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'use strict'; |
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import { createRequire } from 'module'; |
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const require = createRequire(import.meta.url); |
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const https = require('https'); |
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export const handler = async(event, context, callback) => { |
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let content = ""; |
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let userAgent = false; |
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const request = event.Records[0].cf.request; |
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const headers = request.headers; |
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if(headers){ |
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userAgent = request.headers['user-agent']; |
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} |
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// NOTE: Identify the facebook share request by user-agent header |
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// I added few more, but 'facebookexternalhit' is the most important one |
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let prerender = /Facebot|FacebookBot|facebookexternalhit|twitterbot/i.test(userAgent[0].value); |
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if(prerender){ |
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let path = request.uri; |
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let options = { |
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// NOTE: link to your API endpoint |
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hostname: "<api-endpoint>", |
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path: path, |
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headers: { |
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"Content-Type": "application/json", |
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} |
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} |
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const initialResponse = await new Promise((resolve, reject) => { |
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const req = https.get(options, function(res) { |
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res.on('data', chunk => { |
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content += chunk; |
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}); |
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res.on('end', () => { |
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resolve({ |
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statusCode: 200, |
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body: content.toString() |
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}); |
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}); |
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}); |
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req.on('error', (e) => { |
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reject({ |
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statusCode: 400, |
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body: e |
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}); |
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}); |
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}); |
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// Our API returns the meta data in JSON format so we need to parse it |
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let data = JSON.parse(initialResponse.body); |
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// NOTE: We need to get the full url of the page we are sharing |
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let ogUrl = `https://${headers['host'][0]['value']}${request.uri}` |
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// NOTE: We need to generate the HTML code with the meta data |
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// Our meta keys fetched from API are: |
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// metaTitle - title of the page |
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// metaDescription - description of the page |
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// metaImageUrl - image of the page |
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// if any of these are different, don't forget to change them in the code below (f.e. og:locale) |
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// The fb:app_id is the id of your facebook app |
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let htmlContent = ` |
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<\!DOCTYPE html> |
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<html lang="en"> |
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<head> |
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<meta charset="utf-8"> |
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<title>${data.metaTitle}</title> |
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<meta property="fb:app_id" content="<your-fb-app-id>"> |
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<meta property="og:title" content="${data.metaTitle}" /> |
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<meta property="og:description" content="${data.metaDescription}" /> |
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<meta property="og:image" content="${data.metaImageUrl}" /> |
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<meta property="og:url" content="${ogUrl}" /> |
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<meta property="og:type" content="website" /> |
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<meta property="og:locale" content="sk_SK" /> |
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</head> |
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<body> |
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</body> |
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</html> |
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`; |
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const response = { |
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status: '200', |
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statusDescription: 'OK', |
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headers: { |
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"content-type": [{ |
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"key": "Content-Type", |
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"value": "text/html; charset=utf-8" |
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}], |
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"cache-control": [{ |
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"key": "Cache-Control", |
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"value": "max-age=100" |
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}] |
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}, |
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body: htmlContent, |
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}; |
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callback(null, response); |
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} else { |
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callback(null, request); |
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} |
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}; |
