feat: Implement basic link checker in Go with URL parsing and link validation

linkchecker.go

@@ -0,0 +1,98 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"golang.org/x/net/html"
+)
+
+type LinkChecker struct {
+	client *http.Client
+}
+
+func NewLinkChecker() *LinkChecker {
+	return &LinkChecker{
+		client: &http.Client{},
+	}
+}
+
+func (lc *LinkChecker) CheckLinks(baseURL string) ([]string, error) {
+	// Get all links from the page
+	links, err := lc.getLinks(baseURL)
+	if err != nil {
+		return nil, fmt.Errorf("error getting links: %w", err)
+	}
+
+	var brokenLinks []string
+
+	// Check each link
+	for _, link := range links {
+		if !lc.isLinkValid(link) {
+			brokenLinks = append(brokenLinks, link)
+		}
+	}
+
+	return brokenLinks, nil
+}
+
+func (lc *LinkChecker) getLinks(pageURL string) ([]string, error) {
+	resp, err := lc.client.Get(pageURL)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("failed to fetch page: %s", resp.Status)
+	}
+
+	doc, err := html.Parse(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var links []string
+	baseURL, err := url.Parse(pageURL)
+	if err != nil {
+		return nil, err
+	}
+
+	var traverse func(*html.Node)
+	traverse = func(n *html.Node) {
+		if n.Type == html.ElementNode && n.Data == "a" {
+			for _, attr := range n.Attr {
+				if attr.Key == "href" {
+					link := attr.Val
+					if !strings.HasPrefix(link, "http") {
+						// Convert relative URLs to absolute
+						if absURL, err := baseURL.Parse(link); err == nil {
+							link = absURL.String()
+						}
+					}
+					if strings.HasPrefix(link, "http") {
+						links = append(links, link)
+					}
+				}
+			}
+		}
+		for c := n.FirstChild; c != nil; c = c.NextSibling {
+			traverse(c)
+		}
+	}
+	traverse(doc)
+
+	return links, nil
+}
+
+func (lc *LinkChecker) isLinkValid(link string) bool {
+	resp, err := lc.client.Get(link)
+	if err != nil {
+		return false
+	}
+	defer resp.Body.Close()
+
+	return resp.StatusCode >= 200 && resp.StatusCode < 400
+}

main.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+)
+
+func main() {
+	url := flag.String("url", "", "URL to check for broken links")
+	flag.Parse()
+
+	if *url == "" {
+		log.Fatal("Please provide a URL using the -url flag")
+	}
+
+	checker := NewLinkChecker()
+	brokenLinks, err := checker.CheckLinks(*url)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if len(brokenLinks) == 0 {
+		fmt.Println("No broken links found!")
+		return
+	}
+
+	fmt.Println("Found broken links:")
+	for _, link := range brokenLinks {
+		fmt.Printf("- %s\n", link)
+	}
+}