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March 7, 2019 10:06
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| #! /usr/bin/node | |
| /** | |
| * HTTP server for some data transitions Endpoint: http://XXX/compute/<request_id> | |
| * details - https://www.corva.ai/software-engineer-interview-question/ | |
| */ | |
| const http = require('http'), | |
| assert = require('assert'); | |
| const port = process.env.PORT || 3000; | |
| const requestHandler = (request, response) => { | |
| const params = request.url.split('/'); | |
| if(params[1] == 'compute' && params[2] && request.method == 'POST' ){ | |
| try { | |
| const ret = build_output(JSON.parse(request.body), params[2]); | |
| response.end(JSON.stringify(ret)); | |
| }catch (err){ | |
| log('Error parsing request', err, request ); | |
| return error_me( response,'401'); | |
| } | |
| }else{ | |
| log("404 for url / method",request.url, request.method ); | |
| return error_me( response,'404'); | |
| } | |
| }; | |
| /** | |
| * Input POST Value: | |
| { | |
| "timestamp": 1493758596, | |
| "data": [ | |
| { "title": "Part 1", "values": [0, 3, 5, 6, 2, 9] }, | |
| { "title": "Part 2", "values": [6, 3, 1, 3, 9, 4] } | |
| ] | |
| } | |
| The service shall take the array from Part 1 and subtract the values from Part 2, subtracting numbers that exist in the same index of the array. The final array is also the same size (6). | |
| The return value will be a JSON document in the following format containing the resultant array and request ID. | |
| Output: | |
| { | |
| "request_id": "<request_id>", | |
| "timestamp": 1493758596, | |
| "result": { "title": "Result", "values": […] } | |
| } | |
| */ | |
| function build_output(input, request_id){ | |
| if(!input.data || ! input.data.length) | |
| throw("Mailformed input - no data"); | |
| const p1 = input.data.filter(item => item.title == 'Part 1')[0], | |
| p2 = input.data.filter(item => item.title == 'Part 2')[0]; | |
| if(!p1 || ! p2 || !p1.values || !p2.values) | |
| throw("Mailformed input - Part1 or Part2"); | |
| if(p1.values.length != p2.values.length) | |
| throw("Mailformed input - Part1 and Part2"); | |
| return { | |
| request_id, | |
| timestamp: input.timestamp, | |
| result: { | |
| title: 'Result', | |
| values: Array.from(p1.values.keys()).map(i => p1.values[i] - p2.values[i]) | |
| } | |
| }; | |
| } | |
| assert.deepEqual(build_output({ | |
| "timestamp": 1493758596, | |
| "data": [ | |
| { "title": "Part 1", "values": [0, 3, 5, 6, 2, 9] }, | |
| { "title": "Part 2", "values": [6, 3, 1, 3, 9, 4] } | |
| ] | |
| }, '<request_id>'), { | |
| "request_id": "<request_id>", | |
| "timestamp": 1493758596, | |
| "result": { "title": "Result", "values": [-6, 0, 4, 3, -7, 5] } | |
| }); | |
| function error_me(response, code){ | |
| response.writeHead(code); | |
| response.end(); | |
| } | |
| function log(){ | |
| console.log(arguments); | |
| } | |
| const server = http.createServer(requestHandler); | |
| server.listen(port, (err) => { | |
| if (err) { | |
| return log('something bad happened', err); | |
| } | |
| log(`server is listening on ${port}`) | |
| }); |
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