package recon

import (
	"sort"
	"strings"

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

var formFingerprintKeywords = []struct {
	keyword string
	weight  int
}{
	{"url", 12}, {"src", 10}, {"href", 10}, {"callback", 14}, {"redirect", 13},
	{"avatar", 8}, {"import", 11}, {"feed", 9}, {"screenshot", 12}, {"pdf", 10}, {"proxy", 11},
}

func ScoreFormFieldFingerprint(name, id, placeholder string) (score int, matches []string) {
	joined := strings.ToLower(strings.Join([]string{name, id, placeholder}, " "))
	seen := map[string]bool{}
	for _, kw := range formFingerprintKeywords {
		if strings.Contains(joined, kw.keyword) {
			score += kw.weight
			if !seen[kw.keyword] {
				seen[kw.keyword] = true
				matches = append(matches, kw.keyword)
			}
		}
	}
	return score, matches
}

func ExtractFormFieldFingerprints(pageURL, body string) []FormFieldFingerprint {
	root, err := html.Parse(strings.NewReader(body))
	if err != nil {
		return nil
	}
	var out []FormFieldFingerprint
	var walk func(*html.Node)
	walk = func(n *html.Node) {
		if n.Type == html.ElementNode && (n.Data == "input" || n.Data == "textarea" || n.Data == "select") {
			name := fingerprintAttr(n, "name")
			id := fingerprintAttr(n, "id")
			placeholder := fingerprintAttr(n, "placeholder")
			score, matches := ScoreFormFieldFingerprint(name, id, placeholder)
			if score > 0 {
				out = append(out, FormFieldFingerprint{
					PageURL: pageURL, Name: name, ID: id, Placeholder: placeholder,
					Score: score, Matches: matches,
				})
			}
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			walk(c)
		}
	}
	walk(root)
	sort.Slice(out, func(i, j int) bool {
		if out[i].Score != out[j].Score {
			return out[i].Score > out[j].Score
		}
		if out[i].Name != out[j].Name {
			return out[i].Name < out[j].Name
		}
		return out[i].ID < out[j].ID
	})
	return out
}

func fingerprintAttr(n *html.Node, key string) string {
	for _, a := range n.Attr {
		if a.Key == key {
			return a.Val
		}
	}
	return ""
}

func TopFormFieldFingerprint(fields []FormFieldFingerprint) *FormFieldFingerprint {
	if len(fields) == 0 {
		return nil
	}
	top := fields[0]
	return &top
}

func ApplyCanaryPasteTarget(fields []FormFieldFingerprint, canaryURL string) {
	for i := range fields {
		fields[i].PasteTarget = canaryURL
	}
}

func AppendPageFingerprints(report *CrawlReport, pageURL, body string) {
	if report == nil {
		return
	}
	fps := ExtractFormFieldFingerprints(pageURL, body)
	report.FingerprintFields = append(report.FingerprintFields, fps...)
	for _, fp := range fps {
		if fp.Score >= 10 {
			report.SSRFScore += fp.Score / 5
		}
	}
}