package findlinks

import (
	"fmt"
	"io"
	"strings"

	"golang.org/x/net/html"
	"golang.org/x/net/html/atom"
)

// A Link encapsulates the data harvested from a link.
type Link struct {
	Href string
	Text string
}

// findLinks consumes the given [io.Reader], scraping it of anchor
// tags. Each anchor tag is "unmarshalled" into a [Link]. The
// resulting slice of Links is returned, along with an error.
func FindLinks(r io.Reader) ([]Link, error) {
	doc, err := html.Parse(r)
	if err != nil {
		return nil, fmt.Errorf("can't parse html reader: %w", err)
	}

	var links []Link

	for n := range doc.Descendants() {
		trimmedData := strings.TrimSpace(n.Data)

		if n.Type == html.TextNode && trimmedData != "" {
			fmt.Printf("Data: %s\n", trimmedData)
			for anc := range n.Ancestors() {
				fmt.Printf("\tAncestor: %v\n", anc.Data)
			}
			continue
		}

		if n.Type == html.ElementNode && n.DataAtom == atom.A {
			var link Link

			// Scan the href.
			for _, a := range n.Attr {
				if a.Key == "href" {
					link.Href = a.Val
				}
			}

			// FIXME: for now, only scan for hrefs.
			links = append(links, link)
		}
	}

	return links, nil
}