// christmas tree lights 

#define NR_OF_LIGHTS 6
int pins[NR_OF_LIGHTS] = { 3, 5, 6, 9, 10, 11 }; 

int values[NR_OF_LIGHTS];
int steps[NR_OF_LIGHTS];

#define NR_OF_FADESTEPS 4
int fadesteps[NR_OF_FADESTEPS] = { 192, 128, 64, 0 }; 
int fade_delay = 30; // millisec
int fade_cycles = 1000;

int nr_of_blinks = 2;   
int blink_delay = 400; //millisec

int effect = 1;

int randomlights[NR_OF_LIGHTS];
bool chosenlights[NR_OF_LIGHTS];


/**
*
*/
void setup() { 
 randomSeed(analogRead(0));
 for (int i = 0; i < NR_OF_LIGHTS; i++) {
   values[i] = (int)random(230) + 13; // start values between 'max min' and 'min max'
   steps[i] = (int)random(4) + 1; // steps between 1 and 4
 }
} 

/**
*
*/
void loop() { 

 for (int j = 0; j < fade_cycles; j++) {
   for (int i = 0; i < NR_OF_LIGHTS; i++) {
     fadingLight(i);  
   }
   delay(fade_delay);
 }

 if (effect == 1) {
   blinkAll();
   effect = 2;
 }
 else if (effect == 2) {
   runningLight(0);
   effect = 3;
 }
 else if (effect == 3) {
   runningLight(255);
   effect = 1;
 }
} 

/**
*
*/
void fadingLight(int i) {
 
 int minvalue = (NR_OF_FADESTEPS * abs(steps[i])) + 1;
 int maxvalue = 255 - minvalue;

 int fs = NR_OF_FADESTEPS;
 for (int j = 0; fs > 0; fs--, j++) {
   if (values[i] > fadesteps[j]) {
       break;
   }
 }
 values[i] += fs * steps[i];
 
 if (values[i] > maxvalue  ||  values[i] < minvalue) {
     steps[i] *= -1;
 }
 
 analogWrite(pins[i], values[i]);
}

/**
*
*/
void setAllLights(int value) {
 for (int i = 0; i < NR_OF_LIGHTS; i++) {
   analogWrite(pins[i], value);
 }
}

/**
*
*/
void blinkAll() {
 for (int i = 0; i < nr_of_blinks; i++) {
   setAllLights(255);
   delay(blink_delay);
   setAllLights(0);
   delay(blink_delay);
 }
}

/**
*
*/
void runningLight(int startvalue) {
 setAllLights(startvalue);
 for (int j = 0; j < 2; j++) {
   randomize();
   for (int i = 0; i < NR_OF_LIGHTS; i++) {
     analogWrite(pins[randomlights[i]], 255 - startvalue);
     delay(200);
     analogWrite(pins[randomlights[i]], startvalue);
   }
 }
}


/**
*
*/
void randomize() {
 for (int i = 0; i < NR_OF_LIGHTS; i++) {
   chosenlights[i] = false;
 }
 //first one always ok
 int r = (int)random(NR_OF_LIGHTS);
 randomlights[0] = r;
 chosenlights[r] = true;
 //next 4
 for (int i = 1; i < 5; i++) {
   while (true) {
     r = (int)random(NR_OF_LIGHTS);
     if (chosenlights[r] == false) {
       break;
     }
   }
   randomlights[i] = r;
   chosenlights[r] = true;
 }
 //last one  
 for (int i = 0; i < NR_OF_LIGHTS; i++) {
   if (chosenlights[i] == false) {
     randomlights[5] = i;
     break;
   }
 }
}