Can I use Pholcus with a headless browser?

Pholcus is a distributed, high-concurrency, and powerful web crawler software written in Go. It is primarily used for batch crawling of data from various web pages, but it doesn't inherently support headless browsers out of the box because it is designed to fetch web content through HTTP requests directly.

Using a headless browser involves automating a browser instance that doesn't have a graphical user interface. This is particularly useful for scraping JavaScript-heavy websites where the content is dynamically loaded. Popular headless browsers include Headless Chrome and Headless Firefox, which can be controlled using libraries such as Puppeteer for Node.js or Selenium for various programming languages.

If you need to scrape a website that requires a headless browser with Pholcus, you would need to integrate it with a headless browser solution manually. This typically involves using an external library or tool that can run a headless browser, execute JavaScript, and then provide the final HTML content to Pholcus for scraping.

For example, you might use a tool like Chrome DevTools Protocol (CDP) to control a headless Chrome instance in Go. Here's a conceptual example of how you might integrate a headless Chrome instance with Pholcus to scrape a dynamic website:

package main

import (
    "context"
    "log"
    "time"

    "github.com/chromedp/chromedp"
    "github.com/henrylee2cn/pholcus/exec"
    // other necessary pholcus imports
)

func main() {
    // Initialize pholcus
    exec.DefaultRun("web")

    // Task to scrape a dynamic page
    spider := &pholcus.Spider{
        //... configure your spider
    }

    spider.OnStart(func(ctx *Context) {
        // Use chromedp to control headless Chrome
        cdpContext, cancel := chromedp.NewContext(context.Background())
        defer cancel()

        // Capture the final HTML after JavaScript execution
        var htmlContent string
        err := chromedp.Run(cdpContext,
            chromedp.Navigate(ctx.Request.Url),
            // Wait for a specific element to ensure the page has loaded
            chromedp.WaitVisible(`#someElement`, chromedp.ByID),
            chromedp.OuterHTML(`html`, &htmlContent),
        )
        if err != nil {
            log.Fatal(err)
        }

        // Use the final HTML content for Pholcus to scrape
        ctx.SetResponse(&ctx.Response{
            // ...set the response attributes
            Body: []byte(htmlContent),
        })
    })

    // Add the spider to Pholcus and start scraping
    exec.AddSpider(spider)
    exec.Run()
}

The example above is highly conceptual and requires further elaboration based on the actual requirements of the scraping task. The chromedp package is used to navigate to the page, wait for it to load, and then get the outer HTML of the page after JavaScript execution. This HTML is then provided to Pholcus for further processing and scraping.

To actually use Pholcus with a headless browser, you would need to write more detailed and specific code to handle the interaction between the headless browser and Pholcus. You would also need to manage the lifecycle of the browser instances, handle errors, and possibly integrate proxy support, among other considerations.