#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
  #include <avr/power.h>
#endif

#define PIXELS 20
#define PIN 6
#define IN_0 3
#define IN_1 4


#define STATE_RAINBOW 0
#define STATE_HYBRID 1
#define STATE_WHITE 2
#define STATE_CYCLE 3

#define TRANSITION_DELAY 15
#define RAINBOW_DELAY 20

#define WHITE_BRIGHTNESS 200
#define HYBRID_BRIGHTNESS 120

#define HYBRID_RAINBOW_FIRST 0
#define HYBRID_RAINBOW_LAST 11

#define CYCLE_MAX 1000000

// Parameter 1 = number of pixels in strip
// Parameter 2 = Arduino pin number (most are valid)
// Parameter 3 = pixel type flags, add together as needed:
//   NEO_KHZ800  800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)
//   NEO_KHZ400  400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)
//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
//   NEO_RGBW    Pixels are wired for RGBW bitstream (NeoPixel RGBW products)
Adafruit_NeoPixel strip = Adafruit_NeoPixel(PIXELS, PIN, NEO_GRB + NEO_KHZ800);
uint8_t current_state = -1;
uint8_t rainbow_state = 0;
uint32_t cycle_state = 0;
uint8_t hybrid_state = 0;

// IMPORTANT: To reduce NeoPixel burnout risk, add 1000 uF capacitor across
// pixel power leads, add 300 - 500 Ohm resistor on first pixel's data input
// and minimize distance between Arduino and first pixel.  Avoid connecting
// on a live circuit...if you must, connect GND first.

uint8_t readState(){
  uint8_t state = 0;
  if(digitalRead(IN_0) == HIGH){
    state |= 1;
  }
  if(digitalRead(IN_1) == HIGH){
    state |= 2;
  }
  return state;
}

bool stateCheck(){
  uint8_t last_state = current_state;
  current_state = readState();
  return last_state != current_state;
}

void setup() {
  pinMode(IN_0, INPUT_PULLUP);
  pinMode(IN_1, INPUT_PULLUP);
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'

  initRandom();
  rainbow_state = random(256);
  hybrid_state = random(256);
  cycle_state = random(CYCLE_MAX);

  stateCheck();
  switchState();
}


void initRandom(){
  long a = analogRead(3) & 255;
  delay(10);
  long b = analogRead(3) & 255;
  delay(10);
  long c = analogRead(3) & 255;
  delay(10);
  long d = analogRead(3) & 255;

  long seed = a | (b << 8) | (c << 16) | (d << 24);
  randomSeed(seed);
}

void switchState(){
  switch(current_state){
    case STATE_RAINBOW:{
      switchToRainbow();
      return;
    }
    case STATE_HYBRID:{
      switchToHybrid();
      return;
    }
    case STATE_WHITE:{
      showColor(strip.Color(WHITE_BRIGHTNESS, WHITE_BRIGHTNESS, WHITE_BRIGHTNESS), TRANSITION_DELAY);
      return;
    }
    case STATE_CYCLE:{
      switchToCycle();
      return;
    }
  }
}

void switchToRainbow(){
    for(uint16_t i=0; i< strip.numPixels(); i++) {
      strip.setPixelColor(i, getRainbowColor(i));
      strip.show();
      delay(TRANSITION_DELAY);
    }
}

void switchToHybrid(){
    for(uint16_t i=0; i< strip.numPixels(); i++) {
      strip.setPixelColor(i, getHybridColor(i));
      strip.show();
      delay(TRANSITION_DELAY);
    }
}

void switchToCycle(){
    for(uint16_t i=0; i< strip.numPixels(); i++) {
      strip.setPixelColor(i, PreciseWheel(cycle_state));
      strip.show();
      delay(TRANSITION_DELAY);
    }
}

void doStep(){
  if(stateCheck()){
    switchState();
    return;
  }
  switch(current_state){
    case STATE_WHITE:{
      delay(200);
      return;
    }
    case STATE_RAINBOW:{
      rainbowCycleStep();
      delay(RAINBOW_DELAY);
      return;
    }
    case STATE_HYBRID:{
      hybridCycleStep();
      delay(RAINBOW_DELAY);
      return;
    }
    case STATE_CYCLE:{
      colorCycleStep();
      return;
    }
  }
}

void loop() {
  doStep();
}

// Fill the dots one after the other with a color
void showColor(uint32_t c, uint8_t wait) {
  for(uint16_t i=0; i<strip.numPixels(); i++) {
    strip.setPixelColor(i, c);
    strip.show();
    delay(wait);
  }
}

void rainbowCycleStep() {
  for(uint16_t i=0; i< strip.numPixels(); i++) {
    strip.setPixelColor(i, getRainbowColor(i));
  }
  strip.show();
  rainbow_state++;
}

void hybridCycleStep() {
  for(uint16_t i=0; i< strip.numPixels(); i++) {
    strip.setPixelColor(i, getHybridColor(i));
  }
  strip.show();
  hybrid_state++;
}

void colorCycleStep() {
  uint32_t color = PreciseWheel(cycle_state);
  for(uint16_t i=0; i< strip.numPixels(); i++) {
    strip.setPixelColor(i, color);
  }
  strip.show();
  cycle_state++;
  if(cycle_state == CYCLE_MAX){
    cycle_state = 0;
  }
}

uint32_t getRainbowColor(uint16_t i){
  return Wheel(((i * 256 / strip.numPixels()) + rainbow_state) & 255);
}

uint32_t getHybridColor(uint16_t i){
  if(i >= HYBRID_RAINBOW_FIRST && i <= HYBRID_RAINBOW_LAST){
    return Wheel(((i * 256 / (HYBRID_RAINBOW_LAST - HYBRID_RAINBOW_FIRST + 1)) + hybrid_state) & 255);
  }
  else{
    return strip.Color(HYBRID_BRIGHTNESS, HYBRID_BRIGHTNESS, HYBRID_BRIGHTNESS);
  }
}

// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  WheelPos = 255 - WheelPos;
  if(WheelPos < 85) {
    return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  }
  if(WheelPos < 170) {
    WheelPos -= 85;
    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
  WheelPos -= 170;
  return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}

uint32_t PreciseWheel(uint32_t pos){
  float H = pos / (float)CYCLE_MAX;
  uint8_t var_r = 0;
  uint8_t var_g = 0;
  uint8_t var_b = 0;

  float var_h = H * 6;
  //if ( var_h >= 6 || var_h < 0 ) var_h = 0;      //H must be < 1
  int var_i = int( var_h );             //Or ... var_i = floor( var_h )
  uint8_t var_2 = ( 1 - 1 * ( var_h - var_i ) ) * 255;
  uint8_t var_3 = ( 1 - 1 * ( 1 - ( var_h - var_i ) ) ) * 255;

  if      ( var_i == 0 ) { var_r = 255   ; var_g = var_3 ; var_b = 0    ; }
  else if ( var_i == 1 ) { var_r = var_2 ; var_g = 255   ; var_b = 0    ; }
  else if ( var_i == 2 ) { var_r = 0     ; var_g = 255   ; var_b = var_3; }
  else if ( var_i == 3 ) { var_r = 0     ; var_g = var_2 ; var_b = 255  ; }
  else if ( var_i == 4 ) { var_r = var_3 ; var_g = 0     ; var_b = 255  ; }
  else                   { var_r = 255   ; var_g = 0     ; var_b = var_2; }

  return strip.Color(var_r, var_g, var_b);
}