import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import java.util.stream.IntStream;

import javax.net.ssl.HttpsURLConnection;

public class Crawler {

    private static final String USER_AGENT = "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36";

    private final String user;
    private final String password;
    private final TipoLogin tipo;

    public static enum TipoLogin {
        CONTRIBUINTE_ICMS("rdBtnContribuinte"),
        CONSUMIDOR("rdBtnNaoContribuinte"),
        CONTABILISTA("rdBtnContabilista"),
        FAZENDARIO("rdBtnFazendario"),
        PROCON("rdBtnProcon"),
        REPRESENTANTE_CONTRIBUINTE("rdBtnAdvogadoRepresentante");

        private final String radio;

        private TipoLogin(String radio) {
            this.radio = radio;
        }

        public String getRadio() {
            return radio;
        }
    }

    public static void main(String[] args) throws IOException {
        Crawler http = new Crawler("12345678901", "$enh4", TipoLogin.CONTRIBUINTE_ICMS);
        http.sendPost();
    }

    public Crawler(String user, String password, TipoLogin tipo) {
        this.user = user;
        this.password = password;
        this.tipo = tipo;
    }

    // HTTP POST request
    private void sendPost() throws IOException {
        URL url;
        try {
            url = new URL("https://www.nfp.fazenda.sp.gov.br/login.aspx");
        } catch (MalformedURLException e) {
            throw new AssertionError(e);
        }

        HttpsURLConnection get = (HttpsURLConnection) url.openConnection();
        get.setRequestProperty("User-Agent", USER_AGENT);
        get.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
        get.getResponseCode();
        String page = download(get.getInputStream());

        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();

        try {
            con.setRequestMethod("POST");
        } catch (ProtocolException e) {
            throw new AssertionError(e);
        }
        con.setRequestProperty("User-Agent", USER_AGENT);
        con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

        String urlParameters = "__EVENTTARGET=" + buscarCampo(page, "__EVENTTARGET")
                + "&__EVENTARGUMENT=" + buscarCampo(page, "__EVENTARGUMENT")
                + "&__VIEWSTATE=" + buscarCampo(page, "__VIEWSTATE")
                + "&__EVENTVALIDATION=" + buscarCampo(page, "__EVENTVALIDATION")
                + "&ctl00$ddlTipoUsuario=#rdBtnNaoContribuinte"
                + "&ctl00$UserNameAcessivel="
                + "&ctl00$PasswordAcessivel="
                + "&ctl00$ConteudoPagina$Login1$rblTipo=" + tipo.getRadio()
                + "&ctl00$ConteudoPagina$Login1$UserName=" + escapeURI(user)
                + "&ctl00$ConteudoPagina$Login1$Password=" + escapeURI(password);

        System.out.println("Parâmetros parameters : " + urlParameters);

        // Send post request
        con.setDoOutput(true);
        try (DataOutputStream wr = new DataOutputStream(con.getOutputStream())) {
            wr.writeBytes(urlParameters);
            wr.flush();
        }

        int responseCode = con.getResponseCode();
        System.out.println("Enviando 'POST' request para a URL : " + url);
        System.out.println("Response Code: " + responseCode);

        String response = download(con.getInputStream());

        //print result
        System.out.println(response);
    }

    private static String download(InputStream is) throws IOException {
        StringBuilder response = new StringBuilder(1024);
        try (BufferedReader in = new BufferedReader(new InputStreamReader(is))) {
            String inputLine;

            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
        }
        return response.toString();
    }

    private static String buscarCampo(String html, String campo) {
        String input = "<input type="hidden" name="" + campo + "" id="" + campo + "" value="";
        int a = html.indexOf(input);
        if (a == -1) return "";
        int b = html.indexOf('"', a + input.length());
        return html.substring(a + input.length(), b);
    }

    private static final String[] HEX = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"};

    private static String escapeURI(byte c) {
        boolean ok = (c >= 'A' && c <= 'Z')
                || (c >= 'a' && c <= 'z')
                || (c >= '0' && c <= '9')
                || c == '-' || c == '.' || c == '_' || c == '~'
                || c == '$' || c == '#';
        return ok ? String.valueOf((char) c) : "%" + HEX[c >>> 4] + HEX[c & 0xF];
    }

    public static String escapeURI(String in) {
        StringBuilder sb = new StringBuilder(in.length() * 2);
        try {
            byte[] bytes = in.getBytes("UTF-8");
            IntStream.range(0, bytes.length).mapToObj(i -> escapeURI(bytes[i])).forEach(sb::append);
        } catch (UnsupportedEncodingException e) {
            throw new AssertionError(e);
        }
        return sb.toString();
    }
}