basant307/AI_Governance_Project

1'use strict';2 3import stream from 'stream';4import utils from '../utils.js';5 6const kInternals = Symbol('internals');7 8class AxiosTransformStream extends stream.Transform {9  constructor(options) {10    options = utils.toFlatObject(11      options,12      {13        maxRate: 0,14        chunkSize: 64 * 1024,15        minChunkSize: 100,16        timeWindow: 500,17        ticksRate: 2,18        samplesCount: 15,19      },20      null,21      (prop, source) => {22        return !utils.isUndefined(source[prop]);23      }24    );25 26    super({27      readableHighWaterMark: options.chunkSize,28    });29 30    const internals = (this[kInternals] = {31      timeWindow: options.timeWindow,32      chunkSize: options.chunkSize,33      maxRate: options.maxRate,34      minChunkSize: options.minChunkSize,35      bytesSeen: 0,36      isCaptured: false,37      notifiedBytesLoaded: 0,38      ts: Date.now(),39      bytes: 0,40      onReadCallback: null,41    });42 43    this.on('newListener', (event) => {44      if (event === 'progress') {45        if (!internals.isCaptured) {46          internals.isCaptured = true;47        }48      }49    });50  }51 52  _read(size) {53    const internals = this[kInternals];54 55    if (internals.onReadCallback) {56      internals.onReadCallback();57    }58 59    return super._read(size);60  }61 62  _transform(chunk, encoding, callback) {63    const internals = this[kInternals];64    const maxRate = internals.maxRate;65 66    const readableHighWaterMark = this.readableHighWaterMark;67 68    const timeWindow = internals.timeWindow;69 70    const divider = 1000 / timeWindow;71    const bytesThreshold = maxRate / divider;72    const minChunkSize =73      internals.minChunkSize !== false74        ? Math.max(internals.minChunkSize, bytesThreshold * 0.01)75        : 0;76 77    const pushChunk = (_chunk, _callback) => {78      const bytes = Buffer.byteLength(_chunk);79      internals.bytesSeen += bytes;80      internals.bytes += bytes;81 82      internals.isCaptured && this.emit('progress', internals.bytesSeen);83 84      if (this.push(_chunk)) {85        process.nextTick(_callback);86      } else {87        internals.onReadCallback = () => {88          internals.onReadCallback = null;89          process.nextTick(_callback);90        };91      }92    };93 94    const transformChunk = (_chunk, _callback) => {95      const chunkSize = Buffer.byteLength(_chunk);96      let chunkRemainder = null;97      let maxChunkSize = readableHighWaterMark;98      let bytesLeft;99      let passed = 0;100 101      if (maxRate) {102        const now = Date.now();103 104        if (!internals.ts || (passed = now - internals.ts) >= timeWindow) {105          internals.ts = now;106          bytesLeft = bytesThreshold - internals.bytes;107          internals.bytes = bytesLeft < 0 ? -bytesLeft : 0;108          passed = 0;109        }110 111        bytesLeft = bytesThreshold - internals.bytes;112      }113 114      if (maxRate) {115        if (bytesLeft <= 0) {116          // next time window117          return setTimeout(() => {118            _callback(null, _chunk);119          }, timeWindow - passed);120        }121 122        if (bytesLeft < maxChunkSize) {123          maxChunkSize = bytesLeft;124        }125      }126 127      if (maxChunkSize && chunkSize > maxChunkSize && chunkSize - maxChunkSize > minChunkSize) {128        chunkRemainder = _chunk.subarray(maxChunkSize);129        _chunk = _chunk.subarray(0, maxChunkSize);130      }131 132      pushChunk(133        _chunk,134        chunkRemainder135          ? () => {136              process.nextTick(_callback, null, chunkRemainder);137            }138          : _callback139      );140    };141 142    transformChunk(chunk, function transformNextChunk(err, _chunk) {143      if (err) {144        return callback(err);145      }146 147      if (_chunk) {148        transformChunk(_chunk, transformNextChunk);149      } else {150        callback(null);151      }152    });153  }154}155 156export default AxiosTransformStream;157