/*
  Connections:
  - Volume control potentiometer
    - +5V -> pot MAX
    - A0 -> pot sweeper (center)
    - GND -> pot MIN
  - buttons
    - +5V -> [1k ohm] -> common connection to buttons
    - D2 -> button 1
         -> [1M ohm] -> GND
    - D3 -> button 2
         -> [1M ohm] -> GND     
    - D4 -> button 3
         -> [1M ohm] -> GND
    - D5 -> button 4
         -> [1M ohm] -> GND
    (or drop the resistors completely and use the internal pull-down resistors)
*/

#include <DebounceEvent.h>

const int btns = 4;
const int SWITCH_DEBOUNCE_DELAY = 500;
DebounceEvent switches[btns] = {
  DebounceEvent(2, BUTTON_SWITCH, SWITCH_DEBOUNCE_DELAY),
  DebounceEvent(3, BUTTON_SWITCH, SWITCH_DEBOUNCE_DELAY),
  DebounceEvent(4, BUTTON_SWITCH, SWITCH_DEBOUNCE_DELAY),
  DebounceEvent(5, BUTTON_SWITCH, SWITCH_DEBOUNCE_DELAY)
};

const int volumePin = A0;
const int volumeRawMin = 0;
const int volumeRawMax = 850;
const int volumeStep = 5;
int volume = -1;

// === Switches ===

void switchesSetup() {
  for (int i = 0; i < btns; i++) {
    sendButtonEvent(i+1, switches[i].pressed());
  }
}

void switchesLoop() {
  for (int i = 0; i < btns; i++) {
    int event = switches[i].loop();
    if (event != EVENT_NONE) {
      sendButtonEvent(i+1, switches[i].pressed());
    }
  }
}

// === Volume ===

void volumeInit() {
  pinMode(volumePin, INPUT);
  volume = volumeRead();
  sendVolumeEvent();
}

int volumeRead() {
  int volumeRaw = analogRead(volumePin);
  return map(volumeRaw, volumeRawMin, volumeRawMax, 0, 255);
}

void volumeLoop() {
  int newVolume = volumeRead();
  if (abs(volume - newVolume) >= volumeStep) {
    volume = newVolume;
    sendVolumeEvent();
  }
}

// === Serial Events ===

void sendEvent(char *name, int value) {
  Serial.print(name);
  Serial.print("=");
  Serial.println(value);
}

void sendVolumeEvent() {
  sendEvent("volume", volume);
}

void sendButtonEvent(int buttonNumber, int state) {
  String name = "button";
  name.concat(buttonNumber);
  sendEvent(name.c_str(), state);
}

// === MAIN ===

void setup() {
  Serial.begin(9600);
  switchesSetup();
  volumeInit();
}

void loop() {
  switchesLoop();
  volumeLoop();
  delay(100);
}