// Do not change any of the function names

const getBiggest = (x, y) => { return (x >= y) ? x : y; };

const greeting = (language) => {
  // return a greeting for three different languages:
  // language: 'German' -> 'Guten Tag!'
  // language: 'Spanish' -> 'Hola!'
  // language: 'Chinese' -> 'Ni Hao!'
  // if language is undefined return 'Hello!'
  switch (language) {
    case 'German' :
      return 'Guten Tag!';
    case 'Spanish' :
      return 'Hola!';
    case 'Chinese' :
      return 'Ni Hao!';
    default :
      return 'Hello!';
  }
};

const isTenOrFive = num => num === 10 || num === 5;
  // return true if num is 10 or 5
  // otherwise return false


const isInRange = num => num > 20 && num < 50;
  // return true if num is less than 50 and greater than 20


const isInteger = num => Math.floor(num) >= 1 || Math.ceil(num) <= 0;
  // return true if num is an integer
  // 0.8 -> false
  // 1 -> true
  // -10 -> true
  // otherwise return false
  // hint: you can solve this using Math.floor


const fizzBuzz = (num) => {
  // if num is divisible by 3 return 'fizz'
  // if num is divisible by 5 return 'buzz'
  // if num is divisible by 3 & 5 return 'fizzbuzz'
  // otherwise return num
  if ((num % 5 === 0) && (num % 3 === 0)) return 'fizzbuzz';
  if (num % 5 === 0) return 'buzz';
  if (num % 3 === 0) return 'fizz';
  return num;
};

const isPrime = (num) => {
  // return true if num is prime.
  // otherwise return false
  // hint: a prime number is only evenly divisible by itself and 1
  // hint2: you can solve this using a for loop
  // note: 0 and 1 are NOT considered prime numbers
  for (let i = 2; i < num; i++) {
    if (num % i === 0) return false;
  }
  return num > 1;
};

const returnFirst = arr => arr[0];
  // return the first item from the array


const returnLast = arr => arr[arr.length - 1];
  // return the last item of the array


const getArrayLength = arr => arr.length;
  // return the length of the array


const incrementByOne = arr => arr.map(val => val + 1);
  // arr is an array of integers
  // increase each integer by one
  // return the array


const addItemToArray = (arr, item) => {
  arr.push(item);
  return arr;
};
  // add the item to the end of the array
  // return the array


const addItemToFront = (arr, item) => {
  // add the item to the front of the array
  // return the array
  // hint: use the array method .unshift
  arr.unshift(item);
  return arr;
};

const wordsToSentence = words => words.join(' ');
  // words is an array of strings
  // return a string that is all of the words concatenated together
  // spaces need to be between each word
  // example: ['Hello', 'world!'] -> 'Hello world!'


const contains = (arr, item) => {
  // check to see if item is inside of arr
  // return true if it is, otherwise return false
  for (let i = 0; i < arr.length; i++) {
    if (arr[i] === item) return true;
  }
  return false;
};

const addNumbers = (numbers) => {
  // numbers is an array of integers.
  // add all of the integers and return the value
  return numbers.reduce((val, next) => { return val + next; }, 0);
};

const averageTestScore = (testScores) => {
  // testScores is an array.  Iterate over testScores and compute the average.
  // return the average
  return testScores.reduce((val, next) => { return val + next; }, 0) / testScores.length;
};

const largestNumber = (numbers) => {
  // numbers is an array of integers
  // return the largest integer
  return numbers.reduce((last, next) => { return (next > last) ? next : last; });
};

// Do not modify code below this line.
// --------------------------------

module.exports = {
  getBiggest,
  greeting,
  isTenOrFive,
  isInRange,
  isInteger,
  fizzBuzz,
  isPrime,
  returnFirst,
  returnLast,
  getArrayLength,
  incrementByOne,
  addItemToArray,
  addItemToFront,
  wordsToSentence,
  contains,
  addNumbers,
  averageTestScore,
  largestNumber
};