source: node_modules/decompress-response/index.js@ 81bc7da

'use strict';
const {Transform, PassThrough} = require('stream');
const zlib = require('zlib');
const mimicResponse = require('mimic-response');

module.exports = response => {
        const contentEncoding = (response.headers['content-encoding'] || '').toLowerCase();

        if (!['gzip', 'deflate', 'br'].includes(contentEncoding)) {
                return response;
        }

        // TODO: Remove this when targeting Node.js 12.
        const isBrotli = contentEncoding === 'br';
        if (isBrotli && typeof zlib.createBrotliDecompress !== 'function') {
                response.destroy(new Error('Brotli is not supported on Node.js < 12'));
                return response;
        }

        let isEmpty = true;

        const checker = new Transform({
                transform(data, _encoding, callback) {
                        isEmpty = false;

                        callback(null, data);
                },

                flush(callback) {
                        callback();
                }
        });

        const finalStream = new PassThrough({
                autoDestroy: false,
                destroy(error, callback) {
                        response.destroy();

                        callback(error);
                }
        });

        const decompressStream = isBrotli ? zlib.createBrotliDecompress() : zlib.createUnzip();

        decompressStream.once('error', error => {
                if (isEmpty && !response.readable) {
                        finalStream.end();
                        return;
                }

                finalStream.destroy(error);
        });

        mimicResponse(response, finalStream);
        response.pipe(checker).pipe(decompressStream).pipe(finalStream);

        return finalStream;
};