#include <Wire.h>
#include <RTClib.h>
#include <Keypad.h>
#include <LiquidCrystal_I2C.h>
#include <Arduino_FreeRTOS.h>
#include <semphr.h>
#include <queue.h>
  
// Initialize DS1307RTC
RTC_DS1307 rtc;

// Initialize LCD
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define keypad matrix
bool buttonState = false;
const int button = 8; //connected at pin 8 
const int buzzer = 9; //connected at pin 9 
const byte ROWS = 4; //rows 
const byte COLS = 4; //columns
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS] = {22, 24, 26, 28}; //pins
byte colPins[COLS] = {30, 32, 34, 36}; //pins
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS );

const int maxInput = 16;
static int cursorPos = 0;
static char inputBuffer[5];

// Alarm time variables
struct Alarm {
  int hour;
  int minute;
  bool enabled;
};
Alarm alarms[3];
int currentAlarm = 0;

//The use of Semaphores 
SemaphoreHandle_t interruptSemaphore1; 

//The use of Queues
QueueHandle_t queue1;

//The use of Task Handles
TaskHandle_t TaskHandle_1; 
TaskHandle_t TaskHandle_3;
TaskHandle_t TaskHandle_2;

void Task1(void *pvParameters);
void Task2(void *pvParameters);
void Task3(void *pvPArameters);

void setup() {
  Serial.begin(9600);
  pinMode(button, INPUT);
  pinMode(buzzer, OUTPUT);

  // the use of interrupts 
  interruptSemaphore1 = xSemaphoreCreateBinary();

  // the use of queues 
  queue1 = xQueueCreate(1, sizeof(Alarm));

  // this will set the RTC
  xTaskCreate(Task1, "Real_Time_Clock", 128, NULL, 3, &TaskHandle_1);
  // this will set the alarm
  xTaskCreate(Task2, "Set_Alarm", 128, NULL, 2, &TaskHandle_2);
  // this will trigger the alarm
  xTaskCreate(Task3, "Buzzer_On", 128, NULL, 3, &TaskHandle_3);

  // where the real time clock initiates 
  rtc.begin();

  // to initialize the lcd 
  lcd.init();
  lcd.backlight();
}

void loop() {
  //This part of the code must be EMPTY. 
}

//This Tasks is display the real time clock
void Task1(void *pvParameters) {
  for(;;) {
       // vTaskSuspend(TaskHandle_3);
        DateTime now = rtc.now();
        char key = keypad.getKey();
        static unsigned long lastDisplayTime = 0;
        if (millis() - lastDisplayTime >= 1000) {
          lcd.clear();
          lcd.setCursor(0, 0);
          lcd.print("Current Time:");
          lcd.setCursor(0, 1);
          lcd.print(now.hour(), DEC);
          lcd.print(":");
          lcd.print(now.minute(), DEC);
          lcd.print(":");
          lcd.print(now.second(), DEC);
          lastDisplayTime = millis();
        }

         for (int i = 0; i < 3; i++) {
          if (alarms[i].enabled && now.hour() == alarms[i].hour && now.minute() == alarms[i].minute) {
            xSemaphoreGive(interruptSemaphore1); 
          }
        }

        if (key == '*') { 
          vTaskSuspend(NULL); // to suspend the calling task 
          vTaskDelay(1000/portTICK_PERIOD_MS); // giving a delay of 1 second 
        }
}
}

//This Tasks is where the keypad functionalities work
void Task2(void *pvParameters) {
  for (;;) {
      DateTime now = rtc.now();
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Set Alarm " + String(currentAlarm + 1) + ":");
      lcd.setCursor(0, 1);
      lcd.print("HH:MM");
      char key = NO_KEY;
      while (key != '#') {
        key = keypad.getKey();
        if (key != NO_KEY) {
          if (((inputBuffer[0] - '0') * 10 + (inputBuffer[1] - '0') <= 23) && (((inputBuffer[3] - '0') * 10) <= 50)) {
            if (key >= '0' && key <= '9') {
              inputBuffer[cursorPos] = key;
              lcd.setCursor(cursorPos, 1);
              lcd.print(key);
              cursorPos++;
              if (cursorPos == 2) {
                cursorPos += 1;  
              }
              if (cursorPos == 5){
                vTaskResume(TaskHandle_1);
                break;
                }
            }
            else if (key == '*') { // to set the alarm 
              lcd.clear();
              lcd.setCursor(0, 0);
              lcd.print("Set Alarm " + String(currentAlarm + 1) + ":");
              lcd.setCursor(0, 1);
              lcd.print("HH:MM");
              cursorPos = 0;
            }
            else if (key == 'D'){ // to clear the number if the number was inputted wrong
              deleteLastCharacter();
              lcd.setCursor(cursorPos, 2);
            }
          }
          else { // if the user inputs an invalid time
            lcd.clear();
            lcd.setCursor(0, 0);
            lcd.print("Invalid Time");
            vTaskDelay(500/portTICK_PERIOD_MS);
            vTaskSuspend(NULL);
            vTaskResume(TaskHandle_1);
          }
        }
      }
      if (cursorPos == 5) {
        alarms[currentAlarm].hour = (inputBuffer[0] - '0') * 10 + (inputBuffer[1] - '0');
        alarms[currentAlarm].minute = (inputBuffer[3] - '0') * 10 + (inputBuffer[4] - '0');
        alarms[currentAlarm].enabled = true;
        lcd.setCursor(0, 1);
        lcd.print("Alarm set   ");
        vTaskDelay(1000/portTICK_PERIOD_MS);
        lcd.clear();
        currentAlarm++;
        if (currentAlarm >= 3) {
          currentAlarm = 0;
        }
      }

      lcd.setCursor(0, 0);
      lcd.print("Press '*' to set");
      lcd.setCursor(0, 1);
      lcd.print("alarm time");
      vTaskDelay(3000/portTICK_PERIOD_MS);
      cursorPos = 0;
    }
  }

//This Task will set the alarm/trigger the alarm when 
//the user has set their given alotted time. 
void Task3(void *pvParameters) {
  for(;;){
    if(xSemaphoreTake(interruptSemaphore1,portMAX_DELAY) == pdTRUE){
      buttonState = digitalRead(button);
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("ALARM!!");
      //vTaskDelay(2000/portTICK_PERIOD_MS);
      tone(buzzer, 500, 200);
      vTaskDelay(1000/portTICK_PERIOD_MS);
      tone(buzzer, 1000, 200);
      vTaskDelay(1000/portTICK_PERIOD_MS);
      tone(buzzer, 2000, 200);
      vTaskDelay(1000/portTICK_PERIOD_MS);
      tone(buzzer, 3000, 200);
      vTaskDelay(1000/portTICK_PERIOD_MS);
      tone(buzzer, 4000, 200);
      vTaskDelay(1000/portTICK_PERIOD_MS);
    if (buttonState == HIGH) {
      noTone(buzzer);
      lcd.clear();
      lcd.setCursor(0, 0);
      vTaskSuspend(NULL); // suspends any task that is currently doing 
      vTaskResume(TaskHandle_1); // returns back to operate the real time clock
      xSemaphoreGive(interruptSemaphore1); //proceeds back in setting the alarm
      taskYIELD(); // does the context switching
    }
    }
  }
}

//---------------------------------------------

// Deleting the given set alarm time 
void deleteLastCharacter(){
  if (cursorPos > 0){
    cursorPos--;
    if(cursorPos==2)
    cursorPos=1;
  }
}