#include <Adafruit_ILI9341.h>
#include <Adafruit_FT6206.h>
#include "Fonts/FreeSerif9pt7b.h"
#include "Fonts/FreeSerif12pt7b.h"
Adafruit_ILI9341 tft(10,9);
Adafruit_FT6206 ts;

void Text1(int x, int y, int size, int color, String msg) {
  tft.setFont(&FreeSerif12pt7b);
  tft.setCursor(x,y);
  tft.setTextSize(size);
  tft.setTextColor(color);
  tft.print(msg);
}

void Text(int x, int y, int size, int color, String msg) {
  tft.setFont(&FreeSerif9pt7b);
  tft.setCursor(x,y);
  tft.setTextSize(size);
  tft.setTextColor(color);
  tft.print(msg);
}


void printVal(int x, int y, int size, int color, double num) {
  tft.setFont(&FreeSerif9pt7b);
  tft.setCursor(x,y);
  tft.setTextSize(size);
  tft.setTextColor(color);
  tft.print(num);
}

int calcDecimal(String str) {
  int dec = 5;
  for(int i=str.length()-1; str[i] != '.'; i--) {
    if(str[i] == '0') dec--;
    else return dec;
  }
  return dec;
}

void createCalcInterface() {
  String label[] = {"AC", " ", "+/-", "/", "7", "8", "9", "x", "4", "5", "6", "-", "1", "2", "3", "+", "%", "0", ".", "="};
  for(int i=0; i<20; i++) {
    if(i/4 == 0 || i%4 == 3) {
      tft.fillRoundRect(10+(i%4)*60, 90+(i/4)*45, 40, 35, 15, 0xef7f);
      Text(20+(i%4)*60, 120+(i/4)*45, 1, 0x001f, label[i]);
    } else {
      tft.fillRoundRect(10+(i%4)*60, 90+(i/4)*45, 40, 35, 15, 0xf7be); //ef7d
      Text(25+(i%4)*60, 115+(i/4)*45, 1, 0x0, label[i]);
    }
  }
}

void calculate() {
  bool run = true, started = false;
  float n = 0;
  float n1 = 0, n2 = 0;
  int decimal = 0;
  bool point = false;
  bool operatorDefined = false;
  bool calculated = false;
  char operation = '+';
  int userCursor = 0, ansCursor = 0;
  String userDisplay = "";
  String ansDisplay = "";
  while(run) {
    bool reading = true;
    while(reading) {
      if(!ts.touched()) continue;
      int select_x = (Touch_x()-10)/60;
      int select_y = (Touch_y()-90)/45;
      if(select_x > 2 || select_y < 1 || (select_x == 0 && select_y == 4)) {
        if(select_x > 2) {
          if(select_y == 4) {
            if(calculated) {
              delay(200); continue;
            }
            Text1(220-userCursor, 25, 1, 0xffff, userDisplay);
            Text(220-ansCursor, 75, 1, 0xffff, ansDisplay);
            userDisplay = ansDisplay; ansDisplay = "";
            userCursor = 12*(userDisplay.length()-1);
            Text1(220-userCursor, 25, 1, 0xf, userDisplay);
            calculated = true;
            delay(200);
            continue;
          }
          switch(select_y) {
            case 0: operation = '/'; break;
            case 1: operation = '*'; break;
            case 2: operation = '-'; break;
            case 3: operation = '+'; break;
          }
          Text1(220-userCursor, 25, 1, 0xffff, userDisplay);
          if(operatorDefined) {
            userDisplay.remove(userDisplay.length()-1);
            userCursor -= 12;
          }
          operatorDefined = true;
          userDisplay += operation;
          if(userCursor <200 || userDisplay.length() >= 34) userCursor += 12;
          Text1(220-userCursor, 25, 1, 0xf, userDisplay);
          started = true; n=0; n2 = n1; point = false; decimal = 0;
          delay(200);
        }
        else if(select_x == 0 && select_y == 0) {
          Text(220-ansCursor, 75, 1, 0xffff, ansDisplay);//String(n1,calcDecimal(String(n1,5))));
          Text1(220-userCursor, 25, 1, 0xffff, userDisplay);
          userCursor = 0; ansCursor = 0; n1 = 0; n2 = 0; n = 0; userDisplay = ""; ansDisplay = "";
          started = false; operatorDefined = false; point = false; calculated = false; decimal = 0;
          delay(200);
        }
      } else {
        int enteredDigit;
        if(select_y < 4) {
          enteredDigit = 3*(3-select_y)+select_x+1;
        } else {
          if(select_x == 1) enteredDigit = 0;
          else if(select_x == 2) {
            if(point) continue;
            point = true; operatorDefined = false;
            Text1(220-userCursor, 25, 1, 0xffff, userDisplay);
            userDisplay += "."; if(userCursor <200 || userDisplay.length() >= 34) userCursor += 4;
            Text1(220-userCursor, 25, 1, 0xf, userDisplay);
            delay(200);
            continue;
          }
        }
        if(calculated && operatorDefined) calculated = false;
        operatorDefined = false;
        if(point) {
          decimal++;
          n = n + float(enteredDigit)/(pow(10.00000,decimal));
        } else n = 10*n + enteredDigit;
        Text1(220-userCursor, 25, 1, 0xffff, userDisplay);
        userDisplay += String(enteredDigit);
        if(userCursor < 200 || userDisplay.length() >= 34) userCursor += 12;
        Text1(220-userCursor, 25, 1, 0xf, userDisplay);
        if(!started) {
          Text(220-ansCursor, 75, 1, 0xffff, ansDisplay);//String(n1,calcDecimal(String(n1,calcDecimal(String(n1,5))))));
          n1 = n; ansDisplay = String(n1,calcDecimal(String(n1,5)));
          ansCursor = 10*(ansDisplay.length()-1);
          Text(220-ansCursor, 75, 1, 0x8410, ansDisplay);//String(n1,calcDecimal(String(n1,5))));
        } else {
          Text(220-ansCursor, 75, 1, 0xffff, ansDisplay);//String(n1,calcDecimal(String(n1,5))));
          n1 = n2;
          switch(operation) {
            case '/': n1/=n; break;
            case '*': n1*=n; break;
            case '+': n1+=n; break;
            case '-': n1-=n; break;
          }
          ansDisplay = String(n1,calcDecimal(String(n1,5)));
          ansCursor = 10*(ansDisplay.length()-1);
          Text(220-ansCursor, 75, 1, 0x8410, ansDisplay);//String(n1,calcDecimal(String(n1,5))));
        }
        delay(200);
      }
    }
  }
}

int checkPriority(char oper) {
  if(oper == '/') return 1;
  else if(oper == '*') return 2;
  else if(oper == '+') return 3;
  else if(oper == '-') return 4;
  return 5;
}

int compute(String userDisplay) {
  String input = userDisplay;
  int result = 0;

  while(1) {
  Serial.print("input : ");
  Serial.println(input);
  char oper = '+';
  int operatorIdx = 0;
  int priority = 200;
  int start = 0, ending = 0;
  int leftOperand = 0, rightOperand = 0;
  for(int i=0; i<input.length(); i++) {
    if(!isDigit(input[i])) {
      if(checkPriority(input[i]) <= priority) {
        priority = checkPriority(input[i]);
        oper = input[i];
        operatorIdx = i;
      }
    }
  }

  if(priority == 200 || operatorIdx == 0) {
    result = input.toInt();
    return result;
  }

  Serial.print("operator index : ");
  Serial.println(operatorIdx);
  
  int coeff = 1;
  for(int i = operatorIdx-1; i>=0; i--) {
    if(input[i] == '-') {
      leftOperand *= (-1);
      start = i;
      break;
    }
    if(!isDigit(input[i])) {
      start = i+1;
      break;
    }
    leftOperand = leftOperand + coeff * (int(input[i]) - int('0'));
    coeff *= 10;
  }
  for(int i = operatorIdx+1; i<input.length(); i++) {
    if(!isDigit(input[i])) {
      ending = i-1;
      break;
    }
    rightOperand = 10*rightOperand + (int(input[i])-int('0'));
    ending = i;
  }

  Serial.print("Left operand : ");
  Serial.println(leftOperand);
  Serial.print("Right operand : ");
  Serial.println(rightOperand);


  switch(oper) {
    case '/' : result = leftOperand / rightOperand; break;
    case '*' : result = leftOperand * rightOperand; break;
    case '-' : result = leftOperand - rightOperand; break;
    case '+' : result = leftOperand + rightOperand; break;
  }
  Serial.print("input at before edit : ");
  Serial.println(input);
  if(input[start] == '-') {
    if(result < 0) {
      input = input.substring(0, start) + String(result) + input.substring(ending+1);
    } else input = input.substring(0, start) + "+" + String(result) + input.substring(ending+1);
  } else input = input.substring(0, start) + String(result) + input.substring(ending+1);
  Serial.print("input at last : ");
  Serial.println(input);
  result = 0;

  }
}

void takeInput() {
  bool run = true;
  String userDisplay = "";
  bool operatorDefined = false;
  while(run) {
    if(!ts.touched()) continue;
    int select_x = (Touch_x()-10)/60;
    int select_y = (Touch_y()-90)/45;
    if(select_x > 2 && select_y < 4) {
      Text1(220-(12*userDisplay.length()), 25, 1, 0xffff, userDisplay);
      if(operatorDefined) {
        userDisplay.remove(userDisplay.length() - 1, 1);
      }
      operatorDefined = true;
      switch(select_y) {
        case 0 : userDisplay += '/'; break;
        case 1 : userDisplay += '*'; break;
        case 2 : userDisplay += '-'; break;
        case 3 : userDisplay += '+'; break;
      }
    } else if(select_y == 0 && select_x < 3) {

    } else if(select_x < 3 && select_y > 0 && select_y < 4) {
      operatorDefined = false;
      Text1(220-(12*userDisplay.length()), 25, 1, 0xffff, userDisplay);
      userDisplay += String((3-select_y)*3 + select_x + 1);
    } else if(select_y == 4) {
      operatorDefined = false;
      if(select_x == 1) {
        userDisplay += '0';
      }
    }

    Text1(220-(12*userDisplay.length()), 25, 1, 0xf, userDisplay);


    String calculation = userDisplay;
    if(userDisplay[0] == '-') {
      calculation = "0" + userDisplay;
    }
    if(!operatorDefined)
      Serial.println(compute(calculation));

    delay(200);
  }
}

int Touch_x() {
  TS_Point point = ts.getPoint();
  return 240-point.x;
}
int Touch_y() {
  TS_Point point = ts.getPoint();
  return 320-point.y;
}

int currentState = 1;
int subState = 0;
int32_t num1 = 0, num2 = 0;
int currentNum = 1;
bool operationDefined = false;

void setup() {
  tft.begin();
  ts.begin();
  tft.fillScreen(0xffff);
  Serial.begin(115200);
  float numb = 9.7000000;
  Serial.println(String(numb,7));
  //Serial.println(((Touch_x()-10)%60)+4*((Touch_y()-90)%45));
}

void loop() {
  if(currentState == 1) {
    if(subState == 0) {
      createCalcInterface();
      subState = 1;
    }
    if(ts.touched()) {
      takeInput();
      //calculate();
    }
  }

}