Is it possible to handle file downloads with Nightmare?

Nightmare is a high-level browser automation library for Node.js, which is often used for web scraping and automated testing purposes. It is built on top of Electron, which is a framework for creating native applications with web technologies like JavaScript, HTML, and CSS.

Handling file downloads with Nightmare can be a bit tricky because Nightmare itself does not provide a straightforward API for downloading files like some other browser automation tools do. However, it is possible to handle file downloads indirectly by interacting with the web page and using Electron's features.

Here are the steps you can use to handle file downloads with Nightmare:

1. Trigger the download: You can simulate clicks or other events that will trigger the download.
2. Intercept the download event: By using the Electron APIs, you can intercept the download event and handle it in a custom way.
3. Save the file: Once intercepted, you can direct where to save the file or handle the file stream directly.

Here's an example of how you can set this up in a Nightmare script:

const Nightmare = require('nightmare');
const fs = require('fs');
const path = require('path');
const { ipcMain } = require('electron');

// Configure Nightmare to use Electron's `download` event
Nightmare.action('download', function (selector, done) {
  this.evaluate_now((selector) => {
    // This will trigger the download by clicking the link or button
    var element = document.querySelector(selector);
    var event = document.createEvent('MouseEvent');
    event.initEvent('click', true, true);
    element.dispatchEvent(event);
  }, done, selector);
});

// Create a new Nightmare instance
const nightmare = Nightmare({
  show: true // Set this to `false` for headless operation
});

// Set up the download event handler in Electron
ipcMain.on('download', (event, downloadPath) => {
  event.preventDefault();

  // Set the save path for the download
  event.sender.session.on('will-download', (event, item) => {
    const filename = item.getFilename();
    const savePath = path.join(downloadPath, filename);
    item.setSavePath(savePath);

    // Once the download is complete, we can perform additional actions
    item.once('done', (event, state) => {
      if (state === 'completed') {
        console.log(`Download completed: ${savePath}`);
      } else {
        console.log(`Download failed: ${state}`);
      }
    });
  });
});

// Use the custom `download` action to download a file
nightmare
  .goto('https://example.com/page-with-download')
  .download('#download-button') // Assuming the download is triggered by an element with id 'download-button'
  .then(() => {
    console.log('Download action triggered');
  })
  .catch((error) => {
    console.error('Download failed:', error);
  });

In this example, we create a custom Nightmare action called download that uses evaluate_now to click on an element that should trigger a file download. We then listen for the download event using Electron's ipcMain module and set up the will-download event to control where the file should be saved.

Please note that handling file downloads with Nightmare and Electron might not be as straightforward as with other tools specifically designed for downloads, such as wget or curl in a command-line environment, or libraries like requests in Python with a direct file download capability. It's also important to understand that Nightmare is no longer actively maintained, and you might want to consider using more modern and maintained tools such as Puppeteer or Playwright for browser automation tasks that require handling file downloads.