/***************************************************************
 *                                                             *
 *                Taiko Sanro - Arduino                        *
 *   Support Arduino models with ATmega32u4 microprocessors    *
 *                                                             *
 *             Copyright © 2016 Shiky Chang                    *
 *                zhangxunpx@gmail.com                         *
 *                                                             *
 ***************************************************************/

#define MODE_JIRO 1

#define CHANNELS 4

// Input delay ~ (SAMPLE_CACHE_LENGTH + POWER_CACHE_LENGTH) / sample frequency
// _CACHE_LENGTH must be less than 256
#define SAMPLE_CACHE_LENGTH 150
#define POWER_CACHE_LENGTH 3

// _THRES must be less than 2^32 = 4294967296 = 4.29e9
#define LIGHT_THRES 2500000
#define HEAVY_THRES 5000000

#include <Keyboard.h>

int channelSample [CHANNELS];
int lastChannelSample [CHANNELS];
int sampleCache [CHANNELS][SAMPLE_CACHE_LENGTH];
short int sampleCacheIndex [CHANNELS];

long int power [CHANNELS];
long int powerCache [CHANNELS][POWER_CACHE_LENGTH];
short int powerCacheIndex [CHANNELS];

bool triggered [CHANNELS];

void setup() {
  Serial.begin (9600);
  Keyboard.begin ();
  analogReference (DEFAULT);
  for (short int i = 0; i < CHANNELS; i++) {
    for (short int j = 0; j < SAMPLE_CACHE_LENGTH; j++) {
      sampleCache [i][j] = 0;
    }
    sampleCacheIndex [i] = SAMPLE_CACHE_LENGTH - 1; 
    for (short int j = 0; j < POWER_CACHE_LENGTH; j++) {
      powerCache [i][j] = 0;
    }
    powerCacheIndex [i] = POWER_CACHE_LENGTH - 1; 
    power [i] = 0;
    lastChannelSample [i] = 0;
    triggered [i] = false;
  }
}

void loop() {

// Analog input: 0~5V -> 0~1023
  channelSample[0] = analogRead (A0);  // L don
  channelSample[1] = analogRead (A1);  // R don
  channelSample[2] = analogRead (A2);  // L kat
  channelSample[3] = analogRead (A3);  // R kat

  for (short int i = 0; i < CHANNELS; i++) {

    sampleCacheIndex [i] = (sampleCacheIndex [i] + 1) % SAMPLE_CACHE_LENGTH;
    
    sampleCache [i][sampleCacheIndex [i]] = channelSample [i] - lastChannelSample [i];
    
    long int tempInt;
    tempInt = sampleCache [i][(sampleCacheIndex [i] + 1) % SAMPLE_CACHE_LENGTH];
    power [i] -= tempInt * tempInt;
    tempInt = sampleCache [i][sampleCacheIndex [i]];
    power [i] += tempInt * tempInt;
        
    if (power [i] < LIGHT_THRES) {
      power [i] = 0;
    }
    
    powerCacheIndex [i] = (powerCacheIndex [i] + 1 ) % POWER_CACHE_LENGTH;
    powerCache [i][powerCacheIndex [i]] = power [i];

    lastChannelSample [i] = channelSample [i];

    for (short int j = 0; j < POWER_CACHE_LENGTH - 1; j++){
      if (!triggered) {
        if (powerCache [i][(powerCacheIndex [i] + j + 1) % POWER_CACHE_LENGTH] > powerCache [i][(powerCacheIndex [i] + j) % POWER_CACHE_LENGTH] || j != POWER_CACHE_LENGTH - 2) {
          break;
        } else {
#if MODE_JIRO
          if (power [i] >= LIGHT_THRES) {
            triggered [i] = true;
            switch (i) {
              case 0: Keyboard.print ('g'); break;
              case 1: Keyboard.print ('h'); break;
              case 2: Keyboard.print ('f'); break;
              case 3: Keyboard.print ('j'); break;
            }
          }
#else
          if (power [i] >= HEAVY_THRES) {
            triggered [i] = true;
            switch (i) {
              case 0: Keyboard.print ('t'); break;
              case 1: Keyboard.print ('y'); break;
              case 2: Keyboard.print ('r'); break;
              case 3: Keyboard.print ('u'); break;
            }
          } else if (power [i] >= LIGHT_THRES) {
            triggered [i] = true;
            switch (i) {
              case 0: Keyboard.print ('g'); break;
              case 1: Keyboard.print ('h'); break;
              case 2: Keyboard.print ('f'); break;
              case 3: Keyboard.print ('j'); break;
            }
          }
#endif
        }
      }
    }
    
// This is the end of each channel
  }
  
  delay (1);
}