Read a block of code from stdin, submit it to carbon.sh, and output the resulting tweet url.

carbonify.js

#!/usr/bin/env node

/*
Submit code from stdin to carbon.now.sh and return a url to a new tweet containing a screenshot

carbon.now.sh authors: https://dawnlabs.io/
carbonify author: Nick Sweeting <git@nicksweeting.com>
MIT License 2017
*/

const puppeteer = require('puppeteer')

const USAGE = `
    Usage:
        ./carbonify.js < code_file.py

    Output:
        https://twitter.com/intent/tweet?text=pic.twitter.com/abcd1234.png

    Dependencies:
        yarn add GoogleChrome/puppeteer

    To open a new tweet compose window:
        open $(./carbonify.js < code_file.py)

    To trigger from SublimeText, add a build variant:
        {
            "cmd":
            ["open" "$(/path/to/carbonify.js < \"$file\")"],
            "name": "Tweet carbon.now.sh screenshot",
            "shell": true
        }
`

function log(text) {
    process.stderr.write(`${text}\n`)
}

// read stdin into variable
function readInput(buffer) {
    return new Promise(function(resolve, reject) {
        let code = '';
        buffer.on('data', (chunk) => {
            code += `${chunk}\n`
        })
        buffer.on('end', () => {
            const empty_inputs = ['', ' ', '\n', '\n\n']
            if (empty_inputs.includes(code)) {
                log('[!] No input was passed in!')
                reject()
            } else {
                resolve(code)
            }
        })
        buffer.setEncoding('utf8')
        buffer.resume()
    })
}


// screenshot code on carbon.now.sh and get new tweet url
function getCarbonTweetURL(code) {
    return new Promise(async function(resolve, reject) {
        const browser = await puppeteer.launch()  // for testing use: {headless: false}
        const page = await browser.newPage()
        
        // load page and wait for tweet button to go from "Loading..." to "Tweet Image"
        log('[1/4] Opening carbon.now.sh in headless chrome...')
        await page.goto('https://carbon.now.sh')
        await page.waitForFunction(() => {
            const twitter_btn = '#toolbar > div.buttons > button:nth-child(1)'
            const tweet_btn_elem = document.querySelectorAll(twitter_btn)[0]
            return tweet_btn_elem.innerHTML.includes("Tweet Image")
        })

        // clear example code out of code input field
        const code_input = 'div.ReactCodeMirror div.CodeMirror-code > pre:nth-child(11)'
        await page.click(code_input)
        await page.keyboard.down('Meta')
        await page.keyboard.down('a')
        await page.keyboard.up('a')
        await page.keyboard.up('Meta')
        await page.keyboard.press('Backspace')

        const lines = code.split('\n')
        const len = lines.length
        log(`[2/4] Inputting ${len} line code snippet...`)
        if (len < 500) {
            await page.keyboard.type(code)
        } else {
            // if file is large, do it line-by-line for performance reasons
            lines.forEach(async (line, idx) => {
                const mod = (num, amt) => ((num%amt)+amt)%amt
                if (idx == 0 || !mod(idx+1, 25)) {
                    // every 25 lines, show progress
                    log(`     ${idx+1}/${len} lines\n`)
                }
                await page.keyboard.type(`{line}\n`)
            })
            log(`     ${len}/${len} lines\n`)
        }

        // catch twitter popup and log url to console instead
        log('[3/4] Uploading to Twitter...')
        await page.evaluate(() => {
            window.open = (url) => console.log(url)
        })
        page.on('console', async (msg) => {
            log('[4/4] Got tweet URL.')
            const tweet_url = msg.text.replace('Built%20with%20%23Carbon%2C%20by%20%40dawn_labs%20', '')
            await browser.close()
            resolve(tweet_url)
        })
        const tweet_button = '#toolbar > div.buttons > button:nth-child(1)'
        await page.click(tweet_button)
    })
}

// if run from CLI instead of being imported
if (require.main === module) {
    const node_version = Number(process.version.split('.')[0].slice(1))
    if (node_version < 8) {
        log('[X] You need node version >= 8.0.0 to run this.')
        process.exit(1)
    }
    if (process.argv.includes('--help') || process.argv.includes('-h')) {
        log(USAGE)
    }
    (async () => {
        const code = await readInput(process.stdin)
        const picture_url = await getCarbonTweetURL(code)
        console.log(picture_url)
    })()
}