutput;
// PID Tuning (Aggressive P for heater, Slow I for steady state, Reduce D oscillation time)
double Kp = 20.0, Ki = 5.0, Kd = 1.0;

// --- DIRECT mode: Heater speeds UP when Temp goes UP ---
PID heaterPID(&pidInput, &pidOutput, &pidSetpoint, Kp, Ki, Kd, DIRECT);

// --- Sensor objects with clear names ---

DHT DHT22_1PID(DHT22_1PIN, DHTTYPE);   // For PID control
DHT DHT22_2Safety(DHT22_2PIN, DHTTYPE); // For process safety protection

// --- VARIABLES ---

float temp1, humid1;  // Sensor 1 readings
float temp2, humid2;  // Sensor 2 readings

bool Heater_On = true; // Controls PID heater
bool DHT22_2tempHiHi = false;  // Temp > 35°C
bool DHT22_2humidHiHi = false; // Humid > 70%
bool DHT22_1highAlarm = false; // Temp > 25°C
bool DHT22_1lowAlarm = false;  // Temp < 15°C

// --- PWM CONFIGURATION FOR GPIO16 ---

const int PIDHEATER_CHANNEL = 0;  // Use channel 0 for heater

// --- Timing Variables ---
unsigned long lastPIDTime = 0;
const long pidInterval = 2000; // 2 seconds (matches DHT22 speed)

// --- SETUP FUNCTION ---

void setup() {
  Serial.begin(115200);

  Serial.println("\n========================================");
  Serial.println("    HEATING CONTROL SYSTEM");
  Serial.println("========================================");
  Serial.println("\nCONFIGURATION:");
  Serial.println("----------------------------------------");
  Serial.println("DHT22_1 (Sensor 1 PID Control):");
  Serial.print("  Setpoint: "); Serial.print(pidSetpoint); Serial.println("°C");
  Serial.print("  High Alarm: "); Serial.print(HIGH_ALARM); Serial.println("°C");
  Serial.print("  Low Alarm: "); Serial.print(LOW_ALARM); Serial.println("°C");
  Serial.println("  Controls: GPIO16 (PWM)");
  
  Serial.println("\nDHT22_2 (Sensor 2 Safety Protection):");
  Serial.print("  Temp HiHi: "); Serial.print(TEMP_HIHI); Serial.print("°C → GPIO17 OFF");
  Serial.print("  Humid HiHi: "); Serial.print(HUMID_HIHI); Serial.println("% → GPIO17 ON");
  Serial.println("  Controls: GPIO17 (ON/OFF)");
  Serial.println("----------------------------------------\n");

  // --- Initialize sensors ---

  DHT22_1.begin();
  DHT22_2.begin();
  delay(2000);
  
  // --- ESP32 PWM SETUP FOR GPIO16 PID CONTROL HEATER---
  
  // --- SETUP PID CONTROL SIGNAL FOR HEATER (GPI016 - PWM) ---
  
  ledcSetup(PIDHEATER_CHANNEL, 5000, 8);    // Channel 0, 5kHz, 8-bit
  ledcAttachPin(HEATER_CONTROL_PIN, PIDHEATER_CHANNEL);  // Attach GPIO16 to channel 0
  ledcWrite(PIDHEATER_CHANNEL, 0);          // Start with heater OFF
  
  // --- SETUP SAFETY PROTECTION SIGNAL FOR HEATER (GPIO17 - ON/OFF) ---

  pinMode(HEATER_SAFETY_PIN, OUTPUT);        // GPIO17 as digital output
  digitalWrite(HEATER_SAFETY_PIN, LOW);      // Start OFF
  
  // --- SETUP PID controller PARAMETERS  ---
  heaterPID.SetMode(AUTOMATIC);
  heaterPID.SetOutputLimits(0, 255);  // Match PWM range
  heaterPID.SetSampleTime(1000);      // Update every second
  
  Serial.println("System Initialized");
  Serial.println("========================================\n");
}

// --- Rotary Encoder Variables ---
//int encoderPos = 0;
//int lastEncoderPos = 0;
//int encoderAState;
//int encoderALastState = LOW;
//unsigned long lastEncoderRead = 0;
//const long ENCODER_DEBOUNCE = 5;  // 5ms debounce

//bool encoderButtonPressed = false;
//unsigned long lastButtonPress = 0;
//const long BUTTON_DEBOUNCE = 50;

// --- MAIN LOOP ---

void loop() {
  unsigned long currentMillis = millis();
  
  if (currentMillis - lastUpdate >= UPDATE_INTERVAL) {
    lastUpdate = currentMillis;
    
    // 1. READ SENSORS
    readSensors();
    
    // 2. CHECK SENSOR 2 SAFETY CONDITIONS
    checkSafetyConditions();
    
    // 3. CHECK SENSOR 1 ALARMS
    checkPIDAlarms();
    
    // 4. CONTROL HEATER
    controlHeaters();
    
    // 5. DISPLAY STATUS
    displayStatus();
  }
}

// --- 1. READ SENSORS ---

void readSensors() {
  // Read Sensor 1 (PID control)
  temp1 = DHT22_1.readTemperature();
  1humid = DHT22_1.readHumidity();
  
  // Read Sensor 2 (Safety protection)
  temp2 = DHT22_2.readTemperature();
  humid2 = DHT22_2.readHumidity();
  
  // Check for sensor errors
  if (isnan(temp1) || isnan(humid1)) {
  // check whether a value is invalid
    Serial.println("ERROR: Sensor 1 (PID) failed!"); 
  }
  if (isnan(temp2) || isnan(humid2)) {
  // check whether a value is invalid
    Serial.println("ERROR: Sensor 2 (Safety) failed!"); 
  }
}

// --- 2. CHECK SAFETY CONDITIONS (SENSOR 2) ---

void checkSafetyConditions() {
  // Reset flags
  tempHiHiActive = false;
  humidHiHiActive = false;
  
  // Check Temperature HiHi
  if (temp2 >= TEMP_HIHI) {
    tempHiHiActive = true;
    Heater_ON = false;  // CUT OFF PID heater
    digitalWrite(HEATER_SAFETY_PIN, LOW);  // TURN OFF heater for safety purpose
  }

  // Check Humidity HiHi
  if (humid2 >= HUMID_HIHI) {
    humidHiHiActive = true;
    Heater_ON = true;   // TURN ON PID heater
    digitalWrite(HEATER_SAFETY_PIN, HIGH); // TURN ON safety heater
  }
}

// --- 3. CHECK PID ALARMS (SENSOR 1) ---

void checkPIDAlarms() {
  // Reset flags
  DHT22_1highAlarm = false;
  DHT22_1lowAlarm = false;
  
  if (sDHT22_1temp >= DHT22_1HIGH_ALARM) {
    DHT22_1highAlarm = true;
  }
  
  if (DHT22_1temp <= DHT22_1LOW_ALARM) {
    DHT22_1lowAlarm = true;
  }
}

void loop() {
  static unsigned long lastUpdate = 0;
  
  if (millis() - lastUpdate >= 1000) {
    lastUpdate = millis();
    
    // Read both sensors
    float temp1 = sensor1.readTemperature();  // PID sensor
    float temp2 = sensor2.readTemperature();  // Safety sensor
    float humid2 = sensor2.readHumidity();    // Safety humidity

// --- PROCESS SAFETY LOGIC ---

void processSafetyLogic() {
  DHT22_2tempHiHi = false;
  DHT22_2humidHiHi = false;
  
  if (DHT22_2temp >= DHT22_2TEMP_HIHI) {
    sensor2_tempHiHi = true;
    Heater_On = false;
  }
  
  if (DHT22_2humid >= DHT22_2HUMID_HIHI) {
    DHT22_2humidHiHi = true;
    Heater_On = true;
  }
}




// --- RUN PID CONTROL ---

void runPIDControl() {
  pidInput = DHT22_1temp;
  heaterPID.Compute();
  
  int pwmValue = (int)pidOutput;
  ledcWrite(heaterChannel, pwmValue);
}