145 lines
4.4 KiB
JavaScript
145 lines
4.4 KiB
JavaScript
const moment = require("moment");
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const db = require("../dbConfig");
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const crypto = require("crypto");
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const cron = require("node-cron");
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/**
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* Checks if a given string is a valid URL format.
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* @param {string} url - The input string to validate.
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* @returns {boolean} - Returns true if valid URL format, otherwise false.
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*/
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function isValidUrl(url) {
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try {
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new URL(url);
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return true;
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} catch (e) {
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return false;
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}
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}
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/**
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* Generates a deterministic short code based on long URL, expiry date, and user ID.
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* Uses MD5 hashing, encodes the result in base64, and slices to desired length.
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* @param {string} longUrl - Original input URL.
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* @param {number} codeLength - Desired length of output short code.
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* @param {string} expiryDate - Expiry date used in code generation.
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* @param {string} user_id - User identifier to namespace the code.
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* @returns {string} - Base64-based truncated hash used as short code.
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*/
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const generateShortCode = (
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longUrl,
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codeLength,
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expiryDate,
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userId,
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customizedShortnerSlug
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) => {
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const dataToHash =
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longUrl + "_" + expiryDate + "_" + userId + "_" + customizedShortnerSlug;
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return crypto
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.createHash("md5")
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.update(dataToHash)
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.digest("base64")
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.substring(0, codeLength);
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};
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/**
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* Creates and stores a new short code mapping for a given URL.
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* Validates input values and optionally supports user-scoped or custom slugs.
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* @param {object} params - Input parameters for short code creation.
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* @param {string} params.longUrl - Original full URL.
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* @param {number} params.expiryInDays - Days until expiry (0–30 allowed).
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* @param {number} params.codeLength - Short code length (8–30 allowed).
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* @param {string} [params.user_id=""] - Optional user ID for namespace isolation.
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* @param {string} [params.customized_shortner_slug=""] - Optional custom alias.
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* @returns {Promise<string>} - Returns existing or newly created code/slug.
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* @throws {Error} - If input validation fails or database errors occur.
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*/
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const createShortUrl = async ({
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longUrl = "",
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expiryInDays = 30,
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codeLength = 10,
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userId = "",
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customizedShortnerSlug = "",
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}) => {
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if (!String(longUrl).trim() || !isValidUrl(longUrl)) {
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throw new Error("Long url required.");
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}
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if (!Number.isInteger(codeLength)) {
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throw new Error("Code length must be valid integer value.");
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} else if (codeLength < 8 || codeLength > 30) {
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throw new Error("Code length must be between 8 to 30 characters.");
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}
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if (!Number.isInteger(expiryInDays)) {
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throw new Error("Expiry in days must be valid integer value.");
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} else if (expiryInDays < 0 || expiryInDays > 30) {
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throw new Error("Expiry in days must be between 0 to 30 days.");
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}
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const expiryDate = moment()
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.add(expiryInDays, "days")
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.endOf("day")
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.format("YYYY-MM-DD HH:mm:ss");
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// Avoid duplicates: return existing code if it already exists
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const existing = await db.findByLongUrl(
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longUrl,
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expiryDate,
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userId,
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customizedShortnerSlug
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);
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if (existing) return existing.customized_shortner_slug || existing.short_code;
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const shortCode = generateShortCode(
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longUrl,
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codeLength,
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expiryDate,
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userId,
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customizedShortnerSlug
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);
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const res = await db.insertUrl(
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longUrl,
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shortCode,
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expiryDate,
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String(userId).trim(),
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String(customizedShortnerSlug).trim()
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);
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return customizedShortnerSlug || shortCode;
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};
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/**
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* Retrieves the original long URL using a short code or custom slug.
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* @param {string} shortCode - Code or slug used to look up the original URL.
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* @param {string} [userId=""] - Optional user ID for user-specific resolution.
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* @returns {Promise<string>} - Returns the original URL if found and valid.
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* @throws {Error} - If lookup fails or URL is expired.
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*/
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const getOriginalUrl = async (shortCode, userId = "") => {
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try {
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const longUrl = await db.findByShortCode(shortCode, userId);
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return longUrl;
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} catch (error) {
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throw error;
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}
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};
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/**
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* Starts a cron job that runs daily at midnight.
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* Cleans up expired short URL entries from the database.
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*/
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const startScheduler = () => {
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console.log("Starting expiration cleanup scheduler...");
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cron.schedule("0 0 * * *", () => {
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console.log("[Scheduler] Running deletion job...");
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db.deleteAllExpired().then(console.log).catch(console.error);
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});
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};
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module.exports = {
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createShortUrl,
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getOriginalUrl,
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startScheduler,
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getAllData: db.getAllData,
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getPaginatedData: db.getPaginatedData,
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};
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