Fibo Words

;
//Project Euler Problem #230 - Fibonacci Words


(function (exports) {
  // var BigNumber = require('bignumber.js');

  var SQ5 = Math.sqrt(5);
  var RECSQ5 = 1/SQ5;
  var C1 = (1+SQ5)/2;
  var C2 = (1-SQ5)/2;
  var PHI = C1;
  function getNumber (n) {
    // console.log((127+19*n)*(Math.pow(7,n)));
    return (127+19*n)*(Math.pow(7,n));
  }

  exports.nFibo = function (n) {
    //Returns the nth element of Fibonacci Sequence
    return Math.round(RECSQ5 * (Math.pow(C1,n) - Math.pow(C2,n)));
  };

  exports.nthDigit = function (n) {
    // console.log(n);
    if (n < 1) return undefined;
    return (Math.floor(n*PHI) - Math.floor((n-1)*PHI)-1) === 0 ? "A" : "B";
  };

  exports.nWords = function(word, n) {
    //Returns the number of sequence that contains nth number and its length 
    var l = word.length, result, prev = 0;
    // n = getNumber(n);
    // console.log(l, n);
    // if (n===1) return {nSequence:1, s}
    for (var i = 1; i < n; i += 1) {
      result = exports.nFibo(i);
      // console.log(n, i, result);
      if ((result * l) >= n) return {
        nSequence: i,
        sLength: result,
        prevLength: prev
      };
      prev += result;
    }
  };

  function D (a,b,n) {

    var words = nWords(a,n), nu = (n%a.length)-1, res;
    if (nu <0) nu = a.length-1;
    // console.log("Words", words, nu);
    var letter = nthDigit(Math.ceil(n/a.length)+words.prevLength);
    if (letter === "A") {
      res = a; 
    } else {
      res = b;
    }
    // console.log(res.substr(nu,1));
    return res.substr(nu,1);
  }


  exports.smash = function (a,b,n) {
    // console.log(D(a, b, getNumber(n)));
    // return (D(a,b,n));
    var result = D(a,b,getNumber(n));
    console.log(typeof result, n);
    if (n===0) return result;
    return result + (smash(a,b,n-1));
  };  


}(typeof window === 'undefined' ? global : window));

var A = "1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679";
var B = "8214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196";
var testA = "1415926535", testB = "8979323846";

// console.log(smash(A,B,9));
console.log(smash(A,B, 17));

// console.log(nthDigit(1));
// console.log(nWords(testA, 52));