int ditlen = 120;     // dot length mS
bool mode_tx = 0;     // true in transmitting
bool mode_cmd = 0;    // command mode, currently used to change keyer speed
bool mode_msg = 0;    // play canned CW message 

#define HANG_MS 1200  // T/R drop-out delay
#define LONG_PRESS 500  // long press in mS

unsigned long last_mS;

#define PDL_DIT 0
#define PDL_DAH 2
#define SDTN 1
#define PTT_LINE PB3  
#define CW_LINE 4

#define CMD_A  A0   // PB5 (A0) used as analogue input for CMD button

void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(CW_LINE, OUTPUT);
  pinMode(PDL_DIT, INPUT_PULLUP);
  pinMode(PDL_DAH, INPUT_PULLUP);
  pinMode(SDTN, OUTPUT);

  pinMode(PTT_LINE, OUTPUT);
  digitalWrite(PTT_LINE, 0);
  pinMode(CMD_A, INPUT);

  last_mS = millis(); 

  //Serial.begin(9600);

  // test buzzer

   tone(SDTN, 700); delay(300);
   noTone(SDTN);    delay (1000);

   digitalWrite(SDTN, HIGH);
   delay(300);
   digitalWrite(SDTN, LOW);
   delay(300);
}


void didah(bool dit){
  int durn = ditlen;
  if(!dit) durn = 3*ditlen;

  digitalWrite(CW_LINE, HIGH);  // turn the LED on (HIGH is the voltage level)
  tone(SDTN, 700);
  delay(durn);                      // wait for a second
  digitalWrite(CW_LINE, LOW);   // turn the LED off by making the voltage LOW
  noTone(SDTN);
  delay(ditlen);                   
};

void Rx2Tx(){
  mode_tx = 1;
  digitalWrite(PTT_LINE, HIGH); 
  delay(300);
}

void Tx2Rx(){
  mode_tx = 0; 
  digitalWrite(PTT_LINE, LOW); 
  delay(300); 
}


void play_msg(){
  // play a canned CW message
  if(!mode_tx) Rx2Tx();
  
  char msg[] = {'.', '.', '.', '-', ' ',      // V
               // '-', '.', '-', ' ',           // K
               // '.', '.', '.', '-', '-', ' ', // 3
               // '.', '.', '.', '.', ' ',      // H
               // '-', '.',                     // N
                '\n' 
  };

  int i=0; 
  while(msg[i] != '\n'){
    if(msg[i] == '.') didah(1);
    else if(msg[i] == '-') didah(0);
    else if(msg[i] == ' ') delay(ditlen*3);
    i++;
  };
  delay(HANG_MS); 
  Tx2Rx();
  mode_msg = 0;
}


void loop() {
  // read CMD button
  int val = analogRead(CMD_A);
  int cntr = 0;
  if((val > 1022)) {
    // button is pressed, so spin for bit to see if it is a long press 
    while(val > 1022){
      delay(100);
      cntr += 100; 
      val = analogRead(CMD_A);
    }
    if(cntr >= LONG_PRESS) mode_msg = 1;
    else mode_cmd = 1;  // short press enters command mode

    // flash the PTT line to acknowledge button press
    /*digitalWrite(CW_LINE, HIGH);
    delay(200);
    digitalWrite(CW_LINE,LOW);
    delay(200);*/
    //mode_msg = 1;  // temp!
  }

  // if requested, playcanned message
  if(mode_msg) play_msg();

  // read the paddle
  bool dit_b=0, dah_b=0;

  if(!digitalRead(PDL_DIT)) dit_b = true;  // putton pressed returns LOW
  if(!digitalRead(PDL_DAH)) dah_b = true;

  //if((dit_b or dah_b) && !mode_tx) Rx2Tx();
  if(dit_b || dah_b){
    //  a dit, dah or both are pressed
    if(!mode_tx) Rx2Tx();
    if(mode_tx){
      if(dit_b && dah_b) ;  // handle squeeze
      if(dit_b) didah(1);
      if(dah_b) didah(0);
      last_mS = millis(); 
    }
  
  if(mode_cmd){
    if(dit_b) ditlen -= 20;
    if(dah_b) ditlen += 20;
    delay(100);
    last_mS = millis(); 
  }

  }

  dit_b = 0;
  dah_b = 0;
  if(mode_tx && abs((millis()-last_mS)) > HANG_MS)
  {
    if(mode_tx) Tx2Rx();
    if(mode_cmd) mode_cmd = 0; 
    last_mS = millis(); 
  }
}