index.ts

/*!

* Coded by Souren Khetcho

*/

// firebase config
import * as functions from "firebase-functions";
import * as admin from "firebase-admin";
admin.initializeApp();
const db = admin.firestore();

exports.linkHandler = functions.https.onCall((Link) => {
    'use strict';
  
    try{
    //add 4 packages
    const path = require('path');
    const os = require('os');
    const fs = require('fs');
    const urlMetadata = require('url-metadata')
  
  
    // create bucket reference
    const bucket = admin.storage().bucket('blogs');
    const blogFileCounterJSON = path.join(os.tmpdir(), "blogFileCounter.json");

    //download the file counter which keeps track of how many files have been created
    bucket.file('blogFileCounter.json').download({
      destination: blogFileCounterJSON
    }).then(() => {
        //handle file and parse json
      let blogFileCounter = fs.readFileSync(blogFileCounterJSON);
      let blogfileCounterKey = JSON.parse(blogFileCounter);
      //find the count of the number of blog files created
      //note: blog files contain a number of blogs. In this example it's 10 blogs per blog file
      let key = blogfileCounterKey.key
        
      //get the last blog file
      const blogsFileJSON = path.join(os.tmpdir(), `blogs_${key}.json`);
      bucket.file(`blogs_${key}.json`).download({
        destination: blogsFileJSON
      }).then(() => {
        // handle and parse the last file
        let content = fs.readFileSync(blogsFileJSON);
        let jsonContent = JSON.parse(content);
        if (jsonContent[0].key >= 10) {
            //as you notice here is where we specified how many blogs we want per blog file
            //jsonContent[0].key is the counter for the number of blogs inside the blog file
  
          urlMetadata(`${Link}`, {userAgent: 'Unique'}).then(
            (metadata: any) => { // success handler
              let newData = [
                {
                  "key": 1
                },
                {
                  "blogs": [
                    {
                      "title": `${metadata["og:title"]}`,
                      "description": `${metadata["og:description"]}`,
                      "image": `${metadata["og:image"]}`,
                      "source": `${metadata.source}`,
                      "url": `${metadata.url}`
                    }
                  ]
                }
              ]
              // create new data for the blog file
  
              // stringify the new data to be pushed as json
              let newFile = JSON.stringify(newData, null, 2);
  
              // write the new data to a new file numbered based on the previous file number (ex. blogs_1.json ... blogs_99.json)
              const newBlogsFileJSON = path.join(os.tmpdir(), `blogs_${key + 1}.json`);
              fs.writeFileSync(newBlogsFileJSON, newFile);
  
              // update the count of the number of blogs files in blogfileCounter.json
              blogfileCounterKey.key = blogfileCounterKey.key + 1
              let newKey = JSON.stringify(blogfileCounterKey, null, 2);
              fs.writeFileSync(blogFileCounterJSON, newKey)
  
              bucket.upload(blogFileCounterJSON, { destination: 'blogFileCounter.json' }).catch((error) => {
                console.log("error uploading temp blogFileCounter: " + error)
              });
              bucket.upload(newBlogsFileJSON, { destination: `blogs_${key + 1}.json` }).catch((error) => {
                console.log("error uploading temp newBlogFile blogs_xxx.json: " + error)
              });
            }).catch((error: any) => {
              console.log("error in urlMetaData function call: " + error);
            })
        }
        else {
          // add a new blog to the last file
          urlMetadata(`${Link}`, {userAgent: 'DriverHive'}).then(
            (metadata: any) => {
              jsonContent[1].blogs[jsonContent[0].key] = {
                title: `${metadata["og:title"]}`,
                description: `${metadata["og:description"]}`,
                image: `${metadata["og:image"]}`,
                source: `${metadata.source}`,
                url: `${metadata.url}`
              };
              // update the count of the number of blogs in that file
              jsonContent[0].key = jsonContent[0].key + 1;
              let data = JSON.stringify(jsonContent, null, 2);
              fs.writeFileSync(blogsFileJSON, data);
              bucket.upload(blogsFileJSON, { destination: `blogs_${key}.json` }).catch((error) => {
                console.log("error uploading temp newBlogFile blogs_xxx.json: " + error)
              });
            })
  
        }
      }).catch((error) => {
        console.log("failed on linkHandler function - check: " + error)
      })
    }).catch((error) => {
      console.log("failed on linkHandler function - check: " + error)
    })
  }
  catch(error){
    console.log(error)
  }
  });