Widerhall/src/main/java/de/srsoftware/widerhall/data/MailingList.java

package de.srsoftware.widerhall.data;

import de.srsoftware.widerhall.Configuration;
import de.srsoftware.widerhall.mail.ImapClient;
import de.srsoftware.widerhall.mail.MessageHandler;
import de.srsoftware.widerhall.mail.SmtpClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import java.io.UnsupportedEncodingException;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.*;
import java.util.stream.Stream;

import static de.srsoftware.widerhall.Constants.*;
import static de.srsoftware.widerhall.Util.t;
import static de.srsoftware.widerhall.data.User.PERMISSION_ADMIN;

/**
 * this class encapsulates a MailingList db object
 */
public class MailingList implements MessageHandler {
    private static final Logger LOG = LoggerFactory.getLogger(MailingList.class);
    private static final String IMAP_HOST = "imap_host";
    private static final String IMAP_PORT = "imap_port";
    private static final String IMAP_USER = "imap_user";
    private static final String IMAP_PASS = "imap_pass";
    private static final String SMTP_HOST = "smtp_host";
    private static final String SMTP_PORT = "smtp_port";
    private static final String SMTP_USER = "smtp_user";
    private static final String SMTP_PASS = "smtp_pass";
    public static final String TABLE_NAME = "Lists";
    private static final int STATE_PENDING = 0;
    private static final int STATE_ENABLED = 1;
    private static final int STATE_PUBLIC = 2;
    public static final int STATE_FORWARD_FROM = 4;
    public static final int STATE_FORWARD_ATTACHED = 8;
    private static final int VISIBLE = 1;
    private static final int HIDDEN = 0;
    private final String name;
    private final String email;
    private int state;
    private final SmtpClient smtp;
    private final ImapClient imap;

    private static final HashMap<String,MailingList> cache = new HashMap<>();

    /**
     * create a new ML object
     * @param email
     * @param name
     * @param imapHost
     * @param imapPort
     * @param imapUser
     * @param imapPass
     * @param smtpHost
     * @param smtpPort
     * @param smtpUser
     * @param smtpPass
     * @param state
     */
    public MailingList(String email, String name, String imapHost, int imapPort, String imapUser, String imapPass, String inbox, String smtpHost, int smtpPort, String smtpUser, String smtpPass, int state) {
        this.email = email;
        this.name = name;
        this.state = state;
        this.smtp = new SmtpClient(smtpHost,smtpPort,smtpUser,smtpPass);
        this.imap = new ImapClient(imapHost,imapPort,imapUser,imapPass,inbox);
    }

    /**
     * create a new ML object int the database
     * @param email
     * @param name
     * @param imapHost
     * @param imapPort
     * @param imapUser
     * @param imapPass
     * @param smtpHost
     * @param smtpPort
     * @param smtpUser
     * @param smtpPass
     * @return
     * @throws SQLException
     */
    public static MailingList create(String email, String name, String imapHost, int imapPort, String imapUser, String imapPass, String inbox, String smtpHost, int smtpPort, String smtpUser, String smtpPass) throws SQLException {
        return new MailingList(email, name, imapHost, imapPort, imapUser, imapPass, inbox, smtpHost, smtpPort, smtpUser, smtpPass, STATE_PENDING).save();
    }

    /**
     * create underlying db table
     * @throws SQLException
     */
    public static void createTable() throws SQLException {
        var sql = new StringBuilder()
                .append("CREATE TABLE ").append(TABLE_NAME)
                .append(" (")
                .append(EMAIL).append(" ").append(VARCHAR).append(" NOT NULL PRIMARY KEY, ")
                .append(NAME).append(" ").append(VARCHAR).append(", ")
                .append(IMAP_HOST).append(" ").append(VARCHAR).append(", ")
                .append(IMAP_PORT).append(" ").append(INT).append(", ")
                .append(IMAP_USER).append(" ").append(VARCHAR).append(", ")
                .append(IMAP_PASS).append(" ").append(VARCHAR).append(", ")
                .append(INBOX).append(" ").append(VARCHAR).append(", ")
                .append(SMTP_HOST).append(" ").append(VARCHAR).append(", ")
                .append(SMTP_PORT).append(" ").append(INT).append(", ")
                .append(SMTP_USER).append(" ").append(VARCHAR).append(", ")
                .append(SMTP_PASS).append(" ").append(VARCHAR).append(", ")
                .append(STATE).append(" ").append(INT)
                .append(");");
        Database.open().query(sql).compile().run();
    }

    /**
     * load the set of mailing lists a given user is allowed to edit
     * @param user
     * @return
     */
    public static Set<MailingList> editableBy(User user) {
        var list = new HashSet<MailingList>();
        for (String key : ListMember.listsOwnedBy(user)) list.add(load(key));
        return list;
    }

    public String email() {
        return email;
    }


    public void enable(boolean enable) throws SQLException {
        setFlag(STATE_ENABLED,enable);

        if (enable) {
            imap.start().addListener(this);
        } else {
            imap.stop();
        }
    }

    private void forward(Message message) throws MessagingException {
        try {
            var emails = members().stream().map(ListMember::user).map(User::email).toList();
            String sender = (state & STATE_FORWARD_FROM) > 0 ? message.getFrom()[0].toString() : email();
            smtp.bccForward(sender,message,emails);
        } catch (SQLException e) {
            LOG.error("Laden der Listen-Mitglieder von {} fehlgeschlagen. Nachricht kann nicht weitergeleitet werden!",email(),e);
        }
    }

    public void forwardAttached(boolean forward) throws SQLException {
        setFlag(STATE_FORWARD_ATTACHED,forward);
    }

    public void forwardFrom(boolean forward) throws SQLException {
        setFlag(STATE_FORWARD_FROM,forward);
    }


    /**
     * Create a mailing list object from a ResultSet.
     * This is a cached method: if the ML has been loaded before, the already-loaded object will be returned.
     *
     * @param rs
     * @return
     * @throws SQLException
     */
    private static MailingList from(ResultSet rs) throws SQLException {
        String email = rs.getString(EMAIL);
        var ml = cache.get(email);
        if (ml == null) cache.put(email,ml = new MailingList(rs.getString(EMAIL),
                rs.getString(NAME),
                rs.getString(IMAP_HOST),
                rs.getInt(IMAP_PORT),
                rs.getString(IMAP_USER),
                rs.getString(IMAP_PASS),
                rs.getString(INBOX),
                rs.getString(SMTP_HOST),
                rs.getInt(SMTP_PORT),
                rs.getString(SMTP_USER),
                rs.getString(SMTP_PASS),
                rs.getInt(STATE)));
        return ml;
    }

    public boolean hasState(int test){
        return (state & test) > 0;
    }

    public void hide(boolean hide) throws SQLException {
        setFlag(STATE_PUBLIC,!hide);
    }

    /**
     * test, whether the current ML is subscribable by a given user
     * @param user
     * @return
     */
    public boolean isOpenFor(User user) {
        if ((state & STATE_PUBLIC) > 0) return true; // all users may subscribe public mailing lists
        if (user == null) return false;
        try {
            var member = ListMember.load(this,user);
            return member.hasState(ListMember.STATE_OWNER|ListMember.STATE_SUBSCRIBER); // owners may subscribe their own mailing lists
        } catch (SQLException e) {
            LOG.warn("Konnte Listen-Mitglied nicht laden: ",e);
            return false;
        }
    }

    /**
     * Load a ML object by it's identifying email address.
     * This is a cached method: if the ML has been loaded before, the already-loaded object will be returned.
     * @param listEmail
     * @return
     */
    public static MailingList load(String listEmail) {
        if (listEmail == null) return null;
        var ml = cache.get(listEmail);
        if (ml == null) try {
            var rs = Database.open()
                    .select(TABLE_NAME)
                    .where(EMAIL,listEmail)
                    .compile().exec();
            if (rs.next()) ml = MailingList.from(rs);
        } catch (SQLException e) {
            LOG.debug("Konnte Mailing-Liste nicht laden: ",e);
        }
        return ml;
    }

    public boolean mayBeAlteredBy(User user) {
        if (user.hashPermission(PERMISSION_ADMIN)) return true;
        try {
            if (ListMember.load(this,user).hasState(ListMember.STATE_OWNER)) return true;
        } catch (SQLException e) {
            LOG.debug("Fehler beim Laden des Listenmitglieds für ({}, {})",user.email(),email());
        }
        return false;
    }

    public boolean mayBeTestedBy(User user) {
        if (user.hashPermission(PERMISSION_ADMIN)) return true;
        try {
            if (ListMember.load(this,user).hasState(ListMember.STATE_OWNER)) return true;
        } catch (SQLException e) {
            LOG.debug("Fehler beim Laden des Listenmitglieds für ({}, {})",user.email(),email());
        }
        return false;
    }

    public Set<ListMember> members() throws SQLException {
        return ListMember.of(this);
    }

    public boolean membersMayBeListedBy(User user) {
        if (user.hashPermission(PERMISSION_ADMIN)) return true;
        try {
            if (ListMember.load(this,user).hasState(ListMember.STATE_OWNER)) return true;
        } catch (SQLException e) {
            LOG.debug("Fehler beim Laden des Listenmitglieds für ({}, {})",user.email(),email());
        }
        return false;
    }


    /**
     * creates a map from the current ML object containing only email and name of the ML
     * @return
     */
    public HashMap<String, Object> minimalMap() {
        var map = new HashMap<String,Object>();
        String[] parts = email.split("@", 2);
        map.put(EMAIL,Map.of(PREFIX,parts[0],DOMAIN,parts[1]));
        map.put(NAME, name);
        map.put(STATE, stateMap());
        return map;
    }

    public String name(){
        return name;
    }

    @Override
    public void onMessageReceived(Message message) throws MessagingException {
        LOG.debug("Nachricht empfangen: {}",message.getFrom());
        storeMessage(message);
        forward(message);
    }

    /**
     * provide the set of mailing lists that are publicy open to subscriptions
     * @return
     */
    public static Set<MailingList> openLists() {
        var list = new HashSet<MailingList>();
        try {
            var rs = Database.open()
                    .select(TABLE_NAME,"*", "(" + STATE + " & " + STATE_PUBLIC + ") as test")
                    .where("test", STATE_PUBLIC)
                    .compile()
                    .exec();
            while (rs.next()) list.add(MailingList.from(rs));
            rs.close();
        } catch (SQLException e) {
            LOG.warn("Auflisten der Mailinglisten fehlgeschlagen: ", e);
        }
        return list;
    }


    /**
     * creates a map of the current ML containing all fields but passwords.
     * @return
     */
    public Map<String, Object> safeMap() {
        var map = minimalMap();
        if (imap.host() != null) map.put(IMAP_HOST, imap.host());
        if (imap.port() != 0) map.put(IMAP_PORT, imap.port());
        if (imap.username() != null) map.put(IMAP_USER, imap.username());
        if (imap.folderName() != null) map.put(INBOX,imap.folderName());
        if (smtp.host() != null) map.put(SMTP_HOST, smtp.host());
        if (smtp.port() != 0) map.put(SMTP_PORT, smtp.port());
        if (smtp.username() != null) map.put(SMTP_USER, smtp.username());
        map.put(STATE,stateMap());
        return map;
    }


    /**
     * save the current ML object to the database
     * @return
     * @throws SQLException
     */
    private MailingList save() throws SQLException {
        Database.open()
                .insertInto(TABLE_NAME)
                .set(EMAIL, email)
                .set(NAME, name)
                .set(IMAP_HOST, imap.host())
                .set(IMAP_PORT, imap.port())
                .set(IMAP_USER, imap.username())
                .set(IMAP_PASS, imap.password())
                .set(INBOX,imap.folderName())
                .set(SMTP_HOST, smtp.host())
                .set(SMTP_PORT, smtp.port())
                .set(SMTP_USER, smtp.username())
                .set(SMTP_PASS, smtp.password())
                .set(STATE, state)
                .compile()
                .run();
        return this;
    }

    /**
     * send an email to a potential subscriber asking for confirmation
     * @param user
     * @param token
     * @throws MessagingException
     * @throws UnsupportedEncodingException
     */
    private void sendConfirmationRequest(User user, String token) throws MessagingException, UnsupportedEncodingException {
        var subject = t("Bitte bestätigen Sie ihr Listen-Abonnement");
        var config = Configuration.instance();
        var url = new StringBuilder(config.baseUrl()).append("/confirm?token=").append(token);
        var text = t("Botte gehen Sie zu {} um das Abonnieren der Liste abzuschließen!",url);
        smtp.login().send(email(),name(),user.email(),subject,text);
    }

    private void setFlag(int flag, boolean on) throws SQLException {
        state = on ? state | flag : state ^ (state & flag);
        Database.open().update(TABLE_NAME).set(STATE,state).where(EMAIL, email()).compile().run();
    }

    public Map<String,Integer> stateMap(){
        var map = new HashMap<String,Integer>();
        if (hasState(STATE_ENABLED)) map.put("enabled",VISIBLE);
        if (hasState(STATE_PUBLIC)) map.put("public",VISIBLE);
        if (hasState(STATE_FORWARD_FROM)) map.put("original_from",HIDDEN);
        return map;
    }

    /**
     * Provides the set of MailingLists subscribable to visitors. Returns the same value as subscribable(null);
     * @return
     */
    public static Set<MailingList> subscribable() {
        return subscribable(null);
    }

    /**
     * Provides the set of MailingLists subscribable to a given user.
     * If the user is null, the set of openLists is returned.
     * If the user is an admin, the set of all MLs is returned.
     * Otherwise the set of MLs owned by the given user + the set of openLists is returned
     * @param user
     * @return
     */
    public static Set<MailingList> subscribable(User user) {
        try {
            if (user == null) return openLists();
            if (user.hashPermission(PERMISSION_ADMIN)) {
                var rs = Database.open().select(TABLE_NAME).compile().exec();
                var result = new HashSet<MailingList>();
                while (rs.next()) result.add(MailingList.from(rs));
                rs.close();
                return result;
            }
            var listEmails = ListMember.listsOwnedBy(user);
            var rs = Database.open().select(TABLE_NAME).where(EMAIL, listEmails).compile().exec();
            var result = openLists();
            while (rs.next()) result.add(MailingList.from(rs));
            rs.close();
            return result;
        } catch (SQLException e) {
            LOG.warn("Lesen der abbonnierbaren Mailinglisten von {} fehlgeschlagen.",user,e);
            return Set.of();
        }
    }

    /**
     * Request list subscription for the given user.
     * Usually creates a ListMember entry with AWAITING_CONFIRMATION state is created and a confirmation request email is sent.
     * However, if skipConfirmation is set to true, no email is sent and the ListMember's state is set to SUBSCRIBER immediately.
     * @param user
     * @param skipConfirmation
     * @throws SQLException
     * @throws MessagingException
     */
    public void requestSubscription(User user, boolean skipConfirmation) throws SQLException, MessagingException {
        var state = skipConfirmation ? ListMember.STATE_SUBSCRIBER : ListMember.STATE_AWAITING_CONFIRMATION;
        var member = ListMember.create(this,user,state);
        if (skipConfirmation) return;
        try {
            sendConfirmationRequest(user, member.token());
        } catch (UnsupportedEncodingException e) {
            throw new MessagingException(t("Senden der Email an {} fehlgeschlagen",user.email()),e);
        }
    }

    private void storeMessage(Message message){
        // TODO: implement
    }


    /**
     * send a test email to the provided user
     * @param user
     * @throws MessagingException
     * @throws UnsupportedEncodingException
     */
    public void test(User user) throws MessagingException, UnsupportedEncodingException {
        var subject = t("{}: Test-Mail",name());
        var text = "Wenn Sie diese Nachricht empfangen haben, sind die SMTP-Einstellungen Ihrer Mailing-Liste korrekt.";
        smtp.login().send(email(),name(),user.email(),subject,text);
    }

    public static Stream<InternetAddress> toAddress(String email) {
        try {
            return Arrays.asList(InternetAddress.parse(email)).stream();
        } catch (AddressException e) {
            LOG.debug("Parsen von {} fehlgeschlagen",email,e);
            return new ArrayList<InternetAddress>().stream();
        }
    }
}