Shopify Coding Challenge

index.js

/*
    Author: Salman Tariq Mirza
    node/JavaScript solution to the Shopify Internship Coding Challenge
    
    Assumptions: 
    - No duplicates, a flat list of the variants of all the products maintains uniqueness.
    - For each computer there should be a keyboard.
    - However if all computers/keyboards are purchased and there is still money left,
      then spares need to be purchased of the remaining type.
      
    Difficulties:
    - Tried to use the product_type filter for Computer/Keyboard. Did not work,
      returned products that were not Computers and Keyboards
      
    Notes:
    - hackathon.hardware.basic represents the pair of Computer/Keyboard pairs that need to be purchased
    - Once shopicruit runs out of either computers or keyboards, we need to purchase spares of the remaining
      type within the budget. This is represented by hackathon.hardware.spares
 */

// npm modules
var request = require('sync-request');
var _ = require('lodash');

// Initial state
var hackathon = {
    shopicruit: {
        url: 'http://shopicruit.myshopify.com/products.json',
        keyboards: [],
        computers: []
    },
    weights: {
        regular: 0,
        spare: 0
    },
    hardware: {     // Purchase list
        basic: [],  // Pairs of computers/keyboards
        spares: {   // Spare parts
            keyboards: [],
            computers: [],
            category: ''
        },
    },
    budget: 1000.00
};

/**
 * Function to purchase a pair of computer and keyboard. Stack like behavior.
 * @param   object  hackathon   reference object that stores the state of the hackathon
 * @return  boolean             indicates wether Alice was able to purchase a pair or not
 */
function purchaseHardware(hackathon) {
    var store = hackathon.shopicruit;
    var hardware = hackathon.hardware;
    var weights = hackathon.weights;
    
    // Check that both have something left
    if (store.computers.length > 0 && store.keyboards.length > 0) {
        var c = store.computers.shift();
        var k = store.keyboards.shift();
        
        // Check if we still have money left
        hackathon.budget -= (parseFloat(c.price) + parseFloat(k.price));
        
        // If we don't, we stop buying
        if (hackathon.budget < 0) return false;
        
        hardware.basic.push({computer: c, keyboard: k});
        weights.regular += (c.grams + k.grams);
        return true;
    }
    
    return false;
}

/**
 * Function to purchase spare parts
 * @param   object  hackathon   reference object that stores the state of the hackathon
 */
function purchaseSpares(hackathon) {
    var spareCategory = (hackathon.shopicruit.keyboards.length === 0) ? 'computers' : 'keyboards';
    hackathon.hardware.spares.category = spareCategory;
    
    while(hackathon.budget > 0) {
        var c = hackathon.shopicruit[spareCategory].shift();
        hackathon.budget -= parseFloat(c.price);
        if (hackathon.budget < 0) hackathon.budget = 0;
        else {
            hackathon.hardware.spares[spareCategory].push(c);
            hackathon.weights.spare += c.grams;
        }
    }
}

/**
 * Function to fetch products of type from shopicruit
 * @param   object  hackathon   reference object that stores the state of the hackathon
 * @param   integer page        page number to search
 */
function getProducts(hackathon, page) {
    var hasProducts = true;
    
    var store = hackathon.shopicruit;
    
    var reqUrl = hackathon.shopicruit.url + '?page=' + page + '&limit=' + 250;
    var res = request('GET',  reqUrl);
    
    // Shopify is not happy!
    if (res.statusCode !== 200) throw(new Error('Request failed with status code ' + res.statusCode + '.\nResponse: ' + res.getBody()));
    
    var products = JSON.parse(res.getBody()).products;
    
    // No more products
    if (products.length === 0) hasProducts = false;
    
    _.each(products, function(product) {
        var variants = _.filter(product.variants, function(v) {
            return v.available;
        });
        
        switch (product.product_type) {
            case 'Computer':
                store.computers.push.apply(store.computers, variants);
                break;
            case 'Keyboard':
                store.keyboards.push.apply(store.keyboards, variants);
                break;
            default:
                // Alice needs to learn that hackers need more than just Computers and Keyboards
        }
        
    });
    
    
    return hasProducts;
}

try {
    // hackathon.hardware identifies the entire purchase list
    
    // Get all products from the store
    var page = 1;
    while (getProducts(hackathon, page)){
        page++;
    }
    
    var store = hackathon.shopicruit;
    
    // Sort them by price - ascending
    store.keyboards = _.sortBy(store.keyboards, function(keyboard) {
        return parseFloat(keyboard.price);
    });

    store.computers = _.sortBy(store.computers, function(computer) {
        return parseFloat(computer.price);
    });

    // Make purchase list
    while(purchaseHardware(hackathon)) {
        // We just wait till Alice adds to her list
    }
    
    purchaseSpares(hackathon);
    
    // console.log(hackathon);
    console.log('Total Computer/Keyboard pairs: ' + hackathon.hardware.basic.length);
    console.log('Their weight: ' + hackathon.weights.regular + ' g');
    console.log('Spare ' + hackathon.hardware.spares.category + ': ' + hackathon.hardware.spares[hackathon.hardware.spares.category].length);
    console.log('Their weight: ' + hackathon.weights.spare + ' g');
    console.log('Total weight: ' + (hackathon.weights.regular + hackathon.weights.spare) + ' g');
}
catch(err) {
    console.log(err);
    console.log('Oops, something wen\'t wrong. Please contact Shopify support');
}

package.json

{
  "name": "shopify_challenge",
  "version": "1.0.0",
  "description": "Solution for Shopify challenge",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [
    "shopify",
    "challenge"
  ],
  "author": "Salman Tariq Mirza",
  "license": "MIT",
  "dependencies": {
    "lodash": "^4.12.0",
    "sync-request": "^3.0.1"
  }
}