-Refactor the code in index.ts and fix potential bugs and concurrency issues.
-Although the working code is required, you aren’t required to write production-level code or handle all edge cases. Do not add new features, keep crucial functionality and refactor.
-Make your code as extensible and flexible as possible. Your main goal is to demonstrate the skill of writing extensible and flexible code.
-You may add comments explaining your refactoring decisions to avoid misunderstandings
Crucial functional requirements
-
Read several files from API(create a mock), each containing string like:
“Hello world! : 2024-02-22 14:35:30 UTC”
“Goodbye world! : 2024-02-22 16:35:30 UTC”
“Hello? : 2024-02-22 08:35:30 UTC”
“Hi : 2024-02-22 12:35:30 UTC” -
Parse each line, wait for a random number of seconds <5, write a message to the console, and send to the API(create a mock) with the corresponding filename
-
If parsing or writing fails – resolve gracefully, without error
-
Read and process each file and its lines concurrently
Fail criteria
Violation of any criterion would lead to submission failure
Procedural code is not considered a successful solution
The code fails to run
Crucial functionality missing
Fewer than 5 classes and 5 interfaces
Classes with public fields, getters and setters
SOLID, DRY principles violated
Program is not smoothly made up by composing components
(components must compose like in index.ts file in the example)
const mockResponses: Record<string, string> = {
"file1.txt": `Hello world! : 2024-02-22 14:35:30 UTC
Goodbye world! : 2024-02-22 16:35:30 UTC
Hello? : 2024-02-22 08:35:30 UTC
Hi : 2024-02-22 12:35:30 UTC`,
"file2.txt": `How are you doing ? : 2024-02-22 13:59:30 UTC
Fine : 2024-02-22 12:44:30 UTC
How about you ? : 2024-02-22 22:35:30 UTC
Same : 2024-02-22 07:39:30 UTC`,
"file3.txt": `Have you seen high elves ? : 2022-02-22 14:35:30 UTC
HESOYAM : 2023-02-22 14:35:30 UTC
BAGUVIX : 2021-02-22 14:35:30 UTC
THERE IS NO SPOON : 2020-02-22 14:35:30 UTC`,
};
const mockFetch = async (
filePath: string,
params?: { body: string; method: string }
): Promise<string> => {
if (params?.method === "POST") return "";
return mockResponses[filePath] ?? "";
};
class Parser {
constructor() {}
async getContent(file: string): Promise<
{
message: string;
timestamp: string;
}[]
> {
const res = await mockFetch(file);
const messages = res.split("n");
const content: { message: string; timestamp: string }[] = [];
for (let i = 0; i < messages.length; i++) {
const [message, timestamp] = messages[i].split(":");
content.push({ message, timestamp });
}
return content;
}
async saveContent(
messages: { message: string; timestamp: string }[],
file: string
) {
const waitGroup: Promise<any>[] = [];
for (let i = 0; i < messages.length; i++) {
const promise = new Promise<void>(async (resolve) => {
await new Promise<void>((resolve) =>
setTimeout(() => resolve(), Math.random() * 5 * 1000)
);
await mockFetch(file, {
body: JSON.stringify({
...messages[i],
type: messages[i].message.length > 8 ? "long" : "short",
}),
method: "POST",
});
console.log(
`Saved message - ${messages[i].message} to ${file} as ${
messages[i].message.length > 8 ? "long" : "short"
}`
);
});
waitGroup.push(promise);
}
await Promise.all(waitGroup);
}
}
const main = async () => {
const files = {
"file1.txt": "out1.txt",
"file2.txt": "out2.txt",
"file3.txt": "out3.txt",
};
const parser = new Parser();
const waitGroup: Promise<any>[] = [];
for (const [input, output] of Object.entries(files)) {
const promise = new Promise<void>((resolve) => {
parser
.getContent(input)
.catch((error) => {
console.error(`Error while getting file ${input} - ${error}`);
return [];
})
.then((messages) => parser.saveContent(messages, output))
.catch((error) => {
console.error(`Error while reading file ${input} - ${error}`);
})
.then(resolve);
});
waitGroup.push(promise);
}
await Promise.all(waitGroup);
};
main();
This is how I decided, please tell me if there are any mistakes here and how it can be improved
const mockResponses: Record<string, string> = {
"file1.txt": `Hello world! : 2024-02-22 14:35:30 UTC
Goodbye world! : 2024-02-22 16:35:30 UTC
Hello? : 2024-02-22 08:35:30 UTC
Hi : 2024-02-22 12:35:30 UTC`,
"file2.txt": `How are you doing ? : 2024-02-22 13:59:30 UTC
Fine : 2024-02-22 12:44:30 UTC
How about you ? : 2024-02-22 22:35:30 UTC
Same : 2024-02-22 07:39:30 UTC`,
"file3.txt": `Have you seen high elves ? : 2022-02-22 14:35:30 UTC
HESOYAM : 2023-02-22 14:35:30 UTC
BAGUVIX : 2021-02-22 14:35:30 UTC
THERE IS NO SPOON : 2020-02-22 14:35:30 UTC`,
};
interface IMessage {
send: (message: IParserMessage, filepath: string) => Promise<void>;
}
interface IParser {
parse: (content: string) => IParserMessage[];
}
interface IFileFetcher {
fetch: (filepath: string) => Promise<string>;
}
interface IFileWriter {
write: (filepath: string, content: string) => Promise<void>;
}
interface IParserMessage {
message: string;
timestamp: string;
}
const mockFetch = async (
filePath: string,
params?: { body: string; method: string }
): Promise<string> => {
if (params?.method === "POST") return "";
return mockResponses[filePath] ?? "";
};
const LONG_MESSAGE = "long";
const SHORT_MESSAGE = "short";
const POST_METHOD = "POST";
class FileFetch implements IFileFetcher {
async fetch(filepath: string): Promise<string> {
return mockFetch(filepath);
}
}
class FileWriter implements IFileWriter {
async write(filepath: string, content: string): Promise<void> {
await mockFetch(filepath, { body: content, method: POST_METHOD });
}
}
class Parser implements IParser {
parse(content: string): IParserMessage[] {
return content.split("n").map((line) => {
const [message, timestamp] = line.trim().split(" : ");
return { message, timestamp };
});
}
}
class ParserMessage implements IMessage {
private writer: IFileWriter;
constructor(writer: IFileWriter) {
this.writer = writer;
}
async send(message: IParserMessage, filepath: string): Promise<void> {
const delay = Math.random() * 5000;
await new Promise<void>((resolve) => setTimeout(resolve, delay));
const content = JSON.stringify({
...message,
type: message.message.length > 8 ? LONG_MESSAGE : SHORT_MESSAGE,
});
await this.writer.write(filepath, content);
console.log(`${message.message} : ${message.timestamp} `);
}
}
class FileHandler {
private fetcher: IFileFetcher;
private parser: IParser;
private processor: IMessage;
constructor(fetcher: IFileFetcher, parser: IParser, processor: IMessage) {
this.fetcher = fetcher;
this.parser = parser;
this.processor = processor;
}
async handle(inputFile: string, outputFile: string): Promise<void> {
try {
const content = await this.fetcher.fetch(inputFile);
const messages = this.parser.parse(content);
const waitGroup = messages.map((message) =>
this.processor.send(message, outputFile)
);
await Promise.all(waitGroup);
} catch (error) {
console.error(`Error processing file ${inputFile}: ${error}`);
}
}
}
const main = async () => {
const files = {
"file1.txt": "out1.txt",
"file2.txt": "out2.txt",
"file3.txt": "out3.txt",
};
const fetcher = new FileFetch();
const writer = new FileWriter();
const parser = new Parser();
const processor = new ParserMessage(writer);
const handler = new FileHandler(fetcher, parser, processor);
const waitGroup = Object.entries(files).map(([input, output]) =>
handler.handle(input, output)
);
await Promise.all(waitGroup);
};
main();