#include <CapacitiveSensor.h>

#define SERIAL_DEBUG 0

#define MODE_NORMAL 0
#define MODE_SETTIME 1
#define MODE_SETALARM 2

#define PIN_BUTTON 3
#define PIN_BUZZER 5
#define PIN_REG_CLOCK 7
#define PIN_REG_DATA 4
#define PIN_REG_LATCH 6
#define PIN_TOUCH_0 11
#define PIN_TOUCH_1 10
#define PIN_TOUCH_2 2
#define PIN_TOUCH_3 9
#define PIN_TOUCH_COM A1

CapacitiveSensor touch_0 = CapacitiveSensor(PIN_TOUCH_COM, PIN_TOUCH_0);
CapacitiveSensor touch_1 = CapacitiveSensor(PIN_TOUCH_COM, PIN_TOUCH_1);
CapacitiveSensor touch_2 = CapacitiveSensor(PIN_TOUCH_COM, PIN_TOUCH_2);
CapacitiveSensor touch_3 = CapacitiveSensor(PIN_TOUCH_COM, PIN_TOUCH_3);

// Matrix state
unsigned char matrix[8] = {0b10000001, 0, 0, 0, 0, 0, 0, 0b10000001};
unsigned char matrix_row_on = 0;

// Interface mode
unsigned char mode = MODE_NORMAL;

// Selected number (0..4: None, Hour, Minute, Second)
unsigned char number_selection = 0;

// Time added to internal clock, to fit real time
unsigned long time_offset = 0;

unsigned char alarm = false;

unsigned long alarm_time = 0;

// Is alarm ringing
unsigned char alarm_ringing = false;
unsigned long alarm_ring_start;

unsigned long last_light_measure = 0;

unsigned long touch_time[4] = {0, 0, 0, 0};
unsigned long last_touch_measure = 0;
unsigned char touch_step = 0;

// Bytewise reverse
unsigned char reverse(unsigned char b) {
   b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
   b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
   b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
   return b;
}

unsigned char fix_pixels(unsigned char b) {
  return (b << 1) | (b >> 7);
}

void shift_matrix() {
  digitalWrite(PIN_REG_LATCH, LOW);
  shiftOut(PIN_REG_DATA, PIN_REG_CLOCK, MSBFIRST, ~(1 << matrix_row_on));
  shiftOut(PIN_REG_DATA, PIN_REG_CLOCK, MSBFIRST, fix_pixels(matrix[(matrix_row_on+7)%8]));
  digitalWrite(PIN_REG_LATCH, HIGH);
  matrix_row_on = (matrix_row_on + 1) % 8;
}

void draw_time(unsigned long t) {
  unsigned char seconds = t/1000%60;
  unsigned char minutes = t/60000%60;
  unsigned char hours = t/3600000%24;
  matrix[1] = reverse(seconds) >> 1;
  matrix[2] = matrix[1];
  matrix[3] = reverse(minutes) >> 1;
  matrix[4] = matrix[3];
  matrix[5] = reverse(hours) >> 1;
  matrix[6] = matrix[5];
}

void draw_mode() {
  switch(mode) {
    case MODE_NORMAL: matrix[0] = 0b10000001; break;
    case MODE_SETTIME: matrix[0] = 0b10011001; break;
    case MODE_SETALARM: matrix[0] = 0b10111101; break;
  }
  if(alarm) matrix[0] |= 0b01000010;
}

void draw_number_selection() {
  switch(number_selection) {
    case 1: matrix[1] |= 0b10000001; break;
    case 2: matrix[3] |= 0b10000001; break;
    case 3: matrix[5] |= 0b10000001; break;
  }
}

const unsigned char HEX_ALPHA[16] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
void send_hex(unsigned long val) {
  Serial.write(HEX_ALPHA[(val >> 28) & 0xf]);
  Serial.write(HEX_ALPHA[(val >> 24) & 0xf]);
  Serial.write(HEX_ALPHA[(val >> 20) & 0xf]);
  Serial.write(HEX_ALPHA[(val >> 16) & 0xf]);
  Serial.write(HEX_ALPHA[(val >> 12) & 0xf]);
  Serial.write(HEX_ALPHA[(val >> 8) & 0xf]);
  Serial.write(HEX_ALPHA[(val >> 4) & 0xf]);
  Serial.write(HEX_ALPHA[val & 0xf]);
  Serial.write('\n');
}

void setup() {
  pinMode(PIN_REG_DATA, OUTPUT);
  pinMode(PIN_REG_CLOCK, OUTPUT);
  pinMode(PIN_REG_LATCH, OUTPUT);
  pinMode(PIN_BUZZER, OUTPUT);
  pinMode(PIN_BUTTON, INPUT_PULLUP);
  
  pinMode(13, OUTPUT);
  digitalWrite(13, LOW);

  #if SERIAL_DEBUG
  Serial.begin(9600);
  #endif
}

void loop() {
  #if SERIAL_DEBUG
  send_hex(touch_0.capacitiveSensor(10));
  send_hex(touch_1.capacitiveSensor(10));
  send_hex(touch_2.capacitiveSensor(10));
  send_hex(touch_3.capacitiveSensor(10));
  delay(100);
  #endif

  // Calibrate the thresholds according to your resistors
  if(millis() > last_touch_measure + 15) {
    switch(touch_step) {
      case 0:
      if(touch_0.capacitiveSensor(10) > 126 && millis() > touch_time[0] + 250) {
        touch_time[0] = millis();
        mode = (mode+1) % 3;
        stop_ringing();
      }
      break;
      case 1:
      if(touch_1.capacitiveSensor(10) > 126 && millis() > touch_time[1] + 250) {
        touch_time[1] = millis();
        number_selection = (number_selection+1) % 4;
        stop_ringing();
      }
      break;
      case 2:
      if(touch_2.capacitiveSensor(10) > 31 && millis() > touch_time[2] + 150) {
        touch_time[2] = millis();
        change_selected_number(1);
        stop_ringing();
      }
      break;
      case 3:
      if(touch_3.capacitiveSensor(10) > 31 && millis() > touch_time[3] + 150) {
        touch_time[3] = millis();
        change_selected_number(-1);
        stop_ringing();
      }
    }
    touch_step = (touch_step + 1) % 4;
    last_touch_measure = millis();
  }

  if(alarm && !alarm_ringing) {
    unsigned long t = ((millis() + time_offset) / 1000) % 86400;
    if(alarm_time / 1000 == t) {
      alarm_ringing = true;
      alarm_ring_start = millis();
    }
  }

  if(alarm_ringing) {
    if(millis()%1000 < 100) {
      matrix[7] = 0b11111111;
      analogWrite(PIN_BUZZER, 1);
    } else {
      matrix[7] = 0b10000001;
      digitalWrite(PIN_BUZZER, LOW);
    }
    if(digitalRead(PIN_BUTTON) == LOW) {
      stop_ringing();
    }
  }

  draw_mode();
  if(mode == MODE_SETALARM)
    draw_time(alarm_time);
  else
    draw_time(millis() + time_offset);
  draw_number_selection();
  shift_matrix();
}

void change_selected_number(signed int nb) {
  switch(mode) {
    case MODE_NORMAL:
      if(nb > 0) alarm = true;
      else if(nb < 0) alarm = false;
    case MODE_SETTIME: change_time(&time_offset, nb); break;
    case MODE_SETALARM: change_time(&alarm_time, nb); break;
  }
}

void change_time(unsigned long *t, signed int mul) {
  switch(number_selection) {
    case 1: *t += mul * 1000; break;
    case 2: *t += mul * 60000; break;
    case 3: *t += mul * 3600000; break;
  }
  *t %= 86400000;
}

void stop_ringing() {
  digitalWrite(PIN_BUZZER, LOW);
  matrix[7] = 0b10000001;
  alarm_ringing = false;
}