#define STANDBY_PHASE -1
#define ERROR_PHASE 0
#define CALCULATION_PHASE 1

#define NEGATIVE -1
#define POSITIVE 1

#define DEFAULT_VALUE 500
#define DIFF_SENSITIVITY 0.1

int phase = STANDBY_PHASE;
int value = 0;
int value_max = 0;
int value_min = 1000;
int value_diff = 0;
int phase_ticks = 0;
int previous_value_diff = 0;

boolean sensitivity_check() {
  int upper_check = previous_value_diff * (1 + DIFF_SENSITIVITY);
  int lower_check = previous_value_diff * (1 - DIFF_SENSITIVITY);
  if (value_diff >= lower_check && value_diff <= upper_check) return 1;
  else return 0;
}

boolean presenceCheck(){

}


void readCommand() {
  if (Serial.available() > 0) {
    char tempChar = Serial.read();
    switch (tempChar) {
      case 'A': {
          phase = STANDBY_PHASE;
          resetAll();
        }
      case 'B' : {
          phase = ERROR_PHASE;
        }
    }
  }
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(4800);
}
void loop() {
  readCommand();
  value = analogRead(A2);
  if (value > value_max) {
    value_max = value;
  } else if (value < value_min) {
    value_min = value;
  }
  previous_value_diff = value_diff;
  value_diff = value_max - value_min;
  switch (phase) {
    case ERROR_PHASE: {
        debug_Print();
        if (value_diff > 60 || value_max == 1000 || value_min == 0) {
          reset_min();
          reset_max();
        } else {
          if (sensitivity_check()) {
            Serial.println("CHECK");
            phase_ticks++;
          }
          if (phase_ticks == 20) {
            Serial.println("DONE");
            phase = CALCULATION_PHASE;
          }
        }
      }
    case CALCULATION_PHASE: {
        int temp_diff = value -
      }
  }

}

void reset_min() {
  value_min = DEFAULT_VALUE;
}
void reset_max() {
  value_max = DEFAULT_VALUE;
}
void reset_value() {
  value = 0;
}
void reset_value_diff() {
  value_diff = 0;
}
void reset_previous_value_diff() {
  previous_value_diff = 0;
}
void reset_phase_ticks() {
  phase_ticks = 0;
}
void resetAll() {
  reset_value();
  reset_min();
  reset_max();
  reset_value_diff();
  reset_previous_value_diff();
  reset_phase_ticks();
}


void debug_Print() {
  Serial.print("value: ");
  Serial.print(value);
  Serial.print(" value_max: ");
  Serial.print(value_max);
  Serial.print(" value_min: ");
  Serial.print(value_min);
  Serial.print(" value_diff: ");
  Serial.println(value_diff);
}