WDwloadReel.mjs

import fs from 'fs'
import get from 'lodash-es/get.js'
import genPm from 'wsemi/src/genPm.mjs'
import isestr from 'wsemi/src/isestr.mjs'
import isfun from 'wsemi/src/isfun.mjs'
import cint from 'wsemi/src/cint.mjs'
import getPathParent from 'wsemi/src/getPathParent.mjs'
import fsIsFolder from 'wsemi/src/fsIsFolder.mjs'
import fsCreateFolder from 'wsemi/src/fsCreateFolder.mjs'


/**
 * 下載Facebook Reel為mp4檔案至本機指定位置
 *
 * @param {String} url 輸入Facebook Reel網址字串(facebook.com / fb.watch)
 * @param {String} fp 輸入儲存video(*.mp4)檔案路徑字串
 * @param {Object} [opt={}] 輸入設定物件，預設{}
 * @param {Function} [opt.funProg=null] 輸入回傳進度函數，傳入參數為prog代表進度百分比(0~100)、nn代表當前已下載bytes、na代表全部須下載bytes，預設null
 * @returns {Promise} 回傳Promise，resolve回傳'ok'，reject回傳錯誤訊息
 * @example
 * import fs from 'fs'
 * import WDwloadReel from './src/WDwloadReel.mjs'
 *
 * async function test() {
 *
 *     //url
 *     let url = 'https://www.facebook.com/reel/3403300299820247'
 *
 *     //fp
 *     let fp = './abc.mp4'
 *
 *     //funProg
 *     let funProg = (prog, nn, na) => {
 *         console.log('prog', `${prog.toFixed(2)}%`, nn, na)
 *     }
 *
 *     //WDwloadReel
 *     await WDwloadReel(url, fp, {
 *         funProg,
 *     })
 *
 *     //len
 *     let len = fs.statSync(fp).size
 *     console.log('len', len)
 *
 *     console.log('done:', fp)
 * }
 * test()
 *     .catch((err) => {
 *         console.log('catch', err)
 *     })
 * // prog 1.00% 23456 2345678
 * // prog 2.00% 46912 2345678
 * // ...
 * // prog 99.00% 2322221 2345678
 * // prog 100.00% 2345678 2345678
 * // len 8468825
 * // done: ./abc.mp4
 *
 */
async function WDwloadReel(url, fp, opt = {}) {

    //funProg
    let funProg = get(opt, 'funProg')
    let bFunProg = isfun(funProg)

    //check
    if (!isestr(url)) {
        return Promise.reject('invalid url')
    }
    if (!isestr(fp)) {
        return Promise.reject('fp is not a string')
    }

    let isMp4 = (buf) => {
        //mp4 magic: bytes 4..7 = 'ftyp' (ISO base media file type box), 再驗 bytes 8..11 為常見 mp4 brand, 排除 JPEG2000 等其他 ftyp 容器格式
        if (buf.length < 12) {
            return false
        }
        if (buf.slice(4, 8).toString('ascii') !== 'ftyp') {
            return false
        }
        let brand = buf.slice(8, 12).toString('ascii')
        return ['isom', 'mp41', 'mp42', 'avc1', 'iso2', 'iso5', 'iso6', 'mp4v'].includes(brand)
    }

    let getRealData = async (url) => {

        //pm
        let pm = genPm()

        //check
        if (!isestr(url)) {
            pm.reject('invalid url')
            return pm
        }

        //parseString
        let parseString = (string) => {
            return JSON.parse(`{"text": "${string}"}`).text
        }

        //fetch, 參數與解析機制來源: https://github.com/victorsouzaleal/fb-downloader-scrapper/blob/main/src/facebook.ts
        let headers = {
            'sec-fetch-user': '?1',
            'sec-ch-ua-mobile': '?0',
            'sec-fetch-site': 'none',
            'sec-fetch-dest': 'document',
            'sec-fetch-mode': 'navigate',
            'cache-control': 'max-age=0',
            'authority': 'www.facebook.com',
            'upgrade-insecure-requests': '1',
            'accept-language': 'en-GB,en;q=0.9,tr-TR;q=0.8,tr;q=0.7,en-US;q=0.6',
            'sec-ch-ua': '"Google Chrome";v="89", "Chromium";v="89", ";Not A Brand";v="99"',
            'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.114 Safari/537.36',
            'accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9',
            'cookie': 'sb=Rn8BYQvCEb2fpMQZjsd6L382; datr=Rn8BYbyhXgw9RlOvmsosmVNT; c_user=100003164630629; _fbp=fb.1.1629876126997.444699739; wd=1920x939; spin=r.1004812505_b.trunk_t.1638730393_s.1_v.2_; xs=28%3A8ROnP0aeVF8XcQ%3A2%3A1627488145%3A-1%3A4916%3A%3AAcWIuSjPy2mlTPuZAeA2wWzHzEDuumXI89jH8a_QIV8; fr=0jQw7hcrFdas2ZeyT.AWVpRNl_4noCEs_hb8kaZahs-jA.BhrQqa.3E.AAA.0.0.BhrQqa.AWUu879ZtCw',
        }
        fetch(url, { headers })
            .then((res) => {

                //check
                if (!res.ok) throw new Error(`HTTP ${res.status} ${res.statusText}`)

                return res.text()
            })
            .then((data) => {

                data = data.replace(/&quot;/g, '"').replace(/&amp;/g, '&')
                let sdMatch = data.match(/"browser_native_sd_url":"(.*?)"/) || data.match(/"playable_url":"(.*?)"/) || data.match(/sd_src\s*:\s*"([^"]*)"/) || data.match(/(?<="src":")[^"]*(https:\/\/[^"]*)/)
                let hdMatch = data.match(/"browser_native_hd_url":"(.*?)"/) || data.match(/"playable_url_quality_hd":"(.*?)"/) || data.match(/hd_src\s*:\s*"([^"]*)"/)
                let titleMatch = data.match(/<meta\sname="description"\scontent="(.*?)"/)
                let thumbMatch = data.match(/"preferred_thumbnail":{"image":{"uri":"(.*?)"/)
                let duration = data.match(/"playable_duration_in_ms":[0-9]+/gm)

                //check
                if (sdMatch && sdMatch[1]) {
                    let result = {
                        url,
                        duration_ms: cint(duration[0].split(':')[1]),
                        sd: parseString(sdMatch[1]),
                        hd: hdMatch && hdMatch[1] ? parseString(hdMatch[1]) : '',
                        title: titleMatch && titleMatch[1] ? parseString(titleMatch[1]) : data.match(/<title>(.*?)<\/title>/)?.[1] ?? '',
                        thumbnail: thumbMatch && thumbMatch[1] ? parseString(thumbMatch[1]) : '',
                    }
                    pm.resolve(result)
                }
                else {
                    pm.reject('no video url found in page')
                }

            })
            .catch((err) => {
                pm.reject(err)
            })

        return pm
    }

    //getRealData, 解析FB頁面取得mp4直連
    let info
    try {
        info = await getRealData(url)
    }
    catch (err) {
        return Promise.reject(err)
    }

    //check, 須有hd或sd其中之一
    if (!info.hd && !info.sd) {
        return Promise.reject('can not get hd/sd mp4 url (reel may be private/deleted/FB changed)')
    }

    //target, 優先hd
    let target = info.hd || info.sd

    //fetch
    let res
    try {
        res = await fetch(target)
    }
    catch (err) {
        return Promise.reject(`fetch mp4 fail: ${err.message}`)
    }

    //check
    if (!res.ok) {
        return Promise.reject(`HTTP ${res.status} ${res.statusText}`)
    }

    //total, Content-Length未必提供, 取不到視為0(中段不觸發funProg, 最後仍補100%)
    let total = cint(res.headers.get('content-length'))

    //讀取串流並計算進度
    let reader = res.body.getReader()
    let chunks = []
    let received = 0
    let progPre = -1
    while (true) {
        let { done, value } = await reader.read()
        if (done) {
            break
        }
        chunks.push(value)
        received += value.length

        //funProg, 整數百分比變動才觸發避免高頻
        if (bFunProg && total > 0) {
            let prog = (received / total) * 99 //預留1%給最後寫入完成補足
            let progInt = Math.floor(prog)
            if (progInt > progPre) {
                progPre = progInt
                funProg(prog, received, total)
            }
        }
    }

    //buf
    let buf = Buffer.concat(chunks)

    //check mp4 magic, 避免HTML錯誤頁面或非mp4回應被當mp4寫入
    if (!isMp4(buf)) {
        return Promise.reject(`downloaded but not valid mp4 (first 16 bytes: ${buf.slice(0, 16).toString('hex')})`)
    }

    //mkdir, 上層目錄不存在時自動建立
    let dir = getPathParent(fp)
    if (isestr(dir) && !fsIsFolder(dir)) {
        fsCreateFolder(dir)
    }

    //write
    fs.writeFileSync(fp, buf)

    //funProg, 最終補100%(涵蓋無Content-Length時中段未觸發的情況)
    if (bFunProg) {
        let na = total || buf.length
        funProg(100, na, na)
    }

    return 'ok'
}


export default WDwloadReel