#define F_CPU 16000000

#include <avr/delay.h>
#include <stdbool.h>

#define DATA0 PD0
#define DATA1 PD1
#define DATA2 PD2
#define DATA3 PD4
#define DATA4 PD5
#define DATA5 PD6
#define DATA6 PD7
#define DATA7 PB0
#define RS    PB1
#define RW    PB2
#define E     PB3

int pins_data[8] = {DATA0, DATA1, DATA2, DATA3, DATA4, DATA5, DATA6, DATA7};
int pins_misc[3] = {RS, RW, E};

const uint8_t CURSOR_POSITIONS[2][16] = {
  {0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E,0x0F},
  {0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F}
};

unsigned int bit_mask[8] = {0b00000001, 0b00000010, 0b00000100, 0b00001000, 0b00010000, 0b00100000, 0b01000000, 0b10000000};
bool bits[8];

int main(void){
  SET_DDR(pins_data, pins_misc);
  LCD_SETUP();
  ADC_INIT();
  //TIMER1_INIT();

  LCD_CURSOR_POSITION(1, 4);
  LCD_DISPLAY_STRING("HELLO", 5);

  LCD_CURSOR_POSITION(2, 3);
  LCD_DISPLAY_STRING("friend", 6);
  //LCD_CLEAR_DISPLAY();
}

void LCD_CLEAR_DISPLAY(void){
  PORTB &=  ~(1 << RS);
  LCD_SET_DATA_PINS(1);
  LCD_ENABLE();
  PORTB |=  (1 << RS);
}

void LCD_CURSOR_POSITION(uint8_t row, uint8_t column){
  PORTB &= ~(1 << RS);
  LCD_SET_ADDRESS(CURSOR_POSITIONS[row - 1][column - 1]);
  LCD_ENABLE();
  PORTB |= (1 << RS);
}

void LCD_SET_ADDRESS(uint8_t address){
  LCD_SET_DATA_PINS(address);
  PORTB |= (1 << DATA7);
  LCD_ENABLE();
}

void LCD_DISPLAY_STRING(char* str, int size){
  for(int i = 0; i < size; i++){
    LCD_DISPLAY_CHAR(str[i]);
  }
}

void LCD_DISPLAY_CHAR(char ascii_code){
  LCD_SET_DATA_PINS(ascii_code);
  LCD_ENABLE();
}

void LCD_SETUP(){
  LCD_CLEAR_DATA_PINS(pins_data);
  PORTB &= ~(1 << RS); // 0 for CONFIGURATION MODE
  PORTB &= ~(1 << RW); // 0 for WRITE

  // ENTRY MODE SET
  // CURSOR DIRECTION RIGHT
  LCD_SET_DATA_PINS(0b00000110);
  LCD_ENABLE();

  // DISPLAY ON/OFF CONTROL
  // DISPLAY ON, CURSOR ON
  LCD_SET_DATA_PINS(0b0001110);
  LCD_ENABLE();

  // FUNCTION SET
  // 8-BIT MODE, 2 LINES
  LCD_SET_DATA_PINS(0b00111000);
  LCD_ENABLE();

  PORTB |= (1 << RS); // 1 for WRITE MODE
  LCD_CLEAR_DATA_PINS(pins_data);
}

void LCD_CLEAR_DATA_PINS(int* pins){
  for(int i = 0; i < 8; i++){
    if(i < 7){
      PORTD &= (0 << pins[i]); 
    }else {
      PORTB &= ~(1 << pins[7]);
    }
  }
}

void LCD_SET_DATA_PINS(uint8_t value){
  decToBin(bit_mask, bits, value);

  for(int j = 0; j < 8; j++){
    if(bits[j] && j < 7){
      PORTD |= (1 << pins_data[j]);
    }else if(bits[j]){
      PORTB |= (1 << pins_data[j]);
    }
  }
}

/*Arguments:  array of masks for the 8 individual bits, 
              bool array to store the binary numbers in,
              8bit unsigned decimal, 

Return:     Nothing. Stores result in the bit-array*/
void decToBin(unsigned int mask[], bool bits[], unsigned int value){

	for(int i = 0; i<8; i++){
		unsigned int bit_status = value & mask[i];
		bits[i] = bit_status ?  1 :  0;
	}
}

void SET_DDR(int* data_pins, int* misc_pins){
  for(int i = 0; i < 8; i++){
    if(i < 7){
      DDRD |= (1 << data_pins[i]);
    }else{
      DDRB |= (1 << data_pins[i]);
    }
  }
  // 
  for(int j = 0; j < 3; j++){
    DDRB |= (1 << misc_pins[j]);
  }
  // D2 as INPUT
  DDRD |= (1 << PD2);
}

void LCD_ENABLE(void){
		_delay_us(1);
		PORTB ^= (1 << E);
		_delay_us(1);
		PORTB ^= (1 << E);
		_delay_us(1);
    LCD_CLEAR_DATA_PINS(pins_data);
}

void ADC_INIT(){
  ADMUX |= (1 << REFS0); //INTERNAL REF
  ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADATE) | (1 << ADIE)| (0 << ADLAR);  // ADC ENABLE, START CONVERSION, ENABLE INTERRUPTS
  ADCSRB = (1 << ADTS2) | (0 << ADTS1)| (1 << ADTS0);             // TIMER1 COMPARE B
  DIDR0 = (1 << ADC0D);                                         // DISABLE DIGITAL INPUT BUFFER
  sei();
}

void TIMER1_INIT(void){
  TCCR1A = (1 << WGM11) | (1 << WGM10);
  TCCR1B = (1 << WGM12) | (1 << CS12) | (0 << CS11) | (1 << CS10);  // CTC Mode
  //TCCR1C = ();
  TIMSK1 = (1 << OCIE1B);
  OCR1B = 20000;
}

ISR(ADC_vect){
  LCD_DISPLAY_STRING("2", 3);
  ADCSRA |= (1 << ADSC);
}