How do I handle file downloads with headless_chrome (Rust) in Rust?

In Rust, to handle file downloads with headless_chrome, which is a high-level API to control Chrome or Chromium over the DevTools Protocol, you can set up the browser to automatically download files to a specified directory without any dialog boxes interrupting the headless browsing process.

First, make sure you have headless_chrome added to your Cargo.toml:

[dependencies]
headless_chrome = "0.10.0" # Check for the latest version on crates.io

Here's an example of how to configure Chrome to download files in headless mode:

extern crate headless_chrome;

use headless_chrome::{Browser, LaunchOptionsBuilder};
use std::fs;
use std::path::PathBuf;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Specify the download path
    let download_path = PathBuf::from("path/to/downloads");

    // Ensure the download directory exists
    fs::create_dir_all(&download_path)?;

    // Set up the browser options with the custom download path
    let browser = Browser::new(
        LaunchOptionsBuilder::default()
            .headless(true)
            .window_size(Some((800, 600)))
            .user_data_dir(download_path.clone())
            .build()
            .expect("Failed to launch browser"),
    )?;

    // Navigate to the page with the file you want to download
    let tab = browser.wait_for_initial_tab()?;
    tab.navigate_to("https://example.com/page_with_download")?;

    // Wait for the page to load
    tab.wait_until_navigated()?;

    // Here you would find the download link and click it, which would trigger the download
    // For example, to click the first link with the download attribute:
    // tab.wait_for_element("a[download]")?.click()?;

    // You may need to wait for the file to finish downloading before exiting
    // Implement a custom logic to wait for the download to complete

    // Clean up the browser process
    drop(browser);

    Ok(())
}

Please note that headless_chrome crate may not have full support for all Chrome capabilities. The example above sets up a download directory and configures the browser to run in headless mode. The actual clicking of the download link and waiting for the download to finish may require additional implementation based on how the website triggers the download.

Keep in mind that headless_chrome by itself doesn't provide all the necessary features for file download management (like tracking the download progress). You may need to implement custom logic to check if the file has appeared in the download directory and whether it's complete.

If you find that headless_chrome is lacking in functionality, you might want to look into using the lower-level fantoccini crate or binding directly to the DevTools Protocol yourself for more control over the browser's behavior during downloads.