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

// ================= TFT =================
#define TFT_CS   D10
#define TFT_DC   D9

Adafruit_ILI9341 tft(TFT_CS, TFT_DC);

// ================= Buzzer =================
#define BUZZER A3

// ================= LED =================
#define LED_PIN D1

// ================= Keypad =================
const byte ROWS = 4;
const byte COLS = 4;

char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte rowPins[ROWS] = {D2, D3, D4, D5};
byte colPins[COLS] = {D6, D7, D8, A0};

Keypad keypad = Keypad(
  makeKeymap(keys),
  rowPins,
  colPins,
  ROWS,
  COLS
);

String phoneNumber = "";

// ================= HOME SCREEN =================
void showHome() {

  tft.fillScreen(ILI9341_BLACK);

  tft.setTextColor(ILI9341_WHITE);
  tft.setTextSize(2);

  tft.setCursor(65, 15);
  tft.println("MINI PHONE");

  tft.drawLine(10, 45, 310, 45, ILI9341_WHITE);

  // Number
  tft.setTextSize(3);
  tft.setCursor(20, 65);
  tft.println(phoneNumber);

  // Instructions
  tft.setTextSize(2);

  tft.setCursor(30, 160);
  tft.println("A = CALL");

  tft.setCursor(30, 190);
  tft.println("B = END");

  tft.setCursor(30, 220);
  tft.println("C = CLEAR");

  tft.setCursor(30, 250);
  tft.println("D = DELETE");
}

// ================= MESSAGE SCREEN =================
void showMessage(const char *message) {

  tft.fillScreen(ILI9341_BLACK);

  tft.setTextColor(ILI9341_WHITE);
  tft.setTextSize(3);

  tft.setCursor(35, 100);
  tft.println(message);
}

// ================= SETUP =================
void setup() {

  pinMode(BUZZER, OUTPUT);
  pinMode(LED_PIN, OUTPUT);

  digitalWrite(BUZZER, LOW);
  digitalWrite(LED_PIN, LOW);

  tft.begin();
  tft.setRotation(1);

  showHome();
}

// ================= LOOP =================
void loop() {

  char key = keypad.getKey();

  if (key) {

    // Number
    if (key >= '0' && key <= '9') {

      phoneNumber += key;

      showHome();
    }

    // * and #
    else if (key == '*' || key == '#') {

      phoneNumber += key;

      showHome();
    }

    // ================= CALL =================
    else if (key == 'A') {

      digitalWrite(LED_PIN, HIGH);

      tone(BUZZER, 1000);

      showMessage("CALLING...");

      delay(2000);

      noTone(BUZZER);
    }

    // ================= END =================
    else if (key == 'B') {

      noTone(BUZZER);

      digitalWrite(LED_PIN, LOW);

      showMessage("CALL ENDED");

      delay(1500);

      showHome();
    }

    // ================= CLEAR =================
    else if (key == 'C') {

      phoneNumber = "";

      showHome();
    }

    // ================= DELETE =================
    else if (key == 'D') {

      if (phoneNumber.length() > 0) {

        phoneNumber.remove(phoneNumber.length() - 1);
      }

      showHome();
    }
  }
}