smartstream/readme.md

# @push.rocks/smartstream
simplifies access to node streams

## Install
To install `@push.rocks/smartstream`, you can use npm or yarn as follows:

```bash
npm install @push.rocks/smartstream --save
# OR
yarn add @push.rocks/smartstream
```

This will add `@push.rocks/smartstream` to your project's dependencies.

## Usage

The `@push.rocks/smartstream` module is designed to simplify working with Node.js streams by providing a set of utilities for creating and manipulating streams. This module makes heavy use of TypeScript for improved code quality, readability, and maintenance. ESM syntax is utilized throughout the examples.

### Importing the Module

Start by importing the module into your TypeScript file:

```typescript
import * as smartstream from '@push.rocks/smartstream';
```

### Creating Basic Transform Streams

The module provides utilities for creating transform streams. For example, to create a transform stream that modifies chunks of data, you can use the `createTransformFunction` utility:

```typescript
import { createTransformFunction } from '@push.rocks/smartstream';

const upperCaseTransform = createTransformFunction<string, string>(async (chunk) => {
  return chunk.toUpperCase();
});

// Usage with pipe
readableStream
  .pipe(upperCaseTransform)
  .pipe(writableStream);
```

### Handling Backpressure with SmartDuplex

`SmartDuplex` is a powerful part of the `smartstream` module designed to handle backpressure effectively. Here's an example of how to create a `SmartDuplex` stream that processes data and respects the consumer's pace:

```typescript
import { SmartDuplex } from '@push.rocks/smartstream';

const processDataDuplex = new SmartDuplex({
  async writeFunction(chunk, { push }) {
    const processedChunk = await processChunk(chunk); // Assume this is a defined asynchronous function
    push(processedChunk);
  }
});

sourceStream.pipe(processDataDuplex).pipe(destinationStream);
```

### Stream Combiners

`Smartstream` facilitates easy combining of multiple streams into a single pipeline, handling errors and cleanup automatically. Here's how you can combine multiple streams:

```typescript
import { StreamWrapper } from '@push.rocks/smartstream';

const combinedStream = new StreamWrapper([
  readStream,       // Source stream
  transformStream1, // Transformation
  transformStream2, // Another transformation
  writeStream       // Destination stream
]);

combinedStream.run()
  .then(() => console.log('Processing completed.'))
  .catch(err => console.error('An error occurred:', err));
```

### Working with StreamIntake

`StreamIntake` allows for more dynamic control of the reading process, facilitating scenarios where data is not continuously available:

```typescript
import { StreamIntake } from '@push.rocks/smartstream';

const streamIntake = new StreamIntake<string>();

// Dynamically push data into the intake
streamIntake.pushData('Hello, World!');
streamIntake.pushData('Another message');

// Signal end when no more data is to be pushed
streamIntake.signalEnd();
```

### Real-world Scenario: Processing Large Files

Consider a scenario where you need to process a large CSV file, transform the data row-by-row, and then write the results to a database or another file. With `smartstream`, you could create a pipe that reads the CSV, processes each row, and handles backpressure, ensuring efficient use of resources.

```typescript
import { SmartDuplex, createTransformFunction } from '@push.rocks/smartstream';
import fs from 'fs';
import csvParser from 'csv-parser'; // Assume this is a CSV parsing library

const csvReadTransform = createTransformFunction<any, any>(async (row) => {
  // Process row
  return processedRow;
});

fs.createReadStream('path/to/largeFile.csv')
  .pipe(csvParser())
  .pipe(csvReadTransform)
  .pipe(new SmartDuplex({
    async writeFunction(chunk, { push }) {
      await writeToDatabase(chunk); // Assume this writes to a database
    }
  }))
  .on('finish', () => console.log('File processed successfully.'));
```

This example demonstrates reading a large CSV file, transforming each row with `createTransformFunction`, and using a `SmartDuplex` to manage the processed data flow efficiently, ensuring no data is lost due to backpressure issues.

### Conclusion

`@push.rocks/smartstream` offers a robust set of tools for working with Node.js streams, providing a more intuitive and reliable way to create, manipulate, and combine streams. By leveraging TypeScript and ESM syntax, `smartstream` enables developers to build more maintainable and type-safe stream-based solutions.

For more detailed examples and documentation, visit the [GitLab Repository](https://gitlab.com/push.rocks/smartstream) or the [GitHub Mirror](https://github.com/pushrocks/smartstream).

## License and Legal Information

This repository contains open-source code that is licensed under the MIT License. A copy of the MIT License can be found in the [license](license) file within this repository. 

**Please note:** The MIT License does not grant permission to use the trade names, trademarks, service marks, or product names of the project, except as required for reasonable and customary use in describing the origin of the work and reproducing the content of the NOTICE file.

### Trademarks

This project is owned and maintained by Task Venture Capital GmbH. The names and logos associated with Task Venture Capital GmbH and any related products or services are trademarks of Task Venture Capital GmbH and are not included within the scope of the MIT license granted herein. Use of these trademarks must comply with Task Venture Capital GmbH's Trademark Guidelines, and any usage must be approved in writing by Task Venture Capital GmbH.

### Company Information

Task Venture Capital GmbH  
Registered at District court Bremen HRB 35230 HB, Germany

For any legal inquiries or if you require further information, please contact us via email at hello@task.vc.

By using this repository, you acknowledge that you have read this section, agree to comply with its terms, and understand that the licensing of the code does not imply endorsement by Task Venture Capital GmbH of any derivative works.