//#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

Adafruit_SSD1306 display(128, 64, &Wire, 4);  // (SCREEN_WIDTH,SCREEN_HEIGHT,wire,OLED_RESET)

// data refreshed frmo RTC :
String sHour="00"; String sMinute="00"; String sSecond="00";
String sDay="01";  String sMonth="01";  String sYear="2024";
int debuglight=1; // debug

#define BTN_PIN 8 

// Setup
void setup() {
  Serial.begin(9600);

  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }

  pinMode(8, INPUT_PULLUP); // connect the btn

  display.clearDisplay();

  localDrawRect( 0, 0, display.width(), display.height(), WHITE ); // startCol, startLine, endCol, endLine, color
  drawCalendarLines();

  display.setTextColor( SSD1306_WHITE ); // Draw white text
  display.setCursor(4,11);
  display.println(F("SE TE QA QI SE SA DM")); 
  display.setCursor(4,20);
  display.println(F("01 02 03 04 05 06 07")); 
  display.setCursor(4,29);
  display.println(F("08 09 10 11 12 13 14")); 
  display.setCursor(4,38);
  display.println(F("15 16 17 18 19 20 21")); 
  display.setCursor(4,47);
  display.println(F("22 23 24 25 26 27 28")); 
  display.setCursor(4,56);
  display.println(F("29 30 31")); 
  display.display(); 
}

void loop() {
  readRTC();

  display.setTextColor(WHITE, BLACK); // Draw white text
  display.setCursor(4,1);
  display.println("Dec:"+sHour+":"+sMinute+":"+sSecond); 

  // Check if btn was pressed 
  if ( digitalRead(BTN_PIN) == HIGH ) { 
    digitalWrite( 13 , debuglight ); debuglight = invert01(debuglight);
  } 
  
  display.display(); 
  delay(1000);
}


// Draw the lines for the calendar dates, its fixed and draw only once at start
void drawCalendarLines() {
  int16_t i; // Draw day lines separators
  for(i=1; i<7; i+=1) 
    localDrawLine( 0,9*i,display.width(),9*i,WHITE ); // startCol, startLine, endCol, endLine, color
  for(i=1; i<7; i+=1) // Draw day Colunms separators
    localDrawLine( 18*i , 18 , 18*i , display.height() , WHITE ); // startCol, startLine, endCol, endLine, color
}

// Draw a rect, ex: localDrawRect( 0, 0, display.width()-2, display.height()-2, SSD1306_WHITE);
void localDrawRect( int startCol, int startLine, int endCol, int endLine, int color ) {  
  display.drawRect( startCol, startLine, endCol, endLine, color );
  display.display();   //delay(1);
}

// Draw a single like, ex: display.drawLine(0, 0, 0, display.height()-1, SSD1306_WHITE);
void localDrawLine( int startCol, int startLine, int endCol, int endLine, int color ) {
  display.drawLine( startCol, startLine, endCol, endLine, color );
  display.display();   //delay(1);
}

// Used for rtc data get, conversion and set into strings
void readRTC() {
  char Time[] = "  :  :  "; char Calendar[] = "  /  /20  ";
  byte _second, _minute, _hour, _day, _date, _month, _year;  
  
  Wire.beginTransmission(0x68);                 // Start I2C protocol with DS1307 address
  Wire.write(0);                                // Send register address
  Wire.endTransmission(false);                  // I2C restart
  Wire.requestFrom(0x68, 7);                    // Request 7 bytes from DS1307 and release I2C bus at end of reading
  _second = Wire.read();                         // Read seconds from register 0
  _minute = Wire.read();                         // Read minuts from register 1
  _hour   = Wire.read();                         // Read hour from register 2
  _day    = Wire.read();                         // Read day from register 3
  _date   = Wire.read();                         // Read date from register 4
  _month  = Wire.read();                         // Read month from register 5
  _year   = Wire.read();                         // Read year from register 6
  
  // convertBCDtoDecimal :
  _second = (_second >> 4) * 10 + (_second & 0x0F);
  _minute = (_minute >> 4) * 10 + (_minute & 0x0F);
  _hour   = (_hour >> 4)   * 10 + (_hour & 0x0F);
  _date   = (_date >> 4)   * 10 + (_date & 0x0F);
  _month  = (_month >> 4)  * 10 + (_month & 0x0F);
  _year   = (_year >> 4)   * 10 + (_year & 0x0F);  
  Time[7]     = _second % 10 + 48;
  Time[6]     = _second / 10 + 48;
  Time[4]     = _minute % 10 + 48;
  Time[3]     = _minute / 10 + 48;
  Time[1]     = _hour   % 10 + 48;
  Time[0]     = _hour   / 10 + 48;
  Calendar[9] = _year   % 10 + 48;
  Calendar[8] = _year   / 10 + 48;
  Calendar[4] = _month  % 10 + 48;
  Calendar[3] = _month  / 10 + 48;
  Calendar[1] = _date   % 10 + 48;
  Calendar[0] = _date   / 10 + 48;

  // Save date time info into strings with complete0 at left
  sHour="";   sHour+=Time[0];   sHour+=Time[1];   if(sHour.length()==1)   sHour="0"+sHour;
  sMinute=""; sMinute+=Time[3]; sMinute+=Time[4]; if(sMinute.length()==1) sMinute="0"+sMinute;
  sSecond=""; sSecond+=Time[6]; sSecond+=Time[7]; if(sSecond.length()==1) sSecond="0"+sSecond;
  sDay="";    sDay+=Calendar[0];    sDay+=Calendar[1];    if(sDay.length()==1) sDay="0"+sDay;
  sMonth="";  sMonth+=Calendar[3];  sMonth+=Calendar[4];  if(sMonth.length()==1) sMonth="0"+sMonth;
  sYear="";   sYear+=Calendar[8];   sYear+=Calendar[9];   if(sYear.length()==1) sYear="0"+sYear;
}

// Used to invert a int boolean
int invert01( int v01) { if(v01==0) return 1; else return 0;}