deploy-succeeded.js

import fetch from 'node-fetch'
import dotenv from 'dotenv'
import Twitter from 'twitter'
import { decode } from 'html-entities'

dotenv.config()

// URL of notes JSON feed
const NOTES_URL = 'https://mxb.dev/notes.json'

// Configure Twitter API Client
const twitter = new Twitter({
    consumer_key: process.env.TWITTER_CONSUMER_KEY,
    consumer_secret: process.env.TWITTER_CONSUMER_SECRET,
    access_token_key: process.env.TWITTER_ACCESS_TOKEN_KEY,
    access_token_secret: process.env.TWITTER_ACCESS_TOKEN_SECRET
})

// Helper Function to return unknown errors
const handleError = (err) => {
    console.error(err)
    const msg = Array.isArray(err) ? err[0].message : err.message
    return {
        statusCode: 422,
        body: String(msg)
    }
}

// Helper Function to return function status
const status = (code, msg) => {
    console.log(msg)
    return {
        statusCode: code,
        body: msg
    }
}

// Check exisiting notes
const processNotes = async (notes) => {
    if (!notes.length) {
        return status(404, 'No notes found to process.')
    }

    // assume the last note is not yet syndicated
    const latestNote = notes[0]
    if (!latestNote.syndicate) {
        return status(
            400,
            'Latest note has disabled syndication. No action taken.'
        )
    }

    try {
        // check twitter for any tweets containing note URL.
        // if there are none, publish it.
        const q = await twitter.get('search/tweets', { q: latestNote.url })
        if (q.statuses && q.statuses.length === 0) {
            return publishNote(latestNote)
        } else {
            return status(
                400,
                'Latest note was already syndicated. No action taken.'
            )
        }
    } catch (err) {
        return handleError(err)
    }
}

// Prepare the content string for tweet format
const prepareStatusText = (note) => {
    const maxLength = 280 - 3 - 1 - 23 - 20

    // strip html tags and decode entities
    let text = note.content.trim().replace(/<[^>]+>/g, '')
    text = decode(text)

    // truncate note text if its too long for a tweet.
    if (text.length > maxLength) {
        text = text.substring(0, maxLength) + '...'
    }

    // include the note url at the end;
    text += ' ' + note.url

    // if it has a link, let that be the last url
    // so twitter picks it up for the preview
    if (note.link && note.link.length) {
        text += ' ' + note.link
    }

    return text
}

// Push a new note to Twitter
const publishNote = async (note) => {
    try {
        const statusText = prepareStatusText(note)
        const tweet = await twitter.post('statuses/update', {
            status: statusText
        })
        if (tweet) {
            return status(
                200,
                `Note ${note.date} successfully posted to Twitter.`
            )
        } else {
            return status(422, 'Error posting to Twitter API.')
        }
    } catch (err) {
        return handleError(err)
    }
}

// Main Lambda Function Handler
exports.handler = async () => {
    // Fetch the list of published notes to work on,
    // then process them to check if an action is necessary
    return fetch(NOTES_URL)
        .then((response) => response.json())
        .then(processNotes)
        .catch(handleError)
}