#include <LiquidCrystal.h> //Libraries
#include <EEPROM.h>
#include <Wire.h>  // i2C Conection Library

LiquidCrystal lcd(2, 3, 4, 5, 6, 7); 

#define bt_set  A0
#define bt_next A1
#define bt_up   A2
#define bt_down A3

#define relay  8
#define buzzer 13

//RTC DS3231
#define DS3231_I2C_ADDRESS 0x68 //address of DS3231 module

int hh=0, mm=0, ss=0, set_day=0, set_time=0, run_time=0, set_week=0;
int StartHH=0, StartMM=0, Alarm=0, weekend=0;
int set=0, setMode=0, max=30;
int flag0=2, flag1=0, flag2=0, flag3=1;
int flash=0;

word MilliSecond = 0; 
bool timerStart = false;

String show_day[8] = {"","Mon","Tue","Wed","Thr","Fri","Sat","Sun"};

void setup(){
Wire.begin(); //start I2C communication


pinMode(bt_set,  INPUT_PULLUP);
pinMode(bt_next, INPUT_PULLUP);
pinMode(bt_up,   INPUT_PULLUP);
pinMode(bt_down, INPUT_PULLUP);

pinMode(relay, OUTPUT);
pinMode(buzzer, OUTPUT);

digitalWrite(relay, 1);

lcd.begin(16, 2); // Configure LCD number of columns and rows
lcd.setCursor(0,0);  //Show "TIME" on the LCD
lcd.print("   Welcome To   ");
lcd.setCursor(0,1);
lcd.print("  School Bell  ");

if(EEPROM.read(0)==0){  
}else{
for(int x=1; x<max; x++){  
WriteEeprom(1,x); delay(2);
WriteEeprom(2,x); delay(2);
WriteEeprom(3,x); delay(2);
WriteEeprom(4,x); delay(2);
WriteEeprom(5,x); delay(2);
WriteEeprom(6,x); delay(2);
WriteEeprom(7,x); delay(2);
 }
EEPROM.write(0,0);
EEPROM.write(10,0);
EEPROM.write(11,0);
} 

set_time = EEPROM.read(10);
weekend  = EEPROM.read(11);

delay(2000);
lcd.clear();

noInterrupts();         // disable all interrupts
TCCR1A = 0;             // set entire TCCR1A register to 0  //set timer1 interrupt at 1kHz  // 1 ms
TCCR1B = 0;             // same for TCCR1B
TCNT1  = 0;             // set timer count for 1khz increments
OCR1A = 1999;           // = (16*10^6) / (1000*8) - 1
//had to use 16 bit timer1 for this bc 1999>255, but could switch to timers 0 or 2 with larger prescaler
// turn on CTC mode
TCCR1B |= (1 << WGM12); // Set CS11 bit for 8 prescaler
TCCR1B |= (1 << CS11);  // enable timer compare interrupt
TIMSK1 |= (1 << OCIE1A);
interrupts();           // enable
}

void loop() {
GetRtc(); 

if(ss==0){
if(flag0==0 || flag0==2){flag0=0;
Alarm = EEPROM.read(set_day);   
for(int x=1; x<Alarm+1; x++){ 
ReadEeprom(set_day,x);
if(StartHH==hh && StartMM==mm){ run_time = set_time;
digitalWrite(relay, 0);
timerStart = true;
if(Alarm==x) flag3=1;
       else {flag3=0; ReadEeprom(set_day,x+1);}       
   x=100; 
   }   
  }
 }
}else{flag0=0;}

if(digitalRead(bt_set)==0){ digitalWrite(buzzer, 1);
if(flag1==0){flag1=1;
setMode = setMode+1;
if(setMode==6){
if(set_week==0)Alarm=1;
         else{
Alarm = EEPROM.read(set_week);
ReadEeprom(set_week,Alarm); 
}
}
if(setMode>6)setMode=0,set_week=0;
lcd.clear();
 } 
}else{flag1=0;}


if(digitalRead(bt_next)==0){ digitalWrite(buzzer, 1);
if(flag2==0){flag2=1;
if(setMode==2){set=!set;}
if(setMode==6){set=set+1;
if(set>2){set=0;
if(set_week==0){
for(int x=1; x<weekend+1; x++){  
WriteEeprom(x,Alarm);
 }
}else{
WriteEeprom(set_week,Alarm);  
}
lcd.clear();
lcd.setCursor(0,0);
lcd.print("   Ok Stored");
delay(500);
lcd.clear();
if(Alarm<max)Alarm=Alarm+1;   
   }
  }
 } 
}else{flag2=0;}

if(digitalRead(bt_up)==0){digitalWrite(buzzer, 1);
if(setMode==1){set_day = set_day+1;
if(set_day>7)set_day=1;
SetRtc(ss, mm, hh,set_day); 
}

if(setMode==2){
if(set==0)hh=hh+1;
     else mm=mm+1;  
if(hh>23)hh=0;
if(mm>59)mm=0;
SetRtc(ss, mm, hh,set_day);
}

if(setMode==3){
set_time = set_time+1;  
if(set_time>99)set_time=1;
EEPROM.write(10,set_time);
}

if(setMode==4){
weekend = weekend+1;  
if(weekend>7)weekend=1;
EEPROM.write(11,weekend);
}

if(setMode==5){
set_week = set_week+1;  
if(set_week>7)set_week=0;
}

if(setMode==6){
if(set==0)Alarm=Alarm+1;
if(set==1)StartHH=StartHH+1;
if(set==2)StartMM=StartMM+1;

if(Alarm>max)Alarm=1;
if(set==0 && set_week>0)ReadEeprom(set_week,Alarm); 

if(StartHH>23)StartHH=0;  
if(StartMM>59)StartMM=0;  
}

delay(50);
}

if(digitalRead(bt_down)==0){ digitalWrite(buzzer, 1);
if(setMode==1){set_day = set_day-1;
if(set_day<1)set_day=7;
SetRtc(ss, mm, hh,set_day);
}

if(setMode==2){
if(set==0)hh=hh-1;
     else mm=mm-1;  
if(hh<0)hh=23;
if(mm<0)mm=59;
SetRtc(ss, mm, hh,set_day);
}

if(setMode==3){
set_time = set_time-1;  
if(set_time<1)set_time=99;
EEPROM.write(10,set_time);
}

if(setMode==4){
weekend = weekend-1;  
if(weekend<1)weekend=7;
EEPROM.write(11,weekend);
}

if(setMode==5){
set_week = set_week-1;  
if(set_week<0)set_week=7;
}

if(setMode==6){
if(set==0)Alarm=Alarm-1;
if(set==1)StartHH=StartHH-1;
if(set==2)StartMM=StartMM-1;

if(Alarm<1)Alarm=max;
if(set==0 && set_week>0)ReadEeprom(set_week,Alarm); 

if(StartHH<0)StartHH=23;  
if(StartMM<0)StartMM=59;  
}

delay(50);
}


if(setMode>0)flash=!flash;
Display();
delay(150);
digitalWrite(buzzer, LOW);
}


void Display(){
if(setMode==0){
lcd.setCursor(0,0);  
lcd.print(show_day[set_day]);
lcd.print("    ");
lcd.setCursor(8,0); 
lcd.print((hh/10)%10);
lcd.print(hh % 10); 
lcd.print(":");
lcd.print((mm/10)%10);
lcd.print(mm % 10);
lcd.print(":");
lcd.print((ss/10)%10);
lcd.print(ss % 10); 

lcd.setCursor(0,1);
if(timerStart == true){
lcd.print("Bell On  ");
lcd.print((run_time/10)%10);
lcd.print(run_time % 10);
lcd.print(" Sec  ");
}else{
lcd.print("Next Bell=");
if(flag3==0){
lcd.print((StartHH/10)%10);
lcd.print(StartHH % 10); 
lcd.print(":");
lcd.print((StartMM/10)%10);
lcd.print(StartMM % 10);
}else{lcd.print("##:##");}
 }
}

if(setMode==1){
lcd.setCursor(0,0); 
lcd.print("SET Day");  
lcd.setCursor(1,1); 
if(flash)lcd.print(show_day[set_day]); 
    else lcd.print("   "); 
}

if(setMode==2){
lcd.setCursor(0,0); 
lcd.print("SET Clock");  
lcd.setCursor(1,1); 
if(flash){
lcd.print((hh/10)%10);
lcd.print(hh % 10); 
lcd.print(":");
lcd.print((mm/10)%10);
lcd.print(mm % 10);
}
else{
if(set==0)lcd.setCursor(1,1);
if(set==1)lcd.setCursor(4,1);
lcd.print("  "); 
 }
}


if(setMode==3){
lcd.setCursor(0,0); 
lcd.print("SET Bell Time");  
lcd.setCursor(1,1);
if(flash){
lcd.print((set_time/10)%10);
lcd.print(set_time % 10);  
}else lcd.print("  ");

lcd.print(" Sec");
}

if(setMode==4){
lcd.setCursor(0,0); 
lcd.print("SET Weekend");  
lcd.setCursor(1,1);
if(flash){
lcd.print(show_day[weekend]); 
}else lcd.print("   ");
}


if(setMode==5){
lcd.setCursor(0,0); 
lcd.print("SET Bell for");  
lcd.setCursor(1,1);
if(flash){
if(set_week==0)lcd.print("Week Days"); 
          else lcd.print(show_day[set_week]); 
}else     lcd.print("         ");
}

if(setMode==6){
lcd.setCursor(0,0); 
lcd.print("SET Bell");
if(flash){
lcd.setCursor(1,1);
lcd.print((Alarm/10)%10);
lcd.print(Alarm % 10);
lcd.print("/");
lcd.print((max/10)%10);
lcd.print(max % 10);

lcd.setCursor(8,1);
lcd.print("T=");
lcd.print((StartHH/10)%10);
lcd.print(StartHH % 10); 
lcd.print(":");
lcd.print((StartMM/10)%10);
lcd.print(StartMM % 10);
}else{
     if(set==0)lcd.setCursor(1,1);
else if(set==1)lcd.setCursor(10,1);
else if(set==2)lcd.setCursor(13,1);
lcd.print("  "); 
  }
 }
}

//Set RTC
void SetRtc(byte second, byte minute, byte hour, byte dayOfWeek) {
  Wire.beginTransmission(DS3231_I2C_ADDRESS);
  Wire.write(0); //set 0 to first register
  Wire.write(decToBcd(second)); //set second
  Wire.write(decToBcd(minute)); //set minutes 
  Wire.write(decToBcd(hour)); //set hours
  Wire.write(decToBcd(dayOfWeek)); //set day of week (1=su, 2=mo, 3=tu) 
  Wire.endTransmission();
}

//read RTC
void GetRtc() {
  Wire.beginTransmission(DS3231_I2C_ADDRESS);
  Wire.write(0); //write "0"
  Wire.endTransmission();
  Wire.requestFrom(DS3231_I2C_ADDRESS, 7);  //request - 7 bytes from RTC
  ss = bcdToDec(Wire.read() & 0x7f);
  mm = bcdToDec(Wire.read());
  hh = bcdToDec(Wire.read() & 0x3f);
  set_day = bcdToDec(Wire.read());
}

//conversion Dec to BCD 
byte decToBcd(byte val) {
  return((val / 10 * 16) + (val % 10));
}

//conversion BCD to Dec 
byte bcdToDec(byte val) {
  return((val / 16 * 10) + (val % 16));
}


void ReadEeprom(int _day, int _alarm) {
int eeprom = (_day*100)+_alarm*3;
StartHH=EEPROM.read(eeprom);
StartMM=EEPROM.read(eeprom+1);
}

void WriteEeprom(int _day, int _alarm) {
int eeprom = (_day*100)+_alarm*3;
EEPROM.write(eeprom,StartHH);
EEPROM.write(eeprom+1,StartMM);
EEPROM.write(_day,Alarm);
}

ISR(TIMER1_COMPA_vect){   
if(timerStart == true){MilliSecond++;
    if(MilliSecond >= 1000){MilliSecond = 0;
    run_time = run_time-1;
    if(run_time<=0){timerStart = false; digitalWrite(relay, 1);}
    }
  }  
}