#include <string.h>
#include <math.h>
#include <Keypad.h>
#include <LiquidCrystal.h>
#include <EEPROM.h>

const float BETA = 3950;

char Lchar, Rchar;
String buffer;
float numstore[20];
int actionstore[20];
int x = 0;
float result;
int cursorx;
volatile bool deleting = 0;
volatile bool syntaxerror = 0;
int displayOn = 1;
int percent = 0;
unsigned long lastpush = 0;
volatile bool calculated = 0;
int storval, newstor;
float tempres;

LiquidCrystal lcd(11, 10, 9, 8, 7, 6);

const byte ROWS = 4;
const byte COLS = 3;

char leftKeypadMap[ROWS][COLS] = {
  {'7', '8', '9'},
  {'4', '5', '6'},
  {'1', '2', '3'},
  {'.', '0', '='}
};
byte LrowPins[ROWS] = {22, 24, 26, 28};
byte LcolPins[COLS] = {23, 25, 27};

Keypad Lkey = Keypad(makeKeymap(leftKeypadMap), LrowPins, LcolPins, ROWS, COLS);

char rightKeypadMap[ROWS][COLS] = {
  {'+', 'M', 'm'},
  {'-', 'r', 'c'},
  {'x', 'n', '%'},
  {'/', 's', '>'}
};
byte RrowPins[ROWS] = {32, 34, 36, 38};
byte RcolPins[COLS] = {33, 35, 37};

Keypad Rkey = Keypad(makeKeymap(rightKeypadMap), RrowPins, RcolPins, ROWS, COLS);

void EEPROMwrite(int startpos, const String &strToWrite)
{
  byte length = strToWrite.length();
  EEPROM.write(startpos, length);
  for (int i = 0; i < length; i++)
  {
    EEPROM.write(startpos + 1 + i, strToWrite[i]);
  }
}

String EEPROMread(int startpos)
{
  int newStrLength = EEPROM.read(startpos);
  char data[newStrLength + 1];
  for (int i = 0; i < newStrLength; i++)
  {
    data[i] = EEPROM.read(startpos + 1 + i);
  }
  data[newStrLength] = '\0';
  return String(data);
}

void startsplash(){
  String splashtext;
  lcd.setCursor(4,0);
  byte bitcheck = EEPROM.read(0);
  if(bitcheck == 255){
    EEPROMwrite(0,"EEE20003");
  }
  splashtext = EEPROMread(64);
  lcd.print(splashtext); //CHANGE GROUP 9 STRING TO CHANGEABLE using EEPROMread()
  delay(2000);
  lcd.clear(); 
  password();
  lcd.clear();
}

void password()
{
  String passcode = EEPROMread(0);
  String userin;
  Serial.println("Please enter password");
  Serial.flush();

  while(Serial.available() < 1){}
  while (Serial.available() > 0)
  {
    userin = Serial.readStringUntil('\n');
  }
  Serial.println(userin);
  if(userin == passcode){
    Serial.println("Correct");
    mainmenu();
  } else {
    Serial.println("Incorrect, please try again");
    password();
  }
}

void mainmenu(){
  Serial.println("\n\n\n");
  Serial.println("--------- Group 9: Calculator ---------");
  Serial.println("   Please select an option:");
  Serial.println(" 1) Change splash text on display");
  Serial.println(" 2) View add-on module stats");
  Serial.println(" 3) Start calculator function");
  
  String userin;
  Serial.flush();
  while(Serial.available() < 1){}
  while (Serial.available() > 0)
  {
    userin = Serial.readStringUntil('\n');
  }
  Serial.println("");
  Serial.print("Selection: ");
  Serial.println(userin.toInt());

  switch(userin.toInt()){
    case 1:
      changesplash();
    break;
    case 2:
      Serial.print("Entering temperature mode");
      delay(300);
      Serial.print(".");
      delay(300);
      Serial.print(".");
      delay(300);
      Serial.print(".");
      delay(150);
      Serial.println("\n\n");
      displayOn = 3;
    break;
    case 3:
      Serial.print("Entering calulcator");
      delay(300);
      Serial.print(".");
      delay(300);
      Serial.print(".");
      delay(300);
      Serial.print(".");
      delay(150);
      Serial.println("\n\n");
      displayOn = 2;
    break;
    default:
      Serial.println("Invalid entry. Please re-enter");
      mainmenu();
    break;
  }
}

void changesplash(){
  Serial.println("Changing splash text:");
  Serial.print("Please enter new splash text: ");
      
  String splashchange;
  Serial.flush();
  while(Serial.available() == 0){}
  while (Serial.available() > 0)
  {
    splashchange = Serial.readStringUntil("\n");
  }
  EEPROMwrite(64, splashchange);
  Serial.println(splashchange);
  Serial.print("Restarting");
  delay(300);
  Serial.print(".");
  delay(300);
  Serial.print(".");
  delay(300);
  Serial.print(".");
  delay(150);
  Serial.println("\n\n");
}

void calcoff(){
  unsigned long currentpush = millis();
  if(currentpush - lastpush > 200)
  {
    if(displayOn == 0)
    {
      displayOn = 1;
    }else{
      displayOn = 0;
    }
    lastpush = currentpush;
  }
}

float calculations()
{
  float numout, numstor;
  numout = numstore[0];
  switch(x){
    case 1:
      numout = numstore[0];
    break;
    case 2:
      numout = numstore[0];
      switch(actionstore[0]) {
        case 1:
          numstor = numout + numstore[1];
        break;
        case 2:
        numstor = numout - numstore[1];
        break;
        case 3:
          numstor = numout * numstore[1];
        break;
        case 4:
          numstor = numout / numstore[1];
        break;
        case 5:
          numstor = (numout * (numstore[1]/100));
          percent = 0;
        break;
        }
      numout = numstor;
    break;
    default:
      for(int i = 0; i < x; i++)
      {
        switch(actionstore[i]) {
        case 1:
          numstor = numout + numstore[i+1];
        break;
        case 2:
        numstor = numout - numstore[i+1];
        break;
        case 3:
          numstor = numout * numstore[i+1];
        break;
        case 4:
          numstor = numout / numstore[i+1];
        break;
        case 5:
          numstor = (numout *(numstore[i+1]/100));
          percent = 0;
        break;
        }
      numout = numstor;
      }
    break;
  }
  return numout;
}

void setup() {
  Serial.begin(9600);
  lcd.begin(16,2);
  attachInterrupt(digitalPinToInterrupt(21), calcoff, FALLING);
  byte bitchecksplash = EEPROM.read(64);
  if(bitchecksplash == 255){
    EEPROMwrite(64,"Group 59");
  }
  startsplash();
}

void loop() {

  switch(displayOn){
    case 0:    
      lcd.noDisplay();
      lcd.clear();
    break;
    case 1: 
      lcd.display();
      startsplash();
    break;
    case 2:
      Lchar = Lkey.getKey();
      Rchar = Rkey.getKey();
      if(Lchar != NO_KEY ){
        lcd.print(Lchar);
        if(deleting == 1){
          deleting = 0;
        }
        if(isDigit(Lchar) == true || Lchar == '.'){
          buffer = buffer + Lchar;
          cursorx++;
          if(calculated == 1){
            lcd.clear();
            lcd.print(Lchar);
            for (int i = 0; i < x; i++){
              numstore[i] = 0;
              actionstore[i] = 0;
            }
            x = 0;
            deleting = 0;
            cursorx = 0;
            calculated = !calculated;
          }
        }else if (Lchar == '=')
        {
          calculated = 1;
          numstore[x] = buffer.toFloat();
          buffer = "";
          x++;
          result = calculations();
          if(percent == 1){
            lcd.print(result);
            lcd.print('%');
            int lengthof = String(result).length();
            cursorx = cursorx + 2 + lengthof;
          }
          else{
            lcd.print(result);
            int lengthof = String(result).length();
            cursorx = cursorx + lengthof + 1;
          }
        }
      }
      else if(Rchar != NO_KEY){
        if(deleting == 1 && Rchar != '>'){
          deleting = 0;
        }
        if(Rchar == '>')
        {
          if(deleting == 0){
            lcd.setCursor(cursorx-1, 0);
            lcd.print("");
            cursorx = cursorx - 1;
            lcd.setCursor(cursorx, 0);
            deleting = 1;
          } else{
          lcd.clear();
          buffer = "";
          for (int i = 0; i < x; i++)
          {
            numstore[i] = 0;
            actionstore[i] = 0;
          }
          x = 0;
          deleting = 0;
          cursorx = 0;
          calculated = !calculated;
          }
        }
        if(Rchar == '+' || Rchar == '-' || Rchar == 'x' || Rchar == '/' || Rchar == '%')
        {
          lcd.print(Rchar);
          cursorx++;
          numstore[x] = buffer.toFloat();
          if(Rchar == '+')
          {
            actionstore[x] = 1;
          }
          else if(Rchar == '-')
          {
            actionstore[x] = 2;
          }
          else if(Rchar == 'x')
          {
            actionstore[x] = 3;
          }
          else if(Rchar == '/')
          {
            actionstore[x] = 4;
          }
          else if(Rchar == '%')
          {
            actionstore[x] = 5;
          }
          buffer = "";
          x++;
        }
        if(Rchar == 's')
        {
          lcd.clear();
          lcd.print("sqrt(");
          lcd.print(result);
          lcd.print(") = ");
          lcd.setCursor(2,1);
          tempres = sqrt(result);
          lcd.print(tempres);
          result = tempres;
          calculated = true;
        }

        if(Rchar == 'M' && calculated == true){
          float currentmem = EEPROMread(128).toFloat();
          float newmem = currentmem + result;
          EEPROMwrite(128, String(newmem));
        }

        if(Rchar == 'm' && calculated == true){
          float currentmem = EEPROMread(128).toFloat();
          float newmem = currentmem - result;;
          EEPROMwrite(128, String(newmem));
        }

        if(Rchar == 'r'){
          float currentmem = EEPROMread(128).toFloat();
          if(currentmem == 0){}
          else{
          lcd.print(currentmem);
          buffer = buffer + currentmem;
          cursorx = cursorx + String(currentmem).length();
          }
          if(calculated == 1){
            lcd.clear();
            lcd.print(buffer);
            calculated = !calculated;
            for (int i = 0; i < x; i++)
            {
              numstore[i] = 0;
              actionstore[i] = 0;
            }
            x = 0;
            deleting = 0;
            cursorx = 0;
            }
        }

        if(Rchar == 'c'){
          EEPROMwrite(128, "");
        }

        if(Rchar == 'n'){
          if(buffer.startsWith("-")){
            Serial.println("NEG");
            for(int i = buffer.length(); i > 0; i--){
              lcd.setCursor(cursorx - i,0);
              lcd.print("");
            }
            lcd.setCursor(cursorx - buffer.length(),0);
            buffer = buffer.substring(1);
            Serial.println(buffer);
            lcd.print(buffer);
            cursorx++;
          }else{
            Serial.println("POS");
            buffer = '-' + buffer;
            lcd.setCursor(cursorx - buffer.length() + 1,0);
            lcd.print(buffer);
            cursorx++;
          }
        }
      }
    break;
    case 3:
      int analogValue = analogRead(A0);
      float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
      lcd.setCursor(0,0);
      lcd.print("Temperature: ");
      lcd.setCursor(3,1);
      lcd.print(celsius);
      lcd.print(" C");
      delay(500);
      lcd.clear();
    break;
  }
}