#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ILI9341.h>
#include <XPT2046_Touchscreen.h>

// TFT pins (CYD default)
#define TFT_CS   15
#define TFT_DC   2
#define TFT_RST  -1   // often not connected

Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC, TFT_RST);

// Touch pins (CYD default)
#define TOUCH_CS  33
#define TOUCH_IRQ 36   // optional, can be -1

XPT2046_Touchscreen ts(TOUCH_CS, TOUCH_IRQ);

// Paint settings
#define BOXSIZE   40
#define PENRADIUS 5
int currentcolor, oldcolor;

void setup() {
  Serial.begin(115200);
  tft.begin();
  ts.begin();
  ts.setRotation(1);   // match screen orientation

  tft.fillScreen(ILI9341_BLACK);

  // Color palette
  tft.fillRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_RED);
  tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_YELLOW);
  tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_GREEN);
  tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_CYAN);
  tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_BLUE);
  tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_MAGENTA);

  // Default color
  tft.drawRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
  currentcolor = ILI9341_RED;
}

void loop() {
  if (ts.touched()) {
    TS_Point p = ts.getPoint();

    // Map raw touch to screen coordinates
    int x = map(p.x, 200, 3700, 0, tft.width());
    int y = map(p.y, 200, 3700, 0, tft.height());

    if (y < BOXSIZE) {
      oldcolor = currentcolor;
      if (x < BOXSIZE) {
        currentcolor = ILI9341_RED;
        tft.drawRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
      } else if (x < BOXSIZE*2) {
        currentcolor = ILI9341_YELLOW;
        tft.drawRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
      } else if (x < BOXSIZE*3) {
        currentcolor = ILI9341_GREEN;
        tft.drawRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
      } else if (x < BOXSIZE*4) {
        currentcolor = ILI9341_CYAN;
        tft.drawRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
      } else if (x < BOXSIZE*5) {
        currentcolor = ILI9341_BLUE;
        tft.drawRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
      } else if (x < BOXSIZE*6) {
        currentcolor = ILI9341_MAGENTA;
        tft.drawRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
      }

      // restore old box fill
      if (oldcolor != currentcolor) {
        if (oldcolor == ILI9341_RED)
          tft.fillRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_RED);
        if (oldcolor == ILI9341_YELLOW)
          tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_YELLOW);
        if (oldcolor == ILI9341_GREEN)
          tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_GREEN);
        if (oldcolor == ILI9341_CYAN)
          tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_CYAN);
        if (oldcolor == ILI9341_BLUE)
          tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_BLUE);
        if (oldcolor == ILI9341_MAGENTA)
          tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_MAGENTA);
      }
    }

    if (((y-PENRADIUS) > BOXSIZE) && ((y+PENRADIUS) < tft.height())) {
      tft.fillCircle(x, y, PENRADIUS, currentcolor);
    }
  }
}