#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED display configuration
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


//Rotary encoder configuration
#define ENCODER_CLK 15
#define ENCODER_DT 16
#define ENCODER_SW 17

double Kp = 2.0, Ki = 5.0, Kd = 1.0;

double counter = 0; // Initial setpoint
double counterLast = 0;

int currentPage = 0;

// Rotary encoder variables
volatile int encoderPos = 0;
int lastEncoderPos = 0;
bool buttonPressed = false;
//bool setpointConfirmed = false; // Track whether the setpoint has been confirmed
unsigned long lastButtonPressTime = 0;  // For debouncing
//bool previousHeaterState = false; // Store previous heater state

void IRAM_ATTR readEncoderISR() {
    // Check the direction of rotation by comparing CLK and DT
    if (digitalRead(ENCODER_DT) != digitalRead(ENCODER_CLK)) {
        encoderPos++;  // Clockwise
    } else {
        encoderPos--;  // Counterclockwise
    }
}

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

   // Initialize OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);  // Loop forever
  }
  display.clearDisplay();
  display.display();

   // Initialize encoder pins
    pinMode(ENCODER_CLK, INPUT);
    pinMode(ENCODER_DT, INPUT);
    pinMode(ENCODER_SW, INPUT_PULLUP);

    // Attach an interrupt to the CLK pin
    attachInterrupt(digitalPinToInterrupt(ENCODER_CLK), readEncoderISR, CHANGE);

    updateDisplay();
}

void loop() {
// Handle rotary encoder for setting setpoint
    handleButtonPress();
    rotation();

    updateDisplay();

    delay(200);  // Small delay for smooth behavior
}

void rotation() {

  if (encoderPos != lastEncoderPos) {
    if (encoderPos > lastEncoderPos) {
      counter++;  // Increase setpoint
      currentPage = 1;
    } else {
        counter--;  // Decrease setpoint
        currentPage = 0;
      }
        
         
      lastEncoderPos = encoderPos;
           

      Serial.print("Counter: ");
      Serial.println(counter);  // Debugging output to monitor setpoint change
      Serial.print("Page: ");
      Serial.println(currentPage);
                     
  }
}

void handleButtonPress() {
    static bool lastButtonState = HIGH;
    bool currentButtonState = digitalRead(ENCODER_SW);

    if (currentButtonState == LOW && lastButtonState == HIGH && (millis() - lastButtonPressTime > 100)) {
        // Debounce and toggle setpoint change mode
        lastButtonPressTime = millis();

        buttonPressed = true;
        counter = 0;
        Serial.println("Button Pressed");
        Serial.print("Counter set to:");
        Serial.println(counter);
      }

    if (currentButtonState == HIGH && lastButtonState == LOW && (millis() - lastButtonPressTime > 100)) {
        // Debounce and toggle setpoint change mode
        lastButtonPressTime = millis();

        buttonPressed = false;
        Serial.println("Button Released");
      }  

  
    lastButtonState = currentButtonState;
}

void updateDisplay() {
  display.clearDisplay();

  if(currentPage == 0) {  

    display.fillCircle(61,61, 2, WHITE);
    display.drawCircle(68,61, 2, WHITE);
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0, 0);
    display.print("PAGE-1");
    
  }

  if(currentPage == 1) {
    
    display.drawCircle(61,61, 2, WHITE);
    display.fillCircle(68,61, 2, WHITE);
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    
    display.setCursor(30, 0);
    display.print("PID-settings");

    display.setCursor(0, 15);
    display.print("Kp: ");
    display.print(Kp);
   
    display.setCursor(0, 27);
    display.print("Ki: ");
    display.print(Ki);
    
    display.setCursor(0, 39);
    display.print("Kd: ");
    display.print(Kd);
    
  }

  display.display();

}