// Button handling variables
int buttonstate;                 // the current reading from the input pin
int last_buttonstate = LOW;      // the previous reading from the input pin
int debounce_time = 100;         // don't expect two pushes any quicker than this

// Beat counting variables
unsigned long prev_time = 0;     // system time at last button push, in ms
unsigned long current_time;      // system time at this button push, in ms
const int beats_max = 512;       // just in case you push the button too many times
int beat_lengths[beats_max];     // array to store the beat lengths
int beat_length = 500;           // calculated average of beat lengths
int beat_index = 0;              // number of button presses
const int beat_timeout = 2000;  // time after which beat_index resets, in ms

// Animation variables
int anim_time = 0; 										    // time since last frame displayed
const int step_count = 8;                 // how many steps per beat
int step_length = 50;                     // how long a step lasts in ms
int channel_count = 8;                    // maximum 8 connected wires
byte frames[step_count] = {1,2,4,8,16,32,64,128}; // each byte is a frame. Each bit of each byte is a channel.
int current_frame = 0;                                  // index to animation array
unsigned long anim_start = 0;							// system time at start of animation
int frame_threshold = 0;							    // when it decreases, we advance to the next frame
int frame_prev_threshold = 0;

// Pattern switching variables
int anim_index=0;                 // index of list of animations

/*******************Setup Loop***************************/
void setup() {                
  // Initialize elwire outputs
  pinMode(2, OUTPUT);  // channel A index 0
  pinMode(3, OUTPUT);  // channel B index 1
  pinMode(4, OUTPUT);  // channel C index 2
  pinMode(5, OUTPUT);  // channel D index 3  
  pinMode(6, OUTPUT);  // channel E index 4  
  pinMode(7, OUTPUT);  // channel F index 5  
  pinMode(8, OUTPUT);  // channel G index 6  
  pinMode(9, OUTPUT);  // channel H index 7  

 // Initialise button inputs
  pinMode(A1, INPUT_PULLUP); // BPM button

// Pin 13 is the onboard status LED if we need it
  pinMode(13, OUTPUT);    

// Create the animations from binary data
}

/*******************Main Loop***************************/
void loop() {
  // read the current time and calculate time since last good button reading
  current_time = millis();
   int elapsed_time = current_time - prev_time;
  // read the state of the switch
  int reading = digitalRead(A1);

  // if it's the first button push in a while, reset the indexes and timers
    if (reading == HIGH && last_buttonstate == LOW && elapsed_time > beat_timeout){
      beat_index = 0;
      current_frame = 0;
      anim_start = current_time;
      prev_time = current_time;
      frame_threshold = 0;
      frame_prev_threshold = 100;
      digitalWrite(13,HIGH);
    }

 // if it's been long enough, but not too long, then record a new beat.
    if (reading == HIGH && last_buttonstate == LOW && elapsed_time < beat_timeout && elapsed_time > debounce_time) {
    // record this as the new previous time
    prev_time = current_time;
    // increment the beat index and if we reach the end, go back round, just in case
    ++beat_index;
    if (beat_index == beats_max) beat_index = 0;
    // set the current beat to the measured time
    beat_lengths[beat_index] = elapsed_time;
    // calculate the new average beat length and step length
    int running_total = 0;
      for (int i=0; i<=beat_index; i++) {
        running_total += beat_lengths[i];
        }
      beat_length = running_total / beat_index;
      step_length = beat_length / step_count;
      // and set the button state to HIGH so we don't trigger this again too soon
      last_buttonstate == HIGH;      
      }
    else {
      last_buttonstate == LOW;
     }




  // update animation timers and see if we've passed a frame threshold
   anim_time = current_time - anim_start;           // how long since the animation started
   frame_threshold = anim_time % step_length;       // divide by step length and find remainder
  // If a step has passed, increment the frame and set the outputs
  if ( frame_threshold < frame_prev_threshold) {    // when the remainder goes from high to low, we have started a new frame
   
    if (current_frame >= step_count) current_frame = 0;
      int pinout=0;
      int channel_state=LOW;
      for (int i=0; i< channel_count; i++){
        channel_state = bitRead(frames[current_frame], i);
        pinout = i+2;
        digitalWrite(pinout,channel_state);
      }
       ++current_frame;
    }
    frame_prev_threshold = frame_threshold;
    // save the reading. Next time through the loop, it'll be the lastButtonState:
  last_buttonstate = reading;
}