package dnsdumpster

import (
	"context"
	"io/ioutil"
	"net"
	"net/http"
	"net/url"
	"regexp"
	"strings"
	"time"

	"github.com/projectdiscovery/subfinder/pkg/subscraping"
)

var re = regexp.MustCompile("<input type=\"hidden\" name=\"csrfmiddlewaretoken\" value=\"(.*)\">")

// getCSRFToken gets the CSRF Token from the page
func getCSRFToken(page string) string {
	if subs := re.FindStringSubmatch(page); len(subs) == 2 {
		return strings.TrimSpace(subs[1])
	}
	return ""
}

// postForm posts a form for a domain and returns the response
func postForm(token, domain string) (string, error) {
	dial := net.Dialer{}
	client := &http.Client{
		Transport: &http.Transport{
			DialContext:         dial.DialContext,
			TLSHandshakeTimeout: 10 * time.Second,
		},
	}
	params := url.Values{
		"csrfmiddlewaretoken": {token},
		"targetip":            {domain},
	}

	req, err := http.NewRequest("POST", "https://dnsdumpster.com/", strings.NewReader(params.Encode()))
	if err != nil {
		return "", err
	}

	// The CSRF token needs to be sent as a cookie
	cookie := &http.Cookie{
		Name:   "csrftoken",
		Domain: "dnsdumpster.com",
		Value:  token,
	}
	req.AddCookie(cookie)

	req.Header.Set("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36")
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.Header.Set("Referer", "https://dnsdumpster.com")
	req.Header.Set("X-CSRF-Token", token)

	resp, err := client.Do(req)
	if err != nil {
		return "", err
	}
	// Now, grab the entire page
	in, err := ioutil.ReadAll(resp.Body)
	resp.Body.Close()
	return string(in), err
}

// Source is the passive scraping agent
type Source struct{}

// Run function returns all subdomains found with the service
func (s *Source) Run(ctx context.Context, domain string, session *subscraping.Session) <-chan subscraping.Result {
	results := make(chan subscraping.Result)

	go func() {
		resp, err := session.NormalGetWithContext(ctx, "https://dnsdumpster.com/")
		if err != nil {
			results <- subscraping.Result{Source: s.Name(), Type: subscraping.Error, Error: err}
			session.DiscardHttpResponse(resp)
			close(results)
			return
		}

		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			results <- subscraping.Result{Source: s.Name(), Type: subscraping.Error, Error: err}
			resp.Body.Close()
			close(results)
			return
		}
		resp.Body.Close()
		csrfToken := getCSRFToken(string(body))

		data, err := postForm(csrfToken, domain)
		if err != nil {
			results <- subscraping.Result{Source: s.Name(), Type: subscraping.Error, Error: err}
			close(results)
			return
		}

		for _, subdomain := range session.Extractor.FindAllString(data, -1) {
			results <- subscraping.Result{Source: s.Name(), Type: subscraping.Subdomain, Value: subdomain}
		}
		close(results)
	}()

	return results
}

// Name returns the name of the source
func (s *Source) Name() string {
	return "dnsdumpster"
}
