/*
    July 16, 2020
    This will be use to explore the use of 4x4 keypad for
      1. T9 text entry
      2. A, B, C, and D will be use for the menu operations

    Author: George Bantique ( TechToTinker )
*/

#include "LiquidCrystal_I2C.h"
#include "Wire.h"
#include "Keypad.h"
#define DEFAULT_DELAY 300
LiquidCrystal_I2C lcd(0x27,16,2);

const byte ROWS = 4; //four rows
const byte COLS = 4; //four columns

int x = 0;                // Holds the LCD x position
int y = 0;                // Holds the LCD y position
int minValue = 0;         // Lower character location for T9 text entry
int maxValue = 0;         // Max character location for T9 text entry
int keyPressTime = 200;   // Number of loops check of the key
String msg = "";        // Holds the msg
String num = "";        // Holds the key
String alpha = "!@_$%? ABC DEF GHI JKL MNO PQRS TUV WXYZ * # "; // Characters for T9 text entry

char hexaKeys[ROWS][COLS] = { // Character matrix for the keypad
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte rowPins[ROWS] = {7, 6, 5, 4};        // pin assignments for keypad rows
byte colPins[COLS] = {3, 2, 1, 0};        // pin assignments for keypad columns

Keypad customKeypad = Keypad( makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);

byte charUp[8] = {  // arrow up character for LCD
  B00100,
  B01110,
  B11111,
  B00000,
  B00000,
  B00000,
  B00000,
  B00000
};
byte charDown[8] = {  // arrow down character for LCD
  B00000,
  B00000,
  B00000,
  B00000,
  B00000,
  B11111,
  B01110,
  B00100
};
byte charUpDown[8] = {  // arrow up and down character for LCD
  B00100,
  B01110,
  B11111,
  B00000,
  B00000,
  B11111,
  B01110,
  B00100
};

byte menuLevel = 0;     // Level 0: no menu display, display anything you like
                        // Level 1: display main menu
                        // Level 2: display sub menu
                        // Level 3: display sub menu of sub menu
byte menu = 1;          // holds the menu level
byte sub = 1;           // holds the sub menu level
String inputStr, keyStr, outputStr;
int input, output, keyword, inputLength, keyLength;

void setup()
{
  lcd.init();               // initialized the LCD as 16 characters with 2 lines
  lcd.createChar(0, charUp);      // arrow up character
  lcd.createChar(1, charDown);    // arrow down character
  lcd.createChar(2, charUpDown);  // arrow up and down character
  updateLevel_0();                // display the HOME screen
}

void loop() {
  // Process the keys
  processkey();
  // Do other stuffs here
}

void processkey() {
  char key = customKeypad.getKey();
  if (isAlpha(key)) {   // check if key press is a letter
    processKeys(key);   // process it according to keys
  } 
}

void parseKey(int minValue, int maxValue, char keyPress) {
  int ch = minValue;
  char key = keyPress;
  if (keyPress == '*') {              // if *, means backspace
    if ( (x > 0) || (y > 0) ) {       // prevent backspace when no character yet
      x = x - 1;                      // go back to previous character position
      lcd.setCursor(x,y);             // set the new lcd position
      lcd.print("*");                 // write *, which means for editing
      msg.remove(msg.length() - 1);   // remove the last character from the string
    }
  } else {
    for (int i = 0; i < keyPressTime; i++) {
      if (key == keyPress) {          // make sure that same key is press
        lcd.setCursor(x, y);          // set the lcd position
        lcd.print(alpha[ch]);         // print the character according to the character position
        ch++;                         // increment character position
        if (ch > maxValue) {          // if the character counter reached the max value
          ch = minValue;              // reset to min value
          i = 0;                      // reset the loop counter
        }
      }
      key = customKeypad.getKey();  // get the keypress
      delay(10);                    // delay for some time
    }
    x++;                    // increment the x position
    msg += alpha[ch - 1];   // add the character to the variable msg
    if (x > 15) {           // if the lcd reached the rightmost position
      y = 1;                // then wrap to the next line
      x = 0;                // in first character in the left              
    }
  }
}

void enterMSG() {
  char key;      
  lcd.clear();  // clear the LCD display
  x = 0;        // init the x position to zero
  y = 0;        // init the y position to zero
  msg = "";     // clear the msg variable
  do {
    key = customKeypad.getKey();
    if        (key == '1') {    // if a key is pressed, 
      parseKey(0, 6, key);        // compare it to the alpha string array
    } else if (key == '2') {
      parseKey(7, 10, key);
    } else if (key == '3') {
      parseKey(11, 14, key);
    } else if (key == '4') {
      parseKey(15, 18, key);
    } else if (key == '5') {
      parseKey(19, 22, key);
    } else if (key == '6') {
      parseKey(23, 26, key);
    } else if (key == '7') {
      parseKey(27, 31, key);
    } else if (key == '8') {
      parseKey(32, 35, key);
    } else if (key == '9') {
      parseKey(36, 40, key);
    } else if (key == '0') {
      parseKey(43, 44, key);
    } else if (key == '*') {
      parseKey(41, 42, key);
    } else if (key == '#') {
      // do nothing
    }
  } while (key != '#'); // exit the loop when # is pressed
  lcd.setCursor(0, 0);        // these are for verification only
  lcd.print("Msg Inputed");   // feel free to modify it and
  lcd.setCursor(0, 1);        // adapt to your specific requirements
  lcd.print(msg);
  delay(2000);
}

void nextline(){
  char key;
  lcd.clear();  // clear the LCD display
  x = 0;        // init the x position to zero
  y = 0;        // init the y position to zero
  num = "";     // clear the key variable
  do {
    key = customKeypad.getKey();
    if        (key == '1') {    // if a key is pressed, 
      parseKey(0, 6, key);        // compare it to the alpha string array
    } else if (key == '2') {
      parseKey(7, 10, key);
    } else if (key == '3') {
      parseKey(11, 14, key);
    } else if (key == '4') {
      parseKey(15, 18, key);
    } else if (key == '5') {
      parseKey(19, 22, key);
    } else if (key == '6') {
      parseKey(23, 26, key);
    } else if (key == '7') {
      parseKey(27, 31, key);
    } else if (key == '8') {
      parseKey(32, 35, key);
    } else if (key == '9') {
      parseKey(36, 40, key);
    } else if (key == '0') {
      parseKey(43, 44, key);
    } else if (key == '*') {
      parseKey(41, 42, key);
    } else if (key == '#') {
      // do nothing
    }
  } while (key != '#');
  lcd.setCursor(0, 0);        // these are for verification only
  lcd.print("Key Inputed");   // feel free to modify it and
  lcd.setCursor(0, 1);        // adapt to your specific requirements
  lcd.print(num);
  delay(2000);
}

void inputCheck() {
  msg = inputStr;
  inputLength = inputStr.length();
  int i = 0;
  while (i < inputLength) {
    if (inputStr[i] > 95 && inputStr[i] < 123) {
      inputStr[i] -= 32;
    }
    i++;
  }
}

void keyCheck() {
  num = keyStr;
  inputLength = inputStr.length();
  keyLength = keyStr.length();
  int i = 0;
  while (i < keyLength) {
    if (keyStr[i] > 95 && keyStr[i] < 123) {
      keyStr[i] -= 32;
    }
    else if (!isAlpha(keyStr[i])) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Only Alphabet");
      delay (2000);
      break;
    }
    i++;
  }
  while (keyLength < inputLength) { //make the key as long as the input phrase
    keyStr = keyStr + keyStr;
    keyLength = keyStr.length();
  }
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Cipher: ");
  delay(2000);
}
void encodeStr() {
  int i = 0, j = 0;
  while (i < inputLength) {
    if (isWhitespace(inputStr[i])) {
      i++;
    }
    else if (!isAlpha(inputStr[i])) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print(inputStr[i]);
      i++;
    }
    else {
      input = inputStr[i];
      keyword = keyStr[j];
      output = (((input - 65) + (keyword - 65)));
      if (output > 25) {
        output = output + 39;
      }
      else {
        output = output + 65;
      }
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print(output);
      i++;
      j++;
    }
  }
}

void decodeStr() {
  int i = 0, j = 0;
  while (i < inputLength) {
    if (isWhitespace(inputStr[i])) {
      i++;
    }
    else if (!isAlpha(inputStr[i])) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print(inputStr[i]);
      i++;
    }
    else {
      input = inputStr[i];
      keyword = keyStr[j];
      output = (((input - 65) - (keyword - 65)));
      if (output < 0) {
        output = output + 91;
      }
      else {
        output = output + 65;
      }
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print(output);
      i++;
      j++;
    }
  }
}

void processKeys(char keyPressed) {
  switch (menuLevel) {
    case 0:                     // Level 0, home screen
      switch ( keyPressed ) {
        case 'D':               // Enter
          menu = 1;
          menuLevel = 1;        // go to main menu
          updateLevel_1();      // show main menu
          delay(DEFAULT_DELAY);
          break;
        case 'A': // Up
          break;
        case 'B': // Down
          break;
        case 'C': // Back
          break;
          menuLevel = 0;        // go to home screen
          updateLevel_0();      // show home screen
          delay(DEFAULT_DELAY);
          break;
        default:
          break;
      }
      break;
    case 1:                     // Level 1, main menu
      switch ( keyPressed ) {
        case 'D':               // Enter
          sub = 1;
          menuLevel = 2;        // go to sub menu
          updateLevel_2();      // show sub menu
          delay(DEFAULT_DELAY);
          break;
        case 'A':               // Up
          menu--;
          updateLevel_1();      // show main menu
          delay(DEFAULT_DELAY);
          break;
        case 'B':               // Down
          menu++;
          updateLevel_1();      // show main menu
          delay(DEFAULT_DELAY);
          break;
        case 'C': // Back
          menuLevel = 0;        // hide menu, go back to level 0
          updateLevel_0();      // show home screen
          delay(DEFAULT_DELAY);
          break;
        default:
          break;
      }
      break;
    case 2:                     // Level 2, sub menu
      switch ( keyPressed ) {
        case 'D':               // Enter
          if        (sub == 1) {  // Create Msg
            lcd.clear();
            lcd.print("Enter message");
            delay(1000);
            enterMSG();
            lcd.clear();
            lcd.print("Enter Key");
            delay(1000);
            nextline();
            lcd.clear();
            inputCheck();
            keyCheck();
            encodeStr();
            lcd.clear();
            menuLevel = 2;        // go to sub menu
            updateLevel_2();      // show sub menu
          } else if (sub == 2) {  // Send SMS
            menuLevel = 2;        // go to sub menu
            updateLevel_2();      // show sub menu
          }
          delay(DEFAULT_DELAY);
          break;
        case 'A':               // Up
          sub--;
          updateLevel_2();
          delay(DEFAULT_DELAY);
          break;
        case 'B':               // Down
          sub++;
          updateLevel_2();      // show main menu
          delay(DEFAULT_DELAY);
          break;
        case 'C':               // Back
          menuLevel = 1;        // go back to level 1
          updateLevel_1();      // show main menu
          delay(DEFAULT_DELAY);
          break;
        default:
          break;
      }
      break;
    case 3:
      switch (keyPressed) {
        case 'D':               // Enter
          if        (sub == 2) {  // Decode Msg
            lcd.clear();
            lcd.print("Enter message");
            delay(1000);
            enterMSG();
            lcd.clear();
            lcd.print("Enter Key");
            delay(1000);
            nextline();
            delay(2000);
            lcd.clear();
            inputCheck();
            keyCheck();
            decodeStr();
            delay(2000);
            lcd.clear();
            menuLevel = 2;        // go to sub menu
            updateLevel_2();      // show sub menu
          } else if (sub == 2) { 
            menuLevel = 2;        // go to sub menu
            updateLevel_2();      // show sub menu
          }
          delay(DEFAULT_DELAY);
          break;
        case 'A':               // Up
          sub--;
          updateLevel_2();
          delay(DEFAULT_DELAY);
          break;
        case 'B':               // Down
          sub++;
          updateLevel_2();      // show main menu
          delay(DEFAULT_DELAY);
          break;
        case 'C':               // Back
          menuLevel = 1;        // go back to level 1
          updateLevel_1();      // show main menu
          delay(DEFAULT_DELAY);
          break;
        default:
          break;
      }
      break;
      default:
      break;
  }
}

void updateLevel_0() {
  lcd.clear();
  lcd.println("Keypad Msg          ");
  lcd.setCursor(0, 1);
  lcd.println(" D for menu          ");
}

void updateLevel_1 () {
  switch (menu) {
    case 0:
      menu = 1;
      break;
    case 1:
      lcd.clear();
      lcd.print(">Create Msg       ");
      lcd.setCursor(0, 1);
      lcd.print(" Decode Msg       ");
      lcd.setCursor(15, 1);
      lcd.write((byte)1);     // down arrow
      break;
    case 2:
      lcd.clear();
      lcd.print(" Create Msg       ");
      lcd.setCursor(0, 1);
      lcd.print(">Decode Msg       ");
      lcd.setCursor(15, 1);
      lcd.write((byte)0);     // up arrow
      break;
    case 3:
      menu = 2;
      break;
  }
}

void updateLevel_2 () {
  switch (menu) {
    case 0:
      break;
    case 1:                                 // Messages
      switch (sub) {
        case 0:
          break;
        case 1:
          lcd.clear();
          lcd.print(" Messages:      ");
          lcd.setCursor(0, 1);
          lcd.print("  Create MSG    ");
          lcd.setCursor(15, 1);
          lcd.write((byte)0);     // up arrow
          break;
        default:
          break;
      }
      break;
       case 2:                                 // Relay 2
      switch (sub) {
        case 0:
          break;
        case 1:
          lcd.clear();
          lcd.print(" Decode Msg:      ");
          lcd.setCursor(0, 1);
          lcd.print("  Enter Msg ");
          lcd.setCursor(15, 1);
          lcd.write((byte)0);     // up arrow
          break;
        default:
          break;
      }
      break;
    case 3:
      sub = 2;
      break;
  }
}