#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ILI9341.h>
#include <Adafruit_FT6206.h>

#define TFT_CS    5
#define TFT_DC    2
#define TFT_RST   4

#define SCREEN_W  240
#define SCREEN_H  320

#define DISPLAY_X      10
#define DISPLAY_Y      10
#define DISPLAY_W     220
#define DISPLAY_H      50

#define KEY_COLS        3
#define KEY_ROWS        4
#define BTN_W          60
#define BTN_H          58   // fills gap so edge touches work
#define BTN_GAP_X      70
#define BTN_GAP_Y      60
#define BTN_ORIGIN_X   20
#define BTN_ORIGIN_Y   80

#define MAX_DIGITS     10
#define DEBOUNCE_MS   250

Adafruit_ILI9341 tft    = Adafruit_ILI9341(TFT_CS, TFT_DC, TFT_RST);
Adafruit_FT6206  ctouch = Adafruit_FT6206();

const char* KEYS[KEY_ROWS][KEY_COLS] = {
  {"1", "2", "3"},
  {"4", "5", "6"},
  {"7", "8", "9"},
  {"C", "0", "X"}
};

String   currentNumber = "";
uint32_t lastTouchMs   = 0;

// ─────────────────────────────────────────────────────────────────
uint16_t keyColor(const char* label) {
  if (strcmp(label, "C") == 0) return ILI9341_RED;
  if (strcmp(label, "X") == 0) return 0xFD20;
  return 0x2945;
}

// ─────────────────────────────────────────────────────────────────
void drawButton(int x, int y, const char* label, uint16_t color) {
  tft.fillRoundRect(x, y, BTN_W, BTN_H, 8, color);
  tft.drawRoundRect(x, y, BTN_W, BTN_H, 8, ILI9341_WHITE);
  tft.setTextSize(2);
  tft.setTextColor(ILI9341_WHITE);
  int textW = strlen(label) * 12;
  tft.setCursor(x + (BTN_W - textW) / 2,
                y + (BTN_H - 16)  / 2);
  tft.print(label);
}

// ─────────────────────────────────────────────────────────────────
void drawKeypad() {
  for (int r = 0; r < KEY_ROWS; r++) {
    for (int c = 0; c < KEY_COLS; c++) {
      drawButton(
        BTN_ORIGIN_X + c * BTN_GAP_X,
        BTN_ORIGIN_Y + r * BTN_GAP_Y,
        KEYS[r][c],
        keyColor(KEYS[r][c])
      );
    }
  }
}

// ─────────────────────────────────────────────────────────────────
void updateDisplay() {
  tft.fillRect(DISPLAY_X + 1, DISPLAY_Y + 1,
               DISPLAY_W - 2, DISPLAY_H - 2,
               ILI9341_BLACK);
  tft.setTextSize(3);
  tft.setTextColor(ILI9341_CYAN);
  int textW = currentNumber.length() * 18;
  int tx    = DISPLAY_X + (DISPLAY_W - textW) / 2;
  int ty    = DISPLAY_Y + (DISPLAY_H - 24)   / 2;
  tft.setCursor(tx, ty);
  tft.print(currentNumber);
}

// ─────────────────────────────────────────────────────────────────
void flashButton(int row, int col) {
  int x = BTN_ORIGIN_X + col * BTN_GAP_X;
  int y = BTN_ORIGIN_Y + row * BTN_GAP_Y;
  tft.fillRoundRect(x, y, BTN_W, BTN_H, 8, ILI9341_WHITE);
  tft.setTextSize(2);
  tft.setTextColor(ILI9341_BLACK);
  int textW = strlen(KEYS[row][col]) * 12;
  tft.setCursor(x + (BTN_W - textW) / 2, y + (BTN_H - 16) / 2);
  tft.print(KEYS[row][col]);
  delay(80);
  drawButton(x, y, KEYS[row][col], keyColor(KEYS[row][col]));
}

// ─────────────────────────────────────────────────────────────────
// Check touch against every button's exact pixel bounding box
// Much more reliable than math-based col/row calculation
// ─────────────────────────────────────────────────────────────────
bool getTouchedButton(int tx, int ty, int &outRow, int &outCol) {
  for (int r = 0; r < KEY_ROWS; r++) {
    for (int c = 0; c < KEY_COLS; c++) {
      // Pixel coordinates of this button
      int bx = BTN_ORIGIN_X + c * BTN_GAP_X;
      int by = BTN_ORIGIN_Y + r * BTN_GAP_Y;

      // Hit test
      if (tx >= bx && tx <= bx + BTN_W &&
          ty >= by && ty <= by + BTN_H) {
        outRow = r;
        outCol = c;
        return true;
      }
    }
  }
  return false;
}

// ══════════════════════════════════════════════════════════════════
void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);

  tft.begin();
  tft.setRotation(0);
  tft.fillScreen(ILI9341_BLACK);

  if (!ctouch.begin(40)) {
    Serial.println("FT6206 not found!");
    tft.setTextColor(ILI9341_RED);
    tft.setTextSize(2);
    tft.setCursor(10, 150);
    tft.print("TOUCH ERROR");
    while (1) delay(100);
  }

  tft.drawRect(DISPLAY_X, DISPLAY_Y, DISPLAY_W, DISPLAY_H, ILI9341_CYAN);
  drawKeypad();
  updateDisplay();

  Serial.println("Ready.");
}

// ══════════════════════════════════════════════════════════════════
void loop() {
  if (!ctouch.touched()) return;

  uint32_t now = millis();
  if (now - lastTouchMs < DEBOUNCE_MS) return;
  lastTouchMs = now;

  TS_Point p = ctouch.getPoint();

  // Both axes are mirrored on this module
  int tx = SCREEN_W - p.x;
  int ty = SCREEN_H - p.y;

  Serial.printf("\nRAW x=%-4d y=%-4d  →  tx=%-4d ty=%-4d\n",
                p.x, p.y, tx, ty);

  int row, col;
  if (!getTouchedButton(tx, ty, row, col)) {
    Serial.println("  → no button hit");
    return;
  }

  const char* pressed = KEYS[row][col];
  Serial.printf("  → row=%d col=%d KEY=%s\n", row, col, pressed);

  if (strcmp(pressed, "C") == 0) {
    currentNumber = "";
  }
  else if (strcmp(pressed, "X") == 0) {
    if (currentNumber.length() > 0)
      currentNumber.remove(currentNumber.length() - 1);
  }
  else {
    if ((int)currentNumber.length() < MAX_DIGITS)
      currentNumber += pressed;
  }

  flashButton(row, col);
  updateDisplay();
}