Technical exercise answer with comments -- Company House Challenge

gamesService.js

/**
 * Technical Exercise Answer, Companies House
 * Mathew Thomas 16/05/2020
 */

const express = require('express'); // Express NodeJS module  
const path = require('path'); // Path NodeJS module 
const bodyParser = require('body-parser'); // Body-Parser NodeJS module

const port = 8080; // Define port as 8080 as per exercise requirements 
const app = express(); // Create app object 
app.use(bodyParser.json()); // app use bodyparser 

/* This data would usually be stored in a database but,
 for the sake of this exercise I will define as a const */  // No SQL database, MongoDB perhaps?
 // Define games data 
const games = [
  {
    "title": "Uncharted 4",
    "id": 1,
    "description": "For the first time ever in Uncharted history, drive vehicles during gameplay",
    "by": "Sony",
    "platform": ["PS4"],
    "age_rating": "16",
    "likes": 100,
    "comments": [{
      "user": "bob",
      "message": "Cracking game far too much cinematic",
      "dateCreated": "2011-01-03",
      "like": 6
    }, {
      "user": "testingPriest",
      "message": "Not enough shooting for me,far too easy ",
      "dateCreated": "2011-04-02",
      "like": 5
    }]
  },

  {
    "title": "Call of Duty, Infinite Warfare",
    "id": 2,
    "description": "Fast paced shooter",
    "by": "Infiniward",
    "platform": ["XBOX", "PS4"],
    "age_rating": "18",
    "likes": 40,
    "comments": [{
      "user": "jim",
      "message": "Awesome game",
      "dateCreated": "2015-01-25",
      "like": 7
    }, {
      "user": "Dave",
      "message": "Too many n00bs ",
      "dateCreated": "2016-05-00",
      "like": 8
    }, {
      "user": "bob",
      "message": "some comment",
      "dateCreated": "2011-09-19",
      "like": 2
    }, {
      "user": "richard",
      "message": "some other comment",
      "dateCreated": "2011-10-19",
      "like": 1
    }]
  }
]

//// Part 2 Task ////
// Get Games Report
app.get('/games/report', (req, res) => {
  console.log('Returning games report');

  /// Highest likes 
  var highestLikes = getMax(games, "likes"); // Get the game with highest number of likes --  (getMax function below) pass in array and key of json object to compare 

  /// Most comments
  var comms = []; // Init comments array 
  var usrs = []; // Init users arry
  var msgs = []; //  Init messages array

  // Loop through games array and extract comments array into its own array --  comms (minus the game info -- title etc...) -- just to make simpler cleaner data to work with 
  for (var i = 0; i < games.length; i++) {
    comms.push(games[i].comments);
  }

  // Loop through comms array and extract each message object into its own array (msgs) we now have an array of only comnments - no info on which comment belongs to which game
  for (var i = 0; i < comms.length; i++) {
    if (comms.hasOwnProperty(i)) {
      msgs.push(comms[i]);
    }
  }

  // As we still have messages as an array of arrays we need to join the arrays to create a sinlge array then extract only the user key value and push to array containing only the users (usrs)
  var mergedMessgaeArray = [].concat.apply([], msgs);
  for (var i = 0; i < mergedMessgaeArray.length; i++) {
    usrs.push(mergedMessgaeArray[i].user);
  }

  // Avg likes per game
  var gameArr = []; // Init array to hold new game objects 

  // Loop over the games array 
  for (var i = 0; i < games.length; i++) {

    // Loop each game in the games array 
    for (game of games) {

      // Create a new game object (gme) to append to our game array (gameArr)
      var gme = new Object();
      gme.title = game.title; // Append game title to gme object
      gme.comments = game.comments; // Append game comment to gme object
      gme.commentCount = gme.comments.length; // Set gme object commentCount property to ammount of comments the object has

      var commentTotalValue = 0;
      // Loop through the gme object comments and appnend the likes value to a variable (commentTotalValue)
      for (var c of gme.comments) {
        commentTotalValue += c.like;
      }

      // Get the avg likes value by dividing the total comment count (commentTotalValue) by the gme object total number of comments (gme.commentCount) & round up to the nearest integer using Math.ceil
      gme.averageLikeValue = Math.ceil(commentTotalValue / gme.commentCount);

      // Create an object thatr contains the game title and avg likes & push to gameArr array 
      var obj = new Object();
      obj.title = gme.title;
      obj.average_likes = gme.averageLikeValue;
      gameArr.push(obj);

    }
  }

  // Return Object --> Create our return object (Gather all data relevant data into an obj)
  var returnObject = new Object();
  returnObject.user_with_most_comments = highest(usrs); // Set obj user with the most comments (using highest function below)
  returnObject.highest_rated_game = highestLikes.title; // Set obj ighest rated game title
  returnObject.average_likes_per_game = gameArr; // Set avg like per game array 

  res.send(returnObject); // Return the object

});

//// Part 1 Task ////
// Get game by ID
app.get('/games/**', (req, res) => {
  console.log('Returning game by ID');
  const gameId = parseInt(req.params[0]); // Get the game ID passed in the GET request 
  const foundGame = games.find(subject => subject.id === gameId); // Find the game in games where the game ID (subject.id) is equal to the game ID passed in the GET request

  if (foundGame) { // If we find a game that matches the request the we assign the game attriubutes to the request attributes & return the foundgame object 
    for (let attribute in foundGame) {
      if (req.body[attribute]) {
        foundGame[attribute] = req.body[attribute];
        console.log(`Set ${attribute} to ${req.body[attribute]} in game: ${gameId}`);
      }
    }
    res.send(foundGame);
  } else { // If no game was found for the supplied ID we return a 404 and log to console 'game not found'
    console.log(`Game not found.`);
    res.status(404).send();
  }
});

//// Helpers ////
// Get Max (compare array elements and find max)
function getMax(arr, prop) {  // Pass in the array and element to parse
  var max;
  for (var i = 0; i < arr.length; i++) { // Loop through the games array
    if (max == null || parseInt(arr[i][prop]) > parseInt(max[prop])) // compare each element Int value 
      max = arr[i]; // max holds each pass of the loop max
  }
  return max; // return the max 
}

// Highest appearences (Pass array to compare key values)
// Get greatest of an array of objects key values using reduce function & compare element values  
const highest = arr => (arr || []).reduce((acc, el) => {
  acc.k[el] = acc.k[el] ? acc.k[el] + 1 : 1
  acc.max = acc.max ? acc.max < acc.k[el] ? el : acc.max : el
  return acc
}, { k: {} }).max

// App listen on port 8080
console.log(`Games service listening on port ${port}`);
app.listen(port);