REST API Transaction by Average Monthly Spending

api.js

'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', function(inputStdin) {
    inputString += inputStdin;
});

process.stdin.on('end', function() {
    inputString = inputString.split('\n');

    main();
});

function readLine() {
    return inputString[currentLine++];
}



/*
 * Complete the 'getUserTransaction' function below.
 *a
 * The function is expected to return an INTEGER_ARRAY.
 * The function accepts following parameters:
 *  1. INTEGER uid
 *  2. STRING txnType
 *  3. STRING monthYear
 *
 *  https://jsonmock.hackerrank.com/api/transactions/search?userId=
 */
const axios = require('axios');

function getMonthYear(monthYear) {
    const date = monthYear.split("-")
    const month  = parseInt(date[0])
    const year = parseInt(date[1])
    
    return {"month":month, "year":year}
}

function convertAmountToNum(amount) {
    const numAmount = parseFloat(amount.replace("$","").replace(",",""))
    return numAmount
}

async function getSpecificApiData(url, dataKey) { 
    const response = await axios.get(url) 
    const data = response.data[dataKey] 
    
    return data 
}

async function getAllPaginatedData(uid, txnType, totalPages) {
    let url = `https://jsonmock.hackerrank.com/api/transactions/search?userId=${uid}&txnType=${txnType}&page=`
    let allData = []
    
    for (let i = 0; i < totalPages; i++) {
        let curURL = `${url}${i+1}`
        const data = await getSpecificApiData(curURL, 'data')
        allData = [...allData, ...data]
    }
    
    return allData
}

async function getTotalPages(uid, txnType) {
    let url = `https://jsonmock.hackerrank.com/api/transactions/search?userId=${uid}&txnType=${txnType}`
    const totalPages = await getSpecificApiData(url, 'total_pages')
    return totalPages
} 

async function getTrxDataByTotalPages(uid, txnType) {
    const totalPages = await getTotalPages(uid, txnType)
    const data = await getAllPaginatedData(uid, txnType, totalPages)
    
    return data
}

function filterTrxDataByDate(data, refDate) {
    const filtered = data.filter(dat => {
        const tsDate = new Date(dat.timestamp)
        const date = {"month": tsDate.getMonth() + 1, "year": tsDate.getFullYear()}
        
        if(date.month === refDate.month && date.year === refDate.year) {
            return dat 
        }
    })
    
    return filtered
}
/**
 * uid: int
 * refDate : {"month":int, "year":int}
 */
async function getAverageMonthlyTrx(uid, refDate) {
    const debitData = await getTrxDataByTotalPages(uid, 'debit')
    const spendingData = filterTrxDataByDate(debitData, refDate)
    
    const monthlySpending = spendingData.reduce((total, spending) => total + convertAmountToNum(spending.amount), 0)
    const averageMonthlySpending = monthlySpending / spendingData.length
    
    return averageMonthlySpending
}

async function getTrxLargerThanAvgMonthlySpending(uid, txnType, refDate, averageSpending) {
    const trxData = await getTrxDataByTotalPages(uid, txnType)
    const filtered = filterTrxDataByDate(trxData, refDate)
    
    const validIds = filtered.filter(data => {
        const amount = convertAmountToNum(data.amount)
        
        if(amount > averageSpending) {
            return data
        }
    }).map(dat => {
        return dat.id
    })
    
    validIds.sort(function(a, b){return a - b})
    
    return validIds
}

async function getUserTransaction(uid, txnType, monthYear) {
    const refDate = getMonthYear(monthYear)
    
    try {
        const averageMonthly = await getAverageMonthlyTrx(uid, refDate)
        const validTrxIds = await getTrxLargerThanAvgMonthlySpending(uid, txnType, refDate, averageMonthly)
        
        return validTrxIds.length > 0 ? validTrxIds : [-1]
    } catch(err) {
        console.error(err)
        return [-1]
    }
    
}

async function main() {
    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

    const uid = parseInt(readLine().trim(), 10);

    const txnType = readLine();

    const monthYear = readLine();

    const result = await getUserTransaction(uid, txnType, monthYear);

    ws.write(result.join('\n') + '\n');

    ws.end();
}