dograma/gramjs/tl/core/GZIPPacked.ts

NodeJS/Browser MTProto API Telegram client library,

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

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 GZIPPacked.gzip(reader.tgReadBytes());
    }

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