#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SSD1306_NO_SPLASH

#define encoder0PinA  2
#define encoder0PinB  4
#define encoder0Press 5

#define OLED_ADDR 0x3C
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1

#define BUTTONPRESSEDSTATE 0
#define DEBOUNCEDELAY 20
const int menuTimeout = 10;
const bool menuLargeText = 0;
const int maxmenuItems = 12;
const int itemTrigger = 2;
const int topLine = 18;
const byte lineSpace1 = 9;
const byte lineSpace2 = 17;
const int displayMaxLines = 5;
const int MaxmenuTitleLength = 10;

enum menuModes {
  off,
  menu,
  value,
  message,
  blocking
};
menuModes menuMode = off;

struct oledMenus {
  String menuTitle = "";
  int noOfmenuItems = 0;
  int selectedMenuItem = 0;
  int highlightedMenuItem = 0;
  String menuItems[maxmenuItems + 1];
  uint32_t lastMenuActivity = 0;
  int mValueEntered = 0;
  int mValueLow = 0;
  int mValueHigh = 0;
  int mValueStep = 0;
  int mValue = 0;
};
oledMenus oledMenu;

struct rotaryEncoders {
  volatile int encoder0Pos = 0;
  volatile bool encoderPrevA;
  volatile bool encoderPrevB;
  uint32_t reLastButtonChange = 0;
  bool encoderPrevButton = 0;
  int reButtonDebounced = 0;
  const bool reButtonPressedState = BUTTONPRESSEDSTATE;
  const uint32_t reDebounceDelay = DEBOUNCEDELAY;
  bool reButtonPressed = 0;
};
rotaryEncoders rotaryEncoder;

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void demoMenu() {
  resetMenu();
  menuMode = menu;
  oledMenu.noOfmenuItems = 2;
  oledMenu.menuTitle = "demo_menu";
  oledMenu.menuItems[1] = "On or Off";
  oledMenu.menuItems[2] = "Enter value";

}

void menuActions() {
  if (oledMenu.menuTitle == "demo_menu") {
    handleDemoMenuActions();
  }

}

void handleDemoMenuActions() {
  if (oledMenu.selectedMenuItem == 1) {
    resetMenu();
    menuMode = value;
    oledMenu.menuTitle = "on or off";
    oledMenu.mValueLow = 0;
    oledMenu.mValueHigh = 1;
    oledMenu.mValueStep = 1;
    oledMenu.mValueEntered = 0;
  }
  else if (oledMenu.selectedMenuItem == 2) {
    resetMenu();
    menuMode = value;
    oledMenu.menuTitle = "demo_value";
    oledMenu.mValueLow = 1;
    oledMenu.mValueHigh = 10000;
    oledMenu.mValueStep = 1;
    oledMenu.mValueEntered = 0;
  }

  oledMenu.selectedMenuItem = 0;
}

void menuValues() {
  if (oledMenu.menuTitle == "demo_value") {
    demoMenu();
  }

  if (oledMenu.menuTitle == "on or off") {
    demoMenu();
  }

}

void reUpdateButton() {
  bool tReading = digitalRead(encoder0Press);
  if (tReading != rotaryEncoder.encoderPrevButton) {
    rotaryEncoder.reLastButtonChange = millis();
  }
  if (millis() - rotaryEncoder.reLastButtonChange > rotaryEncoder.reDebounceDelay) {
    if (rotaryEncoder.encoderPrevButton == rotaryEncoder.reButtonPressedState && rotaryEncoder.reButtonDebounced == 0) {
      rotaryEncoder.reButtonPressed = 1;
      if (menuMode == off) {
        demoMenu();
      }
      rotaryEncoder.reButtonDebounced = 1;
    } else {
      rotaryEncoder.reButtonDebounced = 0;
    }
  }
  rotaryEncoder.encoderPrevButton = tReading;
}

void menuUpdate() {

  if (menuMode == off) return;

  if ( (unsigned long)(millis() - oledMenu.lastMenuActivity) > (menuTimeout * 1000) ) {
    resetMenu();
    return;
  }

  if (menuMode == menu)
  {
    serviceMenu();
    menuActions();
  }

  if (menuMode == value)
  {
    serviceValue();
    if (rotaryEncoder.reButtonPressed) {
      menuValues();
    }
  }

  if (menuMode == message)
  {
    if (rotaryEncoder.reButtonPressed == 1)   demoMenu();
  }

}

void serviceMenu() {
  checkForRotaryEncoder();
  updateHighlightedMenuItem();
  displayMenu();
}

void checkForRotaryEncoder() {
  if (rotaryEncoder.encoder0Pos >= itemTrigger) {
    rotaryEncoder.encoder0Pos -= itemTrigger;
    oledMenu.highlightedMenuItem++;
    oledMenu.lastMenuActivity = millis();
  }
  if (rotaryEncoder.encoder0Pos <= -itemTrigger) {
    rotaryEncoder.encoder0Pos += itemTrigger;
    oledMenu.highlightedMenuItem--;
    oledMenu.lastMenuActivity = millis();
  }
  if (rotaryEncoder.reButtonPressed == 1) {
    oledMenu.selectedMenuItem = oledMenu.highlightedMenuItem;
    oledMenu.lastMenuActivity = millis();
  }
}

void updateHighlightedMenuItem() {
  if (oledMenu.highlightedMenuItem > oledMenu.noOfmenuItems) oledMenu.highlightedMenuItem = oledMenu.noOfmenuItems;
  if (oledMenu.highlightedMenuItem < 1) oledMenu.highlightedMenuItem = 1;
}

void displayMenu() {
  const int _centreLine = displayMaxLines / 2 + 1;
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setCursor(0, 0);
  if (menuLargeText) {
    display.setTextSize(2);
    display.println(oledMenu.menuItems[oledMenu.highlightedMenuItem].substring(0, MaxmenuTitleLength));
  } else {
    display.setTextSize(1);
    display.println(oledMenu.menuItems[oledMenu.highlightedMenuItem]);
  }
  int _startAt = oledMenu.highlightedMenuItem - _centreLine + 1;
  if (_startAt < 1) _startAt = 1;
  int _endAt = _startAt + displayMaxLines - 1;
  if (_endAt > oledMenu.noOfmenuItems) _endAt = oledMenu.noOfmenuItems;
  display.setTextSize(1);
  for (int _line = _startAt; _line <= _endAt; _line++) {
    display.setCursor(0, topLine
                      + ((_line - _startAt) * lineSpace1));
    if (_line == oledMenu.highlightedMenuItem) {
      display.setTextColor(WHITE);
    } else {
      display.setTextColor(BLACK, WHITE);
    }
    display.println(oledMenu.menuItems[_line]);
  }
  display.display();
}


void serviceValue() {
  const int _valueSpacingX = 30;
  const int _valueSpacingY = 5;

  uint32_t tTime;



  if (rotaryEncoder.reButtonPressed == 0 && tTime < (menuTimeout * 1000))
  {

    if (oledMenu.menuTitle == "demo_value") {

      if (rotaryEncoder.encoder0Pos <= -itemTrigger) {
        rotaryEncoder.encoder0Pos += itemTrigger;
        if (oledMenu.mValueEntered == 1) {
          oledMenu.mValueEntered = 10;
        } else if (oledMenu.mValueEntered == 10) {
          oledMenu.mValueEntered = 100;
        } else if (oledMenu.mValueEntered == 100) {
          oledMenu.mValueEntered = 1000;
        } else if (oledMenu.mValueEntered == 1000) {
          oledMenu.mValueEntered = 10000;
        }
        oledMenu.lastMenuActivity = millis();
      }

      if (rotaryEncoder.encoder0Pos >= itemTrigger) {
        rotaryEncoder.encoder0Pos -= itemTrigger;
        if (oledMenu.mValueEntered == 10) {
          oledMenu.mValueEntered = 1;
        } else if (oledMenu.mValueEntered == 100) {
          oledMenu.mValueEntered = 10;
        } else if (oledMenu.mValueEntered == 1000) {
          oledMenu.mValueEntered = 100;
        } else if (oledMenu.mValueEntered == 10000) {
          oledMenu.mValueEntered = 1000;
        }
        oledMenu.lastMenuActivity = millis();
      }




    } else {
      if (rotaryEncoder.encoder0Pos >= itemTrigger) {
        rotaryEncoder.encoder0Pos -= itemTrigger;
        oledMenu.mValueEntered -= oledMenu.mValueStep ;
        oledMenu.lastMenuActivity = millis();
      }
      if (rotaryEncoder.encoder0Pos <= -itemTrigger) {
        rotaryEncoder.encoder0Pos += itemTrigger;
        oledMenu.mValueEntered += oledMenu.mValueStep ;
        oledMenu.lastMenuActivity = millis();
      }
    }
    if (oledMenu.mValueEntered < oledMenu.mValueLow) {
      oledMenu.mValueEntered = oledMenu.mValueLow;
      oledMenu.lastMenuActivity = millis();
    }
    if (oledMenu.mValueEntered > oledMenu.mValueHigh) {
      oledMenu.mValueEntered = oledMenu.mValueHigh;
      oledMenu.lastMenuActivity = millis();
    }

    display.clearDisplay();
    display.setTextColor(WHITE);

    display.setCursor(0, 0);
    if (oledMenu.menuTitle.length() > MaxmenuTitleLength) display.setTextSize(1);
    else display.setTextSize(2);
    display.println(oledMenu.menuTitle);
    display.drawLine(0, topLine - 1, display.width(), topLine - 1, WHITE);

    display.setCursor(_valueSpacingX, topLine + _valueSpacingY);
    display.setTextSize(3);
    display.println(oledMenu.mValueEntered);

    display.setCursor(0, display.height() - lineSpace1 - 1 );
    display.setTextSize(1);
    display.println(String(oledMenu.mValueLow) + " to " + String(oledMenu.mValueHigh));

    int Tlinelength = map(oledMenu.mValueEntered, oledMenu.mValueLow, oledMenu.mValueHigh, 0, display.width());
    display.drawLine(0, display.height() - 1, Tlinelength, display.height() - 1, WHITE);

    display.display();

    reUpdateButton();
    tTime = (unsigned long)(millis() - oledMenu.lastMenuActivity);
  }
}

void resetMenu() {
  menuMode = off;
  oledMenu.selectedMenuItem = 0;
  rotaryEncoder.encoder0Pos = 0;
  oledMenu.noOfmenuItems = 0;
  oledMenu.menuTitle = "";
  oledMenu.highlightedMenuItem = 0;
  oledMenu.mValueEntered = 0;
  rotaryEncoder.reButtonPressed = 0;
  oledMenu.lastMenuActivity = millis();
  display.clearDisplay();
  display.display();
}

void doEncoder() {
  bool pinA = digitalRead(encoder0PinA);
  bool pinB = digitalRead(encoder0PinB);

  if (rotaryEncoder.encoderPrevA == pinA && rotaryEncoder.encoderPrevB == pinB) {
    return;
  }

  int change = 0;

  if (rotaryEncoder.encoderPrevA != pinA) {
    change = (rotaryEncoder.encoderPrevA == rotaryEncoder.encoderPrevB) ? 1 : -1;
  } else {
    change = (rotaryEncoder.encoderPrevA == rotaryEncoder.encoderPrevB) ? -1 : 1;
  }

  rotaryEncoder.encoder0Pos += change;
  rotaryEncoder.encoderPrevA = pinA;
  rotaryEncoder.encoderPrevB = pinB;
}




void setup() {

  Serial.begin(9600);

  pinMode(encoder0Press, INPUT_PULLUP);
  pinMode(encoder0PinA, INPUT_PULLUP);
  pinMode(encoder0PinB, INPUT_PULLUP);

  !display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);

  rotaryEncoder.encoder0Pos = 0;
  attachInterrupt(digitalPinToInterrupt(encoder0PinA), doEncoder, CHANGE);

  demoMenu();
}

void loop() {
  reUpdateButton();
  menuUpdate();

  Serial.println(oledMenu.menuTitle);

}