'use strict';

const fs = require('node:fs');

const getDataset = (file) => {

const lines = fs.readFileSync(file, 'utf8').split('\n');

lines.shift();

lines.pop();

return lines.map((line) => line.split(','));

};

const buildIndex = (ds, col) => {

const index = new Map();

for (const record of ds) {

index.set(record[col], record);

}

return index;

};

// Usage

const dataset = getDataset('./cities.csv');

console.log(dataset);

const byName = buildIndex(dataset, 0);

console.log(byName);

const byPopulation = buildIndex(dataset, 1);

console.log(byPopulation);

const delhi = byName.get('Delhi');

console.log(delhi);

const record = byPopulation.get('21516000');

console.log(record);