#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27, 20, 4);

#define modePin 3
#define answerPin 8
#define questionPin 9

int16_t a = 1;
int16_t b;
int16_t c;
float lineOfSym = 0.0;
float vertexY = 0.0;
int8_t x1;
int8_t x2;

bool refresh = 0;
bool triggerHistory = 0;
byte mode = 1;

byte powerOf2[] = {
  B11100,
  B00100,
  B01000,
  B10000,
  B11100,
  B00000,
  B00000,
  B00000
};
 
void setup() {
  // put your setup code here, to run once:
  lcd.init();
  lcd.backlight();
  lcd.createChar(0, powerOf2);
  //Serial.begin(9600);

  pinMode(modePin, INPUT); //Mode Button
  attachInterrupt(digitalPinToInterrupt(modePin), modeChange, FALLING);
  pinMode(answerPin, INPUT); //Answer Button
  pinMode(questionPin, INPUT); //New Question Button
}

void loop() {
  //Serial.println(mode);
  //Randomize
  if ((digitalRead(questionPin) == HIGH) || (refresh == 1)) {
    lcd.clear();
    triggerHistory = 1;
    refresh = 0;
    a = random(1, 9);
    x1 = random(-9, 9);
    if (x1 == 0) {
      x1 = 1;
    }
    x2 = random(-9, 9);
    if (x2 == 0) {
      x2 = 1;
    }
  }

  //Set the equation
  b = a * (x1 + x2);
  c = a * (x1 * x2);
  lineOfSym = -b / (2.0 * a);
  vertexY = (a * lineOfSym * lineOfSym) + (b * lineOfSym) + c;

  switch (mode) {
    case 1: //Find X
      //Draw the equation
      if (triggerHistory == 1) {
        delay(500);
        lcd.clear();
        lcd.setCursor(0,0);
        lcd.print("Find X");
        lcd.setCursor(0,1);
        lcd.print(a);
        lcd.print("x");
        lcd.write(0);
        if (b > 0) {
          lcd.print("+");
        }
        if (b != 0) {
          lcd.print(b);
          lcd.print("x");
        }
        if (c > 0) {
          lcd.print("+");
        }
        lcd.print(c);
        lcd.print("=0");
      }

      //Reveal Answer
      if ((digitalRead(answerPin) == HIGH) && (triggerHistory == 1)) {
        lcd.clear();
        lcd.setCursor(3, 0);
        lcd.print("The Answer To:");
        delay(2000); //The amount of time "The Answer To:" is displayed

        lcd.setCursor(0,1);
        lcd.print(a);
        lcd.print("x");
        lcd.write(0);
        if (b > 0) {
          lcd.print("+");
        }
        if (b != 0) {
          lcd.print(b);
          lcd.print("x");
        }
        if (c > 0) {
          lcd.print("+");
        }
        lcd.print(c);
        lcd.print("=0");
        delay(1000); //The amount of time the equation is displayed

        lcd.setCursor(7,2);
        lcd.print("Is....");
        delay(1000); //The amount of time "Is...." is displayed

        lcd.setCursor(0, 3);
        lcd.print("x = ");
        lcd.print(x1 * -1);
        if (x1 != x2) {
          lcd.print(" or ");
          lcd.print("x = ");
          lcd.print(x2 * -1);
        }
        delay(6000); //The amount of time the answer is displayed
        while (digitalRead(answerPin) == 1) {
          delay(1000);
        }
        refresh = 1;
        lcd.clear();
      }

      //Preview Screen
      if (triggerHistory == 0) {
        lcd.setCursor(1, 1);
        lcd.print("Quadratic Equation");
        lcd.setCursor(1, 2);
        lcd.print("Factoring Practice");
      }
      break;
    case 2: //Find the Line of Symmetry
      //Draw the equation
      if (triggerHistory == 1) {
        delay(500);
        lcd.clear();
        lcd.setCursor(0,0);
        lcd.print("Find the Line of Sym");
        lcd.setCursor(0,1);
        lcd.print(a);
        lcd.print("x");
        lcd.write(0);
        if (b > 0) {
          lcd.print("+");
        }
        if (b != 0) {
          lcd.print(b);
          lcd.print("x");
        }
        if (c > 0) {
          lcd.print("+");
        }
        lcd.print(c);
        lcd.print("=0");
      }

      //Reveal Answer
      if ((digitalRead(answerPin) == HIGH) && (triggerHistory == 1)) {
        lcd.clear();
        lcd.setCursor(3, 0);
        lcd.print("The Answer To:");
        delay(2000); //The amount of time "The Answer To:" is displayed

        lcd.setCursor(0,1);
        lcd.print(a);
        lcd.print("x");
        lcd.write(0);
        if (b > 0) {
          lcd.print("+");
        }
        if (b != 0) {
          lcd.print(b);
          lcd.print("x");
        }
        if (c > 0) {
          lcd.print("+");
        }
        lcd.print(c);
        lcd.print("=0");
        delay(1000); //The amount of time the equation is displayed

        lcd.setCursor(7,2);
        lcd.print("Is....");
        delay(1000); //The amount of time "Is...." is displayed

        lcd.setCursor(0, 3);
        lcd.print("Sym Line = ");
        if (int(lineOfSym) != lineOfSym) {
          lcd.print(lineOfSym);
        } else {
          lcd.print(int(lineOfSym));
        }
        delay(6000); //The amount of time the answer is displayed
        while (digitalRead(answerPin) == 1) {
          delay(1000);
        }
        refresh = 1;
        lcd.clear();
      }
      break;
    case 3: //Find Vertex
      //Draw the equation
      if (triggerHistory == 1) {
        delay(500);
        lcd.clear();
        lcd.setCursor(0,0);
        lcd.print("Find the Vertex");
        lcd.setCursor(0,1);
        lcd.print(a);
        lcd.print("x");
        lcd.write(0);
        if (b > 0) {
          lcd.print("+");
        }
        if (b != 0) {
          lcd.print(b);
          lcd.print("x");
        }
        if (c > 0) {
          lcd.print("+");
        }
        lcd.print(c);
        lcd.print("=0");
      }

      //Reveal Answer
      if ((digitalRead(answerPin) == HIGH) && (triggerHistory == 1)) {
        lcd.clear();
        lcd.setCursor(3, 0);
        lcd.print("The Answer To:");
        delay(2000); //The amount of time "The Answer To:" is displayed

        lcd.setCursor(0,1);
        lcd.print(a);
        lcd.print("x");
        lcd.write(0);
        if (b > 0) {
          lcd.print("+");
        }
        if (b != 0) {
          lcd.print(b);
          lcd.print("x");
        }
        if (c > 0) {
          lcd.print("+");
        }
        lcd.print(c);
        lcd.print("=0");
        delay(1000); //The amount of time the equation is displayed

        lcd.setCursor(7,2);
        lcd.print("Is....");
        delay(1000); //The amount of time "Is...." is displayed

        lcd.setCursor(0, 3);
        lcd.print("V = ");
        if (int(lineOfSym) != lineOfSym) {
          lcd.print(lineOfSym);
        } else {
          lcd.print(int(lineOfSym));
        }  
        lcd.print(", ");
        if (int(vertexY) != vertexY) {
          lcd.print(vertexY);
        } else {
          lcd.print(int(vertexY));
        } 
        delay(6000); //The amount of time the answer is displayed
        while (digitalRead(answerPin) == 1) {
          delay(1000);
        }
        refresh = 1;
        lcd.clear();
      }
      break;
  }
}

void modeChange() {
  if (triggerHistory == 1) {
    if (digitalRead(modePin) == HIGH) {
      mode = mode + 1;
      delay(500);
      //Serial.println("Help");
   }
    if (mode >= 4) {
     mode = 1;
    }
  }
}