solution for localytics

solution.js

const path = require('path');
const fs = require('fs');
const _ = require('lodash');
//
//   salesMap : categoryMap = { category: [ price1, price2 ] }
//   salesMap = { category: [ avgSalesPrice ] }
//

/**
 * @param {Array} categoriesRawData input array of categories [ { item: name, category: cat } ]
 * @returns {object} { productName: category }
 */
const prodToCategory = (categoriesRawData) => {
  const categoryMap = new Map();
  categoriesRawData.map(itemData => {
    const prodName = itemData.item;
    if (prodName)
      categoryMap.set(prodName, itemData.category);
  });
  return categoryMap;
};


const categoriesRawDataFromFile = fs.readFileSync(path.resolve('products.tab'), { encoding: 'utf-8' });
const splitByLine = categoriesRawDataFromFile.split("\r\n");
const categoriesRawData = _.map(splitByLine, line => {
  const splitup = line.split('\t');
  return { item: splitup[0], category: splitup[1] || "Uncategorized" };
});

const categoryMap = prodToCategory(categoriesRawData);

// categoryMap.forEach(item => console.log(item));

// go over all prices and assign [price1, price2] to a map { category: prices }
const pricesRawDataFromFile = fs.readFileSync(path.resolve('sales.tab'), { encoding: 'utf-8' });
const pricesSplitByLine = pricesRawDataFromFile.split("\n");

const categoryToPricesMap = new Map();
_.map(_.filter(pricesSplitByLine, l => l && l.trim().length > 1), line => {
  const splitup = line.split('\t');
  const item = splitup[0];
  const price = splitup[1];
  const categoryFromMap = categoryMap.get(item);
  const category = categoryFromMap || 'Uncategorized';
  if (item && price) {
    if (categoryToPricesMap.has(category)) {
      const currentItem = categoryToPricesMap.get(category);
      categoryToPricesMap.set(category, _.concat(currentItem, Number.parseFloat(price)));
    } else {
      categoryToPricesMap.set(category, [ Number.parseFloat(price) ]);
    }
  } else {
    throw new Error(`${line}`);
  }
});

const mapOfAverages = new Map();
categoryToPricesMap.forEach((value, key, map)  => {
  const avg = _.mean(value);
  mapOfAverages.set(key, avg);
});

// print all averages by category
mapOfAverages.forEach(( item, key ) => console.log(`${key} avg: ${item}`));


// print category with max price
const maxPriceItem = _.maxBy(Array.from(mapOfAverages), item => item[1]);
console.log(`\n\n"${maxPriceItem[0]}" has the highest average sales price of ${maxPriceItem[1]}\n\n`);

// print category breakfast sale prices
const breakFastPrices = categoryToPricesMap.get("Breakfast");
const maxPrice = _.max(breakFastPrices);
const minPrice = _.min(breakFastPrices);
console.log(`Max breakfast price ${maxPrice}\nMin breakfast price ${minPrice}`);