#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Fonts/FreeSerif24pt7b.h>
#include "InputDebounce.h"

/**
* Source code:
* https://www.italiantechproject.it/tutorial-arduino/sleep-mode-e-interrupt
*/
#include <avr/sleep.h>

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library. 
// On an arduino UNO:       A4(SDA), A5(SCL)
// On an arduino MEGA 2560: 20(SDA), 21(SCL)
// On an arduino LEONARDO:   2(SDA),  3(SCL), ...
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3c ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32

#define BUTTON_DEBOUNCE_DELAY   20   // [ms]
#define ADC_POT_THRESHOLD 10
#define MS_BEFORE_ASLEEP 20000
#define MS_BEFORE_POFF 5000
#define WAKEUP_PIN 2

unsigned int readPotentiometer() {
  return analogRead(A0);
}

const int pin = 7;
const int rstPin = 8;
const long RST_PRESS_TIME = 1000;
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

enum EnCoinType {
  En1C,
  En2C,
  En5C,
  En10C,
  En20C,
  En50C,
  En1E,
  En2E
};

int Coins[] = {0, 0, 0, 0, 0, 0, 0, 0}; // 1C, 2C, 5C, 10C, 20C, 50C, 1E, 2E

unsigned long duration, lastActivity;
int prevAdcIn = readPotentiometer();
const int K = 9810 / 2;
auto totalCount = 0.0f;
long rstBtnPressedTime = 0;
static InputDebounce buttonTest; // not enabled yet, setup has to be called later
unsigned long startUS = 0;
bool pinPresence = false;
float coinDiameter = 0.0f;
float coinType = 0.0f;
char strTotals[16];

void initDisplay() {
  Serial.print("Initializing display...");

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }

  Serial.println("DONE");

  // Clear the buffer
  display.clearDisplay();

  display.setTextSize(1);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw white text
  display.setCursor(0, 0);     // Start at top-left corner
  display.println("Insert coin...");
  display.display();
}

void setup() {
  Serial.begin(9600);
  while (!Serial);
  initDisplay();
  pinMode(pin, INPUT_PULLUP);
  pinMode(rstPin, INPUT_PULLUP);
  // setup input button (debounced)
  buttonTest.setup(rstPin, BUTTON_DEBOUNCE_DELAY, InputDebounce::PIM_INT_PULL_UP_RES);
  attachInterrupt(digitalPinToInterrupt(WAKEUP_PIN), wakeupCallback, FALLING);
}

void wakeupCallback() {
}

float getCoinType(float diameter) {
  float coinType = 0.0;

  if(diameter >= 16 && diameter <= 17) {
    coinType = 0.01;
  } else if(diameter >= 18 && diameter <= 19) {
    coinType = 0.02;
  } else if(diameter >= 21 && diameter <= 22) {
    coinType = 0.05;
  } else if(diameter >= 19 && diameter <= 20) {
    coinType = 0.1;
  } else if(diameter >= 22 && diameter <= 23) {
    coinType = 0.2;
  } else if(diameter >= 24 && diameter <= 25) {
    coinType = 0.5;
  } else if(diameter >= 23 && diameter <= 24) {
    coinType = 1.0;
  } else if(diameter >= 25 && diameter <= 26) {
    coinType = 2.0;
  }

  return coinType;
}

void showCoinType(float coinType) {
    switch((int)(coinType * 100)) {
      case 1:
        display.println("1C");
        break;

      case 2:
        display.println("2C");
        break;

      case 5:
        display.println("5C");
        break;

      case 10:
        display.println("10C");
        break;

      case 20:
        display.println("20C");
        break;

      case 50:
        display.println("50C");
        break;

      case 100:
        display.println("1E");
        break;

      case 200:
        display.println("2E");
        break;
    }
}

void drawProgress(long buttonTest_OnTime) {  
  static const auto TOP_PROGBAR_Y = display.height()  - 40, LOW_PROGBAR_Y = display.height() - 42;
  
  display.drawRect(0, TOP_PROGBAR_Y, display.width(), LOW_PROGBAR_Y, SSD1306_WHITE);

  auto xMax = map(buttonTest_OnTime, 0, 1000, display.width(), 0);
  
  for(auto i=0; i<xMax; i++) {
    display.fillRect(0, TOP_PROGBAR_Y, i, LOW_PROGBAR_Y, SSD1306_WHITE);
  }
}

void incCoins(float coinType) {  
  switch((int)(coinType * 100)){
    case 1:
      Coins[En1C]++;
    break;

    case 2:
      Coins[En2C]++;
    break;

    case 5:
      Coins[En2C]++;
    break;

    case 10:
      Coins[En2C]++;
    break;

    case 20:
      Coins[En2C]++;
    break;

    case 50:
      Coins[En2C]++;
    break;

    case 100:
      Coins[En1E]++;
    break;

    case 200:
      Coins[En2E]++;
    break;
  }
}

void checkCoinInput() {  
  //duration = pulseInLong(pin, LOW, 300000);
  //duration = random(20000, 1000000);

  // presence
  if(!pinPresence && !digitalRead(pin)) {
    pinPresence = true;
    startUS = micros();
  }

  // end presence
  if(pinPresence && digitalRead(pin)) {
    pinPresence = false;
    duration = micros() - startUS;

    auto seconds = (float)duration/(float)1000000.0f;
    auto power = seconds * seconds;
    coinDiameter = K * power;
    coinType = getCoinType(coinDiameter);

    if(coinType > 0.0f) {
      totalCount += coinType;
      incCoins(coinType);
    }
  }

  if(pinPresence) {
    displayON();
    lastActivity = millis();
  }

  display.setCursor(0, 0);     // Start at top-left corner
  display.print("Duration: "); display.print((float)(duration)/1000.0f); display.println(" ms");
  display.print("Diameter: "); display.print(coinDiameter); display.println(" mm");

  if(coinType > 0.0f) {
    showCoinType(coinType);
  }
}

void checkButtonState() {  
  static unsigned int buttonTest_StateOnCount = 0; // to handle new pressed state, and still pressed state
  static unsigned int buttonTest_OnTimeLast = 0; // to handle new released state, and remember last on-time (button pressed)
  
  unsigned long now = millis();
  
  // poll button state, return continuous on-time [ms] if pressed (debounced)
  unsigned int buttonTest_OnTime = buttonTest.process(now);
  
  // handle input button
  if(buttonTest_OnTime) {
    // save current on-time (button pressed), to be used when released
    buttonTest_OnTimeLast = buttonTest_OnTime;
    // check for state change
    unsigned int count = buttonTest.getStatePressedCount();
    if(buttonTest_StateOnCount != count) {
      buttonTest_StateOnCount = count;
      // handle pressed state
      Serial.print("HIGH");
    }
    else {
      // handle still pressed state
      Serial.print("HIGH still pressed");

      if(buttonTest_OnTime > RST_PRESS_TIME) {
        totalCount = 0.0f;
        buttonTest_OnTime = 0;
        delay(500);
      }
    }
    Serial.print(" (");
    Serial.print(buttonTest_OnTime);
    Serial.println("ms)");

    displayON();
    drawProgress(buttonTest_OnTime);
    lastActivity = millis();
  }
  else {
    if(buttonTest_OnTimeLast) {
      // handle released state
      Serial.print("LOW (last on-time: HIGH ");
      Serial.print(buttonTest_OnTimeLast);
      Serial.println("ms)");
      buttonTest_OnTimeLast = 0; // reset, do not handle this released state again
    }
  }
}

void showTotals() {  
/*
  display.setCursor(0, SCREEN_HEIGHT - 40);
  display.println(" 1C| 2C| 5C|10C");
  sprintf(strTotals, "%3d|%3d|%3d|%3d", Coins[En1C], Coins[En2C], Coins[En5C], Coins[En10C]);
  display.println(strTotals);

  display.println("20C|50C| 1E| 2E");
  sprintf(strTotals, "%3d|%3d|%3d|%3d", Coins[En20C], Coins[En50C], Coins[En1E], Coins[En2E]);
  display.println(strTotals);
*/
  display.setCursor(0, SCREEN_HEIGHT - 10);
  display.print("Tot: "); display.print(totalCount); display.println(" Euro");
}

void checkPotentiometer() {
  static const auto MIN_VAL = 15.0f;
  static const auto MAX_VAL = 30.0f;
  static const auto MIN_ADC = 0;
  static const auto MAX_ADC = 512;
  auto adcIn = readPotentiometer();

  if(abs((int)prevAdcIn - (int)adcIn) > ADC_POT_THRESHOLD) {
    displayON();
    prevAdcIn = adcIn;
    lastActivity = millis();

    auto adcInMap = map(adcIn, MIN_ADC, MAX_ADC, (int)MIN_VAL * 10, (int)MAX_VAL * 10);
    coinDiameter = (float)adcInMap / 10.0f;
    coinType = getCoinType(coinDiameter);

    if(coinType > 0.0f) {
      totalCount += coinType;
      display.setCursor(0, 0);     // Start at top-left corner
      showCoinType(coinType);
      incCoins(coinType);

      display.setCursor(0, SCREEN_HEIGHT - 30);
      display.print("adcIn: "); display.println(adcIn);
      display.setCursor(0, SCREEN_HEIGHT - 20);
      display.print("diameter: "); display.print(coinDiameter); display.println(" mm");
      delay(1000);
    }
  }
}

void displayOFF() {
  display.ssd1306_command(SSD1306_DISPLAYOFF);
}

void displayON() {
  display.ssd1306_command(SSD1306_DISPLAYON);
}

void checkSleep() {  
  if(millis() - lastActivity >= MS_BEFORE_POFF) {
    displayOFF();
    sleep_enable();
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);
    delay(200);
    sleep_cpu();
    sleep_disable();
    lastActivity = millis();
  }
/*
  if(millis() - lastActivity >= MS_BEFORE_ASLEEP) {
    displayOFF();
    lastActivity = millis();
  }*/
}

void loop() {
  display.clearDisplay();

  //checkCoinInput();
  checkButtonState();
  checkPotentiometer();
  checkSleep();
  showTotals();

  display.display();
  delay(10);
}