form.go

package lib

import (
	"net/url"

	"github.com/PuerkitoBio/goquery"
)

type Form struct {
	Name   string
	Fields []string
	Files  []string
}

func documentsToForms(documents ...*goquery.Document) ([]*Form, error) {
	forms := make([]*Form, 0)
	for _, doc := range documents {
		var err error

		doc.Find(
			"form",
		).EachWithBreak(func(_ int, sel *goquery.Selection) bool {

			// e.g. action='https://www.example.com/contact'
			action, ok := sel.Attr("action")
			if !ok {
				// TODO: provide more context in error message
				err = e("No 'action' attribute available for %v", sel)
				return false
			}

			var u *url.URL
			u, err = url.Parse(action)
			if err != nil {
				return false
			}

			if len(u.Path) < 2 || u.Path[0] != '/' {
				err = e("'action' URL is not in the form '/foo'")
				return false
			}

			f := &Form{
				Name:   u.Path[1:], // e.g. string("/contact")[1:] => "contact"
				Fields: []string{},
				Files:  []string{},
			}

			// All of these are submittable according to
			//     https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Content_categories#Form_submittable
			sel.Find(
				"button, input, keygen, object, select, textarea",
			).Each(func(_ int, submittable *goquery.Selection) {
				name, ok := submittable.Attr("name")
				if !ok { // skip elements without names
					return
				}

				if submittable.Is("input[type='file']") {
					f.Files = append(f.Files, name)
				} else {
					f.Fields = append(f.Fields, name)
				}
			})

			forms = append(forms, f)
			return true
		})

		if err != nil {
			return nil, err
		}
	}

	return forms, nil
}