PdfEditor/server.js

const fs = require('fs')
const asfs = require('asfs')
const express = require('express')
const multer = require('multer')
const childProcess = require('child_process')
const bodyParser = require('body-parser')
const pdf2htmlexPath = `${__dirname}/node_modules/@alancnet/pdf2htmlex/bin-win/pdf2htmlEX.exe`
const puppeteer = require('puppeteer')
const uuid = require('uuid')
const parseDataUrl = require('data-urls')
const cors = require('cors')
const path = require('path')

const chromePromise = puppeteer.launch()

const upload = multer({
    dest: 'temp/'
})

const app = express()
app.use(cors({
    origin: '*'
}))
app.use(bodyParser.urlencoded({extended: false, limit: '100mb'}))
app.use(express.static('./public'))

app.post('/edit', upload.single('document'), async (req, res) => {
    let pdfFile, htmlFile
    if (req.file) {
        pdfFile = req.file.path
        htmlFile = `${req.file.path}.html`
    } else if (req.body.url) {
        pdfFile = `temp/${uuid()}.pdf`
        htmlFile = `${pdfFile}.html`
        const pdf = parseDataUrl(req.body.url)
        await asfs.writeFileAsync(pdfFile, pdf.body)
    }
    /*
        Executes pdf2htmlex[.exe] with:
        - 200 horizontal and vertical DPI
        - TrueType Font format (because woff does not render in PhantomJS)
        - No DRM, overriding any PDF settings forbidding copying or modifying
        - The path to the source PDF file
        - The path to the output HTML file
    */
    childProcess.exec(`"${pdf2htmlexPath}" --hdpi 200 --vdpi 200 --font-format ttf --no-drm 1 "${pdfFile}" "${htmlFile}"`, (err, stdout, stderr) => {
        if (err) {
            res.status(500).send(`<pre>${stderr}</pre>`)
        } else {
            fs.readFile('public/edit.html', (err, editHtml) => {
                fs.readFile(htmlFile, 'utf8', async (err, data) => {
                    if (err) {
                        res.status(500).send(`<pre>${err}</pre>`)
                    } else {
                        res.status(200).send(data.replace('</body>', `${editHtml}</body>`))
                    }
                    await asfs.unlinkAsync(htmlFile)
                    await asfs.unlinkAsync(pdfFile)
                })
            })
        }
    })
})



app.post('/save', (req, res) => {
    const tmpUuid = uuid()
    const htmlFile = `temp/${tmpUuid}.html`
    const htmlUrl = `file://${path.join(process.cwd(), htmlFile)}`
    const pdfFile = `temp/${tmpUuid}.pdf`

    const pageWidth = /\.w0{width:([\d\.]*)pt/.exec(req.body.html)[1]
    const pageHeight = /\.h0{height:([\d\.]*)pt/.exec(req.body.html)[1]


    fs.writeFile(htmlFile, req.body.html, 'utf8', async (err) => {
        const chrome = await chromePromise
        const page = await chrome.newPage()
        await page.goto(htmlUrl)
        await page.pdf({
            path: pdfFile,
            preferCSSPageSize: true
        })
        await page.close()
        res.download(pdfFile, 'todo-preserve-filename.pdf', async (err) => {
            if (err) {
                console.error(err)
                res.status(500).send(err)
            }
            await asfs.unlinkAsync(htmlFile)
            await asfs.unlinkAsync(pdfFile)
        })
    })
})
app.listen(process.env.PORT || 3000)