lib/exif.js

const fs = require('fs')
const { tmpdir } = require("os")
const Crypto = require("crypto")
const ff = require('fluent-ffmpeg')
const webp = require("node-webpmux")
const path = require("path")


async function imageToWebp (media) {

    const tmpFileOut = path.join(tmpdir(), `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.webp`)
    const tmpFileIn = path.join(tmpdir(), `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.jpg`)

    fs.writeFileSync(tmpFileIn, media)

    await new Promise((resolve, reject) => {
        ff(tmpFileIn)
            .on("error", reject)
            .on("end", () => resolve(true))
            .addOutputOptions([
                "-vcodec",
                "libwebp",
                "-vf",
                "scale='min(320,iw)':min'(320,ih)':force_original_aspect_ratio=decrease,fps=15, pad=320:320:-1:-1:color=white@0.0, split [a][b]; [a] palettegen=reserve_transparent=on:transparency_color=ffffff [p]; [b][p] paletteuse"
            ])
            .toFormat("webp")
            .save(tmpFileOut)
    })

    const buff = fs.readFileSync(tmpFileOut)
    fs.unlinkSync(tmpFileOut)
    fs.unlinkSync(tmpFileIn)
    return buff
}

async function videoToWebp (media) {

    const tmpFileOut = path.join(tmpdir(), `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.webp`)
    const tmpFileIn = path.join(tmpdir(), `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.mp4`)

    fs.writeFileSync(tmpFileIn, media)

    await new Promise((resolve, reject) => {
        ff(tmpFileIn)
            .on("error", reject)
            .on("end", () => resolve(true))
            .addOutputOptions([
                "-vcodec",
                "libwebp",
                "-vf",
                "scale='min(320,iw)':min'(320,ih)':force_original_aspect_ratio=decrease,fps=15, pad=320:320:-1:-1:color=white@0.0, split [a][b]; [a] palettegen=reserve_transparent=on:transparency_color=ffffff [p]; [b][p] paletteuse",
                "-loop",
                "0",
                "-ss",
                "00:00:00",
                "-t",
                "00:00:06",
                "-preset",
                "default",
                "-an",
                "-vsync",
                "0"
            ])
            .toFormat("webp")
            .save(tmpFileOut)
    })

    const buff = fs.readFileSync(tmpFileOut)
    fs.unlinkSync(tmpFileOut)
    fs.unlinkSync(tmpFileIn)
    return buff
}

async function writeExifImg (media, metadata) {
    let wMedia = await imageToWebp(media)
    const tmpFileIn = path.join(tmpdir(), `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.webp`)
    const tmpFileOut = path.join(tmpdir(), `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.webp`)
    fs.writeFileSync(tmpFileIn, wMedia)

    if (metadata.packname || metadata.author) {
        const img = new webp.Image()
        const json = { "sticker-pack-id": `https://github.com/BOTCAHX/RTXZY-MD`, "sticker-pack-name": metadata.packname, "sticker-pack-publisher": metadata.author, "emojis": metadata.categories ? metadata.categories : [""] }
        const exifAttr = Buffer.from([0x49, 0x49, 0x2A, 0x00, 0x08, 0x00, 0x00, 0x00, 0x01, 0x00, 0x41, 0x57, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x16, 0x00, 0x00, 0x00])
        const jsonBuff = Buffer.from(JSON.stringify(json), "utf-8")
        const exif = Buffer.concat([exifAttr, jsonBuff])
        exif.writeUIntLE(jsonBuff.length, 14, 4)
        await img.load(tmpFileIn)
        fs.unlinkSync(tmpFileIn)
        img.exif = exif
        await img.save(tmpFileOut)
        return tmpFileOut
    }
}

async function writeExifVid (media, metadata) {
    let wMedia = await videoToWebp(media)
    const tmpFileIn = path.join(tmpdir(), `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.webp`)
    const tmpFileOut = path.join(tmpdir(), `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.webp`)
    fs.writeFileSync(tmpFileIn, wMedia)

    if (metadata.packname || metadata.author) {
        const img = new webp.Image()
        const json = { "sticker-pack-id": `https://github.com/BOTCAHX/RTXZY-MD`, "sticker-pack-name": metadata.packname, "sticker-pack-publisher": metadata.author, "emojis": metadata.categories ? metadata.categories : [""] }
        const exifAttr = Buffer.from([0x49, 0x49, 0x2A, 0x00, 0x08, 0x00, 0x00, 0x00, 0x01, 0x00, 0x41, 0x57, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x16, 0x00, 0x00, 0x00])
        const jsonBuff = Buffer.from(JSON.stringify(json), "utf-8")
        const exif = Buffer.concat([exifAttr, jsonBuff])
        exif.writeUIntLE(jsonBuff.length, 14, 4)
        await img.load(tmpFileIn)
        fs.unlinkSync(tmpFileIn)
        img.exif = exif
        await img.save(tmpFileOut)
        return tmpFileOut
    }
}

module.exports = { imageToWebp, videoToWebp, writeExifImg, writeExifVid }