/*______Import Libraries_______*/
#include <Adafruit_GFX.h>    // Core graphics library
#include <MCUFRIEND_kbv.h>   // Hardware-specific library
#include <TouchScreen.h>
/*______End of Libraries_______*/

#define YP A1 // must be an analog pin, use "An" notation!
#define XM A2 // must be an analog pin, use "An" notation!
#define YM 7 // can be a digital pin
#define XP 6 // can be a digital pin
#define LCD_CS A3
# define LCD_CD A2
# define LCD_WR A1
# define LCD_RD A0
# define LCD_RESET A4
# define WHITE 0x0000 //Black->White
#define YELLOW 0x001F //Blue->Yellow
#define CYAN 0xF800 //Red->Cyan
#define PINK 0x07E0 //Green-> Pink
#define RED 0x07FF //Cyan -> Red
#define GREEN 0xF81F //Pink -> Green
#define BLUE 0xFFE0 //Yellow->Blue
#define BLACK 0xFFFF //White-> Black
#define MINPRESSURE 2
#define MAXPRESSURE 1000
#define TS_MINX 0
#define TS_MINY 0
#define TS_MAXX 600
#define TS_MAXY 600

TouchScreen ts = TouchScreen(XP, YP, XM, YM, 300); //300 is the sensitivity
MCUFRIEND_kbv tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET); //Start communication with LCD

String symbol[4][4] = {
    { "7", "8", "9", "/"},
    { "4", "5", "6", "*"},
    { "1", "2", "3", "-"},
    { "C", "0", "=", "+"}
};
int X, Y, action;
long Num1, Num2, Number;

void setup() {
    Serial.begin(9600); //Use serial monitor for debugging
    uint16_t ID = tft.readID();
    if (ID == 0xD3D3)
        ID = 0x9486; // write-only shield
    tft.reset(); //Always reset at start
    tft.begin(ID); // My LCD uses LIL9341 Interface driver IC
    tft.setRotation(0); // I just roated so that the power jack faces up - optional
    tft.fillScreen(WHITE);

    IntroScreen();

    draw_BoxNButtons();
}

void loop() {
    TSPoint p = waitTouch();
    X = p.x;
    Y = p.y;

    DetectButtons();

    DisplayResult();

    delay(300);
}

TSPoint waitTouch() {
    TSPoint p;
    do {
        p = ts.getPoint();
        pinMode(XM, OUTPUT);
        pinMode(YP, OUTPUT);
    } while ((p.z < MINPRESSURE) || (p.z > MAXPRESSURE));
    p.x = map(p.x, TS_MINX, TS_MAXX, 0, 240);
    p.y = map(p.y, TS_MINY, TS_MAXY, 0, 320);
    return p;
}

void DetectButtons() {
    Serial.print("X = ");
    Serial.println(X);
    Serial.print("Y = ");
    Serial.println(Y);

    if (X < 150 && X > 65) { //Detecting Buttons on Column 1
        if (Y > 350 && Y < 410) { //If cancel Button is pressed
            Serial.println("Button Cancel");
            Number = Num1 = Num2 = 0;
            action = -1;
        }
        else if (Y > 280 && Y < 335) { //If Button 1 is pressed
            Serial.println("Button 1");
            Number = (Number * 10) + 1;
        }
        else if (Y > 225 && Y < 270) { //If Button 4 is pressed
            Serial.println("Button 4");
            Number = (Number * 10) + 4;
        }
        else if (Y > 120 && Y < 200) { //If Button 7 is pressed
            Serial.println("Button 7");
            Number = (Number * 10) + 7;
        }
    }
    else if (X < 210 && X > 150) { //Detecting Buttons on Column 2
        if (Y > 350 && Y < 410) {
            Serial.println("Button 0"); //Button 0 is Pressed
            Number = (Number * 10) + 0;
        }
        else if (Y > 280 && Y < 335) {
            Serial.println("Button 2");
            Number = (Number * 10) + 2;
        }
        else if (Y > 225 && Y < 270) {
            Serial.println("Button 5");
            Number = (Number * 10) + 5;
        }
        else if (Y > 120 && Y < 200) {
            Serial.println("Button 8");
            Number = (Number * 10) + 8;
        }
    }
    else if (X < 280 && X > 210) { //Detecting Buttons on Column 3
        if (Y > 350 && Y < 410) {
            Serial.println("Button Equal");
            CalculateResult();
        }
        else if (Y > 280 && Y < 335) {
            Serial.println("Button 3");
            Number = (Number * 10) + 3;
        }
        else if (Y > 225 && Y < 270) {
            Serial.println("Button 6");
            Number = (Number * 10) + 6;
        }
        else if (Y > 120 && Y < 200) {
            Serial.println("Button 9");
            Number = (Number * 10) + 9;
        }
    }
    else if (X < 345 && X > 280) { //Detecting Buttons on Column 4
        tft.setCursor(200, 20);
        tft.setTextColor(RED);
        if (Y > 350 && Y < 410) {
            Serial.println("Addition");
            action = 0;
            tft.println('+');
            Num1 = Number;
            Number = 0;
        }
        else if (Y > 280 && Y < 335) {
            Serial.println("Subtraction");
            action = 1;
            tft.println('-');
            Num1 = Number;
            Number = 0;
        }
        else if (Y > 225 && Y < 270) {
            Serial.println("Multiplication");
            action = 2;
            tft.println('*');
            Num1 = Number;
            Number = 0;
        }
        else if (Y > 120 && Y < 200) {
            Serial.println("Division");
            action = 3;
            tft.println('/');
            Num1 = Number;
            Number = 0;
        }
    }
    X = Y = -1;
    delay(300);
}

void CalculateResult() {
    Num2 = Number;
    if (action == -1) {
        Number = Num1;
        Num2 = 0;
    }
    else if (action == 0) {
        Number = Num1 + Num2;
        Num1 = Number;
        Num2 = 0;
    }
    else if (action == 1) {
        Number = Num1 - Num2;
        Num1 = Number;
        Num2 = 0;
    }
    else if (action == 2) {
        Number = Num1 * Num2;
        Num1 = Number;
        Num2 = 0;
    }
    else if (action == 3) {
        Number = Num1 / Num2;
        Num1 = Number;
        Num2 = 0;
    }
    action = -1;
}

void DisplayResult() {
    tft.fillRect(0, 0, 240, 80, CYAN); //clear result box
    tft.setCursor(10, 20);
    tft.setTextSize(4);
    tft.setTextColor(BLACK);
    tft.println(Number); //update new value
}

void IntroScreen() {
    tft.setCursor(55, 120);
    tft.setTextSize(3);
    tft.setTextColor(RED);
    tft.println("ARDUINO");
    tft.setCursor(30, 160);
    tft.println("CALCULATOR");
    tft.setCursor(30, 220);
    tft.setTextSize(2);
    tft.setTextColor(BLUE);
    tft.println("    CSED 19");
    delay(1800);
}

void draw_BoxNButtons() {
    //Draw the Result Box
    tft.fillRect(0, 0, 240, 80, CYAN);

    //Draw First Column
    tft.fillRect(0, 260, 60, 60, RED);
    tft.fillRect(0, 200, 60, 60, BLACK);
    tft.fillRect(0, 140, 60, 60, BLACK);
    tft.fillRect(0, 80, 60, 60, BLACK);

    //Draw Third Column
    tft.fillRect(120, 260, 60, 60, GREEN);
    tft.fillRect(120, 200, 60, 60, BLACK);
    tft.fillRect(120, 140, 60, 60, BLACK);
    tft.fillRect(120, 80, 60, 60, BLACK);

    //Draw Secound & Fourth Column
    for (int b = 260; b >= 80; b -= 60) {
        tft.fillRect(180, b, 60, 60, BLUE);
        tft.fillRect(60, b, 60, 60, BLACK);
    }

    //Draw Horizontal Lines
    for (int h = 80; h <= 320; h += 60)
        tft.drawFastHLine(0, h, 240, WHITE);

    //Draw Vertical Lines
    for (int v = 0; v <= 240; v += 60)
        tft.drawFastVLine(v, 80, 240, WHITE);

    //Display keypad lables
    for (int j = 0; j < 4; j++) {
        for (int i = 0; i < 4; i++) {
            tft.setCursor(22 + (60 * i), 100 + (60 * j));
            tft.setTextSize(3);
            tft.setTextColor(WHITE);
            tft.println(symbol[j][i]);
        }
    }
}