package recon

import (
	"bytes"
	"io"
	"strings"

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

var urlFieldHints = []string{
	"url", "link", "preview", "webhook", "fetch", "import", "oembed", "image",
}

var cmsPathMarkers = []struct {
	path string
	tag  string
}{
	{"/wp-admin", "wordpress"},
	{"/wp-content", "wordpress"},
	{"/strapi", "strapi"},
	{"/graphql", "graphql"},
	{"/admin/login", "admin_login"},
}

// ParseHTML extracts upload forms, URL fields, SSRF score, and CMS hints from HTML.
func ParseHTML(pageURL, body string) (fileInputs, multipart []FormFinding, urlFields []URLFieldFinding, ssrfScore int, cms []string) {
	root, err := html.Parse(strings.NewReader(body))
	if err != nil {
		return nil, nil, nil, 0, cmsFromText(pageURL, body)
	}
	title := extractTitle(root)
	_ = title

	var walk func(*html.Node)
	walk = func(n *html.Node) {
		if n.Type == html.ElementNode && n.Data == "form" {
			form := parseForm(pageURL, n)
			if form.HasFile {
				fileInputs = append(fileInputs, form)
			}
			if form.Multipart {
				multipart = append(multipart, form)
			}
			ssrfScore += scoreForm(form)
		}
		if n.Type == html.ElementNode && n.Data == "input" {
			if field := parseURLField(pageURL, n); field != nil {
				urlFields = append(urlFields, *field)
				ssrfScore += 10
			}
		}
		if n.Type == html.ElementNode && (n.Data == "textarea" || n.Data == "select") {
			if field := parseURLFieldFromNamed(pageURL, attr(n, "name"), attr(n, "id"), attr(n, "placeholder")); field != nil {
				urlFields = append(urlFields, *field)
				ssrfScore += 8
			}
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			walk(c)
		}
	}
	walk(root)

	cms = cmsFromText(pageURL, body)
	if ssrfScore > 100 {
		ssrfScore = 100
	}
	return fileInputs, multipart, urlFields, ssrfScore, cms
}

func parseForm(pageURL string, form *html.Node) FormFinding {
	f := FormFinding{
		PageURL: pageURL,
		Action:  attr(form, "action"),
		Method:  strings.ToLower(attr(form, "method")),
		Enctype: strings.ToLower(attr(form, "enctype")),
	}
	if f.Method == "" {
		f.Method = "get"
	}
	if strings.Contains(f.Enctype, "multipart") {
		f.Multipart = true
	}
	for c := form.FirstChild; c != nil; c = c.NextSibling {
		collectFormFields(c, &f)
	}
	return f
}

func collectFormFields(n *html.Node, f *FormFinding) {
	if n.Type == html.ElementNode {
		switch n.Data {
		case "input", "textarea", "select":
			name := attr(n, "name")
			if name != "" {
				f.Fields = append(f.Fields, name)
			}
			if n.Data == "input" && strings.EqualFold(attr(n, "type"), "file") {
				f.HasFile = true
				f.Multipart = true
			}
			if field := parseURLField(f.PageURL, n); field != nil {
				f.Fields = append(f.Fields, field.Name+"("+field.Hint+")")
			}
		}
	}
	for c := n.FirstChild; c != nil; c = c.NextSibling {
		collectFormFields(c, f)
	}
}

func parseURLField(pageURL string, n *html.Node) *URLFieldFinding {
	name := attr(n, "name")
	id := attr(n, "id")
	placeholder := attr(n, "placeholder")
	return parseURLFieldFromNamed(pageURL, name, id, placeholder)
}

func parseURLFieldFromNamed(pageURL, name, id, placeholder string) *URLFieldFinding {
	joined := strings.ToLower(strings.Join([]string{name, id, placeholder}, " "))
	for _, hint := range urlFieldHints {
		if strings.Contains(joined, hint) {
			label := name
			if label == "" {
				label = id
			}
			return &URLFieldFinding{
				PageURL: pageURL,
				Name:    label,
				ID:      id,
				Type:    "text",
				Hint:    hint,
			}
		}
	}
	return nil
}

func scoreForm(f FormFinding) int {
	score := 0
	action := strings.ToLower(f.Action)
	for _, hint := range urlFieldHints {
		if strings.Contains(action, hint) {
			score += 15
		}
	}
	for _, field := range f.Fields {
		lower := strings.ToLower(field)
		for _, hint := range urlFieldHints {
			if strings.Contains(lower, hint) {
				score += 5
			}
		}
	}
	if f.HasFile {
		score += 5
	}
	return score
}

func cmsFromText(pageURL, body string) []string {
	seen := map[string]bool{}
	var out []string
	lowerURL := strings.ToLower(pageURL)
	lowerBody := strings.ToLower(body)
	add := func(tag string) {
		if tag == "" || seen[tag] {
			return
		}
		seen[tag] = true
		out = append(out, tag)
	}
	for _, marker := range cmsPathMarkers {
		if strings.Contains(lowerURL, marker.path) || strings.Contains(lowerBody, marker.path) {
			add(marker.tag)
		}
	}
	if strings.Contains(lowerBody, "strapi") {
		add("strapi")
	}
	if strings.Contains(lowerBody, "wp-content") || strings.Contains(lowerBody, "wordpress") {
		add("wordpress")
	}
	return out
}

func extractTitle(root *html.Node) string {
	var title string
	var walk func(*html.Node)
	walk = func(n *html.Node) {
		if n.Type == html.ElementNode && n.Data == "title" && n.FirstChild != nil {
			title = strings.TrimSpace(n.FirstChild.Data)
			return
		}
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			walk(c)
		}
	}
	walk(root)
	return title
}

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

func readBodyLimited(r io.Reader, max int64) (string, error) {
	buf := new(bytes.Buffer)
	_, err := io.Copy(buf, io.LimitReader(r, max))
	if err != nil {
		return "", err
	}
	return buf.String(), nil
}