gramjs/gramjs/tl/core/GZIPPacked.ts

import {serializeBytes} from '../index';
import {inflate} from 'pako';
import {BinaryReader} from "../../extensions/BinaryReader";

export class GZIPPacked {
    static CONSTRUCTOR_ID = 0x3072cfa1;
    static classType = 'constructor';
    data: Buffer;
    private CONSTRUCTOR_ID: number;
    private classType: string;

    constructor(data: Buffer) {
        this.data = data;
        this.CONSTRUCTOR_ID = 0x3072cfa1;
        this.classType = 'constructor'
    }

    static async gzipIfSmaller(contentRelated: boolean, data: Buffer) {
        if (contentRelated && data.length > 512) {
            const gzipped = await (new GZIPPacked(data)).toBytes();
            if (gzipped.length < data.length) {
                return gzipped
            }
        }
        return data
    }

    static gzip(input: Buffer) {
        return Buffer.from(input)
        // TODO this usually makes it faster for large requests
        //return Buffer.from(deflate(input, { level: 9, gzip: true }))
    }

    static ungzip(input: Buffer) {
        return Buffer.from(inflate(input))
    }

    async toBytes() {
        const g = Buffer.alloc(4);
        g.writeUInt32LE(GZIPPacked.CONSTRUCTOR_ID, 0);
        return Buffer.concat([
            g,
            serializeBytes(await GZIPPacked.gzip(this.data)),
        ])
    }

    static async read(reader: BinaryReader) {
        const constructor = reader.readInt(false);
        if (constructor !== GZIPPacked.CONSTRUCTOR_ID) {
            throw new Error('not equal')
        }
        return await GZIPPacked.gzip(reader.tgReadBytes())
    }

    static async fromReader(reader: BinaryReader) {
        const data = reader.tgReadBytes();
        return new GZIPPacked(await GZIPPacked.ungzip(data))
    }
}