#include <Wire.h>

// minutes of "dawn" before alarm
#define TIN 30
// minutes of "dawn" + minutes of blue blinding light
#define TOUT 45

// number of available alarms
#define NALARMS 4

#define RPIN 3
#define YPIN 5
#define BPIN 6

#define DS1307_ADDRESS 0x68

int st = 0; // alarm status (minutes from alarm - TIN)
char alarms[NALARMS][5];
char cmin; // current minute
int a = -1; // current alarm

void setup () {
    Serial.begin(57600);
    Wire.begin();
    
    set_time(11,9,2,5,0,0,0);

    pinMode(RPIN,OUTPUT);
    pinMode(YPIN,OUTPUT);
    pinMode(BPIN,OUTPUT);

    digitalWrite(RPIN,255);
    digitalWrite(YPIN,0);
    digitalWrite(BPIN,0);
    
    // read alarms from storage
    for ( int i = 0 ; i < NALARMS ; i ++ ) {
        alarms[i][0] = 0;
    }
}

void loop () {
  
  // read commands from serial
  
  // read time, check alarms
  
  check_time();
  Serial.println(st);

  
  // act on status: LEDs and buzzer
  if ( st > 0 ) {
      set_leds();
  }
  
  // wait about till the next second
  
  delay(1000);
  
}

// Set the current time
void set_time(int y,int m,int d, int w, int hh, int mm, int ss) {
    Wire.beginTransmission(DS1307_ADDRESS);
    Wire.send(0);
    Wire.send(bin2bcd(ss));
    Wire.send(bin2bcd(mm));
    Wire.send(bin2bcd(hh));
    Wire.send(w);
    Wire.send(bin2bcd(d));
    Wire.send(bin2bcd(m));
    Wire.send(bin2bcd(y));
    Wire.send(0);
    Wire.endTransmission();
}

void check_time() {
    Wire.beginTransmission(DS1307_ADDRESS);
    Wire.send(0);
    Wire.endTransmission();

    Wire.requestFrom(DS1307_ADDRESS, 6);
    Wire.receive();
    int mm = bcd2bin(Wire.receive());
    int hour = bcd2bin(Wire.receive());
    int wday = Wire.receive();
    int day = bcd2bin(Wire.receive());
    int month = bcd2bin(Wire.receive());

    if ( a < 0 ) {
        for ( int i = 0; i < NALARMS ; i ++ ) {
            // check alarm i
            if ( ( alarms[i][0] & ( 1 << (wday - 1) ) ) || 
                    (month == alarms[i][1] && day == alarms[i][2]) ) {
                // this is alarm day!
                if ( hour == alarms[i][3] && mm == alarms[i][4]) {
                    // this is alarm hour!
                    a = i;
                    st = 0;
                    cmin = mm;
                    if ( ( alarms[i][0] & 128 ) == 0 ) {
                        // this alarm won't be repeated
                        alarms[i] = { 0,0,0,0,0 };
                    }
                    break;
                }
            } 
        }
    } else {
        if ( cmin < mm ) {
            cmin = mm;
            st++;
        }
    }

}

void set_leds() {
  if ( st > 0 && st < TIN) {
      int y = int(float(st*255)/TIN);
      int r = 255 - y;
      analogWrite(RPIN,r);
      analogWrite(YPIN,y);
  } else if (st == TIN) {
      analogWrite(RPIN,0);
      analogWrite(YPIN,0);
      analogWrite(BPIN,255);
  } else if (st == TOUT) {
      // reset stuff
      st = 0;
      a = -1;
      analogWrite(RPIN,255);
      analogWrite(YPIN,0);
      analogWrite(BPIN,0);
  }
}

// BCD helper functions from adafruit-RTClib
static uint8_t bcd2bin (uint8_t val) { return val - 6 * (val >> 4); }
static uint8_t bin2bcd (uint8_t val) { return val + 6 * (val / 10); }

// vim: set filetype=c: