feat: send media as stickers (#479)

Adds the option `sendMediaAsSticker` that will take care of converting media to appropriate formats and send it as a sticker. Note that ffmpeg is required to properly convert animated stickers that are not in webp format.

Co-authored-by: Pedro S. Lopez <pedroslopez@me.com>

src/util/Util.js

@@ -1,5 +1,12 @@
 'use strict';
 
+const sharp = require('sharp');
+const path = require('path');
+const Crypto = require('crypto');
+const { tmpdir } = require('os');
+const ffmpeg = require('fluent-ffmpeg');
+const fs = require('fs').promises;
+
 const has = (o, k) => Object.prototype.hasOwnProperty.call(o, k);
 
 /**
@@ -30,6 +37,123 @@ class Util {
 
         return given;
     }
+
+    /**
+     * Formats a image to webp
+     * @param {MessageMedia} media
+     * 
+     * @returns {Promise<MessageMedia>} media in webp format
+     */
+    static async formatImageToWebpSticker(media) {
+        if (!media.mimetype.includes('image'))
+            throw new Error('media is not a image');
+      
+        if (media.mimetype.includes('webp')) {
+            return media;
+        }
+      
+        const buff = Buffer.from(media.data, 'base64');
+      
+        let sharpImg = sharp(buff);
+        sharpImg = sharpImg.webp();
+      
+        sharpImg = sharpImg.resize(512, 512, {
+            fit: 'contain',
+            background: { r: 0, g: 0, b: 0, alpha: 0 },
+        });
+      
+        let webpBase64 = (await sharpImg.toBuffer()).toString('base64');
+      
+        return {             
+            mimetype: 'image/webp',
+            data: webpBase64,
+            filename: media.filename,
+        };
+    }
+      
+    /**
+     * Formats a video to webp
+     * @param {MessageMedia} media
+     * 
+     * @returns {Promise<MessageMedia>} media in webp format
+     */
+    static async formatVideoToWebpSticker(media) {
+        if (!media.mimetype.includes('video'))
+            throw new Error('media is not a video');
+      
+        const videoType = media.mimetype.split('/')[1];
+
+        const tempFile = path.join(
+            tmpdir(),
+            `${Crypto.randomBytes(6).readUIntLE(0, 6).toString(36)}.webp`
+        );
+      
+        const stream = new (require('stream').Readable)();
+        const buffer = Buffer.from(
+            media.data.replace(`data:${media.mimetype};base64,`, ''),
+            'base64'
+        );
+        stream.push(buffer);
+        stream.push(null);
+
+        await new Promise((resolve, reject) => {
+            ffmpeg(stream)
+                .inputFormat(videoType)
+                .on('error', reject)
+                .on('end', () => resolve(true))
+                .addOutputOptions([
+                    '-vcodec',
+                    'libwebp',
+                    '-vf',
+                    // eslint-disable-next-line no-useless-escape
+                    'scale=\'iw*min(300/iw\,300/ih)\':\'ih*min(300/iw\,300/ih)\',format=rgba,pad=300:300:\'(300-iw)/2\':\'(300-ih)/2\':\'#00000000\',setsar=1,fps=10',
+                    '-loop',
+                    '0',
+                    '-ss',
+                    '00:00:00.0',
+                    '-t',
+                    '00:00:05.0',
+                    '-preset',
+                    'default',
+                    '-an',
+                    '-vsync',
+                    '0',
+                    '-s',
+                    '512:512',
+                ])
+                .toFormat('webp')
+                .save(tempFile);
+        });
+      
+        const data = await fs.readFile(tempFile, 'base64');
+        await fs.unlink(tempFile);
+      
+        return {             
+            mimetype: 'image/webp',
+            data: data,
+            filename: media.filename,
+        };
+    }
+      
+    /**
+     * Formats a media to webp
+     * @param {MessageMedia} media
+     * 
+     * @returns {Promise<MessageMedia>} media in webp format
+     */
+    static async formatToWebpSticker(media) {
+        if (media.mimetype.includes('image')) return this.formatImageToWebpSticker(media);
+        else if (media.mimetype.includes('video')) return this.formatVideoToWebpSticker(media);
+        else throw new Error('Invalid media format');
+    }
+
+    /**
+     * Configure ffmpeg path
+     * @param {string} path
+     */
+    static setFfmpegPath(path) {
+        ffmpeg.setFfmpegPath(path);
+    }
 }
 
 module.exports = Util;