#include <TFT_eSPI.h>
#include <SPI.h>       // this is needed for display
#include <Wire.h>      // this is needed for FT6206
#include <Adafruit_FT6206.h>

// The FT6206 uses hardware I2C (SCL/SDA)
Adafruit_FT6206 ctp = Adafruit_FT6206();

// The display also uses hardware SPI, plus #9 & #10
#define TFT_CS 15
#define TFT_DC 2
#define TFT_MOSI 23
#define TFT_SCLK 18
TFT_eSPI tft = TFT_eSPI(); // Invoke custom library with default width and height

#define BLACK           0x0000
#define BLUE            0x2015
#define BLUE2           0x0DDE
#define RED             0xF800
#define GREEN           0x07E0
#define GREEN2          0x43A2
#define CYAN            0x07FF
#define MAGENTA         0xF81F
#define YELLOW          0xFFE0
#define WHITE           0xFFFF
#define GRAY            0x31A6
#define PINK            0xF81F

char option;
int number, number1, number2;
bool result = false;

void setup() {
  Serial.begin(115200);
  //Serial.println(F("Cap Touch Paint!"));

  tft.begin();

  if (! ctp.begin(40)) {  // pass in 'sensitivity' coefficient
    Serial.println("Couldn't start FT6206 touchscreen controller");
    while (1);
  }

  Serial.println("Capacitive touchscreen started");

  tft.fillScreen(WHITE);
  drawButtons();
}

void loop() {
  if (ctp.touched()) {
    TS_Point p = ctp.getPoint();
    p.x = map(p.x, 0, 240, 240, 0);
    p.y = map(p.y, 0, 320, 320, 0);
    selectedButton( p.x,  p.y);
    showNumber();
    delay(250);
  }
}

void selectedButton(int x, int y) {
  char key;
  if (y >= 60 && y < 112) {
    if (x >= 0 && x < 90) {
      key = '(';
    } else if (x >= 90 && x < 180) {
      key = ')';
    } else {
      option = '/';
      number1 = number;
      number = 0;
      tft.setCursor(210, 20);
      tft.setTextColor(CYAN);
      tft.setTextSize(3);
      tft.print("/");
      key = '/';
    }
  }
  if (y >= 112 && y < 164) {
    if (x >= 0 && x < 60) {
      if (number == 0)
        number = 7;
      else
        number = (number * 10) + 7;
      key = '7';
    } else if (x >= 60 && x < 120) {
      if (number == 0)
        number = 8;
      else
        number = (number * 10) + 8;
      key = '8';
    } else if (x >= 120 && x < 180) {
      if (number == 0)
        number = 9;
      else
        number = (number * 10) + 9;
      key = '9';
    } else {
      option = '*';
      number1 = number;
      number = 0;
      tft.setCursor(210, 20);
      tft.setTextColor(CYAN);
      tft.setTextSize(3);
      tft.print("x");
      key = '*';
    }
  }
  if (y >= 164 && y < 216) {
    if (x >= 0 && x < 60) {
      if (number == 0)
        number = 4;
      else
        number = (number * 10) + 4;
      key = '4';
    } else if (x >= 60 && x < 120) {
      if (number == 0)
        number = 5;
      else
        number = (number * 10) + 5;
      key = '5';
    } else if (x >= 120 && x < 180) {
      if (number == 0)
        number = 6;
      else
        number = (number * 10) + 6;
      key = '6';
    } else {
      option = '-';
      number1 = number;
      number = 0;
      tft.setCursor(210, 20);
      tft.setTextColor(CYAN);
      tft.setTextSize(3);
      tft.print("-");
      key = '-';
    }
  }
  if (y >= 216 && y < 268) {
    if (x >= 0 && x < 60) {
      if (number == 0)
        number = 1;
      else
        number = (number * 10) + 1;
      key = '1';
    } else if (x >= 60 && x < 120) {
      if (number == 0)
        number = 2;
      else
        number = (number * 10) + 2;
      key = '2';
    } else if (x >= 120 && x < 180) {
      if (number == 0)
        number = 3;
      else
        number = (number * 10) + 3;
      key = '3';
    } else {
      option = '+';
      number1 = number;
      number = 0;
      tft.setCursor(210, 20);
      tft.setTextColor(CYAN);
      tft.setTextSize(3);
      tft.print("+");
      key = '+';
    }
  }
  if (y >= 268 && y < 320) {
    if (x >= 0 && x < 60) {
      number1 = number2 = 0;
      number = 0;
      result = false;
      tft.fillRect(5, 5, 230, 55, GRAY);
      key = 'C';
    } else if (x >= 60 && x < 120) {
      if (number == 0)
        number = 0;
      else
        number = (number * 10) + 0;
      key = '0';
    } else {
      number2 = number;
      result = true;
      calcResult();
      showNumber();    
      key = '=';
    }
  }
}

void drawBox() {
  tft.drawFastHLine(0, 1, 240, WHITE);
  tft.drawFastVLine(0, 0, 320, WHITE);
  tft.drawFastVLine(238, 0, 320, WHITE);

  tft.drawFastHLine(0, 60, 240, WHITE);
  tft.drawFastVLine(90, 60, 52, WHITE);
  tft.drawFastVLine(180, 60, 52, WHITE);

  for (int y = 112; y <= 216; y += 52) {
    tft.drawFastHLine(0, y, 240, WHITE);
    tft.drawFastVLine(60, y, 52, WHITE);
    tft.drawFastVLine(120, y, 52, WHITE);
    tft.drawFastVLine(180, y, 52, WHITE);
  }

  tft.drawFastHLine(0, 268, 240, WHITE);
  tft.drawFastVLine(60, 268, 52, WHITE);
  tft.drawFastVLine(120, 268, 52, WHITE);
  tft.drawFastHLine(0, 319, 240, WHITE);
}

void drawButtons() {

  // x_start, y_start, altura, largura, cor
  tft.fillRect(0, 0, 240, 60, GRAY);
  //tft.fillRect(0, 0, 240, 60, WHITE);

  //Primeira linha
  tft.fillRect(0, 60, 90, 52, BLACK);

  tft.fillRect(90, 60, 90, 52, BLACK);

  tft.fillRect(180, 60, 60, 52, GRAY);

  for (int y = 112; y <= 216; y += 52) {
    tft.fillRect(0, y, 60, 52, BLACK);

    tft.fillRect(60, y, 60, 52, BLACK);

    tft.fillRect(120, y, 60, 52, BLACK);

    tft.fillRect(180, y, 60, 52, GRAY);
  }

  //Quinta linha
  tft.fillRect(0, 268, 60, 52, RED);

  tft.fillRect(60, 268, 60, 52, BLACK);

  tft.fillRect(120, 268, 120, 52, GREEN);

  drawBox();
  fillButtons();
}

void fillButtons() {
  tft.setCursor(38, 75);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("(");

  tft.setCursor(128, 75);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print(")");

  tft.setCursor(204, 77);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("/");

  tft.setCursor(204, 127);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("x");

  tft.setCursor(204, 180);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("-");

  tft.setCursor(204, 233);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("+");

  tft.setCursor(170, 280);
  tft.setTextColor(WHITE);
  tft.setTextSize(4);
  tft.print("=");

  tft.setCursor(22, 283);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("C");

  tft.setCursor(83, 283);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("0");

  tft.setCursor(22, 127);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("7");

  tft.setCursor(22, 180);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("4");

  tft.setCursor(22, 233);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("1");

  tft.setCursor(83, 127);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("8");

  tft.setCursor(83, 180);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("5");

  tft.setCursor(83, 233);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("2");

  tft.setCursor(143, 127);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("9");

  tft.setCursor(143, 180);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("6");

  tft.setCursor(143, 233);
  tft.setTextColor(WHITE);
  tft.setTextSize(3);
  tft.print("3");
}

void showNumber() {
  if (result)
    tft.fillRect(5, 5, 230, 55, GRAY);
  tft.fillRect(5, 5, 200, 55, GRAY);
  tft.setCursor(10, 20);
  tft.setTextSize(4);
  tft.setTextColor(WHITE);
  tft.println(number); 
}

void calcResult() {
  switch (option) {
    case '+':
      number = number1 + number2;
      break;
    case '-':
      number = number1 - number2;
      break;
    case '*':
      number = number1 * number2;
      break;
    case '/':
      number = number1 / number2;
      break;
  }
}