chore: add project dependencies and configuration files

Initial setup of project dependencies including axios, express, dotenv, and other supporting packages. Added configuration files and documentation for project setup and usage.

node_modules/axios/lib/helpers/AxiosTransformStream.js

@@ -0,0 +1,143 @@
+'use strict';
+
+import stream from 'stream';
+import utils from '../utils.js';
+
+const kInternals = Symbol('internals');
+
+class AxiosTransformStream extends stream.Transform{
+  constructor(options) {
+    options = utils.toFlatObject(options, {
+      maxRate: 0,
+      chunkSize: 64 * 1024,
+      minChunkSize: 100,
+      timeWindow: 500,
+      ticksRate: 2,
+      samplesCount: 15
+    }, null, (prop, source) => {
+      return !utils.isUndefined(source[prop]);
+    });
+
+    super({
+      readableHighWaterMark: options.chunkSize
+    });
+
+    const internals = this[kInternals] = {
+      timeWindow: options.timeWindow,
+      chunkSize: options.chunkSize,
+      maxRate: options.maxRate,
+      minChunkSize: options.minChunkSize,
+      bytesSeen: 0,
+      isCaptured: false,
+      notifiedBytesLoaded: 0,
+      ts: Date.now(),
+      bytes: 0,
+      onReadCallback: null
+    };
+
+    this.on('newListener', event => {
+      if (event === 'progress') {
+        if (!internals.isCaptured) {
+          internals.isCaptured = true;
+        }
+      }
+    });
+  }
+
+  _read(size) {
+    const internals = this[kInternals];
+
+    if (internals.onReadCallback) {
+      internals.onReadCallback();
+    }
+
+    return super._read(size);
+  }
+
+  _transform(chunk, encoding, callback) {
+    const internals = this[kInternals];
+    const maxRate = internals.maxRate;
+
+    const readableHighWaterMark = this.readableHighWaterMark;
+
+    const timeWindow = internals.timeWindow;
+
+    const divider = 1000 / timeWindow;
+    const bytesThreshold = (maxRate / divider);
+    const minChunkSize = internals.minChunkSize !== false ? Math.max(internals.minChunkSize, bytesThreshold * 0.01) : 0;
+
+    const pushChunk = (_chunk, _callback) => {
+      const bytes = Buffer.byteLength(_chunk);
+      internals.bytesSeen += bytes;
+      internals.bytes += bytes;
+
+      internals.isCaptured && this.emit('progress', internals.bytesSeen);
+
+      if (this.push(_chunk)) {
+        process.nextTick(_callback);
+      } else {
+        internals.onReadCallback = () => {
+          internals.onReadCallback = null;
+          process.nextTick(_callback);
+        };
+      }
+    }
+
+    const transformChunk = (_chunk, _callback) => {
+      const chunkSize = Buffer.byteLength(_chunk);
+      let chunkRemainder = null;
+      let maxChunkSize = readableHighWaterMark;
+      let bytesLeft;
+      let passed = 0;
+
+      if (maxRate) {
+        const now = Date.now();
+
+        if (!internals.ts || (passed = (now - internals.ts)) >= timeWindow) {
+          internals.ts = now;
+          bytesLeft = bytesThreshold - internals.bytes;
+          internals.bytes = bytesLeft < 0 ? -bytesLeft : 0;
+          passed = 0;
+        }
+
+        bytesLeft = bytesThreshold - internals.bytes;
+      }
+
+      if (maxRate) {
+        if (bytesLeft <= 0) {
+          // next time window
+          return setTimeout(() => {
+            _callback(null, _chunk);
+          }, timeWindow - passed);
+        }
+
+        if (bytesLeft < maxChunkSize) {
+          maxChunkSize = bytesLeft;
+        }
+      }
+
+      if (maxChunkSize && chunkSize > maxChunkSize && (chunkSize - maxChunkSize) > minChunkSize) {
+        chunkRemainder = _chunk.subarray(maxChunkSize);
+        _chunk = _chunk.subarray(0, maxChunkSize);
+      }
+
+      pushChunk(_chunk, chunkRemainder ? () => {
+        process.nextTick(_callback, null, chunkRemainder);
+      } : _callback);
+    };
+
+    transformChunk(chunk, function transformNextChunk(err, _chunk) {
+      if (err) {
+        return callback(err);
+      }
+
+      if (_chunk) {
+        transformChunk(_chunk, transformNextChunk);
+      } else {
+        callback(null);
+      }
+    });
+  }
+}
+
+export default AxiosTransformStream;