/* EvilGenius Project 30  - Countdown Timer - from second edition of text
REQUIRES the following Libraries: 
	<Adafruit_LEDBackpack.h>; <Adafruit_GFX.h>; <Wire.h>
*/

#include <Adafruit_LEDBackpack.h>
#include <Adafruit_GFX.h>
#include <Wire.h>
Adafruit_7segment display = Adafruit_7segment( );
int times[ ] = {5, 10, 15, 20, 30, 45, 100, 130, 200, 230, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, 3000};
int numTimes = 19;  int buzzerPin = 11;  int aPin = 2;  int bPin = 4;  
int buttonPin = 3;  boolean stopped = true; int selectedTimeIndex = 12; 
int timerMinute;	int timerSecond;   
void setup( )  {  pinMode(buzzerPin, OUTPUT);  
pinMode(buttonPin, INPUT_PULLUP);  
pinMode(aPin, INPUT_PULLUP);    
pinMode(bPin, INPUT_PULLUP);  
Serial.begin(9600);  
display.begin(0x70);  reset( );
}
void loop( )	{  
updateCountingTime();  updateDisplay(); 
 if (timerMinute == 0 && timerSecond == 0 && ! stopped)  {    tone(buzzerPin, 400);   }  
else  {    noTone(buzzerPin);  }  
if (digitalRead(buttonPin) == LOW)  {    stopped = ! stopped;    
while (digitalRead(buttonPin) == LOW);  }  
int change = getEncoderTurn( );  
if (change != 0)  {    changeSetTime(change);  }
}
void reset( )	{    
timerMinute = times[selectedTimeIndex] / 100;    
timerSecond = times[selectedTimeIndex] % 100;    
stopped = true;     noTone(buzzerPin);
}
void updateDisplay( ) // mmss	{  // update I2C display  
int timeRemaining =  timerMinute * 100 + timerSecond;  display.print(timeRemaining, DEC);  
display.writeDisplay( );
}
void updateCountingTime( ){   
if (stopped) return;     static unsigned long lastMillis;   
unsigned long m = millis( );   
if (m > (lastMillis + 1000) && (timerSecond > 0 || timerMinute > 0))   {
if (timerSecond == 0)    {        timerSecond = 59;       timerMinute --;    } 
else    {       timerSecond --;     }    lastMillis = m;  }
}
void changeSetTime(int change)	{   
selectedTimeIndex += change;   
if (selectedTimeIndex < 0)   {     selectedTimeIndex = numTimes;   }   
else
     if (selectedTimeIndex > numTimes)   {     selectedTimeIndex = 0;   }   timerMinute = times[selectedTimeIndex] / 100;
timerSecond = times[selectedTimeIndex] % 100;
}
int getEncoderTurn( ) {  // return -1, 0, or +1  
static int oldA = LOW;  static int oldB = LOW;  int result = 0;  
int newA = digitalRead(aPin);  int newB = digitalRead(bPin);  
if (newA != oldA || newB != oldB)  {    // something has changed    
if (oldA == LOW && newA == HIGH)    {   result = -(oldB * 2 - 1);    } 
}  oldA = newA;  oldB = newB;
return result;
}  	// END