#include <SoftwareSerial.h>

// constants won't change. They're used here to 
// set pin numbers:
const int buttonPin = 7;     // the number of the pushbutton pin
const int ledPin =  8;      // the number of the LED pin
SoftwareSerial mySerial(0, 1); // RX, TX

void setup() {
  mySerial.begin(115200);
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);
}

int NOTHING = 0;
int ZOOM_IN = 97;
int ZOOM_OUT = 115;
int BLOCK_TIME = 500;
int DEBOUNCE_TIME = 125;

int OFF = 0;
int CLICK = 1;
int HOLD = 2;

int state = OFF;
int ledState = HIGH;
int command = NOTHING;

void loop() {
  // read the state of the switch into a local variable:
  int reading = digitalRead(buttonPin);
  //button pressed
  if (reading == LOW) {
    delay(DEBOUNCE_TIME);
    reading = digitalRead(buttonPin);
    // released
    if (reading == HIGH) {
      if (state == OFF) {
        state = CLICK;
        mySerial.write(state);
      } else {
        state = OFF;
        mySerial.write(NOTHING);
      }
    } else {
      if (state == CLICK) {
        state = HOLD;
        mySerial.write(ZOOM_OUT);
        command = ZOOM_OUT;
      } else if (state == OFF) {
        state = HOLD;
        mySerial.write(ZOOM_IN);
        command = ZOOM_IN;
      } else {
        mySerial.write(command);
      }
    }    
  }
}

void switchLed() {
  if (ledState == HIGH) {
    ledState = LOW;
  } else {
    ledState = HIGH;
  }
  digitalWrite(ledPin, ledState);
}