#include <Keypad.h>
#include <LiquidCrystal.h>
#include <Arduino_FreeRTOS.h>
#include <task.h>
#include <queue.h>

LiquidCrystal lcd(12, 11, 10, 9, 8, 7);

const byte KEYPAD_ROWS = 4;
const byte KEYPAD_COLS = 4;
const byte buttonPin = 6;

float Number1 = 0.0;
float Number2 = 0.0;
char Operation = '0'; // if Operation=0 no button was pressed
bool decimalEntered = false;

char keys[KEYPAD_ROWS][KEYPAD_COLS] = {
  {'1', '2', '3', '+'},
  {'4', '5', '6', '-'},
  {'7', '8', '9', '*'},
  {'.', '0', '=', '/'}
};

byte rowPins[KEYPAD_ROWS] = {5, 4, 3, 2};
byte colPins[KEYPAD_COLS] = {A3, A2, A1, A0};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, KEYPAD_ROWS, KEYPAD_COLS);

TaskHandle_t LCDTaskHandle;

void showSpalshScreenTask(void* pvParameters) {
  vTaskSuspend(LCDTaskHandle);
  lcd.setCursor(4, 0);
  String message1 = "FreeRTOS";
  for (byte i = 0; i < message1.length(); i++) {
    lcd.print(message1[i]);
    delay(100);
  }
  lcd.setCursor(3, 1);

  String message = "Calculator";
  for (byte i = 0; i < message.length(); i++) {
    lcd.print(message[i]);
    delay(100);
  }

  vTaskDelay(pdMS_TO_TICKS(500));
  lcd.clear();
  vTaskResume(LCDTaskHandle);
  vTaskDelete(NULL);
}

void updateCursor() {
  if (millis() / 250 % 2 == 0 ) {
    lcd.cursor();
  } else {
    lcd.noCursor();
  }
}

void showSpalshScreenTask2(void* pvParameters) {
  vTaskSuspend(LCDTaskHandle);
  vTaskDelay(pdMS_TO_TICKS(2300));

  lcd.print("By Zainab Husain");

  lcd.setCursor(0, 1);
  lcd.print("& Zainab Redha");

  delay(100);

  vTaskDelay(pdMS_TO_TICKS(800));
  lcd.clear();
  vTaskResume(LCDTaskHandle);
  vTaskDelete(NULL);
}

void keypadTask(void* pvParameters) {
  for (;;) {
    char k = keypad.getKey();

    if (k) {
      lcd.print(k);

      if (k == '+')
        Operation = '+';
      else if (k == '-')
        Operation = '-';
      else if (k == '*')
        Operation = '*';
      else if (k == '/')
        Operation = '/';

      if (isDigit(k) && Operation == '0') {
        if (!decimalEntered) {
          Number1 = (Number1 * 10.0) + (k - '0');
        } else {
          float decimalValue = (k - '0') / 10.0;
          Number1 += decimalValue;
          decimalValue /= 10.0;
        }
      } else if (isDigit(k) && Operation != '0') {
        if (!decimalEntered) {
          Number2 = (Number2 * 10.0) + (k - '0');
        } else {
          float decimalValue = (k - '0') / 10.0;
          Number2 += decimalValue;
          decimalValue /= 10.0;
        }
      } else if (k == '.') {
        decimalEntered = true;
      }

      if (k == '=') {
        lcd.setCursor(0, 1);
        switch (Operation) {
          case '+':
            lcd.print(Number1 + Number2);
            break;
          case '-':
            lcd.print(Number1 - Number2);
            break;
          case '*':
            lcd.print(Number1 * Number2);
            break;
          case '/':
            if (Number2 != 0.0)
              lcd.print(Number1 / Number2);
            else
              lcd.print("Error");
            break;
        }

        Operation = '0';
        Number1 = 0.0;
        Number2 = 0.0;
decimalEntered = false;
      }
    }

    vTaskDelay(pdMS_TO_TICKS(100)); 
  }
}

void ClearButtonTask(void* pvParameters) {
  bool buttonPressed = false;
  for (;;) {
    if (!buttonPressed && digitalRead(buttonPin) == LOW) {
      lcd.clear();

      buttonPressed = true;

      while (digitalRead(buttonPin) == LOW) {
        vTaskDelay(pdMS_TO_TICKS(10)); 
      }

      buttonPressed = false;
    }
    vTaskDelay(pdMS_TO_TICKS(10)); 
  }
}

void setup() {
  lcd.begin(16, 2);
  lcd.clear();
  lcd.cursor();
  lcd.setCursor(1, 0);

  xTaskCreate(showSpalshScreenTask, "SplashScreenTask", 128, NULL, 1, NULL);
  xTaskCreate(showSpalshScreenTask2, "SplashScreenTask", 128, NULL, 1, NULL);
  xTaskCreate(keypadTask, "KeypadTask", 128, NULL, 1, NULL);
  xTaskCreate(ClearButtonTask, "ClearButtonTask", 128, NULL, 1, &LCDTaskHandle);

  vTaskStartScheduler(); 
}

void loop() {
  
}