Widerhall/src/main/java/de/srsoftware/widerhall/Util.java

package de.srsoftware.widerhall;

import de.srsoftware.tools.translations.Translation;
import de.srsoftware.widerhall.data.MailingList;
import de.srsoftware.widerhall.data.User;

import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.Part;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Map;
import java.util.Random;
import java.util.stream.Collectors;

import static de.srsoftware.widerhall.Constants.*;

public class Util {

    private static final MessageDigest SHA256 = getSha256();
    private static final String EMAIL_PATTERN = "^[a-zA-Z0-9_!#$%&'*+/=?`{|}~^-]+(?:\\.[a-zA-Z0-9_!#$%&'*+/=?`{|}~^-]+)*@[a-zA-Z0-9-]+(?:\\.[a-zA-Z0-9-]+)*$";

    public static char boundedChar(int i) {
        i = (i<0 ? -i : i) % 62;
        i += '0';
        if (i>57) i+=7;
        if (i>90) i+=6;
        return (char) i;
    }

    public static String dropEmail(String tx) {
        return tx.replaceAll( "[.\\-\\w]+@[.\\-\\w]+", "[email_removed]");
    }

    private static String encode(Object value) {
        return URLEncoder.encode(value.toString(), StandardCharsets.UTF_8);
    }

    public static boolean getCheckbox(HttpServletRequest req, String key) {
        return "on".equals(req.getParameter(key));
    }

    public static MailingList getMailingList(HttpServletRequest req) {
        var listEmail = req.getParameter(LIST);
        if (listEmail == null || listEmail.isBlank()) return null;
        return MailingList.load(listEmail);
    }

    public static <T> T getNullable(ResultSet rs, String colName) throws SQLException {
        final T val = (T) rs.getObject(colName);
        return rs.wasNull() ? null : val;
    }
    public static String getPath(HttpServletRequest req) {
        var path = req.getPathInfo();
        return path == null ? INDEX : path.substring(1);

    }
    public static MessageDigest getSha256() {
        try {
            return MessageDigest.getInstance("SHA-256");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * Return the primary text content of the message.
     */
    public static String getText(Part p) throws MessagingException, IOException {
        // https://javaee.github.io/javamail/FAQ
        if (p.isMimeType("text/*")) return (String)p.getContent();

        if (p.isMimeType("multipart/alternative")) {
            // prefer html text over plain text
            Multipart mp = (Multipart)p.getContent();
            String text = null;
            for (int i = 0; i < mp.getCount(); i++) {
                Part bp = mp.getBodyPart(i);
                if (bp.isMimeType("text/plain")) {
                    if (text == null) text = getText(bp);
                    continue;
                } else if (bp.isMimeType("text/html")) {
                    String s = getText(bp);
                    if (s != null) return s;
                } else {
                    return getText(bp);
                }
            }
            return text;
        } else if (p.isMimeType("multipart/*")) {
            Multipart mp = (Multipart)p.getContent();
            for (int i = 0; i < mp.getCount(); i++) {
                String s = getText(mp.getBodyPart(i));
                if (s != null) return s;
            }
        }
        return null;
    }

    public static User getUser(HttpServletRequest req) {
        var o = req.getSession().getAttribute(USER);
        return o instanceof User ? (User) o : null;
    }

    private static String hex(byte[] bytes) {
        StringBuffer buf = new StringBuffer(bytes.length*2);
        for (var byt : bytes) buf.append(hex(byt));
        return buf.toString();
    }

    public static String hex(int b){
        int lower = b & 0x0F;
        int upper = (b & 0xF0) >> 4;
        return (char)(upper < 10 ? '0'+upper : 'A'+upper-10)+""+(char)(lower < 10 ? '0'+lower : 'A'+lower-10);
    }

    public static boolean isEmail(String email) {
        return email.matches(EMAIL_PATTERN);
    }

    public static String randomString(int length) {
        Random rand = new Random();
        StringBuilder sb = new StringBuilder();
        for (int i=0; i<length; i++) {
            int k = rand.nextInt();
            char c = boundedChar(k);
            System.out.println("adding '"+c+"'…");
            sb.append(c);
        }
        return sb.toString();
    }

    public static String sha256(String s) {
        byte[] bytes = SHA256.digest(s.getBytes(StandardCharsets.UTF_8));
        return hex(bytes);
    }

    public static boolean simplePassword(String pass) {
        if (pass.length() < 6) return true;
        if (pass.length() < 8){
            for (int i=0; i<pass.length();i++){
                if (!Character.isLetterOrDigit(pass.charAt(i))) return false; // password contains special character
            }
            return true;
        }
        if (pass.length() < 10){
            var digit = false;
            var letter = false;
            for (int i=0; i<pass.length();i++){
                char c = pass.charAt(i);
                if (!Character.isLetterOrDigit(c)) return false; // password contains special character
                digit |= Character.isDigit(c);
                letter |= Character.isLetter(c);
                if (letter && digit) return false; // password contains letters and digits
            }
            return true;
        }
        return false;
    }

    public static String t(String tx, Object ... fills){
        return Translation.get(Application.class,tx,fills);
    }

    public static String urlEncode(Map<String, Object> data) {
        String params = data.entrySet()
                .stream()
                .map(entry -> encode(entry.getKey()) + "=" + encode(entry.getValue()))
                .collect(Collectors.joining("&"));
        return params;
    }


    public static int unset(int value, int...flags) {
        for (int flag : flags){
            if ((value & flag) > 0) value ^= flag;
        }
        return value;
    }
}